China is the country with the largest number of livestock and poultry in the world. In 2003, the total number of poultry in China was about 8.3 billion, with a total of 4.7 billion, the total output value of poultry was 241.5 billion yuan, and the total output of broilers in China was 6.6 million tons. The processing of the split chicken resulted in a large accumulation of chicken skeletons. 90% of the protein in the bone is collagen, collagen and chondroitin (acid mucopolysaccharide), which has the effect of enhancing subcutaneous cell metabolism and delaying aging. Bone protein is a relatively full-price soluble protein with high biological potency and nutritional value. Higher. At present, the processing and utilization of animal bones in China is still relatively backward. Every year, a large number of animal bones are wasted or processed into products with low added value, such as processing into feed additives. As the processing output of poultry meat in China has increased year by year, how to process and use poultry bones has become a very important issue. This paper reviews the nutritional value of chicken bone and the general situation of processing and utilization.
1 Nutritional characteristics of chicken bone
The chicken bone contains 10.35% protein, 13.44% fat, 3.95% calcium, and 2.04% phosphorus. At the same time, the chicken bone contains various trace elements necessary for the human body. The proportion of calcium and phosphorus in chicken bone is moderate, especially for human body absorption. Its main nutrients are water, protein, fat and minerals. It contains a certain amount of protein and has relatively low fat content. It belongs to a kind of high-nutrition and low-calorie food.
1.1 rich minerals
The bone meal is rich in minerals. The most important ones are hydroxyapatite crystals [Ca10(PO4)6(OH)2] and amorphous calcium hydrogen phosphate (CaHPO4) which also adsorb Ca2+, Mg2+, Na+, Cl on the surface. -, HCO3-, F- and citrate plasma. More importantly, the rich calcium and phosphorus in bone powder is an essential mineral element in the human body, and the ratio of calcium to phosphorus in chicken bone mud is 2:1, which is the best ratio of calcium and phosphorus absorption in the body. Milk is better.
1.2 high quality protein
Chicken bone dry products contain 12.0%-35.0% protein, the highest content of which is collagen composed of collagen fibers. Analysis of the amino acids that make up the protein in the bone meal revealed that the bone powder contains 17 kinds of amino acids, including 8 kinds of essential amino acids. Among them, glycine, glutamic acid, alanine and aspartic acid are more abundant. Comparison with essential amino acids in other foods indicates that the protein in chicken bone meal is a high quality protein.
1.3 Reasonable fatty acid composition
The bone meal contains a reasonable proportion of fatty acids. The main saturated fatty acids are palmitic acid and stearic acid, and the unsaturated fatty acids are oleic acid and linoleic acid. The ratio of saturated fatty acids to unsaturated fatty acids is close to 1:1, which is consistent with the composition ratio of fatty acids recommended by the Nutrition Association [7]. In addition, the bone meal also contains a trace amount of unsaturated fatty acids such as myristic acid (14:0), soybean oleic acid (14:1), palmitoleic acid (16:1), and linolenic acid (18:3).
1.4 Other nutrients
The bone meal also contains phospholipids, phosphoproteins, which are indispensable for brain tissue development, and chondroitin, which is believed to enhance subcutaneous cell metabolism and prevent aging. In addition, there are also a variety of vitamins, such as: VA, VD, VB1, VB2, VB12 and so on.
2 chicken bone processing technology
2.1 Preparation of chicken bone gelatin
The traditional extraction process of chicken bone gelatin preparation is: chicken bone → pretreatment → bone vulcanization → crushing → adding water soaking and moistening → adjusting pH value → extracting glue → post-treatment → chicken bone gelatin. The traditional rubber extraction process adopts a step-by-step heating and splitting process, that is, the first glue is extracted from 55 ° C, and after each increase of 5-10 ° C, up to 100 ° C, the entire stripping needs to be carried out. 5-8 times, it takes about 40 hours. The tannin method takes a long time and consumes a large amount of energy, and the obtained glue is too thin, bulky, and has a large energy consumption for concentration. At the same time, concentration itself is also a heated process, which prolongs the time, promotes secondary hydrolysis and reduces the quality of gelatin. Long-term heating also produces a color reaction that makes the gelatin color yellower. Liu Xiaoling et al. (2004) adopted a modified extraction process: bone vulcanization → pulverization → H2O2 solution soaking and moistening → pH adjustment → gel extraction → post-treatment → chicken bone gelatin. The results showed that the addition of 0.2% H2O2 to the bone pigment increased the extraction rate of gelatin by nearly 3 times. At the same time, the gelatin had a light color and good antibacterial property, but the viscosity and gel strength of gelatin decreased. The improved extraction process greatly reduces gelatin production time and energy consumption. The results of determination of amino acid and viscosity average molecular mass showed that the destruction of aromatic amino acids by H2O2 accelerated the cleavage and depolymerization of collagen chains, which led to an increase in the extraction rate of gelatin and a slight decrease in the gelatin molecular weight of gelatin. Infrared spectroscopy showed that the gelatin extracted by this method did not have a helical structure.
