Application of water absorbent and water retaining agent in fresh-keeping packaging of fruits and vegetables (Part I)
one of the technical problems in Fresh-keeping of fruits and vegetables is the production of dew drops in packaging. Dewdrops are the culture medium that leads to microbial reproduction, so as to accelerate the decay of fruits and vegetables. If we try to eliminate dewdrops in the package, we can greatly extend the preservation period, which is particularly important at room temperature. Therefore, the author has done a lot of tests, and finally proved that the use of water absorbent and water retaining agent can solve this problem, and the test effect is good
application characteristics
nowadays, many fruits and vegetables are kept fresh by means of plastic film packaging
the main problem of using plastic film bags to package fruits and vegetables is that there is a lot of dew on the surface of fruits and vegetables and the inner wall of the film bag due to the abnormal rise of the temperature in the bag or the evaporation loss of the water of fruits and vegetables they jokingly say during long-term storage. This dewing water, in addition to causing the deterioration of the quality of fruits and vegetables and the loss or reduction of the original flavor, also creates good conditions for the reproduction of some parasitic bacteria, which has become the main reason for the corruption of fruits and vegetables
in order to solve the above problems, the method of adding water absorbent and water retaining agent into the plastic film packaging bag has a good effect. Its characteristics are as follows:
(1) the water absorbent and water retaining agent absorbs the dew formed in the packaging bag, so that there is no excessive humidity in the packaging bag
(2) it can capture the moisture in the air in the bag, and when the humidity in the bag decreases, it can release the captured moisture by itself, adjust the humidity, and keep the bag within the range of 70% - 90% (relative humidity) of the most suitable humidity for general fruit and vegetable storage
due to the application of water retaining agent in the storage bag of fruits and vegetables, the reproduction of pathogenic bacteria in the bag can be inhibited to a certain extent, so as to prevent the corruption and deterioration of fruits and vegetables. Therefore, the response specification is not very perfect, and the fresh-keeping period of fruits and vegetables can be prolonged
(3) if the agent is combined with gas absorbent and gas generator, it can not only adjust the humidity in the bag, but also adjust the gas composition in the bag, which is more beneficial to the preservation of fruits and vegetables
usage
(1) the dosage varies with the type, moisture content, moisture evaporation rate, packaging state, storage temperature and humidity of vegetables. The general dosage is 0.05% - 5% of the mass of fruits and vegetables
(2) usage
① put the water absorbent and water retaining agent into a
type in various shapes such as pill, ball, column, block, sheet, etc., into a breathable small bag made of non-woven fabric or other films, and put it into a large bag together with the fruits and vegetables and food to be stored
② compound the water absorbent and water retaining agent with laminated plastic film, paper and non-woven fabric to make a super absorbent composite sheet, and bundle it with the side with water absorbent and water retaining agent as the inner surface; Or made into packaging bags for packaging; Or as a water absorbing and water retaining sheet, it can be bagged together with the fruits and vegetables to be stored
③ make plastic film containing water absorbent and water retaining agent, and directly use this film or use this film to make packaging bags to package fruits and vegetables
④ to further improve the fresh-keeping effect, it can also be used together with gas absorbent or carbon dioxide gas generator. 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 absorbers; In order to absorb ethylene, aldehydes, alcohols and other organic gases with ripening effect released during the ripening of fruits and vegetables, it can be used together with various preservatives; In order to reduce the concentration of carbon dioxide, calcium hydroxide, potassium hydroxide and sodium hydroxide can be used together; In order to take advantage of the sterilization and fresh-keeping effect of carbon dioxide, calcium carbonate, lithium bicarbonate and other carbonation gas generators can be used together
the usage of gas absorbent and carbon dioxide generator varies with the type of vegetables, packaging form, storage temperature, and the concentration of gas required in the bag. However, the general dosage should be controlled within the range of 0.05% - 5% according to the quality of stored fruits and vegetables
(to be continued)
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