Comprehensive utilization of waste materials from fish processing

The remaining fish head, fish tail, minced meat, scales, skin, viscera, bone, gallbladder and so on, contain a lot of protein, amino acids, trace elements and vitamins. Using these protein resources, a variety of deep processing products can be made, including soluble edible fish protein meal, liquid fish protein feed, fish scale glue, fish skin glue, bone paste, fish protein calcium sugar, bile pigment calcium salt and bile salt, etc. Comprehensive utilization of fish processing waste can reduce the cost of leading products, increase the added value of aquatic products, maintain the environment, reduce the discharge of waste water and waste, and achieve higher economic, ecological and social benefits. The above products are described as follows.

Soluble edible fish protein meal is rich in nutrition, good water solubility, easy to digest and absorb, can be used as amino acid fortified food base material, milk powder substitute, and can also develop nutritional soup, condiment and fish protein beverage and other products. It is an effective drug for the treatment of diarrhea caused by dyspepsia in children, and it can also be used as a protein source in the food fluid of patients with cancer or postoperative eating difficulties. There are many methods to prepare the product, such as enzymatic hydrolysis, acid hydrolysis, alkali hydrolysis, alcohol extraction degreasing and so on. Especially the enzymatic method is better, which can not only maintain the inherent nutrients of fish, but also taste good and easy to dissolve, so it is a new technology developed abroad recently.

1. Technological process: raw material treatment → enzyme hydrolysis → centrifugation filtration → fish protein hydrolysate → decolorization → vacuum drying → crushing → finished product.

two。 The technological process. Use fish minced meat, fish head and fish tail in the scraps after processing as raw materials, wash and mash them with water. Take the mashed fish paste into the reaction pot, add water to adjust the pH value to 6.5: 7.5, and make the solid-liquid ratio 5 ∶ 8, add 1% ~ 2% protease, react under the condition of 45 ℃ ~ 60 ℃ for 2 hours ~ 4 hours, heat and boil for 10 minutes to inactivate the enzyme, centrifuge filtration, the filter residue is discarded (as fertilizer or feed), the fish protein hydrolysate is obtained. The soluble edible fish protein powder was obtained by decolorizing 10 grams of activated carbon per liter at 65 ℃ for 30 minutes, vacuum drying at 50 ℃ ~ 55 ℃, crushing by ball mill and passing through 200 mesh copper sieve.

Liquid fish protein feed is not only nutritious, but also its protein exists in the form of polypeptides and amino acids, which is more conducive to animal digestion and absorption. The feed preparation methods include molasses fermentation method (using sugar cane to make sugar scraps), acidification method, alkalization method and so on. The acidizing method is as follows.

1. Process: raw material treatment, → acidification, → liquefaction, → finished product → storage.

two。 The technological process. Liquid fish protein feed is made of spoiled fish, low-quality miscellaneous fish, fish head, viscera, etc., which has lost its edible value, is mashed with a hammer crusher, the mashed raw material is placed in an acid-resistant container, and 85% formic acid is added. The dosage is 3.5% of the weight of the raw material, and the pH value of the acidified raw material must be less than 4. The acidified raw materials are placed in an acid-resistant liquefaction pool for liquefaction. The liquefaction time varies with temperature and raw materials, generally 30 ℃ ~ 35 ℃ at room temperature for one or two days. The liquefied fish protein feed was stored in an acid-resistant covered container with a shelf life of 1 ~ 2 years at room temperature.

Third, fish scale glue and fish skin glue are used to extract animal glue from discarded skins and scales in the process of fish processing to replace pig skin, cowhide, mule skin and turtle and turtle carapace. Fish skin accounts for about 5% of the fish body, and fish scales account for about 2.5% and 4%. Therefore, the non-utilization of fish scales and skin is a great waste. Practice has proved that making glue from fish scales and fish skin is one of the best raw materials in animals. Fish scale and fish skin glue can play the same effect of nourishing yin and stopping bleeding as tortoise plate glue and donkey-hide glue, and has a unique effect in moisturizing and tonifying the lungs. Now the glue making technology is introduced as follows.

(1) preparation of fish scale glue

1. Technological process: fish scale → washing, → soaking, → soaking, → liming, → flushing, → boiling, → filtering, → solidification, → scraping, → drying → products.

