The term curd can refer to a dairy product, such as cheese, formed by coagulating milk, or a solidified liquid resembling this milk product. Other types of curd include bean curd, commonly known as tofu, fruit curd and a curd snack from the Baltic region.
Cheese curd involves curdling milk with rennet or another edible acid, such as lemon juice or vinegar. The producer draws off the liquid, called whey, leaving the cheese. Milk can sour naturally, either alone or with additional lactic acid bacteria or yeast, to create types of curd cheese, including sour milk cheese. Cheese curd products include cottage cheese and quark, which is coagulated with bacteria and sometimes rennet, and paneer, which is curdled with lemon juice.
Bean curd, or tofu, involves a similar production process to cheese curd. It uses curdled soy milk with nigari, calcium sulphate, lemon juice or vinegar. Tofu takes its roots from ancient China, but is part of the East Asian and Southeast Asian diet, especially as an important source of vegetarian protein in Buddhist cultures. Bean curd can be fresh or processed, both having barely any flavour or smell. It is available in three main forms: firm tofu for stir-fry, soup or grilling, soft tofu for blending and silken tofu for puréeing or blending.
The sweet dessert, fruit curd, consists of egg yolk, sugar, fruit juice and zest, and sometimes eggs whites and butter. The chef heats the ingredients together, allowing the mixture to thicken, and then cools the spread before serving. The dessert originates from late 19th and early 20th century England, when people had lemon curd, accompanied with bread or scones, for afternoon tea. Now, the curd is popular in lemon meringue pie or in different flavours, such as lime, tangerine, passion fruit, mango, cranberry and blackberry.
The curd snack is a commercial sweet snack eaten mainly in Russia and the Baltic states of Latvia, Estonia and Lituania, but also produced in other European countries. The snacks usually are 2-inch pieces of ground curd, filled with raisins, jam or chocolate, or glazed with vanilla, kiwi or woodland strawberry-flavoured cream.