The astringent persimmon varieties with long harvest time and particularly high tannin content often have incomplete astringency. The most common methods for removing astringency in practice are as follows:
1, the astringency of carbon dioxide will be sealed in a plastic tent, and the concentration of compressed carbon dioxide coming out of the cylinder will reach more than 60%, and it will be astringent in about 24 hours. If the temperature and carbon dioxide concentration increase, the astringency removal time will be shortened accordingly. Under the condition of carbon dioxide at 40℃ and 60℃, the astringency can be removed after about 8- 10 hour. Persimmon after carbon dioxide deastringency; Not easy to rot and deteriorate, long shelf life. If there is no commercial bottled carbon dioxide, the chemical reaction of hydrochloric acid and baking soda can be used to produce carbon dioxide, which has the same convergence effect.
2, alcohol astringency Soft materials are laid on the bottom of the container, and persimmon fruits are placed on it layer by layer. Spray a certain amount of alcohol or white wine on each layer, and seal it after filling. Every 10 kg persimmon fruit needs 80- 100 ml alcohol at 35℃. At 20℃, the astringency removal time of common varieties is 5-6 days, and that of difficult-to-remove varieties is 8- 10 days. Under relatively closed conditions. Spraying 5-7 ml of 35℃ alcohol per kilogram of persimmon can remove astringency after about 1 week. This method can be used to remove the astringency during transportation.
3. Deastringency of ethylene or ethephon
Ethylene deastringency is a gas treatment method; Must be unfolded in a plastic tent or ripening room. The concentration used is generally 0.05%. Temperature 18-25℃, relative humidity about 85%. After 48-60 hours of treatment, it can be taken out and left for 3-5 days to remove astringency. Persimmons that have been deastringed by ethylene have good color and quality, but they are easy to soften and cannot be stored for a long time.
Ethephon is a common liquid ripening agent and does not need to be sealed. Before harvesting, spray 250PPm ethephon on the fruit surface until it is wet, and the astringency can be removed at about 65,438+00. This method can harvest fruits 20-30 days in advance or spray or soak them with 0.05-0.2% ethephon after harvesting, and can also remove astringency for 5-6 days. The effect of removing astringency is similar to that of ethylene.
4, warm water astringent persimmon in aluminum pot or clean jar mouth. Put a stove under the container to keep warm. It usually takes 10-24 hours to get rid of astringency. Persimmon fruit with warm water astringency has high water content, light flavor and short shelf life.
5, cold water to astringent taste will be soaked in the water in the cylinder, if the taste of water is not good, it should be replaced by clear water, which can also be removed after 5-7 days. Generally speaking, the harvest is early and the astringency removal time is long; Late harvest and short astringency removal time. Persimmon fruits with astringency removed by cold water are hard in texture and rich in fragrance, but the astringency removal time is slightly longer.
6. Deastringency of fresh fruit Put persimmon fruit into water in a tank, add 1.5-5 kg of ripe fresh fruit such as apple, papaya, fructus amomi or hawthorn to every 50 kg of persimmon fruit, mix in layers, and seal after filling. In this way, a large amount of ethylene released by fresh fruit can promote the ripening of persimmon fruit, and it can be astringent after 3-5 days, with bright color and rich fragrance.