Keynote: Enzymes and Food Processing

Abstract

The main unifying theme of any conference on this subject must be the use of enzymes to modify biopolymers. As these are almost invariably condensation polymers, the main chemical reaction involved is hydrolysis, which may be very slight or be taken to the stage of complete breakdown to monomers as in the preparation of crystalline glucose from starch.

There are many reasons for wishing to manipulate biopolymers. The improvement of digestibility, palatability and general attractiveness are important; so also are improvements in keeping quality, nutritional value, ease of preparation and yield of edible fraction from raw material. The increasing cost of food has also recently emphasised the economic necessity of utilising polymers formerly regarded as waste or as outside the range of normal foodstuffs, e.g. the recovery of waste protein or the utilisation of cellulose. The same reason leads to a search for cheaper starting materials for the supply of well established foodstuffs, e.g. the switch from sucrose to glucose as a source of fructose since the advent of glucose isomerase. In this economic context it should be borne in mind that enzymes may well encounter political as well as technological opposition. As food becomes more sophisticated, the subtlety of the processes involved in its preparation increases, demanding even stricter control and therefore increasing variety and purity in the catalysts concerned.

Unfortunately, enzymes are not always beneficial—for example, proteolysis in dough, autolysis in vegetables designated for freezing and rancidity in fat-containing foods all involve some degree of enzymic activity. Finally, processes require analytical control, and nowadays some of the most sensitive, rapid and specific methods of analysis are enzymic. In the future, it seems likely that the increasing sophistication demanded of the catalysts and the consequent increase in cost must inevitably lead to attempts to recycle or recover them. Some clue as to how this may be done can be gleaned from looking at the various proposals for solid-supported enzymes, ultrafiltration reactors and non-dividing microorganisms trapped in polymeric matrices.

The papers from this conference serve to emphasise the wide variety of uses of enzymes in food processing at the present time and it seems that this usage can only increase in extent and sophistication in the future.