• 作者： 秦道堅
• 中文摘要： The preservation of food by chemicals,both organic and inorganic, has been thor-oughly studied. Some of them are effectiveonly on certain food, for instance, sodiumbenzoate is good for jams and jellies, butcan not be used for starch paste, or water-melon. Because sodium benzoate would changethe quality of starch paste, caused it lique-fied in texture. While the juice of watermelonwould change its original taste, and make itunfavorable in presence of sodium benzoate. Banana can not be preserved in sodiumbenzoate solution, as it would turn dark incoloration, and the taste is not good. Generally, sodium benzoate is good foracidic food, or food products immersed inacid solution, but not good for the neutralones. The chemical composition and structureof the preservative impart different germi-cidal power. Yet p-hydroxybenzylbenzoate ismuch effective than the methyl ester. Andthe chlorothymol is more powerful than thy-mol. The effective amount of preservativeused in food also depends on the climate ofthe districts. Tropical countries may applya bit more of it than in the cold zone. Be-cause molds and bacteria multiply easily andrapidly in the warm and humid weather. Some food preservatives have been foundharmful to health, and cause cancer, suchas borax, nitrites, and nitrates. Sodium andpotassium nitrites are more effective thannitrates in curing meats. However, theseare banned to be used in most nations. Sodium sulfite may be used as preserva-ative of fish and shrimps, taking the placeof borax, but it may cause the meats to be-come pale in coloration, for it can not actas a color fixative as borax does. Becausesulfite is also a bleaching agent.
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