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Making ice cream for Goldilocks!

Ice cream or gelato should not be too hard or too soft at the serving-temperature.   Hardness is largely dependent on the concentration of frozen water at the serving-temperature which is influenced by the concentration of lactose, sucrose, glucose, other sugars and milk salts in the mix. This article explains the significance of sugar concentration on the freezing point depression (FPD) of ice cream. The effect of individual sweeteners on FPD is discussed. The use of relative freezing point depression (RFPD), which does not include lactose, to control hardness in commercial ice cream production is outlined. A similar method widely used in continental Europe that includes lactose in the calculation, the Potere Anti Congelante (PAC) method, is discussed using worked examples. Examples of how to reformulate ice cream mixes to obtain a controlled hardness whilst maintaining a similar relative sweetness value are also provided.

Resumen

El helado o helado no debe ser demasiado duro o demasiado blando en la porción temperatura. La dureza es en gran parte dependiente de la concentración de agua congelada en la porción-temperatura que está influenciada por la concentración de lactosa, sacarosa, glucosa, otros azúcares y sales de la leche en la mezcla. En este artículo se explica la importancia de la concentración de azúcar en la depresión del punto de congelación (FPD) de helado. Se discute el efecto de los edulcorantes individuales de FPD. Se describe el uso de la depresión relativa del punto de congelación (RFPD), que no incluye la lactosa, para controlar la dureza en la producción comercial de helados. Un método similar se utiliza ampliamente en Europa continental que incluye lactosa en el cálculo, el anti congelante Potere (PAC) método, se discute el uso de ejemplos prácticos. Ejemplos de cómo reformular el helado se mezcla para obtener una dureza controlada, manteniendo un valor dulzura relativa similar también se proporcionan.

Zusammenfassung

Eis oder Eis sollte nicht zu hart oder zu weich an der Portion-Temperatur. Die Härte ist weitgehend abhängig von der Konzentration des gefrorenen Wassers an der Serving-Temperatur, die durch die Konzentration von Lactose, Saccharose, Glucose, Zucker und Milch anderen Salzen in der Mischung beeinflusst wird. Dieser Artikel erklärt die Bedeutung der Zuckerkonzentration auf der Gefrierpunktserniedrigung (FPD) von Speiseeis. Die Wirkung der einzelnen Süßstoffe auf FPD wird diskutiert. Die Verwendung von relativ Gefrierpunktserniedrigung (RFPD), die keine Lactose, um die Härte in der kommerziellen Herstellung von Eiscreme steuern skizziert. Ein ähnliches Verfahren weit verbreitet in Kontinentaleuropa verwendet die Laktose in der Berechnung berücksichtigt, wird die Anti Potere Congelante (PAC)-Methode, diskutiert mit Beispielen gearbeitet. Beispiele, wie man Eis formulieren mischt, um eine kontrollierte Härte bei gleichzeitiger Wahrung eines ähnlichen relativen Süße Wert sind ebenfalls vorhanden zu erhalten.

Sommario

Gelato o gelato non dovrebbe essere troppo duro o troppo morbido al servizio-temperatura. Durezza dipende in larga misura la concentrazione di acqua congelata al serving temperatura che è influenzata dalla concentrazione di lattosio, saccarosio, glucosio, altri zuccheri e sali latte nella miscela. Questo articolo spiega il significato della concentrazione zuccherina sulla depressione del punto di congelamento (FPD) di gelato. È discussa l'effetto dei singoli dolcificanti sul FPD. L'uso di relativa depressione del punto di congelamento (RFPD), che non include il lattosio, per controllare la durezza di ghiaccio commerciale produzione crema è delineato. Un metodo simile ampiamente utilizzato in Europa continentale che comprende lattosio nel calcolo, il metodo Potere Anti Congelante (PAC), è discusso con esempi pratici. Esempi di come riformulare il gelato mix per ottenere una durezza controllata mantenendo un simile valore di dolcezza relativa sono anche previste.

Résumé

La crème glacée ou de glace ne doivent pas être trop dur ou trop mou à la portion température. La dureté est largement dépendante de la concentration de l'eau congelée à la portion de température qui est influencé par la concentration de lactose, de saccharose, de glucose, d'autres sucres et des sels de lait dans le mélange. Cet article explique l'importance de la concentration de sucre sur l'abaissement du point de congélation (FPD) de crème glacée. L'effet des édulcorants individuels sur FPD est discutée. L'utilisation de l'abaissement du point de congélation par rapport (RFPD), qui ne comprend pas le lactose, pour contrôler la dureté de la production de la crème glacée du commerce est décrit. Une méthode similaire largement utilisé en Europe continentale qui inclut lactose dans le calcul, la méthode Potere Anti congelante (PAC), est examinée en utilisant des exemples pratiques. Des exemples de la façon de reformuler mélanges à crème glacée pour obtenir une dureté contrôlée, tout en conservant une valeur de douceur relative similaire sont également fournis.

الآيس كريم أو الجيلاتي لا ينبغي أن يكون من الصعب جدا أو لينة جدا في درجة الحرارة خدمة. صلابة يعتمد إلى حد كبير على تركيز المياه المجمدة في درجة الحرارة التي تخدم يتأثر تركيز اللاكتوز، السكروز، الجلوكوز والسكريات الأخرى وأملاح الحليب في هذا المزيج. وهذا المقال يوضح أهمية تركيز السكر على الاكتئاب نقطة التجمد (حماية الأسرة) من الآيس كريم. وتناقش تأثير المحليات الفردية على حماية الأسرة. ويرد استخدام النسبية تجميد الاكتئاب نقطة (RFPD)، والتي لا تشمل اللاكتوز، للسيطرة على صلابة في إنتاج الآيس كريم التجارية. وهناك طريقة مشابهة تستخدم على نطاق واسع في أوروبا القارية التي تضم اللاكتوز في الحساب، وPotere مكافحة Congelante (PAC) الأسلوب، وتناقش باستخدام أمثلة عملت. أمثلة على كيفية إعادة صياغة الآيس كريم يمزج للحصول على صلابة تسيطر عليها مع الحفاظ على القيمة النسبية حلاوة مماثلة كما تقدم.

Opsomming

Roomys of gelato moet nie te hard of te sag op die bediening-temperatuur. Hardheid is grootliks afhanklik van die konsentrasie van bevrore water op die bediening-temperatuur wat deur die konsentrasie van laktose, sukrose, glukose, ander suikers en melk sout in die mengsel beïnvloed word. Hierdie artikel verduidelik die betekenis van suiker konsentrasie op die vriespuntverlaging (FPD) van roomys. Die effek van individuele versoeters op FPD bespreek word. Die gebruik van relatiewe vriespuntverlaging (RFPD), wat nie laktose sluit, hardheid te beheer in kommersiële roomys produksie word geskets. 'N Soortgelyke metode wyd gebruik word in die vasteland van Europa wat insluit laktose in die berekening, is die Potere Anti Congelante (PAC) metode, bespreek die gebruik van uitgewerkte voorbeelde. Voorbeelde van hoe om roomys te herformuleer meng 'n beheerde hardheid te verkry, terwyl die handhawing van 'n soortgelyke relatiewe soet waarde word ook voorsien.

 Overzicht

Ijs of gelato moet niet te hard of te zacht zijn op de portie-temperatuur. Hardheid is grotendeels afhankelijk van de concentratie van bevroren water in de portie-temperatuur die wordt beïnvloed door de concentratie van lactose, sucrose, glucose, andere suikers en melkzouten in de mix. Dit artikel legt de betekenis van de concentratie suiker op de vriespuntdaling (FPD) van ijs. Het effect van afzonderlijke zoetstoffen op FPD wordt besproken. Het gebruik van relatieve vriespuntdaling (RFPD), die geen lactose, hardheid beheersen commerciële productie van ijs wordt geschetst. Een soortgelijke methode op grote schaal gebruikt in continentaal Europa, dat lactose in de berekening opgenomen, de Potere Anti Congelante (PAC)-methode, wordt besproken met behulp van uitgewerkte voorbeelden. Voorbeelden van hoe je ijs herformuleren mixen om een gecontroleerde hardheid te verkrijgen met behoud van een vergelijkbare relatieve zoetheid waarde zijn ook aanwezig.

 

תקציר

גלידה או גלידה לא אמורה להיות קשה מדי או רכה מדי בהגשה בטמפרטורה. קשיות היא תלויה במידה רבה את הריכוז של מים קפואים בהגשה בטמפרטורה שמושפעת מהריכוז של לקטוז, סוכרוז, גלוקוז, סוכרים ומלחים אחרים חלב בתערובת. מאמר זה מסביר את חשיבותו של ריכוז סוכר בדיכאון נקודת הקיפאון (FPD) של גלידה.ההשפעה של ממתיקים בודדים על FPD נדונה.השימוש בדיכאון יחסי הקפאת נקודה (RFPD), שאינו כולל לקטוז, כדי לשלוט בקשיות קרם ייצור קרח המסחרי הוא התווה.שיטה דומה בשימוש נרחב ביבשת אירופה הכוללת לקטוז בחישוב, Potere אנטי Congelante (PAC) שיטה, נדונה באמצעות דוגמאות עבדו. דוגמאות כיצד לנסח מחדש את הגלידה מתערבבת להשיג קשיות מבוקרת, תוך שמירה על ערך מתיקות יחסי דומה גם כן.

