One, pre-storage pretreatment
1, the choice of storage varieties. In general, late ripe chestnut varieties more resistant to storage, in fact, this northern varieties than southern varieties of storage.
2, timely harvest. Chestnut ripening according to origin and varieties vary, generally to full maturity when harvesting is appropriate. Also pay attention to the weather when harvesting, rainy days or rain after clearing, dew at the end of the dry shall not be harvested. Premature harvesting or a one-time hit chestnut bract method of harvesting immature chestnut fruit, will not only affect the increase in the weight of the chestnut fruit and chestnut fruit quality, but also intolerance of storage.
3, pest control. Chestnut fruit mechanical damage and chestnut pests, such as weevils, peach borers and other damage, very susceptible to disease infiltration. Therefore, the pre-harvest to strengthen the prevention and control of chestnut pests, in the process of storage and transportation should pay attention to light load and light put, to prevent mechanical damage, while doing a good job of pre-storage disease prevention. Such as the use of "carbon disulfide" fumigation insecticide. With 500 times of Tobacco or 1000 times of Tecdor dipping fruit for three minutes, the effect of disease control is good, but to be carried out in 1-2 days after harvesting the fruit.
4, selection. Selection of chestnuts with 10% salt water, in order to remove the disease chestnut and the end of the mature empty, deflated corn, is conducive to the storage of chestnuts to keep fresh.
5, pre-storage. The harvested chestnuts in a cool, dry place to spread out and dry, to about 8% weight loss rate is appropriate, less than 5% or more than 12% weight loss rate are affected by the storage effect.
Two, storage methods
1, sand method. In a cool room or cellar, lay 10 cm of wet sand, 1 layer of chestnut fruit 1 layer of wet sand pile hiding, the most covered with 10 cm above the sand layer, pile height of no more than 1 meter. River sand humidity is maintained at about 65% (hand-held into a ball, hand-placed scattered) appropriate, usually depending on the dryness of the sand in a timely manner to spray water to moisturize. Guangxi Research Institute that the river sand must be clean, the first sun 2-3 days, add 0.1% Tobacco dissolved in water 5%, stacked thickness of about 20 cm, every 5-7 days turn over to check once, combined with the humidification of picking up moldy and bad fruits, 30 days of storage, good fruit rate of up to 86.6%. The method is used in the north, because these areas in the chestnut harvest season, the ground temperature is lower, the ground temperature recovery is also late.
Similar to this, there is also the use of huller or sawdust shavings instead of river sand for storage medium, or a mixture of river sand and sawdust shavings, the effect is also good.
2, with bushel fresh storage. Chestnut with bushels in a bamboo basket, stacked in a cool room. In the early stages of the chestnut fruit moisture retention and nutrient accumulation, play a certain role in freshness. After 40 days of storage check, the commercial good fruit rate as high as 95% -98.3%, water loss rate of ≤ 2%, insect rot rate of 1.5% or so. Storage effect is good, high economic benefits. However, late storage, chestnut bushes lose water and wind drying, resulting in serious water loss of chestnut fruit, the benefits are not good. Therefore, this method as a short-term storage means is feasible, it is a simple storage method, can ease the labor tension during the harvest period of contradiction. If the long-term storage, it is necessary to convert other ways of storage.
3, plastic bag indoor room temperature storage. Will "sweat" after the chestnut, and then 70% of methytropine 500 times liquid dip 5 minutes, take out and dry, loaded into 50 cm × 60 cm, both sides have a number of small holes 1.5 cm in diameter in a plastic bag, placed in a well-ventilated indoor, not close to the pressure, the initial change of the bag turning 3 times, and later depending on the room temperature to open or tighten the mouth of the bag! Generally more than 10 ℃ to open the mouth of the bag, less than 1O ℃ to tighten the mouth of the bag. There are also methods of changing bags, that is, the storage of the initial high temperature season, with plastic mesh bags or sacks, in order to facilitate the bag cooling and discharge of toxic gases, such as ethanol, acetaldehyde, CO2, etc., thus inhibiting a large number of mold occurs, and later the temperature drop (down to below 1O ℃), mold activity is inhibited, that is, change to the perforated plastic bags, in order to maximize the reduction of water evaporation, to maintain chestnut freshness, that is, predominantly mold prevention, later on the room temperature to turn over 3 times. That is, the first to prevent mold-based, late to prevent water loss-based. First chestnut fruit open sand storage for a period of time (generally l months role), and then switch to plastic bag storage, the effect is also ideal.
4, dilute acetic acid dip storage. Selected chestnut fruit, with 1% acetic acid solution dip 1 minute, drained and loaded into the bottom mat pine needles in a bamboo basket, covered with plastic film, 4 times a month washing, storage 142 days good fruit rate of up to 94%.
5, water or saline water immersion fresh storage. Will "sweat" after the chestnut fruit into the basket, in water or 2% salt +2% sodium carbonate solution in the immersion 1-2 minutes, and then the basket of chestnut storage on the shelf, and then every certain time to dip the fruit, 140 days later, the rate of good fruit up to 84-92%. The principle of this method is:
(1) reduce the temperature and thus reduce respiration;
(2) replenish water;
(3) wash off the debris on the chestnut fruit to reduce the infiltration of pathogens;
(4) saline water treatment of the PH value rises, inhibit the activity of certain enzymes, so as to achieve the purpose of inhibition of germination.
