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Following my recent article "Are we closer to understanding why viable cells of Mycobacterium avium subsp. paratuberculosis are still being reported in pasteurised milk? (https://doi.org/10.1111/1471-0307.12617)" I agreed to do a Podcast with Dr Aleks Marsh and Dr Alan Mullan of Andor Technology in an attempt to explain some of the questions that the general public might have about pasteurisation. The Podcast will be broadcast on the 16 January 2020 and is available from the "The Good, the Bad and the Curious" webpage at the Andor website.
I have agreed to write an article on raw milk as part of a series of chapters in a new book produced by Elsevier that will be published in 2020. I will cover the antimicrobial factors and other topics including the presence of probiotic bacteria in modern hygienically-produced milk. The safety of raw milk for human consumption, particularly for children, will also be included.
One of the points I want to make is how easy it is for milk to become contaminated and how difficult it is to prevent some forms of contamination. I am trying to source photographs showing dirty 'drinkers', birds and rodents in/on cattle feed e.g. Total Meal Replacement (TMR), dirty udders, dirty cows.
Below are some of the images that I have found/ obtained or been given so far.
The photograph below shows starlings (a major pest and potential carrier of many human pathogens) eating components in the TMR fed to dairy cows. Farms are not operating theatres and farmers live in the real world. Hence we need to use all the options at our disposal to reduce risk e.g. pasteurisation.
Image from: Anon. (2013) Practical Control Strategies for Starling Infestations. Report prepared for DairyCo by Kingshay. Download url:https://dairy.ahdb.org.uk/non_umbraco/download.aspx?media=16123 .
A further picture clearly showing the nuisance value of starlings in a dairy farm in the US.
Image kindly provided by Professor Amber Adams Progar, Department of Animal Sciences, Washington State University.
Boetech (2019) have claimed that "half of the cows (in Europe) are drinking dirt and shit" I am trying to get some images of cow faeces in drinkers.
Below is a typical picture of crows perching on a water trough in a field. Bird faeces in outside water troughs is not uncommon.
Picture courtesy of Aidan Brennan Irish Farmers Journal
Research continues to associate Mycobacterium avium subsp. paratuberculosis (MAP) with Crohn's disease. At an open lecture at Queen's University Belfast on the 16th October, global expert Professor Irene Grant will unravel the relationship between MAP and this intestinal disease.
A beta version of a calculator that uses the results of a titration with NaOH to calculate the % lactic acid, Soxhlet Henkel degrees, Thörner degrees, Soxhlet Henkel degrees and Dornic degrees of a milk sample has been added. Users may vary the molarity of the NaOH solution, note normality and molarity are identical for NaOH, and the volume of milk used. An accompaning tutorial that provides the underpinning science remains to be added.
The article "Isolating lactic acid bacteria from milk" has been updated following queries why controls are required using M17 agar to selectively enumerate Streptococcus thermophilus in environments containing L. delbrueckii subsp. bulgaricus. While many strains of L. delbrueckii subsp. bulgaricus are inhibited by the β-glycerophosphate in M17, Shankar and Davies (1977) found that 23% of the strains of L. delbrueckii subsp. bulgaricus tested grew well on this medium. Hence the need for controls to confirm colonies as S. thermophilus.
There is considerable interest in alternatives to thermal processing. A recent review in the International Journal of Dairy Technology by Ahmad and his colleagues looks at the effects of non thermal processes on the activity of milk enzymes. I have included the abstract below.
Despite the extensive research on the effects of low temperature storage of milk on the quality and yield of cheese, cheese companies continue to experience periodic problems due to milk being stored for several days on farms. Below is an abstract of some research published in 1994. It is as relevant today as then!
Milk stored at 3°C and 7°C was used to manufacture cheese and the quality and yield of cheeses were assessed. Storage of milk at both temperatures resulted in reduced yields. Storage at 7°C for 3 or more days and 3°C for 5 days adversely affected cheese quality while storage at 3°C for 3 days resulted in an improvement in quality. There was a significant correlation between cheese quality and the psychrotrophic count and total viable count (TVC) of the raw milks. Evidence indicated that the reduction in quality was largely due to the action of extracellular lipolytic enzymes produced by psychrotrophic bacteria. It was concluded that milk for Cheddar cheese manufacture should have a TVC of < 1 x 106 cfu/ml and preferably a count of < 1 x 105 cfu/ml.