 

總結

冰淇淋或冰淇淋不宜太硬或太軟在現任溫度。硬度在很大程度上依賴於送達受濃度的乳糖,蔗糖,葡萄糖,其他糖和牛奶的鹽在混合溫度對冷凍水的濃度。這篇文章解釋了冰淇淋的冰點抑鬱症(FPD)的糖濃度的意義。個別對FPD甜味劑的效果進行了討論。概述使用的相對凝固點降低(RFPD),的,其中不包括乳糖,來控制硬度在商業生產冰淇淋。在歐洲大陸廣泛使用類似的方法,包括在計算乳糖的,的potere:反CongelantePAC)的方法,討論使用工作的例子。作為如何改寫冰淇淋混合,得到控制,還提供了類似的相對甜度值,同時保持硬度。

 

8th NIZO Dairy Conference, 11-13 September 2013

8th NIZO Dairy Conference
Functional Enzymes for Dairy Applications
11-13 September 2013, Papendal, The Netherlands

Enzymes play a crucial role in achieving and maintaining the desired textural and sensorial properties of almost all dairy products. Prime examples include role of enzymes in the conversion of milk into a cheese and its subsequent flavor formation during ripening and the role of enzyme inactivation in extending the shelf-life of liquid dairy products. In addition, enzymes are widely employed to add further value to dairy ingredients and products, e.g., in the production of oligosaccharides from lactose, lysophospholipids and the various enzymatic tools available to optimize milk protein functionality. All these topics, from fundamental understanding to application in consumer products, will be covered during the conference.

Key Speakers and conference papers

Herwig Bachmann, VU University Amsterdam / NIZO food research, The Netherlands
Enzymes and their role for the selection and improvement of dairy starter cultures

Richard IpsenUniversity of Copenhagen, Denmark
Enzymatic modification to improve milk lipid functionality

Paul JelenUniversity of Alberta, Canada
Abstract: Enzymatic production of lactose derivatives

Alan KellyUniversity College Cork, Ireland
Abstract: Physiological and technological significance of proteases in mammalian milk

Isidra Recio, Universidad Autónoma de Madrid, Spain
Abstract: Dairy protein and technological significance of proteases in mammalain milk

Fred van de Velde, NIZO food research, The Netherlands
Abstract: Enzymatic modification of milk proteins

Luc van LoonMaastricht University Medical Centre+, The Netherlands
Milk protein and muscle maintenance

For more information see the NIZO website.

Mycobacterium avium subsp. paratuberculosis

The article on Mycobacterium avium subsp. paratuberculosis (MAP) was updated in May 2013 to correct  typographical errors in two of the equations used and a formatting error where the first few paragraphs of the article were not shown in some browsers. 

News at April 2013

The calculator for determining the decimal reduction time (D) of a microorganism at a temperature other than the reference temperature has been updated to show the very low values of D at high temperatures. Previously values lower than 0.001 seconds were shown as 0. Values are now shown in decimal notation.

I have had several discussions regarding the scientific assessment of the safety of ESL (processed at around 120 °C) milk stored at 4 °C for extended periods. In one situation an EHO wanted to see the evidence that justified the company claiming a 35 day safe shelf life. I was pleased to have the opportunity to work with the HACCP team to calculate the lethality of the process, decimal reduction values of appropriate pathogens, the concentration of relevant pathogenic spore formers in milk, the effect of heat treatment on residual numbers and the use of free On Line databases to model pathogen growth in the product subjected to temperature abuse. A report on this risk assessment is available from the author on request.

Dough greying and gas production in frozen ready to bake biscuits has been another interesting problem. This illustrated again, at least to me, the importance of companies employing food scientists to deal with complex problems. It also illustrated the need to retain samples of critical raw materials to enable the investigation of product problems at a later time. Interestingly, despite the product being frozen the company incurred significant expense and wasted time on microbiological analysis. The product used encapsulated bicarbonate to prevent the release of carbon dioxide on storage. The gas production was caused by the reaction of the supposedly inert bicarbonate with dough constituents.

Consumer attitudes to in vitro or cultured meat

A student has posted a link to his/her Face Book page on the forum that is turn linked to an On Line survey on attitudes to cultured meat, also known as in vitro or test tube meat. 

I would applaud this student’s use of social media and Survey Monkey as a method of getting consumer feedback on an interesting topic. Obviously there are qualifications about the methodology used and it would be interesting to see how they are dealt with.

I have included a link to an article on in vitro meat. This gives a good overview and there are several useful references. 

It will be interesting to see how vegans and vegetarians view cultured meat. I would also have liked to have seen a question aimed at faith groups to see if there are religious objections.

New ice cream mix spread sheet added

A customised artisanal gelato / ice cream spread sheet offering sweetness and hardness control options for small batch product manufacture using whole milk, cream, skim milk powder, sucrose, dextrose, fructose, a range of glucose powders or syrups, and flavourings is now available and can be downloaded from http://www.dairyscience.info/technology/180-excel-ice-cream.html .

The spread sheet is called: Pack 7. Customised artisanal gelato / ice cream spreads sheet offering sweetness and hardness control options for small batch mix manufacture using whole milk, cream, skim milk powder, sucrose, dextrose, fructose, a range of glucose powders or syrups, and flavourings.

An On Line demonstration version can be tested at http://www.dairyscience.info/a125/a125.asp .

How do you get bacteriophages to form plaques?

The article discussing factors affecting plaque formation by bacteriophages "How do you get bacteriophages to form plaques?" has been updated and is available at: http://www.dairyscience.info/index.php/enumeration-of-lactococcal-bacteriophages/factors-affecting-plaque-formation.html.

Abstract

Current data indicate that some 1031 bacteriophages exist globally, including about 108 genotypes. Some phages form very tiny or micro plaques. These can sometimes be so small that it is almost impossible to see them. Frequently 'new' phages can be observed using e.g. electron microscopy under conditions where there is strong evidence of a potential host yet it can be very time consuming or in some instances not possible to get the phage to form plaques. Less than 1% of the phages observed using microscopy have ever been grown in culture, this is sometimes called "the great plaque count anomaly".

The conditions required to get a newly isolated phage to form plaques have been reviewed. The importance of testing both logarithmic and stationary phage cells, a range of incubation temperatures, replacing agar with agarose, using low strength agarose top agar overlays in initial experiments, media supplemented with Ca++ and Mg++ that do not contain cation chelators, modifications to the double agar assay method including a) changes to the initial assay step so that phage adsorption takes place at ambient temperature  and b) the use of antibiotics and other activators of the host cell’s SOS system are discussed.

Astratto  IT

I dati attuali indicano che alcuni batteriofagi 1031 esiste a livello mondiale, tra cui circa 108 genotipi. Alcuni fagi formare placche molto piccoli o micro. Questi possono essere a volte così piccolo che è quasi impossibile vederli. Frequenti "nuovi" fagi si può osservare utilizzando ad esempio microscopia elettronica in condizioni in cui vi è una forte evidenza di un potenziale ospite ma può richiedere molto tempo o in alcuni casi non è possibile ottenere il fago a formare placche. Meno dell'1% dei fagi osservati con il microscopio sono mai stati coltivati in coltura, questa è a volte chiamato "il grande numero di targa anomalia".

Le condizioni richieste per ottenere un fago di recente isolato a placche forma sono stati rivisti. L'importanza di testare cellule fagiche sia logaritmiche e fissi, una gamma di temperature di incubazione, in sostituzione di agar con agarosio, con bassa intensità sovrapposizioni agar migliori agarosio in esperimenti iniziali, i media integrati con Ca + + e Mg + + che non contengono chelanti di cationi, modifiche al sistema di duplice agar metodo di dosaggio compreso a) modifiche al passo saggio iniziale in modo che fago adsorbimento avviene a temperatura ambiente e b) l'uso di antibiotici e altri attivatori della cellula ospite SOS sistema sono discussi.

Abstract

Huidige gegevens tonen aan dat sommige 1031 bacteriofagen wereldwijd bestaan, met inbegrip van ongeveer 108 genotypen. Sommige fagen vormen zeer kleine of micro plaques. Deze kunnen soms zo klein dat het bijna onmogelijk is om ze te zien. Vaak 'nieuwe' fagen kunnen worden waargenomen met behulp van bijvoorbeeld elektronenmicroscopie onder omstandigheden waarbij er duidelijk op een potentiële gastheer maar kan zeer tijdrovend of in sommige gevallen niet mogelijk de faag om plaques te vormen krijgen. Minder dan 1% van de fagen waargenomen met behulp van microscopie ooit zijn geteeld in cultuur, wordt dit ook wel 'de grote plaquette tellen anomalie ".

