Detoxifying Enzymes

Abstract

Natural, often well-accepted, foods and food components often contain substances that can produce toxic or anti-nutritional effects after ingestion. They may be of vegetable, animal or microbial origin, but in all cases specific toxicants can be generated by interaction between endogenous enzymes and substrates if processing releases cellularly bound materials. Substrates are commonly non-toxic in themselves but release toxicants as a result of autolysis of glycosidic or ester bonds. Occasionally, substrates are toxic but can be degraded enzymically to harmless material. In both cases, appropriate process control can benefit the operator and yield an innocuous product.

Endogenous enzymes are released by wetting and rupturing cell material. Contact with substrate follows; at this point, either non-toxic substrates or active enzymes may be removed, deactivated or destroyed. Alternatively, heat processing may be used to denature the enzyme. A third possibility is to promote controlled autolysis and finally remove the resulting toxicants by physical or chemical methods.

Examples of these processing strategies are discussed, with special reference to the processing of: (a) Glucosides of toxicants such as the goitrogenic thiocyanates, isothiocyanates and oxazolidine-thiones; (b) oligosaccharides such as stachyose and lactose, which can result in abnormal carbohydrate metabolism; (c) phosphate esters such as nucleic acids and phytic acid, whose harmful effects can be mitigated by enzyme action.