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Liu Xiaoling also studied the process of producing medicinal and edible chicken bone gelatin with chicken leg bone as raw material. The gelatin process is: commercial chicken leg bone → pretreatment → osteosynthesis → liming → gel extraction → filtration → centrifugation → concentration → drying → Finished gelatin. The optimum extraction conditions were temperature 70 ° C, pH 5, and the ashing conditions were: Ca(OH) 2 mass fraction 0.1%, temperature 10 ° C, and liming time 6 d. The liming treatment can remove the impurity protein, improve the purity of the gelatin, and increase the viscosity and the freezing power. The gelatin obtained by processing chicken bone can be widely used in various industrial fields such as food, medicine, photography, cosmetics, etc., and has a wide range of uses.
2.2 Production of chicken bone meal and meat and bone meal feed
2.2.1 Production of chicken bone powder
The process for producing chicken bone powder includes a crude process, a steaming process, and a drying process. The processing process of the crude bone powder is to crush the bone into small pieces and put it in a pot for 3-8 hours to remove the fat in the bone. When the crude bone powder is processed, it is combined with the extraction of bone oil. In addition to processing the bone powder, part of the bone oil and bone glue can be extracted. The boiled bone is drained, dried, and pulverized and sieved. The processing technology of steamed bone powder is to use steam steamed bone to extract bone oil and bone glue, so that bone glue, bone oil and bone are separated, and bone slag is dried and pulverized to form bone powder. The processing of the dried bone powder is to scrape the bones of the bones and soak them in the lime water for 20-30 days, remove all the oils, take them out and dry them, and then pulverize them into bone powder.
In order to improve the body's full absorption and utilization of bone nutrient components, bone powder can be modified or treated before being applied to food processing to improve its edible value. The main methods used now are acid hydrolysis, alkaline hydrolysis, enzymatic hydrolysis, and microbial fermentation. Bone meal is rich in nutrients, enhances appetite, and is easily absorbed by calcium and phosphorus. It is widely used in food and feed. Wang Hongxin et al (2005) reported that enzymatic hydrolysis of chicken bone powder is carried out by enzymatic hydrolysis. The obtained product is rich in nutrients such as calcium, phosphorus, amino acids, peptides, proteins and other chicken bones, and the nutrients are more easily absorbed by the human body, and can be used for making chicken essence. Give the chicken a full chicken flavor.
2.2.2 Production of meat and bone meal feed
Wu Lili and other studies have shown that using chicken leg bones as raw material, steam compression and high temperature sterilization can be processed to obtain meat and bone meal feed with good palatability to livestock and poultry. The prepared meat and bone meal contains 30% crude protein and 13% calcium. The available phosphorus is 6%, and the proportion of essential amino acids in the feed is higher than that of Zhejiang fish (dry) powder, peanut meal, intestinal feather powder and leather protein powder. The lysine content of meat and bone meal made with chicken leg bones is very high, reaching 2.74%. It can be replaced by fish meal after partial feeding of methionine by feeding test, partially replacing soybean meal; the feed can be used in corn-soybean-type pig and chicken feed. All of them replace calcium hydrogen phosphate, which reduces the cost of feeding. At the same time, the effective phosphorus content in the meat and bone meal is rich, and the use of 215% in the feed of the laying hen can increase the egg production rate by about 10%.
