乳酪

乳酪(cheese)

从乳汁中凝聚出的半固体营养食品。如果奶未及时饮用，会自然凝聚，产生酸凝乳；将这种酸性物质与含有水溶物的液体--乳清分离，即成为鲜乳酪。世界很多地方仍然利用奶的自然凝聚制作乳酪，或在奶中加酸汁使其分解为乳酪和乳清。软凝聚物由奶中蛋白质--酪素形成，酪素在乳糖经乳液内微生物的作用转化为足够的乳酸时或在凝乳的作用下形成。为分离出乳清需将凝聚物破碎，但仍有部分乳清混於凝聚物中。牛、山羊、绵羊、水牛、马、驴、骆马、犁牛的奶可制成品种数以百计的乳酪。成品随着下述不同条件而异，如选择不同奶质和不同制作法，改变脂肪含量，加热或杀菌，加入或培养细菌、霉菌或酵母等。凝乳的形成因温度、时间、凝聚酸度、酸或凝乳用量、分离乳清的程度或速度的不同而异。乳酪的成熟和加工处理，包括一系列生物与化学的反应，水分、酸度、质地、形状、规格及乳酪内部所含微生物均对之有影响。这些条件变化能影响乳酪的成分及香味。乳酪种类包括硬乳酪、半软乳酪和软乳酪。乳酪是蛋白质、脂肪、矿物质（钙、磷、硫、铁）和维生素A的来源。

English version：

cheese

Food consisting of the coagulated, compressed, and usually ripened curd of milk separated from the whey. When milk sours, it forms both a protein-rich gel, or curd, and a lactose-rich fluid, or whey. Coagulation is often facilitated by adding rennin, an enzyme that acts on the milk's chief protein, casein. The resulting curd is then cut or broken to release most of the whey. Ripening and curing are affected by moisture content, acidity, presence of microorganisms, and other factors. Cheese is made from the milk of cows, goats, sheep, water buffalo, llamas, yaks, and other animals; in the West, cow's milk is most common. Products vary according to fat content of the milk, heating or pasteurization, and addition of enzymes or cultures of bacteria, molds, or yeasts. Cheese varieties include hard cheeses (e.g., cheddar, Edam, Emmental, Gouda, Provolone, Romano, Swiss), semisoft cheeses (Gorgonzola, Limburger, Muenster, Roquefort), and soft cheeses (Brie, Camembert, cottage, Neufchatel, and ricotta). Cheese is a source of protein, fat, minerals (calcium, phosphorus, sulfur, iron), and vitamin A.