Meat - Food Chemistry

Food Chemistry “ Meat”  Meat animal tissue used as food. Most often it refers to skeletal muscle and associated fat. may also refer to non-muscle organs, including lungs, livers, skin, brains, bone marrow and kidneys. Main source of meat in the Philippines are pig, goat,...

Food Chemistry “ Meat”  Meat animal tissue used as food. Most often it refers to skeletal muscle and associated fat. may also refer to non-muscle organs, including lungs, livers, skin, brains, bone marrow and kidneys. Main source of meat in the Philippines are pig, goat, carabao, cow, Chicken, and horse  U.S. per capita consumption of meat, 1970-1996
Retail weight Year Beef Veal Pork Lamb Total Chicken Turkey Fish Total 1970 79.6 2.0 48.0 2.1 131.7 27.4 6.4 11.7 177.3 1975 83.0 2.8 38.7 1.3 125.8 26.4 6.5 12.1 170.9 1980 72.1 1.3 52.1 1.0 126.5 32.5 8.1 12.4 179.4 1985 74.6 1.5 47.7 1.1 124.9 36.1 9.1 15.0 185.1 1990 64.0 0.9 46.4 1.0 112.3 42.5 13.8 15.0 183.6 1991 63.1 0.8 46.9 1.0 111.8 44.2 14.2 14.9 185.1 1992 62.8 0.8 49.5 1.0 114.1 46.7 14.2 14.8 189.8 1993 61.5 0.8 48.9 1.0 112.2 46.5 14.1 15.0 187.8 1994 63.8 0.8 49.5 0.9 115.0 49.5 14.2 15.2 193.9 1995 64.0 0.8 49.1 0.9 114.8 49.4 14.1 15.0 193.3 1996 64.2 1.0 46.1 0.8 112.1 50.5 14.7 14.8 192.0 Source: Livestock and Poultry, Situation and Outlook Report,  Heme Iron Sources (3 oz Milligrams cooked) Iron Beef Calves liver 5.3 Sirloin 2.9 Ground, lean 1.9 Pork Tenderloin 1.3 Ham, 1.2 boneless Lamb Loin 2.1 Veal Loin.9 Chicken Breast.9 Meat, contain heme iron which is more easily absorbed by the body. Plants contain : mainly nonheme iron which is not as easily absorbed by the body. Pork culinary name for meat from the domestic pig (Sus scrofa), often specifically the fresh meat but can be used as an all- inclusive term.  It is one of the most commonly consumed meats worldwide According to the USDA's Foreign Agricultural Service, nearly 100 million metric tons of pork were consumed worldwide in 2006  2006 worldwide pork consumption Region Metric tons Per capita (kg) (millions) 1 People's Republic of 52.5 40.0 China 2 EU25 20.1 43.9 3 United States 8.7 29.0 4 Russian Federation 2.6 18.1 5 Japan 2.5 19.8 Others 12.2 n/a  Beef culinary name for meat from bovines, especially domestic cattle. Beef can be cut into steaks, pot roasts or short ribs, or it can be ground. The blood is also used in some varieties of blood sausage.  Veal the meat of young calves (usually male) appreciated for its delicate taste and tender texture.  characteristic odor is sour and aromatic Best age is 4-14 weeks Meat is hung 8 days before use  Lamb, Hogget or Mutton are culinary names for the meat of a domestic sheep. The meat of a sheep a year old or younger is generally known as lamb the meat of an older sheep is either hogget or mutton depending on its age and characteristics. The meat of a lamb is taken from the animal between one month and one year old, with a carcass weight of between 5.5 and 30 kilograms The meat of a lamb is taken from the animal between one month and one year old, with a carcass weight of between 5.5 and 30 kilograms Best quality of meat is obtained from 2-4 year old sheep  Goat Meat The taste of goat meat is similar to that of lamb meat It can be prepared in a variety of ways including stewed, curried, baked, grilled, barbecued, minced, canned, or made into sausage. Nutritionally, goat meat is healthier than mutton as it is lower in fat and cholesterol, and comparable to chicken. It also has more minerals than chicken and is lower in total and saturated fats than other meats.  Horse meat culinary name for meat cut from a horse. It is slightly sweet, tender, low in fat, and high in protein.  Sausage is a type of food usually consisting of ground meat, animal fat, salt, and spices, and sometimes other ingredients such as herbs, sometimes packed in a casing. Sausage may be fresh or preserved by curing or smoking. Classification of Sausage Cooked sausages Cooked smoked sausages Fresh sausages Fresh smoked sausages Dry sausages Classification of Sausage Cooked sausages- made with fresh meats and then fully cooked. They are either eaten immediately after cooking or must be refrigerated. Cooked smoked sausages - cooked and then smoked or smoke-cooked. They are eaten hot or cold, but need to be refrigerated. Fresh sausages -made from meats that have not been previously cured. They must be refrigerated and thoroughly cooked before eating. Fresh smoked sausages -fresh sausages that are smoked. They should be refrigerated and cooked thoroughly before eating. Dry sausages -are fresh sausages that are dried. They are generally eaten cold and will keep for a long time.  