De voorwaarden om een onlangs geïsoleerd faag naar vorm plaques zijn beoordeeld. Het belang van testen van zowel logaritmische en stationaire faag cellen verschillende incubatietemperaturen, vervangen agar met agarose, met lage sterkte agarose top agar overlays in initiële experimenten media aangevuld met Ca + + en Mg + + die geen kation chelatoren, wijzigingen van de dubbele agar assay werkwijze omvat a) aanpassing van het aanvankelijke stap assay zodat faag adsorptie plaatsvindt bij omgevingstemperatuur en b) het gebruik van antibiotica en andere activatoren van SOS de gastheercel systeem besproken.

абстрактный

Текущие данные показывают, что некоторые бактериофаги 1031 существуют во всем мире, в том числе около 108 генотипов. Некоторые фаги образуют очень маленькие или микро бляшек. Они могут иногда быть настолько мала, что это почти невозможно, чтобы увидеть их. Часто «новых» фагов можно наблюдать с помощью, например электронной микроскопии в условиях, когда имеются убедительные доказательства потенциальной принимающей но он может быть очень много времени, а в некоторых случаях не удается получить фага с образованием бляшек. Менее 1% фагов наблюдать с помощью микроскопа когда-либо выращенных в культуре, это иногда называют "великим аномалии количества налета".

Условия, необходимые для получения новых изолированных фагов в форме бляшек были пересмотрены.Важность тестирования и логарифмической и стационарной фагом клеток, ряд температуру инкубации, заменив агар с агарозы, используя низкую прочность агарозном верхней накладки агар в начальных экспериментах, среде с Ca + + и Mg + +, которые не содержат катион энтеросорбенты, изменения в двойном агар метода анализа в том числе) изменения в начальной стадии анализа, так что адсорбции фага происходит при комнатной температуре и б) использование антибиотиков и других возбудителей SOS клетки-хозяина системе обсуждается.

Abstrakt

Aktuelle Daten zeigen, dass einige 1031 Bakteriophagen weltweit existieren, darunter etwa 108 Genotypen. Einige Phagen bilden sehr kleine oder Mikro Plaques. Dies kann manchmal so klein, dass es fast unmöglich ist, sie zu sehen. Häufig "neuen" Phagen beobachtet zB mit werden Elektronenmikroskopie unter Bedingungen, wo es starke Hinweise auf einen möglichen Host dennoch kann es sehr zeitaufwendig sein oder in einigen Fällen nicht möglich, die Phagen-Plaques bilden bekommen. Weniger als 1% der Phagen beobachtet mittels Mikroskopie jemals in Kultur angebaut wird dies manchmal als "die große Plaque Anzahl Anomalie".

Die Voraussetzungen für eine neu isolierten Phagen zu bilden Plaques erhalten wurden überprüft. Die Bedeutung der Prüfung sowohl logarithmische und stationäre Phagen-Zellen, eine Reihe von Inkubationstemperaturen, ersetzen Agar mit Agarose mit niedriger Festigkeit Agarose Topagar Overlays in ersten Versuchen, Medien ergänzt mit Ca + + und Mg + +, die nicht enthalten Kation Chelatoren, Änderungen an der Doppel-Agar Assayverfahren, einschließlich a) Veränderungen der anfänglichen Analysenschritt sodass Phagen Adsorption erfolgt bei Raumtemperatur und b) die Verwendung von Antibiotika und anderen Aktivatoren von der Wirtszelle SOS-System diskutiert.

抽象

目前的數據表明,1031噬菌體的存在全球範圍內,其中包括約108基因型。有些噬菌體形成非常微小的或微斑塊。有時,這些可以是如此之小,這幾乎是不可能看到它們。常見''的噬菌體可以觀察到,例如使用電子顯微鏡下一個潛在的主機有確鑿證據的情況下,它可以是非常耗時的,或在某些情況下不可能得到的噬菌體形成斑塊。只有不到1%的用顯微鏡觀察到的噬菌體曾經在培養基中生長,這有時被稱為偉大的斑塊數量異常

 

需要得到一個新分離的噬菌體形成斑塊的條件進行了審查。測試兩個對數和固定噬菌體細胞,孵化溫度的範圍內,取代瓊脂用瓊脂糖,使用低強度瓊脂糖頂部瓊脂疊加在最初的實驗中,補充有媒體的重要性的Ca++和鎂++,並沒有包含陽離子螯合劑,修改的雙重瓊脂測定方法包括:a)改變的初始測定步驟,使噬菌體吸附發生在環境溫度下,和b)的使用,抗生素和其它宿主細胞的活化劑SOS系統進行了討論。

抽象的な

現在のデータは、いくつかの1031バクテリオファージは約108の遺伝子型を含めて、世界的に存在することを示している。いくつかのファージは、非常に小さなまたはマイクロプラークを形成する。これらは、時にはそれがそれらを参照することはほとんど不可能であるように小さくすることができる。頻繁に"新しい"ファージは例えばを用いて観察することができます潜在的なホストの強い証拠がある条件下では、電子顕微鏡では、まだそれは非常に時間がかかるまたはプラークを形成するために、ファージを取得することはできませんいくつかのインスタンスであることができる。顕微鏡を用いて観察したファージの1%未満では、これまで培養で増殖されているが、これはしばしば "偉大なプラークカウント異常"と呼ばれています。

フォーム斑に新たに単離したファージを得るために必要な条件が見直されました。初期の実験、を補充した培地では、低強度アガローストップ寒天オーバーレイを使用して、アガロースを寒天に置き換える、対数と固定両方ファージ細胞、培養温度の範囲をテストすることの重要性Ca + +およびMg + + doubleに陽イオンキレート剤、修正を含まないファージ吸着は周囲温度で行われ、b)は、抗生物質および宿主細胞のSOSシステムの他の活性化剤の使用が議論されるように、初期の検定ステップへ)の変更を含む寒天アッセイ法。

Abstrait

Les données actuelles indiquent que certains bactériophages 1031 existent dans le monde, y compris environ 108 génotypes. Certains phages former des plaques très petites ou micro. Ceux-ci peuvent parfois être si petit qu'il est presque impossible de les voir. Foire aux «nouveaux» phages peuvent être observés à l'aide par exemple microscopie électronique dans des conditions où il ya des preuves solides de l'hôte potentiel mais il peut être très coûteuse en temps ou, dans certains cas, ne sont pas possibles pour obtenir le phage pour former des plaques. Moins de 1% des phages observés par microscopie ont déjà été mises en culture, ce qui est parfois appelé "l'anomalie grand nombre de plaque».

Les conditions requises pour obtenir un phage nouvellement isolée de plaques de forme ont été examinés. L'importance de tester les cellules de phages à la fois stationnaire et logarithmique, une gamme de températures d'incubation, en remplacement de la gélose d'agarose, en utilisant à faible résistance superpositions d'agarose agar haut dans les expériences initiales, les médias complétés par Ca + + et Mg + + qui ne contiennent pas des chélateurs de cations, des modifications à la double méthode de dosage agar, y compris a) les changements à l'étape de dosage initial de sorte que le phage adsorption a lieu à température ambiante et b) l'utilisation d'antibiotiques et d'autres activateurs de SOS de la cellule hôte système sont discutées.

Training event:"I Laboratori Nazionali di Riferimento per Listeria monocytogenes e Campylobacter. Seminario" - Italy - Teramo, 10 - 12 Dicembre- Montecarlo Room Hotel Sporting

I had the opportunity to present a paper on ‘Bacteriophage and food fermentations. Phage assay and enumeration’ at a training event in Teramo, Italy on the 11th December 2012.One of my former PhD students Dr Giuseppe Aprea is now working at the Istituto G. Caporale in Teramo, Italy. The institute is home to a national, reference laboratory for campylobacter and listeria and undertakes a wide range of food safety work in addition to veterinary research that includes ‘Blue tongue disease’.Giuseppe Aprea is evaluating the effectiveness of listeria bacteriophages in reducing the numbers of listeria in food processing environments, food and their effectiveness in eliminating listeria from biofilms.EM unit in Teramo

The research institute is very well resourced and researchers can access transmission and scanning electron microscopes plus extensive gene sequencing laboratories.Professor Vincenza Prencipe from the Istituto G. Caporale in Teramo has excellent facilities for studying the behaviour of pathogens in foods and I was delighted to have the opportunity to look at their cheese and meat processing facilities.

