It has been half a month since the one-and-a-half-week production practice. We have experienced a lot, learned a lot and learned a lot. Production practice can be divided into four parts: listening to special lectures, visiting outside the school, production practice experiment and summary.
First, listen to the lecture on special report.
First of all, we listened to Fan Shoulin, Secretary-General of Fisheries Industry Association, introducing the development status of aquatic resources market. At present, the annual output of aquatic products in the world is maintained at about 65.438+0.2 billion tons. With the increasing concern of the international community for the environment and fishery resources, countries have strengthened the protection of fishery resources, and the fishery resources on the high seas have also been protected through international cooperation. In this case, the output growth of marine fishery products is weak, or even negative. In the future, the dependence of aquatic products supply on aquaculture will increase, and the international trade of aquaculture varieties will be paid more and more attention and developed by the international community.
Shanghai Fishery Industry Association is a cross-departmental, cross-ownership and non-profit industrial social group legal person voluntarily composed of enterprises and institutions such as offshore fishing, marine fishing, aquaculture, aquatic product processing, marine pharmaceuticals, aquatic product circulation, wholesale markets, import and export enterprises, leisure fisheries, aquarium ornamental fish, scientific research institutions, universities and fishery management departments. The association has more than 170 group members.
Second, visit outside the school.
Last Thursday afternoon, we went to the powerful laboratory of East China University of Science and Technology with Qu and Chen Shunsheng. Through the introduction of Qu alumni and the director of sales and production, we know that Shanghai Schlick Commodity Inspection Co., Ltd. is one of the holding companies of Schlick Group (one of the five major companies of France Melia Group) in France Melia Nutrition Science Co., Ltd. in China, specializing in food safety inspection and technical services. As a testing and consulting laboratory certified by international ISO 17025, Shrek Group has 40 laboratories in 10 countries around the world. Our mission is to provide global food producers, retailers and service providers with perfect scientific solutions in food safety and quality. With a history of 1967, Dr. John H. Silliker founded the strength group with his technical advantages in the field of food safety and testing.
Led by Qu, we visited the laboratory of Xerox Company located in the office area on the fifth floor. The laboratory is divided into two sides, one is the inspection laboratory and the other is the physical and chemical laboratory. Every laboratory has all kinds of fresh instruments that attract our attention.
Third, the production practice experiment
Extraction of soluble chitin
The following week, we practiced in the school laboratory. On the morning of June 22nd, the first day, odd students from Class 2 of Food Science 1 1 led by Teacher Shi started to extract soluble chitin, from which we learned how to extract soluble chitin from shrimps and crabs. Chitin, also known as chitin and chitin, is a nitrogen-containing polysaccharide. It is the main structural component of invertebrate carapace, and soluble chitin is obtained by removing acetyl groups in chitin molecules. Soluble chitin is made from shrimp and crab shells, and calcium in the shells is removed by acid and alkali treatment. Protein, fat, pigment, etc. And then treated with more than 40% sodium hydroxide solution to remove acetyl groups in chitin molecules.
First of all, raw materials are treated, and fresh shrimp and crab shells are cleaned to remove meat and impurities. The second step is pickling, that is, soaking the treated fresh shrimp and crab shells in 5% aqueous solution containing hydrochloric acid, stirring every 4 hours and soaking for 24-48 hours. After pickling, wash with water until neutral. 3. Soft shrimp and crab shells boiled in alkali and soaked in acid still contain a small amount of impurities such as protein and fat. In order to remove the above impurities, it is necessary to cook with alkali, the concentration of alkali liquor is 6 ~ 8% of sodium hydroxide content, and the boiling time is 1 hour to neutrality. 4. Sun-dried or dried, and the dried or dried product is chitin after being washed to be neutral. 5. Concentrated alkali is used for heat preservation. After concentrated alkali treatment, chitin is deacetylated into soluble chitin. Soak the dried chitin in 40% sodium hydroxide solution and heat it to 65438 000℃ for 24 hours. After deacetylation, stop heating, take out chitin, wash until neutral, and dry to obtain soluble chitin. The method to check whether the acetyl group is removed: take a little chitin in the heat preservation, wash off the alkali solution, drain it and put it into 2% acetic acid solution, and dissolve it within 2 hours, then the heat preservation can be terminated, otherwise the heat preservation will continue.
In which potassium permanganate is strongly oxidized and sodium bisulfite is reduced.
Data processing and recording:
Total * * * is: 12. 14g chitin is 6. 12g yield: 50.4 1% soluble chitin is 5.6 1g yield: 46.2 1%.
Make mayonnaise
On the morning of June 23rd the next day, under the guidance of Qu, we made salad dressing. Mayonnaise is a semi-fluid food made of refined vegetable oil, vinegar and egg yolk by emulsification. In mayonnaise, the internal oil droplets are dispersed in the external components such as vinegar and egg yolk, which is an O/W emulsion. Lecithin contained in egg yolk acts as an emulsifier in this system.