Hot dog type of fully-cooked, cured and/or smoked moist sausage of soft, even texture and flavor. Hot dogs are traditionally made from beef, pork, or a combination of both meats. Ham the thigh and rump of any animal that is slaughtered for meat,  is usually restricted to a cut of pork, the haunch of a pig or boar. Storage and Preservation of Meat  Drying Ancient method of food preservation  usually used in combination with salting, curing and smoking It should not affect the water holding and aroma characteristic of meat  Cooling/ Freezing Process of freezing the meat for prolonged preservation of it’s freshness lengthens the shelf life of meat. Cooling slows down lipid oxidation Curing refers to various preservation and flavoring processes of meat addition of a combination of salt, sugar and nitrate and/or nitrite. Many curing processes also involve smoking. Kills bacteria Prolonged shelf life of processed meat products  Salting Addition of salt Salt inhibits the growth of spoilage-causing microorganisms by drawing water out of microbial cells through osmosis. Smoking is the process of flavouring, cooking, or preserving food by exposing it to the smoke from burning or smoldering plant materials, most often wood.  it is a decent antimicrobial and antioxidant main problem is that the smoke compounds adhere only to the outer surfaces of the food; smoke doesn't actually penetrate far into meat  Heating Cause grayish-brown color, protein coagulation, release of juices, decrease water holding capacity and increased the pH of meat.  Tenderizing Tenderizing meat using plant enzyme ( ficin, papain, bromelain)  This substance is sprayed to the meat  Suggested Storage Times for Raw Meat Product Freezer Refrigerator (0 °F) (40 °F) Beef, roasts and steaks 6-12 months 3-5 days Lamb, roasts and chops 6-9 months 3-5 days Pork, roasts and chops 4-6 months 3-5 days Beef and lamb, ground 3-4 months 1-2 days Pork, sausage 1-2 months 1-2 days  Meat Aroma  Raw meat has weak aroma  Heating increase the aroma of meat Meat aroma is consist of  Nonvolatile flavor substances  Flavor enhancer  Volatile aroma constituents  Meat composition Water – ~75% Protein – ~18% Lipid – ~3% Non-protein nitrogen – ~1.6% Carbohydrate – ~1.2% Minerals – ~0.7% Traces of vitamins, etc. PhysicalCompositionofMeat Muscle cells Muscle cells are unique in that they allow the conversion of chemical energy in the form of ATP (high energy phosphate bonds) into mechanical energy and, hence, the ability to do work The basic unit of muscle tissue is the muscle cell (10-100 μm x several centimeters long) Muscle Structure Sarcolemma Each muscle fiber is surrounded by a thin membrane called the sarcolemma Motor nerve endings terminate on the Sarcolemma This is how the signal gets to the muscle cell that it is supposed to contract Sarcoplasm Inside the muscle fiber are the myofibrils These are suspended in a fluid called the sarcoplasm There are about 2000 myofibrils per muscle fiber Muscle fiber divisions Myofibrils Some protein in the myofibril forms the thick filaments Other proteins comprise the thin filaments The particular arrangement of thick and thin filaments in the myofilament produces a distinct light/dark repeating pattern in electron microscopy Thick filaments The A band is principally thick filament protein This is almost entirely myosin – Myosin comprises about 45% of muscle protein MW of myosin = 470,000-480,000 There are about 400 myosin molecules per thick filament Myosin Thin filaments The I band is almost completely thin filament protein This protein is called actin, and it constitutes about 20-25% of muscle protein The actin comes in two forms, G-actin and F-actin Thin and Thick Filaments Actin G-actin – Globular – 42,000-48,000 MW F-actin – Fibrous – 92% alpha helix Fibrous Actin  Tropomyosin – 2 stranded alpha helix – About 5% of muscle protein – 33,000-37,000 MW – Length 400 Å – Lies in actin double helix groove – Each tropomyosin interacts with seven Gactin Connective Tissue Elastin – Gristle Collagen – Principal connective tissue protein. Built up from tropocollagen units. - The more collagen in a muscle tissue, the tougher it is. - It is converted into (tender) gelatin by treatment with moist heat. Adipose tissue Adipocytes – Fat cells Surface fat – Subcutaneous Intramuscular fat – Marbling Related to tenderness and flavor in high grades of meat Post-mortem changes in muscle On the death of the animal, a series of complex biochemical reactions occur that bring about the conversion of muscle into meat As the animal is bled at slaughter, the aerobic pathway for energy metabolism can no longer function For a time, an anaerobic pathway takes over This results in the conversion of D-glucose into lactic acid, which builds up in the muscle and causes a drop in tissue pH This pH drop affects meat quality Effect of pH on meat quality If pH decreases too rapidly – Muscle proteins will denature and cause a loss of water holding capacity – A pale myoglobin color If pH remains too high – Meat will be too dark in color – Meat surface will be dry pH Decline in Meats Generation of meat flavor potentiators during aging As meat ages ATP is converted into ADP, then AMP, and finally in IMP (inosinemonophosphate) and ammonia These molecules provide some of the characteristic flavors of cooked meat Rigor Mortis and Aging Rigor is a stiffening of the carcass a short time post mortem As muscle ATP is depleted and cannot be replaced, actin and myosin react to form the contracted muscle protein actomyosin  Rigor Mortis and Aging Aging - is the process of simply holding the meat so as to allow for resolution of rigor (muscle relaxation) Alterations in the structure of the myofibrils is noted during this process Accompanying rigor are – Loss of muscle elasticity and extensibility – Increase in muscle tension – Sarcomere shortening Note that meat cooked in rigor tends to be quite tough