G-aprea

Bacteriophage and food fermentations. Phage assay

While many food microbiologists are familiar with the disruption of food fermentations by phages some may be less familiar with the more positive applications of phages including their use in preventing bacterial diseases of fruit and vegetables, their use in controlling the concentrations of pathogens in foods e.g. E. coli 0157, their role in nutrient recycling in the oceans and in soil, and in nanotechnology.Despite the high numbers of phages in the environment e.g. concentrations of 107- 108 plaque forming units (PFU) /ml are common in soil whereas concentrations of 106- 107 PFU/g are often found in sea water, it can be difficult to isolate hosts and to get phages to produce plaques. Plaque formation is very important in phage purification and the inability to get plaque formation does limit the application of genetic and other molecular biology studies.It was good to get the opportunity to review the challenges of phage isolation, and subsequent assay using the double agar phage assay method. The work of Abedon and co-workers on the mathematical modelling of plaque production e.g. Abedon and Yin (2009) has revealed the importance of phage diffusivity (the rate of virus particle diffusion in the absence of the host), phage-bacterium attachment, phage latent period, burst size, and host density on plaque production and overall size. Abedon’s work combined with recent work on the tendency of some large Siphophages to aggregate (will not pass through normal filters), not plaque in overlays containing >0.2% agrose combined with the use of antibiotics that activate the SOS response in cells has the potential to get even more phages to plaque and to markedly increase the size of micro plaques.I intend to update the bacteriophage pages to reflect these developments over the next few months.

Nutritional article / tools updated

The article on labelling dealing with the calculation of the energy of food components, the associated energy calculator and the sodium to salt (sodium chloride) calculator has been updated.

Starting up an ice cream business

An article aimed at helping new ice cream 'startups' was added to the Dairyscience and Food Technology website today the 3rd May 2012.

The author, Lee Williams owns and operates Valenti’s Gelato-Artisan, a Company dedicated to promoting Artisan Ice Cream and Gelato making throughout the UK.

Training course at Universita' Degli Studo Di Napoli, Federico 11 in Italy

On the 24th September 2009 I had the opportunity to talk to the “Graduate Quality Course on Health, Hygiene and Technology on milk and milk-product chain production” at the Universita' Degli Studo Di Napoli, Federico 11 in Italy.

Discussing issues in cheese science and technology with postgraduate students from a range of disciplines and companies in Italy was a very pleasant and interesting experience.

My thanks to Professor Nicoletta Murru for the invitation and to Dr. Giuseppe Aprea (Virology and Serology Unit, Animal Health Department, Experimental Zooprophilactic Institute of Southern Italy) who acted as interpreter.

One of the topics discussed was the use of HACCP in milk production at farm level. I look forward to helping to organise a study tour to Northern Ireland to look at HACCP use on farm and the food processing facilities at the Loughry campus of the College of Agriculture, Food and Rural Enterprise.

Students on milk products course

 

Professor Nicoletta Murru and Dr Giuseppe Aprea with students from the “Graduate Quality Course on Health, Hygiene and Technology on milk and milk-product chain production” at the Universita' Degli Studo Di Napoli, Federico 11 Italy.

 

Thermal processing report updated

The downloadable report "Thermal processing of acid fruit and vegetable products. Significant microorganisms, recommended processing time / temperatures, and public health significance of spoilage" has been updated.

The report:

1) Identifies the potential spoilage organisms of acidic foods
2) Discusses the decimal reduction times and Z-values of the major spoilage organisms of acid foods
3) Lists F or P values and reference temperatures for ensuring the production of commercially sterile acid foods
4) Explains how to calculate F values and the number of log reductions of spoilage organisms following processing
5) Explains how to calculate equivalent processes e.g. at higher temperatures using published data
5) Explains the importance of measuring pH over the shelf life of acidified products
6) Provides a summary of the major causes of spoilage of acidic foods and their control
7) Lists literature, including a free On Line database containing around 6000 D-values, concerning the manufacture and control of acid foods.

This report contains 17 pages, 5 tables and 19 references (the table of contents is shown in figure 1).

Figure 1. Table of contents for thermal processing report

 

Worked examples are provided and the author is prepared (within reason) to help users having
problems providing they are posted on the forum. The report will be converted to an Ebook with additional sections including the manufacture of acidic milk products, validation and quality assurance of heat processes. Donors will be advised of updates which will be available at no cost.

More information is available at http://www.dairyscience.info/index.php/thermal-processing.html.

Jaap de Jonge visits CAFRE's Loughry Campus

I was delighted to have the opportunity to meet Jaap de Jonge, MD of Jongia (UK), today (15-5-2012) when he visited CAFRE's Loughry Campus. Jongia have supplied soft cheesemaking equipment to Loughry and the visit was an opportunity to explore recent developments in cheese making technology particularly for artisanal producers.


Jaap de Jongia

Jaap pictured with Gary Andrews and Joy Alexander from CAFRE

Congratulations to Dr Giuseppe Aprea

 Congratulations to Dr. Giuseppe Aprea who received his PhD at the Universita' Degli Studo Di Napoli, Federico 11 on Monday the 15th January 2007. I was particularly pleased to be a member of the Commision responsible for examing Guiseppe and the other doctoral candidates.

 

The author pictured with Professor M. L. Cortesi, Professor N. Murru and Dr G. Aprea at the University of Naples

 

The author pictured with Professor M. L. Cortesi, Professor N. Murru and Dr G. Aprea at the University of Naples 

Dr Aprea worked with the author and colleagues at Loughry to study fermentation problems with Mozzarella cheese produced using buffalo milk in Southern Italy. The cheeses were manufactured using natural whey or artisanal cultures. 

The research involved the isolation and identification of lactic acid bacteria from the starters and the determination of their sensitivity to bacteriophage.  The work identified that many of the lactic acid bacteria, particularly lactobacilli, present in the whey starters contained inclusion bodies comprised of polyphosphate. This work has been published. Two unusual phages for Lactobacillus brevis, the first reported for this organism were also identified.

 Giuseppe Aprea working with Professor Ger Fitzgerald at University College Cork has characterised the genome of both phages and determined their sensitivity to high pressure and temperature.

Milk protein derived bioactive peptides

An article on 'Milk protein derived bioactive peptides' by Emily Haque and Dr. Rattan Chand from the National Dairy Research Institute in India has been added to the Dairy Science and Food Technology website.

This article reviews recent research that has shown that milk proteins can yield bioactive peptides with opioid, mineral binding, cytomodulatory, antihypertensive, immunostimulating, antimicrobial and antioxidative activity in the human body.

The authors review the properties of bioactive peptides, explain that bioactive peptides are encrypted in milk proteins and are only released by enzymatic hydrolysisin vivoduring gastrointestinal digestion, food processing or by microbial enzymes in fermented products.

Mention is made of the significant research being undertaken on the health effects of bioactive peptides.The naturally formed bioactive peptidesin fermented dairy products, such as yoghurt, sour milk and cheeseare discussed e.g. antihypertensive peptides have been identified in fermented milks, whey and ripened cheese. Some of these peptides have been commercialised.

The authors conclude with their perspectives on the future of bioactive peptides and suggest that "Bioactive peptides have the potential to be used in the formulation of health-enhancing nutraceuticals, and as potent drugs with well defined pharmacological effects".

Calculate the energy density of food

An article on how to calculate the energy density of food has been added.The purpose of this article is to discuss how to calculate the energy density or energy content of foods. A calculator is also included to calculate energy density using the the Atwater factors.

Dairy farming in a new environment

Students studying dairy science, food science, nutrition and food technology should have at least an appreciation of the macro aspects of food production on the farm.

Farming in Europe and in North America is challenging for many farm families at present. Farm incomes are lower than many farmers need to sustain and develop their businesses and the costs of meeting environmental legislation are increasing. All of this combined with the considerable purchasing power of the food retailers who tend to drive down farm prices requires farmers to have excellent business management skills.

What are the business management challenges for farmers? In a challenging but positive article Ian McCluggage discusses 'Dairy farming in a new environment.'

In his article Ian mentions benchmarking. Further information on benchmarking is also available under the Focus Farm programme. In this innovative DARD-led programme some 80 farmers throughout Northern Ireland share their business expertise through a mentoring programme. Many of these farmers use benchmarking.

Site updated on the 23rd August

The article on the science of modified atmosphere packaging has been updated to include additional information on non-dairy foods. I have also included some advice on how to cite this and other articles. The article and other articles on packaging can be viewed here.

Thanks to James Atherton for sharing a Javascript used on his Teaching and Learning site.

Finally after many months an article on the use of starter cell concentrates has been added. This material had been written quite a few years ago and I was disappointed to learn that facilities for innoculating bulk starter vessels with cell concentrate have not improved much. No wonder we still have phage problems.

Biotherapeutic properties of yeasts

A paper on the 'Biotherapeutic properties of probiotic yeast Saccharomyces species in fermented dairy foods' by Kalpana Dixit and D.N.Gandhi, Dairy Microbiology Division, National Dairy Research Institute, Karnal-132001, INDIA has been added to the Dairy Science and Food Technology site.