First, we separate the egg yolk from the egg white, and the egg yolk stays. Egg whites should be used by the students who make minced fish. The egg yolk was homogenized in a 60℃ water bath for 3 minutes and kept warm for 3 minutes to kill Salmonella. After the preparation work is completed, we begin to pre-emulsify. Beat the egg yolk with an egg beater, add 0.5 vinegar, and put oil while stirring. The refueling speed should be very slow and basically in a straight line, otherwise the refueling speed will not be fully emulsified if it is too fast. The mayonnaise is whipped into a light yellow emulsion, which is basically completed. Then add the remaining seasoning and stir well, and the mayonnaise is ready.
Through the study of this experiment, I understand the function of colloid mill: colloid mill is composed of stainless steel and semi-stainless steel colloid mill, and the basic principle is through the high-speed relative linkage between fixed teeth and moving teeth. Except for the motor and some parts, all parts in contact with materials are made of high-strength stainless steel. In particular, the key dynamic and static grinding discs have been strengthened, which has good corrosion resistance and wear resistance, making the processed materials pollution-free, hygienic and pure.
Production of yogurt
On the third day, we learned how to make yogurt (turn milk into yogurt). First, we are divided into four groups. We add yogurt and 30g sugar into four stainless steel cups, stir them evenly with a glass rod, cover them with aluminum foil paper, sterilize them in a water bath at 80℃ for 65,438+05min, immediately cool them to 40-45℃ with cold water, then inoculate the strains on an ultra-clean workbench, cultivate them at 42℃, and finally cool them.
Yogurt works well: 1. Yogurt can enhance human immune function; 2. Reduce serum cholesterol level. Experiments have proved that even without any drugs. Drink about 24 grams of yogurt every meal, and cholesterol can be reduced after one week. 3. Regular consumption of yogurt can promote intestinal movement, shorten the transit time of food from mouth to anus, soften the contents of colon by glycolysis, increase the amount of fecal excretion, prevent constipation, and help prevent colon cancer. So yogurt is called longevity food abroad. Who should drink yogurt best? Most of the sugar contained in milk is lactose. However, due to the lack of lactase in digestive juice of some adults, it affects the digestion, absorption and utilization of lactose, causing stomach discomfort and even diarrhea after drinking milk, which is called lactose intolerance. This is why many people don't drink milk. At this time, you can choose yogurt instead of milk, and don't worry about lactose. Yogurt contains lactic acid bacteria; Lactose in milk can be converted into lactic acid by lactic acid bacteria fermentation, and lactose intolerant people will not have diarrhea symptoms when drinking yogurt, which just solves the problems that some people may have when drinking milk. But it is worth noting that many yogurt drinks (not yogurt) are made of milk, water and sour agents. Such products also contain lactic acid, which can also cause lactose intolerance.
Preparation of fish gluten from surimi products
On the morning of June 26th, the fourth day, under the leadership of Teacher Yu Jun, we made surimi gluten, which was made of silver carp meat, egg white, starch, salt and other seasonings. Its technological process is: 1. Raw materials 2. Pretreatment 3. Wash with water 4. Pick meat 5. Rinse 6. Centrifugal dehydration 7. Crush (chop) 8. Granulation 9. Boiling 10. Cooling 1 1. Freeze 12. Packaging and refrigeration.
The production of fish gluten does not have too many restrictions on the types of fish, which can be marine fish such as white mushroom fish and mackerel, or freshwater fish such as four major fish. The appropriate dosage for individual fish is 1 to 2 kg. Raw fish should be fresh and not go bad, otherwise it will affect the quality of finished products. For raw material treatment, the most important thing is to take three paths: viscera removal, head removal, fish skin removal and fish scales removal. For the rinsing step, it is mainly to remove fish stains, fishbones, fat-soluble magazines, fish black films and other wastes that are not conducive to processing. Rinse with clean water twice. During rinsing, fish tissues absorb water and swell, which is not conducive to subsequent dehydration. Therefore, brine is used for the third rinse. The addition of salt is 0.5% of the weight of minced fish. Washing with salt water can make the water in fish tissues easily separated. After dehydration, it is the process of crushing. Let's start with the beat. When beating, we have to beat the fish in the air for a few minutes, then add salt to completely separate out the salt-soluble protein, and then add egg white and starch until it is beaten evenly. Finally, Mr. Yu helped us fry the finished product, and everyone tasted the fish tendon and enjoyed the process.
Fourth, summary.
As the saying goes, practice is the only criterion for testing truth. We all live and study at school and are exposed to textbooks or formulas. It is difficult to get in touch with the physical objects and processes of the factory. I always feel that what we learn is aimless, and what we learn in society is chicken ribs. But through a week of production practice, my wrong view has changed. Knowledge in books is the foundation and guarantee. Without the support of these knowledge formulas, you will be confused in your work, and you will be at a loss if you can't find the result, and the result will be semi-solution. The one-week internship really transformed us from a student to a company employee, and made us realize what a real society is and what a real job is. The internship time is not long, but it has taught us something that we will never learn in school. During the internship, I thank all the teachers for their help in our internship. With your help, we have learned a lot, but we know that graduation is only a small step in learning, and society is the real university.
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