6, radiation preservation storage. Guangxi Botanical Research Institute with cobalt irradiation chestnut fruit, irradiation dose of 1.1 mKu / (kg?) (250 roentgens). Seconds) (250 roentgen / min) irradiation amount of 7.7, 15.5, 23, 31 library / kg (3, 6, 9, 120,000 roentgen), the inhibition of germination benefit is significant. 7.7 library / kg (30,000 roentgen) or more, storage for 7 months, no germination, storage of 103 days of good fruit rate of 86% -92%.
7, temperature preservation storage. This is the current domestic and foreign advanced fruit and vegetable storage and preservation methods, the use of CO2 ≤ 10%, O23-5%, temperature -1-0 ℃, relative humidity 90-95% of the conditions of storage, can be stored for four months, Lutian County, Hubei, supply and marketing cooperatives of the local products company and Huazhong University of Science and Technology **** with the study of chestnut air-conditioning storage test, built the chestnut air-conditioning freshness library. This gas-conditioning preservation equipment carbon molecular sieve nitrogen technology for chestnut preservation and storage in the country is advanced technology. The results successfully solved the library insulation, moisture, sealing, gas regulation, temperature, humidity control questions interesting, by the preservation of 6 months of sampling, water loss rate of 1% or less, the rate of good fruit 87.5%, color, aroma, taste, quality are in line with the national standards for chestnut fruit and export health standards, the success of this preservation technology, so that the bulk of the chestnut preservation storage has a more ideal method, but the method of one-time Large investment.
According to foreign research on chestnut air-conditioned storage reports, mature chestnut fruit at 21 ℃, 20% of the O2 storage effect is better, and O2 content is higher or less mature chestnut fruit, its post-harvest loss is greater, the quality is poorer.
8, coating fresh storage. The use of various coatings to deal with chestnut fruit, the formation of a layer of film on it, can prevent water loss and germination, reduce the infiltration of pests and diseases. Guangxi Institute of Botany (1977) using fruit paint treatment, the effect is good, the weight loss rate in storage decreased significantly, the rate of corruption is also reduced, and can inhibit germination. Anhui Agricultural University (1994) with non-toxic natural polymer compounds as a film-forming material, containing low-toxicity and efficient fungicides and germination inhibitors made of fresh liquid film, storage at room temperature for 150 days, compared with the control, the rate of good fruits in more than 93.79%, up to 95.32%, the rate of water loss of 3% or so, the rate of mold and mildew in 5% or so. Fresh liquid film treatment of chestnut storage 150 days after artificial tasting still has a pleasant sweetness, to maintain its original flavor.
9, refrigerated storage freshness. Chestnut storage at room temperature, due to the chestnut chestnut fruit with high water content, chestnut fruit and pathogenic bacteria respiration and metabolism are very active, it is easy to cause decay of chestnut fruit. And storage at low temperatures, can reduce the chestnut fruit and pathogenic bacteria metabolic activity, reduce the loss of water, is conducive to storage. But the chestnut fruit belongs to the recalcitrant seeds, intolerance of 0 ℃ below low temperature storage, so the cold storage method is usually more suitable for the temperature in 1-4 ℃. Specific operation is the chestnut fruit with sacks, storage in 1-4 ℃, relative humidity 85-95% of the cold storage, regular inspection. If the amount of water evaporation is large, every 4-5 days in the sack on the appropriate amount of water spray once. This method can be long-term preservation of freshness, but the high cost of building a warehouse.
10, cooked fruit dry storage. Ordinary air-dried raw chestnut fruit flavor sweet, but long time easy to dry rot. If the first boil after drying sun-dried, it can be a long time to hide. Specific practice is: the chestnut fruit in boiling water for about 10 minutes, so that the flesh is cooked and not paste (paste is dry for powder), sun-dried or dried, shelled and kept in a dry environment. Cooked and dried chestnut fruit, although the flavor is greatly reduced, but the inconvenient mountainous areas can be chestnut instead of food, or the annual supply of the market.
Each of the above storage methods have their own advantages and disadvantages, in order to improve the storage effect of chestnut, sometimes several methods combined in the application, can obtain good results. For example, refrigeration and air-conditioning, refrigeration and radiation and storage and liquid film fresh storage combination; plastic bags and liquid film combination.
In addition to the above storage methods, there are cylinder storage, chaff storage, air ion storage. Although the chestnut storage methods, but the progress made in this area is not great, from the current report, the longest effective storage only about half a year, can not realize the annual supply. Most of the research focuses on mold, water loss, disease and insect prevention measures, but the chestnut in storage physiological changes in the study is still very insufficient, especially in the south of the chestnut storage research is more rare. In fact, the chestnut water loss, mold decay and so on with the seeds of the inherent physiological and biochemical changes have a direct or indirect relationship. Therefore, in the study of storage and preservation at the same time, should strengthen the chestnut storage and preservation of physiological research.