Enzymes can indicate quality of food
Enzymes are not inactivated after harvest or slaughter and act as factors detrimental to food quality as assessed in term of color, flavour, aroma, texture and nutritional value.
Superior quality food can be obtained when heat treatment is applied just sufficient to inactivate the most crucial enzymes responsible for deterioration.
For each product, specific changes are responsible for deterioration in its quality.
Generally, polyphenoloxidase, chlorophyllase, lipoxygenase, lipase, esterase and protease may be responsible for color, flavor and aroma changes.
Pectic enzymes cellulose and hemicellulose may responsible for texture changes in plant materials.
Thiaminase, ascorbic acid oxidase or other oxidoreductase may cause a loss of nutritional quality in terms of some vitamins, or essential fatty acids.
These can act as indicator enzymes.
Among these, in the food industry peroxidase and alkaline phosphatases, the most heat stable enzymes, found in raw fruits and vegetables and milk respectively, have been used for testing the efficacy of blanching and pasteurization.
In fact heat treatment sufficient for the inactivation can lead to overheating of the sample leading to loss of quality.
It has been proved that best quality frozen food, stored peas , green beans, cauliflower and Brussels spirits can be obtained when 6.0-6.3%, 0.7-3.2%, 2.9-8.2% and 7,5-11.5% respectively, of peroxidase activity remains at the end of blanching.
Off flavour development and color loss in green beans peas and corn is caused by lipoxygenase.
Aroma deterioration in broccoli and cauliflower is by cystine lyase. Thus there is a need to pinpoint the indicator enzymes in each food and develop simple sensitive methods for their essay to be adaptable by the industry for routine online quality assessment.
Enzymes can indicate quality of food
