1. Aseptic animals refer to animals without any parasites (microorganisms and parasites) inside and outside their bodies. This kind of animal does not exist in nature and must be cultivated artificially. Methods: Generally, healthy animals before labor were put to death by narcotic drugs or cervical mortar method, immediately soaked in 37℃ sterile solution, sent to aseptic room (or aseptic isolator), and performed laparotomy according to aseptic operation. The uterus with fetus was taken out (the uterus was sterilized first), immersed in disinfectant, transported to another isolator, cut the uterus to get the fetus, wiped the fetus with sterile gauze, and cut the umbilical cord (cut by electric knife). It is troublesome to feed mice artificially, so it is more convenient to adopt a nanny. Because guinea pigs can drink milk by themselves to a certain extent, it is easier to breastfeed artificially. In addition, birds, fish and insects are all carried out under the premise of sterility in eggs, and only need to disinfect the eggs with drugs, and then move them into sterile isolators for incubation. Moreover, these animals can generally eat by themselves after birth, so it is easier to reproduce.
2. Biologists refer to animals with known microorganisms (animals or plants). This animal was originally a sterile animal, and the designated microbial flora was artificially thrown into its body. For example, Escherichia coli was colonized in sterile mice, and only Escherichia coli could be detected during microbial examination. There are also more than two known microorganisms artificially applied. Known animals are generally divided into single bacteria, double bacteria, triple bacteria or multi-bacteria animals. Like aseptic animals, these animals are kept in isolators, but because their microorganisms are known, there are microorganisms and their metabolites in isolators. For example, artificially raised microorganisms can not only breed in drinking water, but also release a large amount of ammonia in the isolator.
3. Animals without specific pathogens refer to animals without specific microorganisms and parasites in their bodies, referred to as SPF animals. But nonspecific microorganisms and parasites are allowed to exist, so they actually refer to healthy animals without infectious diseases. Because it is not practical to use vaccines and drugs to prevent and treat, or to eliminate infected animals as SPF animals (it is a waste of time and it is difficult to ensure the removal of pathogens). Therefore, it is common to cultivate sterile animals or learned animals first, and then transfer them to facilities in specific pathogen free for breeding. Pathogenic bacteria are not allowed in SPF animal rooms in principle, but in a closed system environment, many non-pathogenic microorganisms will inevitably gradually enter the animals, so some people call this transfer process normal animalization. The ancestors of SPF animals are sterile animals. It stands to reason that the uterus and eggs of infertile animals should be sterile. However, some viruses are actually transmitted to the fetus through parents. Therefore, this problem must be fully considered before making infertile animals and SPF animals.
4. Clean-grade conventional animals (CCV) (also known as minimal disease animals MOA) or clean-grade animals (CL).
SPF animals without specific pathogens are raised in ordinary facilities with two corridors and constant temperature and humidity. Cushion, feed, utensils, etc. It should be sterilized by high pressure. The pH value of drinking water is 2.5 ~ 2.8, the rat box is equipped with a filter cap, and the air should be filtered to some extent. Workers should wear clean clothes for operation. The microbial control standard of such animals is basically the same as SPF, but the difference is that serum virus antibody examination (encephalomyelitis virus, mouse hepatitis virus ...) can often detect a certain titer of antibodies, but clinical symptoms, organ diseases and natural death are not allowed.
Traditional animals refer to animals that are usually kept in an open and hygienic environment without active microbial control. Mats and food are not autoclaved, drinking water is tap water, and green feed is not fed. Rats should exclude pneumonia virus, salmonella and streptococcus, and hamsters should not have pinworms. Ordinary animals can only be used for reproduction and general experiments, but not for research experiments.
Browning and microbial control of fresh-cut vegetables
First, the control of browning:
In the processing of fresh-cut vegetables, heat treatment will destroy the tissue, thus accelerating the deterioration of the products. However, sulfite treatment will cause sulfur dioxide residue, which will have some adverse effects on human body. Therefore, in the processing of fresh-cut vegetables, other methods must be adopted to inhibit the occurrence of enzymatic browning.
