Rendering process tallow

Rendering Process Tallow Meat and Bone Meal... 

Rendering. The rendering process is applied on a large scale to the production of animal fats, such as tallow, lard, bone fat, and whale oil. The fatty tissues are chopped into small pieces and are boiled in steam digesters. The fat is gradually liberated from the cells and floats to the surface of the water, where it is collected by skimming. A similar method is used in the extraction of palm oil from fresh palm fruits. 

Fat fractionation as we know it today has its origins in the late nineteenth century with the invention of margarine in 1869. The secret was the careful crystallization of freshly rendered edible tallow at temperatures between 25°C and 30°C [2]. The resultant grainy mass was then hydraulically pressed to obtain a crude 60 40 separation of a soft fraction (olein) and a hard fraction (stearin). This has remained the basic principle of the modern process. The softer fraction had physical properties similar to those of anhydrous milkfat (AMF) and was easily rendered into a plastic product that could be used in place of butter. 

Along with the reduced consunq>tion of meat products, the production of rendered animal fats has also declined. Beef tallow consumption has increased greatly since 1950 due to its distinctive flavor and stability as a frying medium. In 1985, 460,000 metric tons of beef tallow were used in the U.S. for baking and frying, but this figure was reduced to 289,000 metric tons in 1990 and is probably less this year. The decreased production of beef tallow has made it unprofitable for renderers to continue Ae processing procedures required to produce edible tallow (i). 

As animal fats are a potential feedstock for biodiesel production, Cummins et al. (142) assessed the danger of a human contracting CJD as a result of the use of tallow as a fuel in diesel engines. They concluded that the risk was several orders of magnitude less than the rate of spontaneous appearance of CJD. Thus, scientific analysis indicates that processed (i.e., rendered) animal fat is not an agent of transmission of BSE. Nonetheless, especially in the United Kingdom, the public remains skeptical. This has in some cases led to less use of animal fats in feed applications. Especially in the United Kingdom, the BSE epidemic has reduced the amount of domestically available tallow (because of condemnation) and increased the use of other lipids in place of animal fats. 

Edible animal fat in the United States can be rendered only in food grade plants under inspection of the U.S. Department of Agriculture (USDA) (1). The majority of tallows and greases used domestically in animal feeds and pet foods are feed grade. The National Renderer s Association (NRA) describes rendering as a process that... 

In general, crude fish oils and animal fats cannot be used directly to produce oleo-chemical compounds they must first be refined or further processed. Free fatty acids are usually thought of as impurities in commercially available rendered fats. Consequently, manufacturers of purer grades of tallow will refine tallow and other fats by adding a caustic material compound such as sodium hydroxide to form soaps of fatty acids, which are washed out with water. 

As a result of processing methods, condition of the original byproduct raw material, storage conditions, and other factors, rendered fats may have a minimum color that can be achieved by refining and bleaching. This best attainable color can be determined by the AOCS Method Cc 8d-55, refined and bleached color (tallow and greases for soaps). The various grades of rendered fats reflect different R B color values as outlined by the AFOA (14). 

Edible beef tallow (premier jus) is obtained by rendering approved edible stock and frequently does not require further refining (free fatty acid 0.3%). The USDA exerts very close control on the processing and transport of edible tallow. Recent specifications for different grades of tallow are given in Tables 3.173 and 3.174. The fatty acid compositions of beef tallow are given in Table 3.164. 

Scenario II In contrast to the previous setting, the system boundaries for biodiesel from tallow are set outside the gate of the slaughtering house. Rendering products leaving the slaughtering process are considered as waste-stream comparable to UVO in scenario I. These render products are... 

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