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Rendering is a process that converts waste animal tissue into stable, value-added materials. Rendering can refer to any processing of animal products into more useful materials, or, more narrowly, to the rendering of whole animal fatty tissue into purified fats like lard or tallow. Rendering can be carried out on an industrial, farm, or kitchen scale. The majority of tissue processed comes from slaughterhouses, but also includes restaurant grease and butcher shop trimmings, expired meat from grocery stores. This material can include the fatty tissue, bones, and offal, as well as entire carcasses of animals condemned at slaughterhouses, and those that have died on farms, in transit, etc. The most common animal sources are beef, pork, sheep, and poultry. The rendering process simultaneously dries the material and separates the fat from the bone and protein. A rendering process yields a fat commodity (yellow grease, choice white grease, bleachable fancy tallow, etc.) and a protein meal (meat and bone meal, poultry byproduct meal, etc.). Rendering plants often also handle other materials, such as slaughterhouse blood, feathers and hair, but do so using processes distinct from true rendering. The occupation of renderer has been deemed one of the "dirtiest jobs". ==Process variations== The rendering process varies in a number of ways. *Whether the end products are to be used as human or animal food depends on the quality of input material and the processing methods and equipment. *The material may be processed by wet or dry means. In wet processing, either boiling water or steam is added to the material, separating fat into a floating phase. In dry processing, fat is released by dehydrating the raw material. *The temperature range used, whether high or low. *Rendering may be done either in discrete batches or in a continuous process. *The processing plant may be operated by an independent company which buys input material from suppliers, or by a packing plant that produces the material in-house. 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「Rendering (animal products)」の詳細全文を読む スポンサード リンク
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