Meat and bone meal is a product made by heating, degreasing, drying and crushing the body, bone, viscera and other raw materials that are not suitable for consumption in animal slaughterhouses. In addition to the normal production process can not avoid a small amount of impurities, but also mixed with hair, horn hoof, feces and other products. The crude protein of the product is generally in the range of 5 %~60%, and the amino acid component is relatively balanced, and the price is relatively cheaper than fish meal.
Meat and bone meal is rich in nutrients, but it varies with different raw materials and production techniques. Meat-and-bone meal is rich in calcium, phosphorus and rich B vitamins, vitamins A and D. The fat content of meat-bone meal is 8 to 12 percent, and combined with a high crude protein content, it can provide a certain amount of energy for livestock. The content of lysine and sulfur-containing amino acid in meat and bone meal is relatively high. However, the content and availability of amino acid vary greatly with the different sources of raw materials. The amino acid content should be considered in the application of meat and bone meal. Studies have shown that the digestibility of sulfur-containing amino acids in meat and bone meal differs greatly from that in fish meal, while the digestibility of other amino acids is 3%-8% lower than that of fish meal, but the digestibility of tryptophan in meat and bone meal is slightly higher than that of fish meal.
1. Production process
The conventional production process of meat and bone meal is to make animal waste tissue and bone through cooking, degreasing, drying, grinding and other procedures. But for different countries, the specific production conditions of meat and bone meal are different. Australia generally adopts the method of continuous cooking under atmospheric pressure and low temperature for production. The hot processing conditions for protein are relatively mild, with the temperature below 125 ℃ and pressure 0Pa, and the cooking time is short. However, the EU production regulations require the production conditions of meat and bone meal to be 133 ℃, 200 kPa and 20 min, but such production conditions will reduce the digestibility of meat and bone meal.
The traditional processing method of meat and bone meal in China is generally simple pressing and crushing, which can only degreasing, but can not remove harmful substances. Now meat and bone meal processing generally adopts the press -- hot spray technology. The process of pressing and hot spraying refers to the process of making meat and bone meal by drying, grinding and sifting after degreasing animal waste tissue and bone by pressing and degreasing, and then combining with the available nutrients of each raw material in a certain proportion. The hot spray process of meat and bone meal allows raw materials to be treated in a high-pressure tank for 10 min under the conditions of 1.10 MPa pressure, 160 ℃ temperature and 40% water content. The swelling effect and hydrolysis generated can effectively improve the product quality, improve the absorption rate of nutrient elements, and kill harmful bacteria, eliminate bad odor and destroy toxic components. Improve palatability, improve the quality and digestibility of meat and bone meal. In addition, studies have shown that treating meat-and-bone meal with gamma rays improves its nutritional value and can kill salmonella.
2. Storage method and time
The nutrients in meat and bone meal will deteriorate with the extension of storage time and different storage methods. Hendriks W.H. et al. (2006) studied the influence of preservatives added or not on the nutritional value of meat and bone meal and found that the lipids contained in meat and bone meal without preservatives were easily oxidized and deteriorated, but with the extension of storage time, the change was very weak.
It was also found that the contents of dry matter, crude protein, crude fat, cysteine, histidine and methionine in meat and bone meal without preservatives were significantly reduced. However, with the exception of methionine, the ileal apparent digestibility of other amino acids generally did not change over time.
3. Detection method of meat and bone meal
As there is no relevant restriction on the amount of meat-bone meal added in complex feeds and the price of meat-bone meal is low, it can replace a certain proportion of fish meal and become an important source of protein adulteration in complex feeds. Therefore, it is necessary to identify the quality of meat and bone meal by different detection techniques. Normal meat and bone meal color should be yellow to light brown, high fat, processing overheating color will be deepened, pig products color is lighter. It is uniform and powdery, with obvious greasy feeling. Aroma of roast meat and animal fat, should not be burnt or ammonia smell. Do not contain too much hair, hoof, horn and blood meal.
The doping of meat and bone meal is quite common, the most common is hydrolyzed feather powder, blood powder is worse is added raw feather powder, shell powder, stone powder, urea, ammonium salt phosphate hoof horn powder and leather powder and other toxic and harmful substances. At present, the most commonly used microscopy, PCR, near infrared diffuse reflection spectroscopy and enzyme linked immunosorbent method.
(1) Microscopic examination
As a traditional method to detect the quality of meat and bone meal, microscopic examination can detect muscle fibers, hair, feathers, bone and cartilage tissues in meat and bone meal. But microscopic techniques cannot detect other components of meat and bone meal besides those of animal origin, such as fats.
(2)PCR
It is commonly used to detect animal-derived components in meat and bone meal. Due to the instability of protein in heat treated meat and bone meal, PCR method can achieve precision that is not achieved by microscopy and immunoenzymatic reaction. The test is usually performed using conventional PCR techniques and Real-Time PCR.
(3) Near infrared diffuse reflection spectroscopy
Near infrared diffuse reflectance spectroscopy is an objective, rapid, sensitive and highly selective method for the detection of meat and bone meal in compound feed. It is based on the fact that different particles in the feed absorb light differently. But near infrared spectroscopy requires a large number of sample reference values to form a correction and reference model, and then other methods for further detection.
(4) Enzyme linked immunosorbent assay (EISA)
The main principle of enzyme-linked immunosorbent method is the specific combination of antigen and antibody, that is, the specific antigen of a species is made specific antibody, and then the antibody is used to detect whether a substance contains the presence of the component of this species. In the process of production, meat and bone meal has to be treated with high temperature, so it is necessary to find a heat-resistant protein as a marker, and then this protein can be made into specific monogram antibody.
Application of meat and bone meal in pet food
Pet food ingredients commonly used include protein raw materials, energy raw materials, minerals, additives and flavors. Meat and bone meal belongs to the protein raw material of pet food.
Its advantages are:
1. High protein content, balanced amino acid composition, and contains promoting animal growth factors;
2. Low carbohydrate content;
3. High ash content, high calcium and phosphorus content, reasonable proportion and high utilization rate;
4. Rich in vitamins.
Its disadvantages are:
1. High fat content, easy oxidation rancidity, not suitable for long-term preservation;
2. Serious adulteration (feather powder, leather powder, etc.).
Depending on the amount of other feed materials and the physiological stage of the dog (growth, pregnancy and lactation), 20%~25% meat and bone meal can be used in dog food. When meat and bone meal is used in cat food, its ash content needs to be considered. Low ash meat and bone meal (<20%) can be used in larger amounts, but the selection and availability of other raw materials should also be considered.