Fruit is fresh food, which is perishable after harvest. In order to prolong the preservation period, researchers all over the world have invented many new preservation technologies, and now 1 kinds are introduced.
1. Fresh-keeping carton: This is a new carton developed by Japan Food Distribution System Association in recent years. The researchers used a kind of "Li stovall stone" (a kind of silicate rock) as an additive for paper pulp. Because this kind of stone powder has a unique good adsorption effect on various gases, and it is cheap and does not need low-temperature and high-cost equipment, especially it has a long-term preservation effect, and the weight of the fresh fruit will not be reduced, so merchants love to use it, which is even better for long-distance storage and transportation.
2. Microwave preservation: This is a method of keeping fruits fresh by low-temperature disinfection by a Dutch company. It is heated to 72℃ by microwave in a short time (12s), and then the processed food is put on the market at ~4℃, which can be stored for 42~45 days without deterioration. It is very suitable for supplying "seasonal fruits" in the off-season, and is favored by people.
3. Edible fruit preservative: This is an edible fruit preservative developed by a British food association. It is a kind of "translucent emulsion" made of sucrose, starch, fatty acid and polyester. It can be sprayed, brushed, dipped and covered on the surfaces of watermelon, tomato, sweet pepper, eggplant, cucumber, apple and banana, and its preservation period can be as long as more than 2 days. This is because this preservative forms a "sealed film" on the surface of fruits and vegetables, which completely prevents oxygen from entering the interior of fruits and vegetables, thus achieving the purpose of prolonging the ripening process of fruits and enhancing the fresh-keeping effect.
4. New film preservation: This is a disposable moisture-absorbing and fresh-keeping plastic packaging film developed in Japan. It is composed of two translucent nylon films with strong water permeability, and natural paste and sugar syrup with high osmotic pressure are filled between the films, which can slowly absorb the water oozing from the surface of fruits and meat to achieve the preservation effect.
5. Pressurized preservation: a method of making food by pressure, which was successfully developed by the Institute of Food Science of Kyoto University in Japan. After pressure sterilization, the fresh-keeping time of fruits can be prolonged and the fresh taste can be improved. However, acid can't play a role under pressure, so it is ideal to keep fruits in the best state.
6. Ceramic fresh-keeping bag: This is a kind of fruit fresh-keeping bag with far-infrared effect developed by a Japanese company. It is mainly coated with a very thin layer of ceramic material on the inside of the bag, so the infrared ray released by the ceramic can have a strong "* * * vibration" movement with the moisture contained in the fruit, thus promoting the fruit to get fresh-keeping effect.
7. Microbial preservation method: Ethylene can promote the aging and ripening of fruits, so it is necessary to remove ethylene in order to keep fruits fresh. After screening and research, scientists isolated a kind of "NH-1 strain", which can be made into an "ethylene remover NH-T" substance to remove ethylene, which can prevent grapes from browning, loosening and dropping during storage, prevent tomatoes and peppers from losing water, discoloring and softening, and has obvious fresh-keeping effect.
8. decompression preservation method: it is a new fruit storage method with good preservation effect, convenient management, simple operation and low cost. At present, some countries such as Britain, America, Germany and France have developed low-pressure containers with standard specifications, which have been widely used in long-distance transportation of fruits.
9. Hydrocarbon mixture preservation method: This is a "natural edible preservative" developed by a British biotechnology company, which can double the storage life of pears, grapes and other fruits. It uses a complex hydrocarbon mixture, which is dissolved in water to form a solution when it is used, and then the fruit to be preserved is soaked in the solution, so that the surface of the fruit is evenly coated with a layer of liquid agent. In this way, the absorption of oxygen is greatly reduced, and almost all CO2 produced by fruits is discharged. Therefore, the effect of preservative is similar to that of "anesthetic" applied to the fruit, which makes it dormant.
1. electronic technology preservation method: it uses negative oxygen ions and ozone generated in high-voltage negative electrostatic field to achieve the goal. Negative oxygen ions can inactivate enzymes that metabolize fruits, thus reducing the respiration intensity of fruits and weakening the survival of ethylene, a fruit ripening agent. Ozone is a strong oxidant and a good disinfectant and bactericide, which can not only kill and eliminate microorganisms and toxins secreted by fruits, but also inhibit and delay the hydrolysis of organic matter in fruits, thus prolonging the storage period of fruits.