Preliminary studies of chemical reactions as indices of heat lethality : a thesis presented to the Faculty of the Department of Food Science and Biotechnology, Massey University in partial fulfilment of the requirements for the Degree of Master of Technology (Food Technology) in Food Processing

Abstract

In commercial canning, food put into a container always contains micro­ organisms that would cause spoilage if they were not subsequently destroyed. When the destruction of the spores of a certain organism in food has reached a certain pre-established point, the food is said to be sterile with respect to that organism and the object of heat processing canned foods is the at­tainment of sterility with respect to the most resistant micro-organisms present that would bring about spoilage. Since the discovery of the principle of sterilisation by heat and the initial development of the art of heat processing by Appert at the begin­ning of the 19th century, considerable progress had been made in the fields of processing techniques and their evaluation. Standard methods have evolved for determining minimum processing conditions necessary to attain commercial sterility in products. However, as yet, there are no sensitive and reliable methods which do not involve the use of thermocouples for temperature measurement to check on under or over-processing during the routine sterilisation of canned products. The preparation of cans with inserted thermocouples and the recording of temperatures is too laborious and time consuming to become a routine check on processing and so the need for a more convenient method is obvious. The purpose of this investigation was to carry out preliminary studies to ascertain the possibility of using chemical reactions occurring in model systems or food products as indices of heat lethality and so determine if correlations between a chemical index and heat lethality can be established and have commercial application. [From Introduction]