Predicting the grade of Cheddar cheese

The production of mature cheese is expensive and involves management of several risks. There is increasing interest in using models to predict grade or to reject those cheeses that are likely to develop faults on storage.

An article on the use of the Lawrence model to predict the grade value of Cheddar cheese has been added.

The article also provides access to a calculator where users can input actual cheese data and use the Lawrence model to predict the cheese grade.

Safe shelf life of smoked vacuum packed cheese

A small UK business wishes to manufacture smoked cheese and to sell the cheese vacuum-packed. The Environmental Health Officer (EHO) dealing with the business demands that the products produced should have a restricted shelf life in accordance with his/her interpretation of guidance from the Food Standards Agency (FSA). However the company is aware of other businesses selling similar products without restriction.

The above query was posted on the forum today the 6th May 2012. Have you a view? Has the EHO made a mistake?

Theoretical yield of Cottage cheese

A calculator to determine the theoretical yield and process efficiency in Cottage cheese manufacture has been added. Using the solids-not-fat, protein or preferably casein concentration in the cheese milk an estimate of theoretical yield can be obtained. This can be compared with the actual yield to obtain values for cheesemaking efficiency.

Posting on Cottage cheese & site news

The latest posting concerns how to predict the theoretical yield of Cottage cheese.

The site forum has been updated from SimpleForum 3.3 to the professional version. The latter enables forum posts to be viewed without having to register.It alsoenables simpler and faster registrationfor posting anda range of other features e.g. personal messaging, posting attachments; these have still to be enabled. One downside of the upgrade is that the original statistics have been lost. On the positive side posters, providing they have enabled the feature in their profile, will receive an Email each time a response to their topic has been posted.

Finally peace and happiness to all users of this website in 2007.

DSFT is a consultancy. Knowledge transfer is our business and there is a charge for providing independent, scientifically valid and ethical advice.

We normally charge £500 per day with discounts for longer projects, £250 for half day projects and £100 per hour for consultations using Skype, Facetime, Email or phone.

We recognise that everyone cannot afford these rates and provide a facility through the forums to respond to queries at no cost. At busy periods it can be a week or longer before we can respond in the forums but the forums are good for non-urgent queries.

There is a limit to how much free consultancy we provide after purchasing spreadsheets or Ebooks and it would be appreciated if you would consider making a donation to cover business costs before asking for advice.

You can use the PayPal donate button below to make a donation.

 

Thank you for your donation to the DSFT website. Your donation will help me fund the running costs of the website.

Best wishes.

Michael Mullan 

Help for lethal rate calculator

How does the calculator work? The calculator converts temperature readings to lethal rates, plots the lethal rates against time, and determines the F values for the overall heat-process. The area under the curve is determined using the Trapezoid rule and the calculator is capable of giving accurate F determinations for most thermal processes. In general the more values, and the smaller the time interval between the values, the more accurate the value for F will be.

Lethal rate is calculated using the formula, lethal rate= 10 (T-Tr/Z) where T is the temperature, in Celsius, at which the lethal rate is required and Tr is the reference temperature.

Tr will vary on whether Fo is being calculated or whether a pasteurisation process or other heat treatment is being assessed. A Tr of 121.1° C is used in the determination of Fo. If F70 or other F value is required then Tr must be set to 70° C or other temperature.

The Z-value, is measured in °C, and is the reciprocal of the slope of the thermal death curve for the target microorganism or spore; 10° C is the value frequently used in Fo calculations performed on low acid foods. Note this calculator uses a default value of 10°C for Z. The Z-value has a significant effect on the F value of a process. The effect of the Z-value can be seen in the free lethal rate tables that can be downloaded from here.

Tr can be varied by the user. If you need to use a different Z-value then try the other calculator.

Using the calculator

Reference temperature should be set first. Next the data grid for entering data is produced.

The starting time e.g. 2 minutes from the beginning of heating and the final time e.g. 180 minutes from the start of heating should be set. The time interval between the temperature readings (∆t) must also be set e.g. 2 minutes. Once this information has been set, the user should press the “New data grid” button to create a data entry table. Temperature values are entered using the edit control.

The application can be tested using internal test data. This data when used with the set values should give a Fo value of 8.43. You may also change the Tr values once the data has been loaded and use the “Recalculate button” to investigate the effects of changing these variables on the F values generated by your dataset.

Uploading a csv file

Instead of creating a new data grid to enter time and temperature data you can upload a text file containing your data and the application will determine the F value. If you want to use a different Tr value you should set the Tr-value after you have uploaded the data and then use the Recalculate button to determine the F value. The data must be submitted as a comma separated value (CSV) text file. Use a '.' and not a ‘,’ as the decimal separator. The file must have the extension “.csv”.

A csv file looks like:

Time, Temperature
2,90.2
4,100.9
6,112.45
8,115.9
9,101.6
10,95
16,93

and can be generated using a spreadsheet programme, if you do not want to prepare the data manually. While a csv file will enable users to use actual values, and will work with uneven time intervals, the use of uneven time (t) intervals is not recommended; keep the ∆t constant! Numerical integration (this is what we are actually doing) using the Trapezoid rule gives more accurate results when even time intervals are used.

Note. When a .csv file is imported the data in the table and on the chart will change to reflect the new values entered. Once this data has been entered you can vary the Tr and z-values and use the recalculate button to calculate a new F value.

The number of log cycles that a designated microbial population has been reduced can be calculated by dividing the F value by the D value at Tr. A 12 log cycle reduction is required for spores of Clostridium botulinum in 'commercially sterile' low acid canned foods.

Please post any queries in the forum.

You can also download Excel spreadsheets to calculate F values.

Return to lethal rate calculator

See survivor probability calculator


How to cite this article

Mullan, W.M.A. (2008). [On-line]. Available from: https://www.dairyscience.info/index.php/technology.html . Accessed: 21 September, 2017. Updated 2010, 2015. 

Note this article is still in draft form and is available On Line to facilitate editing. It is scheduled to be completed by June 2015.

There are several programming languages used to construct models that will run on web servers. These include Perl, PHP, Python, Classic ASP, JavaScript and ASP.Net. These languages can be used with appropriate databases to develop powerful web-based applications.

PHP has become particularly popular and is fairly easy to learn. Classic ASP is very easy to learn but is increasingly being replaced by ASP.NET. Virtually anyone who can put a spreadsheet together is capable of learning a basic language such as ASP.

The purpose of this article is to show how the calculator for predicting salmonella growth on tomatoes was written in ASP. I would like to encourage lecturers and students to learn how to programme. While ASP is being replaced by ASP.NET the basic premises using in ASP coding can be applied to other languages and even if you decide to learn PHP which is a particularly versatile web language you will be able to apply the concepts learned

Constructing the data entry form

The HTML and ASP code used to construct the data entry form is shown below. For simplicity web page header information, value information in ASP and some form security information has not been shown.

The input form was constructed by writing the code for a table in HTML and adding in HTML text boxes to allow initial number (no), temperature (t) and incubation time (hr) to be entered.

 <%@LANGUAGE="VBSCRIPT" CODEPAGE="1252"%>

<form id="form1" name="form1" method="post" action="sam1.asp">

<table width="75%" border="1" cellspacing="0" cellpadding="1">
<tr>
<th colspan="2" scope="col">Predict the growth of salmonella in cut tomatoes at 10&deg;C to 35&deg;C</th>
</tr>
<tr>
<td width="41%">Initial number of salmonella / gram</td>
<td width="59%"><input name="no" type="text" id="no" value="<%=no%>" /></td>
</tr>
<tr>
<td>Temperature, &deg;C</td>
<td><input name="t" type="text" id="t" value="<%=t%>" /></td>
</tr>
<tr>
<td height="20">Incubation time, hours</td>
<td><input name="hr" type="text" id="hr" value="<%=hr%>" /></td>
</tr>
<tr>
<td height="20" colspan="2"><div align="center">
<input type="submit" name="Predict number of samonella" id="Predict number of samonella" value="Predict number of salmonella" />
</div></td>
</tr>
</table>
<p>&nbsp;</p>
</form>


 

Writing the data processing script

A simplified version of the processing script is given below. The notes which are preceded by a ' explain how the script works.

<%@LANGUAGE="VBSCRIPT" CODEPAGE="1252"%>


<% Option Explicit
'Use of option explicit will ensure that error messages are displayed if there are coding problems. These are helpful in finding solutions. %>

<%


'List variables

Dim no
Dim t
Dim hr

'no, t and hr are values that have been entered on the form
Dim r
Dim g
Dim gen
Dim pop

'r,g,gen, pop are the products of calculations that will be undertaken

'We will now obtain the information from the entry form to perform the calculation

no=CSng(Request.form("no"))
t=CSng(Request.form("t"))
hr=CSng(Request.form("hr"))


'Taking information from the form we will calculate r,g, gen and pop. This could easily be done in one calculation. The calculation has been broken down into its component parts so that it can be followed more easily.

