奶(milk)

雌性哺乳动物在产後一段时期从乳腺分泌的汁液，可用来喂养幼雏。驯养动物的奶也是人类重要的食物来源。西方国家主要从母牛身上取得奶，在别的地区，奶的主要来源包括绵羊、山羊、水牛和骆驼。奶基本上是水中脂肪和蛋白质的乳状物，也含有已溶解的糖（碳水化合物）、矿物质（包括钙和磷）以及维生素（维他命）（特别是维生素B复合体）。商业上出售的牛奶还添加了维生素A和D。许多国家都要求对牛奶进行巴氏杀菌法，以防止天然滋生或是人为造成的细菌。进一步冷冻可防止腐败（变酸或凝结）。全脂奶（3.5%的脂肪含量）可经过乳脂分离器加工产出乳脂和含1～2%的脂肪的低脂奶或含0.5%脂肪的脱脂奶。商业上出售的奶通常已经透过高压被均质化，奶油分布均匀。奶可以被浓缩或脱水以便保存和运输。其他的奶制品还包括奶油、乳酪和酸奶。

English version：

milk

Liquid secreted by the mammary glands of female mammals to nourish their young. The milk of domesticated animals is also an important food source for humans. Most milk consumed in Western countries is from the cow; sources important elsewhere include the sheep, goat, water buffalo, and camel. Milk is essentially an emulsion of fat and protein in water, along with dissolved sugar, minerals (including calcium and phosphorus), and vitamins (particularly vitamin B complex); commercial cow's milk is commonly enriched with vitamins A and D. Many countries require pasteurization to protect against naturally occurring and artificially introduced microorganisms. Cooling further prevents spoilage (souring and curdling). Fat from whole milk (about 3.5% fat content) can be removed in a separator to produce cream and leave low-fat milk (1-2% fat) or skim milk (0.5% fat). Commercially sold milk is usually homogenized, forced under high pressure through small openings to distribute the fat evenly. It may also be condensed or dehydrated for preservation and ease of transport. Other dairy products include butter, cheese, and yogurt.

参考文章

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