One of the technical problems in the preservation of fruits and vegetables is the production of dew in the packaging. The dew is a culture medium that causes microorganisms to multiply and accelerates the decay of fruits and vegetables. If you try to eliminate the dew in the packaging, you can greatly extend the shelf life, which is especially important at room temperature. For this reason, the author has done a lot of experiments and finally proved that the use of water-absorbing and water-retaining agents can solve this problem, and the experimental results are better.
At present, many fruits and vegetables are kept fresh with the help of plastic film packaging to achieve moisture and preservation of fruits and vegetables.
The main problem with using plastic film bags to package fruits and vegetables is that due to the abnormal rise of the temperature in the bag, or the evaporation and loss of water in the fruits and vegetables during long-term storage, a lot of condensation water is generated on the surface of the fruits and vegetables and the inner wall of the film bag. And this kind of dew water, in addition to causing deterioration of fruit and vegetable quality and loss or reduction of the original flavor, it also creates good conditions for the reproduction of some parasitic bacteria, which becomes the main cause of fruit and vegetable spoilage.
In order to solve the above-mentioned problems, the method of adding water-absorbing and water-retaining agent into the plastic film packaging bag has a good effect. Its characteristics are as follows:
(1) The water-absorbing and water-retaining agent absorbs the condensation water generated in the packaging bag, so that the packaging bag does not appear excessively wet.
(2) It can capture the moisture in the air in the bag, and when the humidity in the bag decreases, it can release the trapped water by itself, adjust the humidity, and keep the bag in the bag often at the optimum humidity for general fruit and vegetable storage 70% ~ 90% (Relative humidity) range. Due to the application of water-absorbing and water-retaining agent in the fruit and vegetable storage bag, the propagation of pathogenic bacteria in the bag can be inhibited to a certain extent, and the spoilage and deterioration of fruits and vegetables are prevented, thereby prolonging the fresh-keeping period of fruits and vegetables.
(3) If the agent is combined with a gas absorbent and a gas generating agent, not only the humidity in the bag can be adjusted, but also the gas composition in the bag can be adjusted, which is more beneficial to the preservation of fruits and vegetables.
(1) The dosage varies depending on the type of fruits and vegetables, moisture content, water evaporation rate, packaging state, storage temperature and humidity, etc. The general dosage is 0.05% to 5% of the quality of fruits and vegetables.
① After molding the water-absorbing and water-retaining agent in various shapes such as pellets, spheres, columns, blocks, sheets, etc., put them into air-permeable pouches made of non-woven fabrics or other films, together with fruits and vegetables to be stored fresh, Store food in big bags.
②Laminate the water-absorbing and water-retaining agent and plastic film, paper and non-woven fabric to form a super absorbent composite sheet, and pack the side with the water-absorbing and water-retaining agent as the inner surface; or make it into a packaging bag. Packaging; or as a water-absorbing and water-retaining sheet, together with the fruits and vegetables to be stored in bags.
③ Make a plastic film containing water-absorbing and water-retaining agent, directly use this film or use this film to make packaging bags for packaging fruits and vegetables.
④ In order to further improve the preservation effect, it can also be used together with gas absorbent or carbon dioxide gas generating agent. For example, in order to reduce the oxygen concentration in the bag, it can be used together with reduced iron powder, ferrous sulfate or ferrous carbonate oxygen absorbent; to absorb the ripening effect of Z ene, aldehydes and alcohols released during the ripening process of fruits and vegetables It can be used together with various preservatives; in order to reduce the concentration of carbon dioxide, the carbon dioxide absorbent calcium hydroxide, potassium hydroxide, sodium hydroxide, etc. can be used together; for the sterilization and preservation effect of carbon dioxide, Gas generating agent calcium carbonate, lithium bicarbonate, etc. are used together.
The amount of gas absorbent and carbon dioxide generator used varies with the types of fruits and vegetables, packaging, storage temperature, and the concentration of gas needed in the bag. However, the general dosage should be controlled within the range of 0.05% ~ 5% based on the quality of the fruits and vegetables stored.