1. Chemical method. The main chemical reagents that are expected to replace sulfite to inhibit enzyme browning are citric acid, ascorbic acid, cysteine and 4-hexylresorcinol. For example, peeled and sliced potatoes, soaked in 0.5% cysteine and 2% citric acid for 3 minutes, can effectively control browning. The mixed solution of sodium ascorbate, cysteine and ethylenediamine tetraacetic acid with PH value of 5.5 can effectively control the browning of mushrooms. Fresh-cut lettuce slices, treated with 1%-5% acetic acid solution or vinegar with 6% acetic acid content, can effectively inhibit the browning of products during refrigeration and circulation.
Generally, chemical treatment should be carried out to prevent browning before packaging, and the mixed impregnation effect of several chemicals is better. Using anti-browning agent combined with edible film treatment can achieve good results. For example, fresh mushroom slices treated with edible film containing 1% ascorbic acid and 0.2%EDTA can control the occurrence of enzymatic browning more effectively than packaging with chemical anti-browning agent or edible film alone.
2. Physical methods. Modified atmosphere packaging of fresh-cut vegetables with low oxygen and high carbon dioxide can effectively control enzymatic browning during storage. Generally, the suitable oxygen concentration is 2%- 10%, and the carbon dioxide concentration is 10%-20%. For example, if potato slices are packaged in modified atmosphere packaging containing 20% carbon dioxide and 80% nitrogen, browning during storage can be effectively controlled.
3. Enzymatic method. This method is based on the hydrolysis of polyphenol oxidase by protease, thus inhibiting its activity and enzymatic browning. At present, ficin, papain and bromelain have been separated from fig, papain and pineapple, which can effectively control the occurrence of enzymatic browning. If fig protease is used to inhibit potato browning, its effect is equivalent to sulfite. Because pineapple contains protease, treating fresh-cut apple slices with pineapple juice can also effectively inhibit the browning of the products.
Second, the control of microbial growth:
There are several methods to control the growth of microorganisms in production:
1. Create low temperature conditions. Creating a low temperature environment can effectively inhibit the growth of microorganisms, thus achieving the purpose of maintaining quality and prolonging shelf life. Therefore, in the process of processing, storage and circulation of fresh-cut vegetables, suitable low temperature conditions should be created as much as possible, generally 0-5℃.
2. Use chemical preservatives. Acetic acid, benzoic acid, sorbic acid and their salts can effectively inhibit the growth and reproduction of microorganisms. This is an effective control measure for spoilage bacteria and pathogenic bacteria that can still grow at low temperature.
3. Implement modified atmosphere packaging: Appropriate modified atmosphere packaging with low oxygen and high carbon dioxide can inhibit the growth of aerobic microorganisms. But we must pay attention to avoid anoxic environment, prevent the growth of anaerobic microorganisms and the applause of anaerobic fermentation of the product itself.
4. lower the PH value. The PH value of fresh-cut vegetable tissues is generally 4.5-7.0, which is suitable for the growth of various spoilage bacteria and pathogenic bacteria. Adding proper amount of acetic acid, citric acid and lactic acid to fresh-cut vegetables can reduce the PH value of vegetable tissues and inhibit the growth and reproduction of microorganisms. But be sure to master the dose. Otherwise, too much acid will spoil the flavor of fresh vegetables.
5. Use biological preservatives. Biological preservatives refer to a kind of antibacterial substances from plants, animals and microorganisms. Because fresh vegetables are ready-to-eat products, the application of chemical preservatives is limited, so the research and application of natural preservatives from biology are paid more and more attention. It was found that bacteriocin, a metabolite of lactic acid bacteria, could effectively inhibit the growth of harmful microorganisms such as Aeromonas hydrophila and Listeria monocytogenes in fresh-cut vegetables.
Strengthen the control of pathogenic microorganisms in the process of hatching production
Various pathogenic microorganisms will multiply rapidly when they meet suitable environmental conditions. The suitable incubation temperature and humidity in the hatchery provide good conditions for microbial reproduction. Once the pathogenic microorganism infects the embryo or chick, it will cause the early death of the embryo, and the quality of chick products will decline, which will lead to the decline of economic benefits and threaten the survival of the hatchery. It can be seen that strengthening the control of pathogenic microorganisms in the incubation process has become the most important content in the management of hatcheries.
