During the production and storage of foods, microorganisms, oxygen, etc. may cause spoilage and mildew, causing great loss to people's lives and production. Synthetic anti-corrosion and anti-mold agents often cause certain adverse effects on human health. influences. Therefore, the research on extracting preservatives from natural products and using them for food preservation has attracted increasing attention. Here are some natural food preservatives with development value and their applications. 1. Tea polyphenols: Tea polyphenols are polyhydric phenolic organic compounds extracted from tea leaves. Their main components are catechins and their derivatives. The antioxidant capacity of tea polyphenols is 10-20 times that of vitamin E. It has good antioxidant activity for fish oil, salad oil and other foods containing animal and vegetable oils. The dosage is about 30--100mg/kg. (by fat weight). The minimum inhibitory concentration of tea polyphenols to various bacteria such as Staphylococcus aureus, Proteus vulgaris, Salmonella typhi, Bacillus subtilis, Shigella dysenteriae, Pseudomonas aeruginosa, and Escherichia coli is 0.01% -- 0.1% (W/W), it is a good natural antibacterial agent that can be added to foods and medicines. 2. Propolis extract: 25g of ground propolis powdered into powder is placed in a Soxhlet extractor and extracted with 300ml of 70% ethanol, refluxed at 70°C for 8 hours (hours), cooled, and the resulting solution is filtered through a suction filter. The filtrate is concentrated to a dark brown, pleasantly scented propolis extract. The extract has the functions of antibacterial, anti-inflammatory, virus-inhibitory, and immunity enhancement. The propolis extract is directly added to milk, coffee, oral liquids for health products, as well as beverages, dairy products, and liquid foods all have good preservation effects. 3. Orange peel extract: Citrus peel (air-dried product) is extracted with 3- to 6-fold alcohol at normal temperature or under heating, and the solvent is removed from the extract solution by distillation to obtain an orange yellow with a mildewing effect. Sticky concentrates. Adding this preservative to food or feed at a ratio of 1% to 3% can greatly extend the shelf life of food and feed. It can even be used as a mildew inhibitor for certain live bacterial preparations in medicine. Orange peel extract had no inhibitory effect on bacteria, but it showed strong inhibition on molds and yeasts. 4. Konjac Mannan: The konjac bulbous tuber contains about 50% konjac mannan. The polysaccharide extraction method is simple, and it is used for the preservation of foods such as fruits, meat, fish, tofu and so on. The effect is ideal. The fresh strawberries were immersed in a 0.05% (by weight) aqueous solution of konjac mannan for 10 seconds. The strawberry surface was evenly stained with an aqueous mannan solution, which was then dried and stored for 1 week. The surface was only slightly lustrous. , Storage for 3 weeks is still not moldy; and without this treatment of fresh strawberries, only 2 days to lose luster, storage began to mold 3 days. 5. Protamine: Protamine is a small, simple, basic globular protein that is usually extracted from fish such as cockroaches, cockroaches, cockroaches, and cockroaches. Protamine has a natural antibacterial function, inhibiting bacteria such as Bacillus subtilis, adding 0.05%--0.1% protamine in milk, eggs, pudding and other foods, can be stored at 15% of the temperature for 5- to 6 days . 6. Forsythia extract: dried fruit of Forsythia Suspensa, with heat and detoxification, swelling, Sanjie, anti-inflammatory and antibacterial effects. Its main components are forsythiaquinone, sterols, triterpene saponins, flavonol glycosides, resin glycosides, and fruit peels contain oleanolic acid. The 95% alcohol extract of Forsythia suspensa has been used as a food preservative in Japan. 7. Rosemary extract: The alcohol extract of rosemary contains the ingredients of carnosol and sage phenolic acid. It has the characteristics of high temperature resistance, can be added to barbecue oil, can also be added to meatballs, Meat products such as meat loaf, salad oil, and rice sausage can extend shelf life. The amount used is generally 200 - 1000mg/kg. The rosemary extract can be used as a liquid or as a microcapsule. In grill oils, synergistic effects can be produced when rosemary or sage extracts are combined with 0.02% citric acid. 8. Phytic acid: Phytic acid is the inositol hexaphosphate, which can be separated from rice bran, wheat bran and other cereals and oil seed cakes, it is a high safety natural food additives. One part of 50% phytic acid and 3 parts of sorbitol fatty acid esters were mixed in soybean oil at 0.2%, which greatly delayed the deterioration of soybean oil. Samples of broiled chicken breast meat treated with phytic acid still had no odor after storage for 28 days, while samples of chicken breast without phytic acid treatment had significant odor after 4 days of storage. Adding 0.1%--0.5% phytic acid to canned fish can prevent blackening and struvite formation. 9. Luteolin in the peanut shell: the peanut shell is crushed and leached with 90% alcohol for 24 hours (hours). The filter residue is leached once more and combined. The rotary evaporator is used for distillation to recover the alcohol and the concentrate is dried to obtain the peanut shell. The flavonoids are mainly composed of luteolin. Luteolin has antioxidant properties, and can inhibit the growth of Staphylococcus and Bacillus subtilis at a concentration of 1:350000. It also has inhibitory effects on Candida, Candida albicans and Proteus, and can be used as a food preservative, such as extended The shelf life of moon cakes and peach cakes suppresses the deterioration of food containing fats. 10. Chitosan: Chitosan is a natural high molecular compound derived from shrimp and crab shells as a raw material, decalcified by dilute acid, and deacetylated with dilute alkali to remove protein and concentrated alkali. It has the advantages of non-toxicity, low cost and high efficiency. It is an excellent natural food preservative. The chitosan solution was dissolved in an aqueous solution of 0.6% acetic acid to obtain a 1% solution of chitosan. The strawberry was soaked in this solution for 1 minute, then it was taken out and allowed to air dry, and then stored in a refrigerator at 4-15°C. . Experiments have shown that strawberries treated with chitosan can significantly inhibit fruit softening and mold growth, and reduce Vc loss, can extend its shelf life. Similarly, Chinese kiwifruit treated with chitosan can extend the preservation period of Chinese kiwifruit from the original 10--13 days to 80 days at room temperature, while maintaining good fruit quality and flavor. China Agricultural Network Editor
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