two。 The technological process. After washing, the fish scales are soaked in 5% caustic soda solution for about 5 minutes to remove grease, fat skin and expand the scales. Rinse the alkali-soaked fish scales with water immediately, then soak them in clean water to remove alkalinity, until phenolphthalein does not produce red. The washed fish scales were then immersed in hydrochloric acid, and the dosage was 12% at the beginning (the volume concentration of hydrochloric acid was 31%), and then decreased gradually. The ratio of scales to water was 2 ∶ 3. After washing the fish scales soaked in acid solution, they can be soaked in 2 ~ 4 grams of lime water per liter for 7 ~ 14 days to remove other impurity, and then rinse with clean water. Add a small amount of hydrochloric acid to the washed fish scales to adjust the pH to 5: 6. The fish scales treated above were heated in a sandwich steamer at a temperature of 60 ℃ ~ 70 ℃ and heated for 2 ~ 3 hours. The boiled glue is filtered to remove impurities, the transparent and clarified glue is placed on a fixed plate to allow it to naturally condense, scraped into pieces 5 cm thick with a scraper, and the scraped pieces are dried into fish scale glue. Every 100 kg wet scale can be made into 10 kg ~ 12 kg dry glue. Its uses include photographic glue, biological glue, pharmaceutical glue and industrial glue, each of which has different quality standards.

(2) the process of preparing fish skin glue from fish skin glue is basically the same as fish scale glue, but the previous processes are different, which are described as follows: soaking alkali: the concentration of alkali water is 0.04%, and the alkali water is changed once a day until the fish meat and most of the oil are removed.

Liming: after soaking alkali, the fish skin is impregnated with lime water (the concentration is 0.4%), and the lime is changed every 2 to 3 days, which takes about 30 days (including alkali soaking).

Washing lime: wash the lime, wash with water first, after most of the lime is removed, wash with dilute acid water (pH 3-4), and then wash with water.

The following procedures such as boiling glue are the same as fish scale glue. The gumming rate of fish skin is about 15%.

Bone paste and fish protein calcium sugar in the process of fish processing, the middle bone (spine) of fish is often discarded as waste. In fact, fish bones contain natural high-quality active calcium and a variety of trace elements that can promote human growth and development, such as phosphorus, iron, selenium and so on. The middle bone of fish can be made into nutrition and health food-bone paste by cooking, drying, crushing and adding excipients. It is the best healthy food for pregnant women, infants and the elderly to supplement calcium and trace elements.

Another kind of "fish protein calcium sugar" is also made from fish protein bone meal by deodorization, deodorization and adding vitamin D, etc. The product is rich in nutrition, easy to digest and absorb, can increase appetite, promote growth and development, is also suitable for pregnant women, infants and the elderly, and has a certain health care and treatment function.

Fifth, bile pigment calcium salt and cholate fish gallbladder are often discarded first as waste in fish processing, which is a pity. After processing, bile can be made into bile pigment calcium salt, bile salt and taurine, which is more valuable than gold. These bile products can be used as raw materials for the pharmaceutical industry, artificial bezoar and antibiotic preparations; medical use can promote the digestion and absorption of fat in pancreatic juice; and can also be used as one of the components of bacterial culture medium for scientific research. Now the production technology is introduced as follows.

1. Bile pigment calcium salt. The bile is saturated with 20% calcium hydroxide solution, and then heated by steam for 4 to 5 hours, when a yellow-green solid floats on the liquid surface or precipitates attached to the inner wall of the container, and the solid is separated after 2 to 3 hours, that is, bile pigment calcium salt, which is the finished product after drying and can be bottled and stored.

The calcium salt mixture, such as adding dilute hydrochloric acid to form calcium chloride, is soluble in water, while the reduced bilirubin and biliverdin are insoluble in water, and after filtration and separation, the filter residue is added with chloroform to separate bilirubin from biliverdin (the former is soluble in chloroform while the latter is insoluble), and then purified by recrystallization, the pure products of bilirubin and biliverdin can be obtained.

two。 Bile salt. Using the bile extracted from bile pigment calcium salt, the pH value of the bile was adjusted to the degree of the original fresh bile (pH 7.8), and the impurities were filtered. Heat and concentrate in a concentration pot, remove 5x6 water, add 3 times the amount of 95% alcohol and 5% activated carbon into a paste, move it into a distillation bottle, and distillation according to the fractionation column (the distilled alcohol can be recovered and reused). When the residue in the bottle is 1pm 3 of the raw material volume, remove and filter, the filter residue is extracted with alcohol twice and then discarded (can be used as fertilizer), and the filtrate is combined for 3 times in a cold storage of 0 ℃. Add ether and stir until there is a stable opacifying state. The amount of ether is about 2 times that of the concentrated liquid, the time is about 10 minutes, and then stand for 48 hours, you can see delamination, separate the lower liquid (the upper layer is ether, which can be used after distillation and purification), and then inject the enamel plate and spread it into a thin layer. blow off the residual ether under ventilated conditions and dry it in a vacuum drying box. After drying, it is ground by a ball mill, screened by a 150-mesh sieve and bottled immediately, which is the finished product. The finished product absorbs moisture easily, so fine grinding and bottling must be carried out in a dry environment. The bile salt is a mixture of sodium salt of taurocholic acid and glycocholic acid and can be separated and purified.