'For an explanation of the calculation please see http://www.dairyscience.info/index.php/food-model/258-predict.html
 
r=0.026*(t)-0.1065
g=1/(r*r)  'note r is the square root of the growth rate, we need to obtain the growth rate by multiplying r by r
gen=hr/g
pop = no*2^gen

'We next need to provide the results of the calculation for pop which is the total number of salmonella after growth at the temperature chosen for the time inputted.

If t >9.99 AND t <35.01 THEN ' basic validation to ensure that the results are within the temperature parameters modelled

'The  'If Statement' is used to make a decision to execute code if some condition is True.
 
response.write ("The predicted number of samonella after" & "&nbsp;" & (hr)& "&nbsp;" & "hours has been calculated as" & "&nbsp;" & round(pop,0) & "&nbsp;" & "CFU/g.")
 END IF

'END IF is used to indicate the end of code execution


IF t < 10 THEN
Response.Write ("&nbsp; Caution. This model as not been validated at temperatures <10&deg;C.")
END IF

IF t > 35 THEN
Response.Write ("&nbsp; Caution. This model as not been validated at temperatures >35&deg;C")
END IF
%>

About the data processing script

These scripts will work on a Windows web server or a Windows PC running Microsoft's free IIS or PWS components. They are compressed and must be un-zipped before use. They have been provided free and are not warranted in any way. They are intended for educational use only. They can easily be adapted to work using PHP or JavaScript.

Qualifications/Disclaimer

To be added.

Acknowledgements

I learned ASP, how to use Access Databases and HTML from a former colleague Dr Raymond Martin. Raymond generously helped me correct concatenation and many other errors and though his help I gradually learned how to write quite sophisticated data-base driven ASP applications. I gratefully acknowledge Raymond's help over many years.


How to cite this article

Mullan, W.M.A. (2015). [On-line]. Available from: https://www.dairyscience.info/index.php/technology.html . Accessed: 21 September, 2017.  

DRAFT Article.

This article is available On Line to enable editing. Its draft status is scheduled to be removed by September, 2015. In the meantime comments are invited from scientists and technologists familiar with the subject area to help improve this article. I wish to acknowledge the generous comments and advice received from workers in this area. As a result of the feedback I will include more information about the principles behind modelling bacterial growth and the limitations of models.

Michael Mullan. 17th April, 2015

The purpose of this article is to explain how to derive a simple Ratkowsky square root model (Ratkowsky et al., 1982) that describes the growth of a fault causing bacterium on cooked meat over the temperature range 10° - 35 °C. 

An example of the growth curve of the fault causing bacterium on tomatoes at 35°C is shown in figure 1.

The curve shows the 4-typical growth phases, lag, logarithmic, stationary and decline.

 

The specific growth rate (k) is calculated for the  logarithmic phase using equation 1.

Equation 1. k=log10(Nt) - log 10 (N0)
                          T x 0.301

Where:

Nt = is the number of bacteria at the end of the observation period.
N0 = is the number when the observation period started.
T = is the time that has elapsed over the growth period in hours.

k= 9.146-6.669
        2 x 0.301

k= 4.115 generations h-1 at 37 °C.

Next we need to construct a series of curves at 10°, 20°, and 30 °C to find the specific growth rate at each temperature. We have got the growth curve at 35 °C already (Figure 1 above). The specific growth rates at each temperature are then tabulated using equation 1 against time (Table 1). Note I have not shown the growth curves at the other temperatures. 

  Table 1. The effect of temperature on the specific growth rates of a bacterial isolate on tomatoes
 Temperature, °C  Specific growth rate, h-1
 10  0.023
 20  0.16
 30  0.384
 35 0.518

 We can now use the Ratkowsky square root model (Ratkowsky et al., 1982) to derive the relationship between the growth rate constant, temperature and the initial number of microorganisms.

The equation has been described previously, √r= b (T-To), where r is the growth rate constant.  In particular we need to calculate b, the slope of the square root of specific growth rate versus temperature plot, and, To, the value at which the square root of growth rate intercepts the x axis.

The curve produced using linear regression (black line) and the actual data (blue line) using the data in table 1 is shown in figure 2.

 

Using Excel, the linear regression equation that describes the trend line (black line in figure, for the growth of the fault causing bacterium on cooked meat over the temperature range 10° to 35 °C is:

√r= 0.0228 (T-0.0693) where √r is the square root of the growth rate constant and T is the temperature in °C.

Use of Combase Tools

While the calculations described previously are not difficult it is possible to automate the derivation of growth rate equations using free tools from Combase.  DMFit is an Excel add-in to fit log counts vs. time data and extract parameters such as growth rate. It can be downloaded from Combase.

Model validation

Validation is an important element in model development. The literature cited below provides useful insights into model development and may prove useful during validation. The USDA Pathogen Modelling Program (PMP) and ComBase should be consulted for pathogen-models.

Qualifications/Disclaimer

To be added.

Literature cited

Baranyi, J., Pin, C. and  Ross, T. (1999). Validating and comparing predictive models. Int. J. Food Microbiol. 48:159-166.

Baranyi, J.,  Ross, T., Roberts, T.A. and  McMeekin, T. (1996). The effects of overparameterisation on the performance of empirical models used in predictive microbiology. Food Microbiol. 13:83-91.

 Pin, C.,  Sutherland, J. P. and Baranyi, J. (1999). Validating predictive models of food spoilage organisms. J. Appl. Microbiol. 87:491-499.

Acknowledgements

To be added.


How to cite this article

Mullan, W.M.A. (2015). [On-line]. Available from: https://www.dairyscience.info/index.php/technology.html . Accessed: 21 September, 2017.  

DSFT has been providing science based consultancy services globally since 2002, however, Dr Michael Mullan has been providing training in a wide range of food technology-related areas and a range of consultancy services on a personal basis for more than 25-years.

DSFT can provide a wide range of services. These include :

 Recruitment of professional staff. Few people understand how colleges and universities select students and deliver science-based qualifications and what an employer can realistically expect from a graduate. What literacy and numeracy skills can you expect from an employee with Functional or Essential Skills? Are scientific and technological knowledge and skills important in a particular post? What about an On Line, time-limited, objective assessment to screen out the technically less qualified?
 Validation and audit of HACCP schemes. e.g. have you a science-basis for your thermal process? Can you convince your EHO that you have a valid HACCP plan?
 The manufacture of a wide range of food products.
 Ice cream and gelato manufacture e.g. do you want all your flavours to have the same sweetness and ‘scoopability’ or hardness at the serving temperature? Do you want to replace expensive imported mixes with locally sourced alternatives and save potentially hundreds of thousands of pounds / dollars per year? Have you problems with rapid melting or texture? Do you have recipes that you want converted to % MSNF, % fat, % sugar etc. so that you can optimise them for taste, texture or cost? You may also want to 'tweak' composition to develop new products? Do you want to replace or reduce fat and/or sugar in formulations and want to know the issues from PhD - trained scientists?
 Preventing or eliminating spoilage in acidic products through process design. This also includes pharmaceutical products ie.g. mouthwashes.
 Training. Particularly, advanced science and technology training for groups or individual senior staff e.g. one to one fast track training for senior mangers.  IT training also included. Validation through major European universities as part of a CPD process may also be an option.

Discussing HACCP plan


 Pathogen control. Optimisation of thermal processes. Use of phages in biocontrol. Pathogen modelling.
 Cheese manufacture, optimisation of yield and resolution of problems e.g. strategies for accelerating maturation. DSFT can also help you develop new cheese varieties.
 Isolation and exploitation of the antimicrobial proteins in bovine milk e.g. in mouthwashes, toothpaste, calf milk replacers, baby foods.
 Bacteriophage control in fermented dairy products.
 Grant applications and project appraisal. Cases for R&D funding.Project appraisal.
Desktop research.  Interested in developing a new product or concerned about a potential risk, then consider commissioning a confidential research report.
Editing and revision of reports translated into English. Want the use of scientific English in a research report, paper or thesis rewritten to reflect best practice in scientific-writing?
Biofilm control. 
Statistical analysis and sampling plans.

Note chemical and microbiological analytical services through partner organisations are currently being developed.

For more information and to enquire about consultancy services click here.

 

The tables of data from the gassy cheese article.

 

Table 1. Major microbial groups that can produce gas in cheese

Microbial group

Substrate

Gaseous products

Clostridia
  Clostridium tyrobutyricum

Lactate

CO2, H2

Lactobacilli
  E.g. Lactobacillus brevis
  E.g. Lactobacillus casei

Lactose

Citrate

CO2

Streptococci
  Streptococcus thermophilus1

Urea

CO2

Coliforms

Lactose

CO2, H2

Yeasts

Lactose

CO2

Lactococci
 Lactococcus lactis ssp. lactis biovar. diacetylactis

Citrate

CO2

Bacillus species
  Bacillus subtilis

Lactose

CO2, H2

Leuconostocs
  E.g. Leuconostoc mesenteroides
  E.g. Leuconostoc dextranicum

Lactose/citrate

CO2

Propionibacteria
  Propionibacterium shermani

Lactate

CO2

Notes:1 Streptococcus thermophilus can also produce gas from other substrates.