Weatherup,W. and Mullan,W.M.A. (1993) Effects of low temperature storage of milk on the quality and yield of cheese. Proceedings of IDF Seminar on Cheese Yield and Factors Affecting Its Control, Cork, Ireland, pp. 85–94.
University College Cork has announced an International Training Course on “Ice Cream Science and Technology”, which will take place in Ireland on 18-20 February 2020. This follows previous successful courses at UCC held biennially since 2004. The course will be delivered by Professor Douglas Goff.
For further information please contact:
Food Industry Training Unit, School of Food and Nutritional Sciences
College of Science, Engineering and Food Science
University College Cork
University College Cork (UCC), in association with Teagasc, has developed a part-time, blended-learning Postgraduate Certificate in Dairy Technology and Innovation. This qualification launched and ran very successfully in 2016/17 and is now being run for a fourth year. This year a once-off bursary has been made available by Taste 4 Success Skillnet. Eligible candidates will receive 50% funding towards the cost of their registration fees.
For further information please contact:
Dr Amy-Jane Troy Programme Manager, Food Industry Training Unit, School of Food and Nutritional Sciences College of Science, Engineering and Food Science, University College Cork. Tel: 021 490 2799. Email: firstname.lastname@example.org
Please click on this link to download a brochure to read about the Postgraduate Certificate in Dairy Technology and Innovation 2018: PG Certificate brochure.
My article on why we are still finding viable cells of Mycobacterium avium subsp. paratuberculosis (MAP) in pasteurised milk has been published On Line ahead of print. Details are given below:
Mullan, W M A (2019) Are we closer to understanding why viable cells of Mycobacterium avium subsp. paratuberculosis are still being reported in pasteurised milk? International Journal of Dairy Technology. DOI-10.1111/1471-0307.12617.
Full Open Access is available for 1-month at https://onlinelibrary.wiley.com/doi/full/10.1111/1471-0307.12617 . Thereafter Read Only Access is available through ReadCube at https://rdcu.be/bGnES .
The Dairy Industry Student Award is sponsored by The Society of Dairy Technology.
This award recognises the efforts of new entrants to the Dairy Industry and promotes their talent to a wide audience. The work of the winning individual will be communicated to a global audience, showcasing their achievement. The award will be presented at the prestigious trade lunch (on the Tuesday of the ICA) at the Nantwich International Cheese Awards in July 2019.
The award is open to any student studying a food science and technology course in the United Kingdom or the Republic of Ireland. Courses may be vocational qualifications, diploma, degree and so on. There is no age restriction to applicants; however the student must be undertaking a dairy project or be employed within the dairy industry.
ALL submissions must be electronically submitted in both PDF and Word formats and NOT as a hard copy. It should be emailed to email@example.com by May 30th and judging will take place during June.
There is relatively little information on the diversity of Polish cheeses. Professor Marek Kosmulski has decided to change this and has published a book detailing some 600 Polish cheeses. This is available free as a download. The book, in Polish, consists of a series of brief descriptions of each cheese accompanied by photographs. Using Google Translate it is relatively easy to get a good understanding of the major attributes of each cheese. The book can be downloaded from http://bc.pollub.pl/dlibra/publication/13557 .
Arguably one of the most significant scientific development's in the last 10 years has been the development of an unique gene editing technology that can be applied to whole cells called CRISPR/Cas9. This technology has many applications in biomedical research, including the potential to treat human genetic disease. However, the technology also has the potential to modify the human genome and change human society.
One of the best free videos explaining how the technology works and giving the background to the discovery is given in the animation below produced at the McGovern Institute for Brain Research, MIT where Professor Feng Zhang, a leader in the development of this technology works.
Further information can be found on Professor Zhang’s website.
Two calculators for determining equilibrium moisture values corresponding to selected Aw values using the Guggenheim–Anderson–de Boer (GAB) model and the Brunauer-Emmett-Tellet (BET) model have been added.
To use the models, the constants for the product concerned must be inputted. Selected Aw values are then added. The calculator will then calculate the equilibrium moisture content for each value and plot it against Aw, to give a sorption or desorption isotherm.
Ireland has a well-deserved reputation as a global leader in food innovation and it is fitting that a new world food resource, bia-biz.com, was recently launched by Michael Creed, the Irish Minister for Agriculture, Food and the Marine.
bia-biz.com is a comprehensive online directory of valuable technical content and free training for food producers, entrepreneurs, scientists, technologists and advisers.
