There will be occasions when a food manufacturer wishes to use a different, but equivalent lethal thermal process. How does the processor calculate the equivalent process?

This article explains how to calculate an equivalent thermal or heat process at a higher or lower temperature and provides access to a free On Line calculator for checking your calculations.

Providing that the F value at Tref and the z value are known then the F value at the required temperature, T, can be calculated using equation 1.

Equation 1.  heq1 articles


Equation 1 has been derived from Stumbo (1973).

Why is the freezing curve of an ice cream or gelato mix important?

Freezing curves are useful in developing new ice cream and gelato products and predicting the hardness of the ice cream produced from particular mixes at designated temperatures, including the serving temperature. Curves can also be used to predict sensitivity to heat shock, storage stability and resistance of packaging materials to deformation during distribution and storage.

The infection of a growing bacterial culture with phage is initiated by the adsorption of the phage to the host cell. The specificity of adsorption of lactococcal phages and the location of phage receptor substances have been studied and has been reviewed (Lawrence et. al., 1976).

Characteristics (Denomination of Protected Origin 12 June 1996) - Grana Padano is a cylindrical cheese with a diameter of 35-40 cm, an edge of 18-25 cm and a weight of 24-40 kg. Ripening lasts at least 270 days. The crust is hard, regular with a dark beige colour. The dough is white or pale-yellow with very small and sparse holes. The texture is solid, granular and the odour aromatic with almond characteristics. The taste is very savoury and mainly salty.

What are starter concentrates?

Traditionally 'bulk starter' in liquid form was used to inoculate the milk used in the manufacture of cheese, yoghurt, buttermilk and other fermented products. Over the past 15-20 years, the use of starter cell concentrates designated as either Direct Vat Set (DVS) or Direct Vat Inoculation (DVI) cultures are increasing being used, particularly in small plants, to replace bulk starter in cheese manufacture.  DVI / DVS cultures for cheese manufacture normally contain defined blends of lactococci and Streptococcus thermophilus. These organisms respond different to salt and temperature and these differences, if not understood, can impact on cheese quality.

Note that the terms DVI and DVS are used interchangeably although particular culture suppliers will tend to use only one term.

In addition to these high activity cell concentrates, lower activity commercial cell concentrates have been used for many years to inoculate milk for bulk starter manufacture, and in the manufacture of 'long set products' that require extended incubation.

Milk is an excellent source of well balanced nutrients and also exhibits a range of biological activities that influence digestion, metabolic responses to absorbed nutrients, growth and development of specific organs, and resistance to disease. These biological activities are mainly due to the peptides and proteins in milk. However, some of the biological activity of milk protein components is latent, and is released only upon proteolytic action. Bioactive peptides are produced during digestion of milk in the gastrointestinal tract, and also during fermentation and food processing.

Bioactive peptides have been defined as specific protein fragments that have a positive impact on body functions or conditions and may ultimately influence health. Upon oral administration, bioactive peptides, may affect the major body systems—namely, the cardiovascular, digestive, immune and nervous systems. The beneficial health effects may be classified as antimicrobial, antioxidative, antithrombotic, antihypertensive, antimicrobial or immunomodulatory (FitzGerald and Meisel, 2003; Korhonen and Pihlanto, 2003a).

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I have included a range of calculators e.g. aids for determining yield, milk component retention in cheese manufacture, ice-cream mix composition and the F-value of thermal processes. Wizards to help students produce correctly cited references have also been included. These aids are included for the use of students and trainees and are not intended for commercial use or to replace support from lecturers and tutors.

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The views expressed are either mine or those of the other contributors. Note contributing authors, including those posting in the forum, are solely responsible for the content of their articles including all views and statements made. 

 Where I have listed URLs of other sites no guarantees are made that any of the links on these pages still work, or are appropriate for your intended use. Site URLs change and others sometimes use these previously appropriate links for purposes that may be offensive or illegal. It is not my intention to direct anyone to sites other than those that contain academically relevant 'food' related content. If you find a broken link or that a link has been changed please let me know and I will modify the link or remove the reference to that link on this site.


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Dr Michael Mullan, FIFST
Dairy Science and Food Technology website


The purpose of this section is to provide some advice on how the nutrient density or energy content of foods is calculated and displayed on food labels. A calculator is also included to enable students producing new products to calculate the energy density using the chemical constituents of the food. The calculator can also be used as a food calorie calculator.

Food manufacturers in most countries are legally obliged to make several declarations on food labels. The UK Food Standards Agency has a very good overview of labelling from a consumer perspective including an interesting review of public perception of labels .

The calculator below is based on a model developed by Giles and Lawrence (1973) to predict the grade value of Cheddar cheese. Instructions on how to use the calculator are given below. Note that the pH and other values should be obtained from 24-hour old cheese.

  Harvard reference generator button   Harvard reference list-writer button  

So you want to know how to cite a reference?  Here you can use 50 Harvard reference wizards to generate a bibliography, "Works Cited", references or citations to books, speeches, images, legal rulings, websites and many other sources of information using the Harvard style, author-date citation method; the legal rulings are not referenced using the Harvard system but are included because many students need to cite at least one legal citation. 

Over the past 10-15 years, there has been an enormous increase in the sources of information available to students; if you are an academic just look at your own thesis and determine how many different citations you used.  If you graduated more than 10-years ago it is unlikely that you used more than 10-different reference types. The diversity of information sources that today's students encounter can create difficulties when it comes to correctly citing some sources, particular electronic sources, let alone judging the validity of the source. Perhaps it should not be a surprise that referencing causes so many problems across higher education wherever it is undertaken!

Following my experiences as a research supervisor, lecturer, education manager and external examiner I decided that I would try to make referencing a little easier by creating a series of 'wizards'; these are forms in which information is entered, and if entered correctly, will  result in a correctly formatted reference. Hopefully through this facility, supervisors may avoid the tautology of citations with ISBN numbers, incorrect Mintel citations and web references!


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