|
Browning is the process of becoming brown, especially referring to food. Browning foods may be desirable, as in caramelization, or undesirable, as in an apple turning brown after being cut. Foods, including beverages, can turn brown through either enzymatic or non-enzymatic processes. Browning has an important economic cost, causing deterioration of the value of products in the market of food. == Enzymatic browning == Enzymatic browning is a chemical process, involving polyphenol oxidase, catechol oxidase, and other enzymes that create melanins and benzoquinone from natural phenols, resulting in a brown colour. In general, enzymatic browning requires exposure to oxygen, for example the browning that occurs when an apple is cut. Enzymatic browning can be beneficial for: * Developing flavour in tea * Developing colour and flavour in dried fruit such as figs and raisins. Enzymatic browning is often detrimental to: * Fresh fruit and vegetables, including apples, potatoes, bananas and avocados * Seafood such as shrimp A variety of techniques for preventing enzymatic browning exist, each exploiting a different aspect of the biochemical process. * Lemon juice and other acids lower the pH and remove the copper cofactor necessary for the responsible enzymes to function * Blanching or roasting, to denature enzymes and destroy responsible reactants, as used in the "kill green" phase of tea processing * Low temperatures can also prevent enzymatic browning by reducing rate of reaction. * Inert gas, like nitrogen, prevent necessary oxygen from reacting * Chemicals such as sodium bisulfite and citrates Arctic Apples are a suite of trademarked apples that contain a nonbrowning trait. Specifically, gene silencing is used to turn down the expression of polyphenol oxidase (PPO), thus preventing the fruit from browning. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Browning (food process)」の詳細全文を読む スポンサード リンク
|