Reflecting the complexity and knowledge needed in today’s food and beverage industry bia-biz.com has 13 pages, 130 sections over 2000 web links, 73 free online trainings, a global events calendar and a national regulations and support page for 112 countries. The layout, site-plan and search functionality is intuitive and user friendly.
There have been several updates to the Dairy Science and Food Technology website in May, 2018.
- An article on how to use Excel to make a calculator for determining the F value of a heat process has been added and can be accessed at https://www.dairyscience.info/index.php/thermal-processing/304-excel-spreadsheets.html .
- A range of Excel Spreadsheets for calculating F, B*, C* values of thermal processes and thermal processing indicators can be downloaded. These can be accessed at https://www.dairyscience.info/index.php/thermal-processing.html .
- The article "Dry heat sterilisation and depyrogenation" has been updated to reflect the biphasic nature of the destruction of pyrogens particularly at temperatures below 180 °C. Access is available at https://www.dairyscience.info/index.php/thermal-processing/238-dry-heat-sterilisation-and-depyrogenation.html .
The article "Factors affecting plaque formation by bacteriophages" has been updated to reflect research by Luhtanen et al., 2018* on cold-active phages.
*Luhtanen,A.-M.,Eronen-Rasimus,E., Oksanen,H.M., Tison,J.-L., Delille,B.,Dieckmann,G.S.,Rintala,J.-M. and Bamford,D.H. (2018). The first known virus isolates from Antarctic sea ice have complex infection patterns. FEMS Microbiology Ecology, 94, 4, 1-15. (available from https://doi.org/10.1093/femsec/fiy028).
The author with chemist colleague Ronnie Irvine visited The Echlinville Distillery at Rubane, just outside Kircubbin, in the Ards Peninsula. A brief account of our visit to Ireland's newest whiskey distillery is given here.
Six new site calculators have been added.
Three are concerned with determining holding tube length, average holding time and Reynolds number:
• Calculator for determining Reynolds number
• Calculator for determining average holding time in a pasteurizer or UHT holding tube
• Calculator for determining holding tube length in pasteurizing and UHT plant
Following feedback from users of data loggers a unique highly flexible F value calculator designed to work with thousands of pasted values of time -temperatures has been added. This calculator allows users, for perhaps the first time, to compare F values obtained by numerical integration using the industry standard method, the trapezoid rule with the more accurate Simpson's 1/3 and 3/8 rules:
A calculator for predicting the concentration of HMF, lactulose and furosine in heated milks (whole, semi-skim and skimmed milk) that also calculates the F0, B* and C* values and the destruction of thiamine has been added. The calculator has been designed to work with thousands of pasted values of time -temperatures. The values are integrated using the industry standard method, the trapezoid rule, and are compared with the more accurate method of numerical integration, Simpson's 1/3 and 3/8 rules:
• Calculator for predicting the concentration of HMF, lactulose and furosine in heated milks (whole, semi-skim and skimmed milk). It also calculates the F0, B* and C* values and the destruction of thiamine. The values are integrated using the industry standard method, the trapezoid rule, and are compared with a more accurate method of numerical integration, Simpson's 1/3 and 3/8 rules.
A generic F calculator for UHT and similar high temperature processes has been added. The calculator has been designed to work with thousands of pasted values of time-temperatures. The values are integrated using the industry standard method, the trapezoid rule, and are compared with the more accurate method of numerical integration, Simpson's 1/3 and 3/8 rules
• Calculator for determining the lethality (F, B* values) and chemical changes (C* value) for UHT processes using the trapezoid and Simpson's rules. Applicable to all UHT processes and designed to take thousands of pasted values.
A free article, "Ultra-high-temperature (UHT) processing of milk. Process lethality, chemical effects and use of temperature-time-integrators (TTIs) to predict heat treatment and over-processing" has been added to the Dairy Science and Food Technology website.
This article investigates how to calculate the lethal effects of UHT treatment and the usefulness of TTIs for differentiating sterilised, direct and indirectly processed UHT-treated milk. The importance of accessing accurate temperature time-data and knowing holding tube dimensions, flow rate, average and minimum holding time and the flow characteristics (Reynolds number) are discussed. The reliability of a model developed by Claeys et al. (2003) to predict the effects of UHT-processing on hydroxymethylfurfural, lactulose and furosine concentrations in milk is discussed. Free On Line calculators for calculating holding time, average flow rate, holding tube length in UHT and HTST plants are provided. A free On Line calculator programmed using the thermal constants calculated by Claeys et al. (2003) is provided to calculate hydroxymethylfurfural, lactulose and furosine concentrations following heat treatment in skim, semi fat and full fat milks. This calculator also calculates F0, B*, C* and % destruction of thiamine. Two methods of numerical integration are used to measure the cumulative lethal and chemical effects of UHT treatment, namely the Trapezoid and Simpson's rules.