First, strictly control the source of pathogenic microorganisms.
1. Breeding eggs are required to be provided by healthy chickens without epidemic situation, but they may still be contaminated by pathogenic microorganisms during the production of breeding eggs. After the eggs are transported to the hatchery, in addition to disinfection in the farm, they must be fumigated and disinfected with three times of formaldehyde and potassium permanganate 1 time. After testing, the total number of bacteria is less than 20, among which the main pathogenic bacteria such as Escherichia coli, Salmonella and Staphylococcus are 0. The hatched eggs are fumigated with 1 times formaldehyde and potassium permanganate every week to control the growth of bacteria.
2. The human body is one of the main carriers of pathogenic microorganisms, and all outsiders are required to refuse to enter the production area of the incubator. Workers in this field are required to disinfect and shower in the workshop every day, change their work clothes, hats, masks and slippers after cleaning and disinfection, and take a shower when leaving the workshop. The dirty area and the clean area of the workshop cannot be connected together. Under special circumstances, it is necessary to take a bath and change clothes from the dirty area to the clean area. Wash hands and disinfect before touching eggs and chickens. It is forbidden to cough, sneeze and spit on eggs and chicks during work or rest to reduce the spread of bacteria.
Broadcast.
3. Vehicles It is forbidden for foreign vehicles to enter the venue. When the egg truck enters the site, it is required to spray disinfection. Drivers can only enter the venue after getting off the bus through the disinfection channel. Drivers are not allowed to get off the bus during egg unloading. Egg trucks are not allowed to transport other articles except eggs, and the compartments are required to be fumigated and disinfected at least once a week/kloc-0.
4. All utensils in the incubator, such as egg baskets, egg trays, mops, brooms, etc. Once entering the site, it must be disinfected to control the spread of pathogenic microorganisms caused by unclean utensils.
5. The main packaging material used in the packaging material incubation place is the chick box, which should be put into the warehouse 50 meters away from the production area before use. It is strictly forbidden for any unsterilized packaged goods to enter the production area.
6. The airborne pathogenic microorganisms are more random. Most of the pathogenic microorganisms detected are brought in through the air. Because of the specific environment of egg bank and incubation hall, it is often difficult to control this link In management, it is required to clean the air inlet and filter screen at least three times a week, especially the air inlet and air outlet of the incubator and incubator should be kept clean frequently to prevent bacteria from circulating.
Second, control the reproduction of pathogenic microorganisms.
Because of the specific greenhouse and humidity conditions in the incubator, it provides an ideal place for bacterial reproduction, which requires managers to start from all aspects of the culture process, detect the survival state of bacteria in time, and take various effective measures to cut off the transmission channels of pathogenic microorganisms. In addition to the above, from the strict control of the incubation area, we should also pay attention to keeping the incubator clean and hygienic, and thoroughly wipe it at least twice a week, especially the air inlet and air outlet, and no dust is allowed. The walls and floors around hatches and hatcheries should be thoroughly cleaned with disinfectant at least three times a week, and the total number of bacteria detected should not exceed 32. After the chicks are hatched, the incubator should be carefully cleaned, no foreign bodies are allowed to remain, and disinfection should be thorough. Incubators should be thoroughly cleaned and disinfected to prevent pathogenic microorganisms from polluting the next batch of chicks. After each incubation, the incubation site should be thoroughly cleaned and disinfected. Because the hatching production process is circular, it is required that the disinfection, hatching, washing and hatching of eggs should be done completely, so as to cut off the transmission route of pathogenic microorganisms as a whole and reduce their survival number, and finally achieve the purpose of improving the quality of chicks and increasing economic benefits.
Other information reference
/s？ wd = % CE % A2 % C9 % FA % CE % EF % B5 % C4 % BF % D8 % D6 % C6 & amp； lm = 0 & ampsi = & amprn= 10。 ie = GB 23 12 & amp； ct = 0 & ampcl = 3 & ampf= 1。 rsp= 1