2.3 Chicken bone mud processing
Liang Shu (2000) used 0.1MPa, heat preservation for 25min, and added water, spices, rice wine, vinegar and salt to achieve the purpose of softening the chicken bone. The steamed chicken bone was broken, coarsely ground and finely ground. It is a chicken bone mud with a high calcium content. Gao Xiang (2002) and other research techniques for the study of chicken bone mud are: frozen chicken skeleton → thawing → elective → high temperature softening → crushing → grinding → chicken bone mud. The chicken bone mud prepared by the process is rich in nutrients. In addition to containing a large amount of calcium, it also contains phospholipids and phosphoproteins which are indispensable to the human brain, can moisturize the skin, supplement the blood, prevent aging of chondroitin, collagen and energy. Methionine and vitamin A, B1, B2, B3 and other nutrients that promote liver function.
Chicken bone mud can be used to make foods rich in chicken bones such as chicken bone mud spicy sauce, chicken bone paste, chicken bone meat meatballs and chicken bones. After adding chicken bone mud, the nutrition of chili sauce increased significantly, and it was rich in glial protein, phospholipid and minerals such as calcium and phosphorus, and greatly improved the flavor and taste of traditional chili sauce. The purpose of seasoning and nutrition. After the chicken bone is made into chicken bone paste, it not only makes full use of the meat attached to the bone, but also obtains protein, calcium and bone marrow beneficial phospholipids, chondroitin, rich amino acids and vitamins A and B1. , B2 and other trace elements necessary for the human body, the protein content of the chicken bone paste exceeds l1%, and the bone paste is added to the calcium-rich sausage which is made in wax and sun according to 5% and 10%, and the calcium content It can reach 48mg/100g and 95mg/100g respectively; adding the bone paste to the noodle product in 10% can increase the calcium and phosphorus content of the series by 2-3 times. Therefore, foods with added bone paste are very suitable for the elderly, children and people with calcium deficiency. Adding chicken bone mud to the meatballs will greatly improve the nutritional value of the meatballs, making the products rich in calcium which is easily absorbed by the human body.
2.4 Preparation of chicken bone extract
The processes for preparing chicken bone extract mainly include atmospheric pressure boiling, high pressure cooking, alkali hydrolysis, acid hydrolysis and proteolysis. The preparation of chicken bone extract by alkaline hydrolysis method makes the natural L-amino acid racemic reaction to form D-amino acid, so it is less used; the acid used for hydrolysis of bone is hydrochloric acid, sulfuric acid, phosphoric acid, citric acid, acetic acid and malic acid. Lian Xijun compared the acetic acid, phosphoric acid, citric acid and lactic acid hydrolyzed bone powder. The percentages of four acid-transformed bone calcium were 19.3%, 28.8%, 30.7% and 12.2%, respectively. Lin Jinqi et al. (2000) studied the acid hydrolysis process using chicken bone as the raw material. The optimum conditions for extracting the ingredients as raw materials for the seasoning were water: chicken skeleton was 3:1, citric acid was 1.0%, and hydrolysis temperature was 121. °C, hydrolysis time is 2h. Xie Rui et al (2003) washed the chicken skeleton as raw material, added water refining pretreatment, and added enzyme thermostatic hydrolysis enzyme to centrifuge to obtain enzymatic hydrolyzate. The study showed that the optimum conditions for papain hydrolysis of chicken bone mud were substrate concentration 5 %, temperature 70 ° C, pH value 6.0, enzyme amount 4000 u / g, hydrolysis time 6h, based on the hydrolyzate, through the temperature control reaction and the addition of some spices can be made into a variety of flavored compound seasonings.
3 Conclusions and prospects
In summary, chicken bone is rich in protein, unsaturated fatty acid and vitamin B. The proportion of essential amino acids in protein is high, the titer is high, and the content of calcium and phosphorus is high. The ratio is 2:1, which is suitable for human body absorption. It is a potential High nutrient low heat food. At present, the processing utilization rate of chicken bone is not high, mainly through the rough processing of animal feed. The research on the processing and utilization of chicken bone has been carried out, including the preparation of chicken bone gelatin, chicken bone powder, chicken bone mud and chicken bone extract. It can be used as a seasoning, food and feed additive in food and feed processing. In particular, chicken bone extract has a good flavoring effect, and has the advantages of enhancing nutritional value and flavor, and is in line with the high quality of food in the international market today. The need for natural seasonings in the process. The research on the processing and utilization of chicken bones can make rational use of the by-products produced in the current development of the chicken industry and turn waste into treasure, which has a good development prospect.
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