Food Freezing

The remarkable growth of food technology in industry has been matched by an equal development of related educational programs in food science in colleges and universities in many countries. A vast and growing body of reference books is now available to profes sionals in the field. They have at their fingertips the current state of the art and knowledge in the various areas of specialization embraced by the food industry. For example, excellent reference books are available in the general area of food freezing. The Freezing Preservation of Foods by Tressler et al. is a four volume reference work which covers the subject in detail. Fundamentals of Food Freezing is a book written as a textbook. It repre sents the accumulated art and knowledge in the field of food freezing and draws upon the four volumes of The Freezing Preservation of Foods and the current literature in reference. This new textbook is designed as a unit of instruction in food freezing. As such, it is presented in 16 chapters. The total effect we have attempted to develop is a rounded overall presentation for the student. It is a pleasure to acknowledge the contributions of our many col laborators in preparing this text. These collaborators are identified in the list of contributors; to each, we are most deeply obliged. However, the undersigned are responsible for errors of omission or commission.

Translation of: Conserves naturelles des quatre saisons.

Food Freezing: Today and Tomorrow represents the contributions of the invited speakers to an advanced study seminar held by the Institute for Applied Biology of the University of York during April 1990. The main objective of the seminar was to bring together food scientists and engineers to discuss their mutual problems and to seek new directions for possible solutions.

Freezing time and freezing heat load are the two most important factors determining the economics of food freezers. This Brief will review and describe the principal methods available for their calculation. The methods can be classified into analytical methods, which rely on making physical simplifications to be able to derive exact solutions; empirical methods, which use regression techniques to derive simplified equations from experimental data or numerical calculations and numerical methods, which use computational techniques such as finite elements analysis to solve the complete set of equations describing the physical process. The Brief will evaluate the methods against experimental data and develop guidelines on the choice of method. Whatever technique is used, the accuracy of the results depends crucially on the input parameters such as the heat transfer coefficient and the product's thermal properties. In addition, the estimation methods and data for these parameters will be reviewed and their impacts on the calculations will be evaluated. Freezing is often accompanied by mass transfer (moisture loss, solute absorption), super cooling and nucleation and may take place under high pressure conditions; therefore methods to take these phenomena into account will also be reviewed.

This work presents a comprehensive overview of existing knowledge regarding the influence of freezing, frozen storage and thawing of specific food-stuffs. It delineates how freezing processes alter the colour, appearance, palatability, nutritional value, intrinsic chemical reactions, microbiological safety and consumer acceptance of foods. The fundamental concepts upon which food-freezing technologies are based, are reviewed.