 

Table   2. Microbiological analysis of blown and normal cheese from factory X

 

CFU/g

 

Blown cheese-A

Blown cheese-B

Normal cheese

'Total count' on milk agar

1.3 x 10 8

6 x 107

2 x 107

Yeasts and moulds

<10

<10

<10

Coliforms

<10

<10

<10

Catalase-negative citrate   utilisers(1)

8 x 107

4 x 107

<1 x 106

Clostridia

<1 x 10 2

<1 x 102

<1 x 102

Group D streptococci

<1 x 102

1.3 x 103

2 x 102

Lactobacilli(2)

4.1 x 104

4.1 x 105

1 x 103

Aerobic sporeformers

1 x 102

1 x 102

1 x 102

Notes:

All cheeses were obtained from the same commercial plant and from the same production run.
Cheeses had been held at 7°C for 8 weeks after manufacture before sampling. Moisture, pH and salt
levels were within acceptable limits and similar in all samples.
(1)Determined using differential agar media13,14.
(2) Determined using Rogosa agar15

TABLE 3.   Relationship between citrate level in cheese, ex-press, and gas production in   Cheddar cheese

Days after manufacture

Starter code

Milk citrate level (% w/w)

Cheese citrate level(2) (% w/w)

Condition of barrier bag(3)

1

1607

ND

0.05

Blown

3

1607

ND

< 0.001

Slack

15

1607

0.17

0.09

Blown

29 (vat 1)

1607

0.17

0.01

Blown

29 (vat 3)

SLA(1)

0.17

0.21

Blown

53

MS(1)

0.17

0.19

Tight, no gas

60

1607

0.18

0.14

Blown

Notes:

(1) Defined multi-strain cultures that did not contain citrate utilising strains.
(2) Cheese analysed immediately after pressing for citrate (12 hours).
(3) Cheese was stored at 7C for 6 weeks before examination.
ND - not determined

 

TABLE 4.   Characteristics of Rogosa-agar isolates from a commercial mixed-strain   culture

Isolate

HM8/4

HM8/11

HM8/10

HM8/14

Morphology

Cocco/ bacillus

Cocco/ bacillus

Cocco/ bacillus

Cocco/ bacillus

Gram reaction

+

+

+

+

Catalase

-

-

-

-

NH3 from arginine

-

-

-

-

Nitrate reduction

-

-

-

-

Lactic acid (isomer present)

(D)

(D)

(D)

(D)

Acid produced in RSM(1)

0.25%

0.20%

0.48%

0.39%

Gas from glucose

+

+

+

+

Gas from gluconate

+

+

+

+

Acid from arabinose

-

-

-

-

Acid from xylose

(+)

-

(-)

+

Acid from maltose

+

+

+

+

Growth at 40ºC

-

-

-

-

Growth at 10ºC

+

+

+

+

Growth at 6ºC

-

+

+

-

Growth in 6% NaCl

+

+

+

+

Growth in 6.5% NaCl

-

-

-

-

Citrate utilisation

+

+

+

+

 

TABLE 5. Maximum volumes 1,2 (L) of carbon dioxide available from citrate and lactose in cheese (3)

% substrate (w/w)

Volume of CO2(1)

 

Citrate(4)

Lactose(5)

0.8

NC

18.8

0.5

NC

11.8

0.2

12.6

4.7

0.1

6.3

2.4

0.02

1.3

0.48

Notes:

(1) Volumes at standard temperature and pressure (STP)
(2) No allowance made for adsorption/solution. Values are rounded
(3) Cheese mass 18 kg
(4) Assuming 3 moles of CO2 produced from 1 mole citrate
(5) Assuming 2 moles of CO2 produced from 1 mole lactose
NC. Not calculated. Citrate levels of >0.2% w/w are not normally found in Cheddar cheese.

Return to gassy cheese article.

Microsoft Excel standardisation calculator for whole milk powder manufacture

The calculator used on this web site for producing milk powder to a target fat concentration was validated using a Microsoft Excel spreadsheet. This spreadsheet is available for download subject to a small donation (£4.99, < €6 or <US $10, conversions based on the exchange rate at March 2012) to contribute towards the running costs of the Dairy Science and Food Technology website.

The download contains one Microsoft Excel spreadsheet and a document in PDF form. The PDF file explains the basis of the calculations. A screenshot of the spreadsheet is shown in figure 1.

 Image of Excel spreadsheet for producing whole milk powder to fat target

Figure 1. Screenshot of the Microsoft Excel spreadsheet for undertaking calculations to determine the fat concentration required to produce a milk powder to a defined fat concentration.

All the cell formulas are unlocked. The spreadsheet is for your own personal educational use. Only make a donation if you accept the Terms and Conditions for the use of Spreadsheets from this site.


£4.99
Visa MasterCard Discover American Express

 

 

Following secure payment you will shortly receive an Email with a download link. The link is valid for 7-days and during this time you can download the spreadsheet 4-times.

 

The deadline for applications for the food jobs below has closed.

 

VSO International have two agrifoods jobs starting in August 2011.

1. Veterinary adviser for the Central Region Milk Producer's Association (CREMPA), in Lilongwe, Malawi for 24 months

Whats the context and purpose of the role?

VSO has been supporting CREMPA since 2001, looking at the most appropriate ways to support smallholder dairy farmers to improve their living standards with VSO volunteer providing long term support to CREMPA mostly in the area of dairy husbandry, health and nutrition.

The overall purpose of the placement is to build capacity in CREMPA to provide appropriate, robust and demand driven animal husbandry and veterinary services to its members and to firmly embed these services within the members associations themselves to ensure future sustainability through skill building of the farmer livestock technicians.

What does the role involve?

  • Plan and deliver training for Farmer Livestock Technicians (FLTs) regarding fertility problems, disease detection, drug administration and the use of animal feeding.
  • Support the Technical officer on data collection and record keeping.
  • Monitoring performance of all services in order to improve conception rate.
  • Supervision of FLTs and technicians.
  • Develop a plan for parasite treatment based on disease assessment.
  • Work with member organisations for improved productivity and feed supply.
  • Work with breeding units for ongoing improvements in breeding quality.
  • Build a good relationship with the Central Veterinary Laboratory and assist them to improve turnaround time on test results and generally improve efficiencies in service provision to CREMPA members.

What skills, experience and personal qualities are needed for the role?

You’ll have a degree in veterinary medicine, ideally with an emphasis on tropical disease or dairy farming. You’ll have practical experience of working with large animals and of artificial insemination. Exposure to or knowledge of diagnostic testing (laboratory) is desirable. You’ll be comfortable with providing on the job training to technicians with minimal education standards, using your strong people skills to help support staff and develop interventions.

You’ll be willing to ride a motorbike (VSO will provide the training) to allow you to visit farms in rural areas.

And the rest

Because of the nature of the role, you’ll to be flexible regarding your working hours - cows do not respect office hours!  CREMPA will take a flexible approach on flexitime volunteers time off in lieu of weekend or evening work.  The office has an informal environment; however the hierarchical structure of the Management and Executive is rigidly respected. You’ll be given 33 days annual leave per year (including Malawi’s 12 public Holidays). The position is based within Lilongwe City limits and as such has access to the best facilities available within a half hour minibus ride.

You’ll be working in the capital Lilongwe and will probably be living in accommodation near the City Centre. The city is very sociable with many other expats and about 20 VSO volunteers living there. This ensures that there’s a fairly busy social side to life as a volunteer. There are art galleries, restaurants and shops, but Lilongwe is also a very green and calm city. From Lilongwe it is possible to visit the rest of Malawi’s beautiful countryside and nature reserves.

 Well ask you to commit 12-24 months to make a sustainable contribution to our development goals. In return, well give you comprehensive financial, personal and professional support. We'll provide you with extensive training before your placement, and our financial package includes a local salary, return flights, accommodation, insurance and more. When you return to your home country, we'll help you to resettle and many of our returned volunteers stay involved with us long after their placement ends.

 Reference number (please quote in your application form: [M448-0007-0001]

To apply go to http://www.vso.org.uk/volunteer/apply-now/

2. Dairy Production Manager, Individual Entrepreneur (IE) Muminov, Soughd, Northern Tajikistan for 8 months

What’s the context and purpose of the role?