The article can be viewed at https://www.dairyscience.info/index.php/thermal-processing/325-uht-processing.html .
This website gets a lot of Email and occasionally one connects.
According to the Daily Mail as many as 9.75 million people - 15 per cent of the UK population - are believed to have been hit by flu symptoms this week. Some 120 flu deaths have been recorded in England, 21 are known to have died in Scotland and eight in Northern Ireland.
It was against this background that a reader who works for a major food processing company sent me a picture of unpackaged bakery-items completely exposed to the environment at a food retailers with a global reputation for producing safe food. She was surprised that the retailer was not taking action to prevent contamination of their bakery items with airborne viruses and from customers with virus-contaminated hands.
The article on "Factors affecting plaque formation by bacteriophages" has been updated and can be accessed at
Plaques of phage D29 produced by Mycobacterium avium spp paratuberculosis assayed using Mycobacterium smegmatis. Image courtesy of Dr Irene Grant, Queens University Belfast.
Fat agglomeration is affected by the process parameters used in gelato and ice cream manufacture, the emulsifer stabiliser system and ingredients. Fat agglomeration has a significant role in dryness of extruded ice cream, slow meltdown, good shape retention and resistance to shrinkage during storage. Too much protein can result in an over stable fat emulsion and insufficient fat agglomeration.
A calculator to determine the maximum MSNF compatible with normal fat agglomeration has been added and can be accessed here.
The latest forum post concerns raw milk and A2 milk. The posts can be viewed at http://www.dairyscience.info/forum/nutrition-and-health_forum14.html .
There is a legislative requirement in most developed countries for food companies to have validated-HACCP plans for all products. The current E.coli 01507:H7 outbreak in Scotland has been linked to raw milk cheese and the death of one child has been reported. Note there are few examples of well validated HACCPs even from large companies!
There are a number of published risk assessements for raw milk cheeses. One of the most comprehensive, "Microbiological Risk Assessment of Raw Milk Cheese", has been produced by Food Standards Australia /New Zealand using quantitative models developed by the University of Tasmania. The assesment can be downloaded from https://www.foodstandards.gov.au/code/proposals/documents/P1007%20PPPS%20for%20raw%20milk%201AR%20SD3%20Cheese%20Risk%20Assessment.pdf .
Recent deaths associated with the consumption of lettuce and other salad vegetables have been well publicised in the media. How do you advise parents to respond to the risks associated with eating salads and maintain consumption of healthy foods? And would this advice differ if they had an immunocompromised family member? Perhaps you have a view on my response to a query from a parent? Please see http://www.dairyscience.info/forum/preparing-salads_topic432.html .
Is Thermus thermophilus the causal agent of pinking in cheese?
“Pinking” the development of a red / pink colour in many cheese-types has been known for many years and has been the attention of significant research interest for decades. Much of this research has been inconclusive although some association with lactobacilli has been suggested.
Recently Quigley et. al. (2016) used shotgun metagenomic sequencing to reveal the presence of bacteria corresponding to three phyla, Firmicutes, Actinobacteria, and Deinococcus-Thermus in 8 ‘continental’ cheeses exhibiting pinking. The phylum Deinococcus-Thermus was absent in control cheese.
I purchased one pot of fat-free-natural yoghurt produced by a major dairy company from the Asda supermarket in Cookstown a few days ago. I opened it this lunchtime today (12th June). It had a use before date of the 24th June 2014 (see below).
I noticed the lumps, clumps of curd on the lid immediately. See below.
Looking at the inside of the container the top part of the yoghurt was less viscous than the bottom, syneresis was starting and grains/lumps/nodules were clearly visible.
The grains / nodules can be clearly seen on the spoon images below.
It is always interesting to see how companies respond to problems. No one answered the contact phone number given on the carton. I also completed a web form on the company website and attempted to contact their PR company using the information on their website. The contact information was not correct however I managed to get the correct information from their website. I eventually got a response of sorts from the website form.
This is the second time in a month that I have bought a stirred yoghurt with this fault. The first time was from a local company in Northern Ireland and it was a natural yoghurt made with whole milk.