Technologists producing acidic foods such as pickles and sauces often find it difficult to get information on the processing conditions required to obtain commercial sterility or how to calculate the processing time at a higher temperature. Following the experience of working with processors experiencing technical issues, including spoilage problems and difficulties in exporting products, I have produced a concise Ebook (Thermal processing of acid fruit and vegetable products. Significant microorganisms, recommended processing time / temperatures, and public health significance of spoilage) that may be helpful. Currently the Ebook (figure 1):


Thermal processing Ebook1) 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.

 The booklet can also be used on an iPhone or Android device that can view PDF files.

This Ebook currently contains 17 pages, 5 tables and 19 references (the table of contents is shown in figure 2). Worked examples are provided and the author is prepared (within reason) to help users having problems.

The Ebook was updated to version 1.3 on the 30th June 2012.

The Ebook will continue to be updated periodically and donors will be advised of updates through the News Section of the website. Updates will be available at no cost. Updates must be requested to webmaster at this website and reference should be made to the website used when donating.

Note the Ebook should also be of use to food technology students, manufacturers of pasteurized, acidic beverages, including 'health foods' and some pharmaceutical products such as mouthwashes.

While the Ebook focusses on acidic products, the equations used and the underlying thermal bacteriology apply to a much wider range of products.


 Table of contents

 Figure 2. Table of contents of the thermal processing Ebook.

The Ebook is available as an immediate download following a donation of £40 (about $51 or 44 Euros) to the Diary Science and Food Technology website. 


Pay with PayPal, PayPal Credit or any major credit card

Donors can request, at no cost, working spreadsheets using any of the formulas discussed in the Ebook. Please mention the Email address used in the original donation. This option is not available to students accessing this book through  E-Learning or Virtual Learning Environments.

Librarians wishing to use the Ebook for students on E-Learning or Virtual Learning Environments can contact me on webmaster at this website to make the arrangements.



Article updated 13th May 2021.