IE is one of the first private dairy companies in Northern Tajikistan. Correct, a business arm of IE employs more than 40 full time workers and obtains milk for processing from more than 100 small scale producers in neighboring villages. Correct provides opportunity to village women to sell their milk at significantly higher prices than others and provides employment opportunities for many farmers who would otherwise struggle to generate any income.  Correct need the technical skills of a VSO volunteer to develop the quality of products by implementing improvements in the supply of inputs into dairy processing by working with suppliers and Correct employees. 

You’ll work to support plans to implement international standards on hygiene and collection baselines and work with Correct to enable to inception of an effective system for milk production and collection to help them to expand and support more rural farmers in northern Tajikistan.

What does the role involve?

Developing hygiene standards and communicate to local farmers.

Provide advice and train milk suppliers to follow sanitary and hygiene while milking.

Assist in improving methods of milk collection.

To support producers and Correct to devise and implement an effective system of milk collection point.

To advise producers and Correct on quality standard and testing of milk products (bacteriology and chemical test).

What skills, experience and personal qualities are needed for the role?

You’ll have a degree in veterinary science or a similar and significant experience in the field of livestock management and advising small scale livestock producers. We’re looking for someone with people skills. You’ll need excellent communication and diplomacy skills and a proven ability to share knowledge through facilitation and coaching skills. Practical experience in the dairy sector and/or in a developing country setting would be desirable. You’ll need to be prepared to work in rural settings, often with limited or low quality equipment.

And the rest...

Most local shops are not supermarket-type facilities where you can simply pick up what you need. The best and cheapest place to go on food shopping and miscellaneous, especially for fruits and vegetables, is markets (bazaar), which are central and easily accessible, although you may prefer to go to local shops.  In winter time vegetables and fruits are available, but more expensive.  There is a policlinic (family doctor services) and a hospital in Khujand.

We’ll ask you to commit to 12 months to make a long-term contribution tackling poverty. In return we’ll provide you with invaluable training before your placement, a local living allowance, return flights, accommodation and insurance. When you return to your home country, we’ll help you resettle and we’ll invite you to stay involved with us through campaigning, development awareness and fundraising.

 Reference number (please quote in your application form: [Taj0036-0002-0001]

 To apply go to http://www.vso.org.uk/volunteer/apply-now/

The Ulster Farmers Union has Insurance and Agriculture Business Opportunities at  Senior Group Manager and Assistant Group Manager level in Northern Ireland.  More information is available at the UFU website.

COMMUNICATIONS OFFICER: 

Based in Belfast., Northern Ireland

Salary:

£19,028 - £29,597; commensurate with experience.

The Ulster Farmers' Union, Northern Ireland's leading farming organization, wishes to appoint a Communications Officer.

Working in the UFU Membership and Communications Department, main duties and responsibilities will include: working effectively and efficiently in a dynamic team environment to produce news releases and publications; building and maintaining good relations with the media; developing the UFU Website and E-communications; and coordinating the UFU presence at events such as the Balmoral Show.

This is an exciting opportunity to work in a very busy, diverse and rewarding environment.

So if you have a commitment to the local agriculture industry, a demonstrable interest in press/public relations, have strong ICT skills and possess a third level qualification in an agriculture related subject, then contact the Ulster Farmers' Union for full details and an application form. Tel: 02890 370222 or download the application form from www.ufuni.org.

The closing date for receipt of applications is Friday 30 July 2010 at 12 noon.

This section provides an access point to a range of calculators and models. These include calculators for determining the theoretical yields of Cheddar cheese (Van Slyke), the yield of Cottage cheese, the volumes of skim and whole milk required to standardise milk to a required fat content, the predicted grade value of Cheddar cheese, casein retention, fat retention, casein to fat ratio, protein to fat ratio, the quantities of ingredients required for a balanced ice cream mix, the ideal MSNF value for ice cream, MSNF in unwashed butter, MSNF in cream and the energy value of foods. Software for calculating the F value of thermal processes has also been provided. This software can be used to teach the principles of thermal processing or to check the adequacy of, for example, a canning process. It is easy to use and applicable to a broad range of thermal processes.

Click to stop cracks and slits in cheese

If you find the applications useful please visit an advert or two or consider donating to support the site. These simple actions will help to cover the running costs of the Dairy Science and Food Technology website.

Processing aids
Pearson square or rectangle for use with milk, cream, wine, meat manufacture. 
 Calculate milk fat concentration required to produce a whole milk powder of specified fat concentration.
Calculate casein:fat and protein:fat ratios in milk for product manufacture.

Cheese yield
Van Slyke theoretical yield
Van Slyke adjusted for moisture
Casein retention
Fat retention
Yield analysis spreadsheet
Calculate the yield of Cottage cheese

Cheese quality
Grading value predictor for Cheddar

Nutrition / labelling tools
Energy density or calorie counter for foods
Sodium chloride (salt) calculator

Writing tools
Improve your writing by using an On Line readability calculator
Harvard-style reference generator
 Convert numbers to scientific notation
Convert numbers in scientific notation to standard format

Food safety / spoilage models
Model the probability of Listeria monocytogenes growing in cheese.
Model the probability of detecting a pathogen in a food.

Determine whether a product containing acetic acid meets the Comité des Industries des Mayonnaises et Sauces Condimentaires de la Communauté Économique Européenne (CIMSCEE) model for a safe and stable product.
Predicting the growth of Salmonella spp on sliced-tomatoes.
Predict microbial numbers using doubling or generation time.

 
 Models for shelf life prediction

• Shelf life of pasteurised milk. 
 Mould free shelf life of cakes. 

Random number generator
 Generate a random number sequence

Thermal processing
 Calculator for determining the F or P value of a thermal process
Simplified version of the Dairy Science and Food technology F and P value calculator.
Calculate an equivalent heat process at a higher (or lower temperature) knowing the z-value and the F (P) value at the reference temperature
Flexible calculator for determining the F, B* and C* values following ultra-high temperature (UHT) processing of milk
Spread sheet for calculating the F0, B* and C* values and the concentration of lactulose following ultra-high temperature (UHT) processing of milk
 Spoilage probability calculator
Modelling the destruction of Mycobacteriumavium subsp. paratuberculosis (MAP) during HTST pasteurisation of milk
Calculator for determining the Decimal Reduction Time (D) at a specified temperature knowing the D value at a given temperature and the Z-value
Calculator for determining the number of survivors of a microbial population after a defined heat treatment
Calculator for determining the time required to reduce an initial population of a microorganism to a predetermined number of survivors

Ice cream / gelato manufacture
Note. With the exception of the calculator for determining the maximum MSNF compatible with normal fat agglomeration the other calculators in this section are only available to subscribers to the On Line Ice Cream Mix calculator.

Ice cream mix calculator (subscription access only)
MSNF concentration of cream (demo only- 
MSNF concentration of unwashed butter
MSNF concentration required for a balanced ice-cream mix
Ice cream density and weight calculator
Calculation of maximum safe overrun for ice cream
Calculator for determining maximum MSNF compatible with normal fat agglomeration in ice cream or gelato

Unit converters.
Temperature

Molarity
Prepare a solution to a given molarity
Using a standard solution prepare an assay or test solution of designated volume and molarity

 

The author’s chapter on the science and technology of modified atmosphere packaging (MAP) in the book 'Food Packaging Technology' has been updated. The second edition of the book was be published in 2011. As a result of this revision, the list of references previously available for downloading has been extensively updated and is available for downloading subject to a small donation towards the running costs of the Dairy Science and Food Technology website.

The list of references is in rich text format (RTF) and can be viewed and edited using most word processing software on PCs and Macs.

The references have been prepared in a Harvard-style format e.g.

Lalitha, K.V. and Gopakumar, K. (2001). Growth and toxin production by Clostridium botulinum in fish (Mugil cephalus) and shrimp (Penaeus indicus) tissue homogenates stored under vacuum. Food Microbiology. 18: 651-65.

The reference list when printed on to A4 paper will give ten  to 12 (10-12) pages of single spaced citations, depending on how your word processing programme is configured, containing some 132 individual references.

Who will benefit from the reference list?

Anyone starting project work on MAP who wants "to hit the ground running"!  The list contains refereed publications, reports from national governments and a small number of quality 'downloadable' resources.

Making a contribution to the development and operating costs of the Dairy Science and Food Technology website

The list can be downloaded after making a donation of £4.99 towards site hosting, maintenance and development using PayPal by clicking the payment button below. 

Once you have paid you will shortly receive an Email giving you a download URL.  You will be able to download the references for 7 days from your payment date; you can make up to 4-downloads over this time.

Legal and other information

While the list of references has been carefully checked there may still be some errors. If you cannot find a particular reference because the details provided contain an error or errors then, Email the details to me at michael.mullan@dairyscience.info including ‘Reference list errors’ in the title and I will usually respond within 3 working days except during holiday periods. Note you will still have to obtain the individual references. These can be obtained from libraries and or the Internet. If you are unhappy with the list of references I will return your donation minus PayPal processing fees.

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