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The general process of winemaking is initiated by the enzymatic oxidation of phenolic compounds by polyphenol oxidases. [4] Contact between the phenolic compounds in the vacuole of the grape cell and the polyphenol oxidase enzyme (located in the cytoplasm) triggers the oxidation of the grape. Thus, the initial browning of grapes occurs as a ...
Rancidification is the process of complete or incomplete autoxidation or hydrolysis of fats and oils when exposed to air, light, moisture, or bacterial action, producing short-chain aldehydes, ketones and free fatty acids. [1] When these processes occur in food, undesirable odors and flavors can result.
Autoxidation (sometimes auto-oxidation) refers to oxidations brought about by reactions with oxygen at normal temperatures, without the intervention of flame or electric spark. [1] The term is usually used to describe the gradual degradation of organic compounds in air at ambient temperatures.
In archaeology, the Maillard process occurs when bodies are preserved in peat bogs. The acidic peat environment causes a tanning or browning of skin tones and can turn hair to a red or ginger tone. The chemical mechanism is the same as in the browning of food, but it develops slowly over time due to the acidic action on the bog body.
Food preservation includes processes that make food more resistant to microorganism growth and slow the oxidation of fats. This slows down the decomposition and rancidification process. Food preservation may also include processes that inhibit visual deterioration, such as the enzymatic browning reaction in apples after they are cut during food ...
PPO has importance to the food industry because it catalyzes enzymatic browning when tissue is damaged from bruising, compression or indentations, making the produce less marketable and causing economic loss. [31] [32] [33] Enzymatic browning due to PPO can also lead to loss of nutritional content in fruits and vegetables, further lowering ...
Pyrolysis has many applications in food preparation. [23] Caramelization is the pyrolysis of sugars in food (often after the sugars have been produced by the breakdown of polysaccharides). The food goes brown and changes flavor. The distinctive flavors are used in many dishes; for instance, caramelized onion is used in French onion soup.
This process is aided by the release of iron from iron-containing proteins in the meat, including myoglobin and hemoglobin. The iron is released by the heat of cooking, or by mechanical grinding. The free iron then acts as a catalyst, or promoter, of oxidation reactions. The reactions break down some of the fats in the meat to form primary ...