Animal by-products may include blood, skin, bones, leftover meat and their derivatives. We have to be concerned with the halal status of processed products since a lot of their ingredients originate from non-Muslim countries that are derived from pigs or animals that are not slaughtered according to Islam. Ingredients used in animal by-products are,
Blood. In Europe blood is used to make a product similar to sausage. In Germany there are various sausages that use blood as their raw materials such as sausage Thueringer, tongue sausage, blood sausage, etc.
Beside directly processed into curd and blood sausage, blood can also be dried directly and processed into blood meal used as a feed ingredient (fodder) or added in certain processed foods to increase their nutritional value (iron or protein). In addition, blood meal can serve as a binder or filler material that can improve flavour or quality of processed food. For example, dried blood is often added into sausages so that the colour and the water holding capacity of the sausages are better.
Blood can also be processed further, for example separation of the blood in order to obtain the blood plasm and the blood serum. The plasm and the serum are then dried so that they are ready to be used as additives or ingredients in food processing. Processing of blood can also produce globin concentrate which can be used as a substitute for partial lean meat on patty products (meat pie). Blood, especially dried blood can also be used as a red dye in foods.
Skin and Bones. For large animals like cows, buffaloes and horses, generally the outer skin is tanned and subsequently made into craft items. Inner skin (tanning rest), is generally collected and processed further into casings (sausage casings). For small animals, especially pig skin can be directly processed into transparent sausage casing. Pig skin can also be processed further into gelatine. Keep in mind, in principle, gelatine can be made from materials that are rich in collagen such as skin and bone from both pigs and cows, and even now some are made from fish bones. However, if it is made from cow skin and bones, the process is much longer and requires more washing water / neutralizer (chemicals), so it is less developed. Recently halal beef gelatine is available in Muslim countries because of its urgent need to replace gelatine derived from pigs.
Use of gelatine is very extensive, is not only used in food products but also in pharmaceutical and cosmetic products. This is because gelatine is an all-rounder, which could serve as a filler material, emulsifier, binder, clarifier, and nutrient enrichment. It is also flexible. It can form an elastic thin layer, create a transparent and strong film, and has a high dissolve power.
Leftover meat. In deboning process (removal of bone from meat) there is still quite a lot of meat to become waste. Similarly, from cut of meat, often some meat are left that actually can be exploited further.
Leftover meat can be fractionated into protein isolates such as salt-soluble protein (SSP), insoluble myofibrillar protein (IMP) and connective tissue protein (CTP). Each of which has specific functional properties that have been used in making sausages. Protein isolates may be derived from pork mince. Besides, leftover meat can be processed into meat extract that is used for preparation of meat flavour.
There is also the so-called meat protein concentrate produced from leftover meat and protein hydrolyzate made from chicken heads and used for sausage ingredients, supplements for soups, beverages and bakery products. In Germany, they have formulated hydrolyzate collagen protein (usually from bone) that is applied in pate, spread and ready meals.
