Enzymes are organic catalysts produced by living cells (but capable of acting independently of the cells producing them). They are highly perishable proteins, very susceptible to change by heat, and most of them are very rapidly destroyed by temperatures of above 104∞F (about 40∞C). Although they are proteins, in many instances for an enzyme to be active, some co-factor of a non-protein nature is required (co-enzymes or co-activators; TABOR’S MEDICAL DICTIONARY). Cooking, pickling, pasteurizing, smoking and other such processes quickly destroy them.
Enzymes are very specific in their action i.e., each will act only upon a certain substance or group of closely related substances and no other. The more common groups of enzymes are: (a) hydrolytic enzymes fat, protein, starch and sugar-splitting enzymes; (b) coagulating enzymes those which cause clotting; (c) oxidases, or oxidizing and deaminizing enzymes those destroying amino groups during oxidation; (d) reducing enzymes; (e) those producing carbon dioxide without the use of free oxygen; (f) those enzymes which result in the breakdown of a larger molecule into a smaller one without changing molecular structure;(g) and muctases those enzymes which bring about chemical rearrangement without change of the molecules in size. TABOR’S CYCLOPAEDIC MEDICAL DICTIONARY lists 23 enzymes required in the process of digestion alone.
Each enzyme has an optimum temperature at which it acts with greatest efficiency (usually from about 30∞ to 40∞C. or 104∞ F.). Furthermore, each enzyme is influenced by the medium in which it acts, there being an optimum degree of acidity and alkalinity. Enzyme activity can be retarded or inhibited by (a) low temperatures; (b) the presence of salts of heavy metals (copper, mercury); (c) dehydration; (d) ultraviolet radiation.
During the growth of a fruit or vegetable, until it ripens, enzymes are essential to the manufacture of vitamins. When the fruit is gathered, the same enzymes bring about the destruction of these vitamins. Thus, preserving nutritional value when preparing foods depends largely on preventing enzyme action, and excluding oxygen and light. Vitamins A, C, and E are destroyed by combining with oxygen. This combination of oxygen with vitamins is brought about largely by enzymes. Enzyme action can be inhibited by exposure to cold (many enzymes are most active at room temperature and their acitivity decreases as the temperature approaches boiling, at which point they are destroyed); by the addition of acid (lemon juice or vinegar, for example); and by the absence of light, depending upon which nutrients you are trying to preserve. The action of the enzyme which destroys vitamin C, for example, is inhibited by acids, while the enzymes which affect vitamin B2 are active only in the presence of light.
Preserving minerals primarily involves keeping the food out of water. When whole (unsliced) vegetables are soaked, washed or boiled for only 4 minutes, 20 to 45% of the total mineral content (and 75% of the sugars) they contain dissolve into the water. Vegetables are frequently soaked or washed before (and/or during) cooking for longer than 4 minutes, and the losses are accelerated when they are soaked after being peeled, chopped, sliced, minced or shredded.
Besides vitamins and minerals lost by cooking, enzymes are destroyed by temperatures above 104∞F. Numerous diseases are known to exist which are caused by the deficiency or malfunction of certain enzymes. Digestive enzymes, for example, are necessary before proteins can be converted to amino acids, starches and complex sugars to simple sugars, and fats to fatty acids and glycerol. These changes must take place before nutrients can be utilized by the body efficiently and without causing allergies.
Many claim that it is an enzyme deficiency itself which produces signs of age such as loss of vitality, wrinkled skin, thinning hair, and sagging muscles. In one rather interesting study, Dr. Frances Potenger divided a group of 900 cats. Half of the animals were fed raw milk and raw meat; they remained extremely healthy and produced similarly healthy offspring for three generations. The other group were fed exclusively on cooked meat and pasteurized, evaporated or sweetened condensed’ milk. They displayed gingivitis, loss of teeth, loss of fertility, diminished sexual interest, allergies, infections, diarrhea, pneumonia, heart trouble, kidney and thyroid diseases and paralysis, besides sway backs and other skeletal anomalies.
These findings are supported by the work of Steiner, an investigator for the Swiss Board of Health in Berne, who took a large number of guinea pigs off their normally raw diet and fed them food cooked in a pressure cooker. The animals developed softened teeth, gum diseases, anemia, and goiter, among other disturbances. When pasteurized milk was added to their diet, arthritis appeared as well.
The Chinese use cooking methods which do not kill the food being cooked, but rather, enhance it. For example, the method of chow, or stir frying, consists in cooking with very high temperatures using only a small amount of vegetable oil (water can be used instead of oil), stirring the ingredients constantly so that they won’t overcook. Cooking time is short, totaling 3 to 6 minutes, and allows for preservation of nutrients, color, flavor, and texture.
A word about the esthetics of eating: The preparation of food should be a joy. It should be gentle. Above all, it should be inspired. Eating should turn you on. That’s what food is for to make us live!