Preservative and fresh-keeping technology of the h

2022-08-12
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Preservative and fresh-keeping techniques of loquat fruits

1. Pre harvest treatment

1. Bagging young fruits 20-30 days after flowering, and thinning the ears before bagging. Select and reserve 3-5 young fruits that are relatively concentrated, well-developed and of the same size for each ear, and spray 1000 times of 50% methyltobuzin solution once. Soak the paper bag with fungicide for several minutes, then dry it and set the fruits. Compared with non bagging, bagging can not only effectively prevent fruit rust, but also significantly reduce the occurrence of physiological diseases such as frost damage, sunburn and fruit cracking

2. Before harvest, spray 0.5% Bordeaux liquid or 50% fungicide wettable powder 5000 times, 65% mancozeb wettable powder 600 times, 70% methyltobuzin wettable powder 800 times or 50% carbendazim wettable powder 1000 times to protect the fruit. Spraying 2-3 times every 10-15 days can reduce the occurrence of anthracnose, scab and gray mold after fruit harvest. During the expansion period of young fruits, the application of 0.2% borax or 0.2% potassium dihydrogen phosphate outside the root can prevent fruit cracking. Ripening with Ethephon 1000-1500 times solution can prevent fruit cracking and improve fruit quality when the fruit is green and the temperature is 20-25 ℃

II. Fruit harvesting

1. The harvest period of timely harvesting loquat is relatively short, so it must be harvested in time. Loquat fruit has no post ripening effect and can be picked only when it is fully colored. Generally, the fruit will reach the maturity of 89, that is, the fruit surface is shiny, the skin is easy to peel, and the fruit will be harvested after 4-5 days of full coloring. The research shows that the harvest maturity seriously affects the quality of loquat. Comparing the fruit quality of different maturity, it is found that it is most suitable to harvest when the fruit slightly turns orange. At this time, the content of soluble solids in the fruit is high, which is a tool to measure the linear size change, and the respiratory intensity of the fruit is not high, which is conducive to storage and preservation

2. Harvesting method

the quality of picking technology is directly related to the commodity value of loquat. The skin of loquat fruit is thin, tender and juicy, and there is a layer of fuzz on the peel. If you touch it a little, the peel will be injured and discoloured. Therefore, when picking, it is required to hold the fruit handle and cut it with scissors, handle it gently, and never pull it directly with your hands. Do not pinch the fruit with your fingers. The fruit handle should be cut flat to avoid damage to the fruit. The damaged and diseased fruits shall be removed in time and graded

III. post harvest preservative

after the harvest of loquat, immediately use benlat 500 μ Soak the fruit in g/ml for 30 seconds and store it at room temperature for 28 days. The fruit does not shrink or change color, which can effectively prevent decay. The research points out that the use of Shi Baogong is 1000 μ G/ml plus Bacardi 200 μ G/ml washed fruit, combined with ethylene absorbent treatment, can be inched with PE fresh-keeping film; The fruit has good antiseptic effect. After 66 days storage, the decay index was only 3, while the control was as high as 54.2. Other experts think how to make better use of the metallographic polishing machine. After the harvested loquat is pre stored by air cooling, it is put into the plastic basket covered with PE, and the comprehensive technical measures such as preservative, decompression and low temperature are applied to keep it fresh for 45 days, with a good fruit rate of 100% and the fruit color and freshness unchanged. In addition, the harvested fruits were immediately fumigated with 1% sulfur dioxide (volume ratio) for 20 minutes, or 1% carbendazim plus 2,4-d2 × 10-4 soak for 1 minute, then dry the package, or treat with 0.5% calcium chloride, or fumigate with 0.1 ml/kg sec butylamine, which can greatly reduce fruit decay

IV. storage technology

1. With the increase of storage temperature, the water loss and fruit cracking of loquat fruits increased significantly. The results showed that loquat was a non climacteric fruit, and its postharvest respiration and ethylene production showed a downward trend. Low temperature can significantly inhibit fruit respiration and ethylene production. At the same time, loquat is a non cold sensitive fruit, which does not show cold injury symptoms at 1 ℃. The suitable storage temperature is 1 ~ 5 ℃. The content of cryptoxanthin and phenol will change when the temperature is lower than 10 ℃, and the activity of polyphenol oxidase is related to fruit browning. Therefore, cold storage can effectively control fruit decay and prolong the storage period. However, when the temperature drops rapidly, the content of total acid and sucrose decreases significantly. After long-term low-temperature storage, the fruit will appear the phenomena of weak flavor, difficult peel, hard flesh, rough and less juice

the study found that at 1-5 ℃, combined with film packaging, the good fruit rate was more than 90% after 30 days of storage; In addition, under the condition of cold storage, treated with sulfur dioxide releasing agent of 2-4 g/kg, the decay index after 35 days of storage is 0, but the control is as high as 9.3. Cold storage combined with sulfur dioxide treatment can significantly inhibit the respiratory intensity and polyphenol oxidase activity of fruits, delay the decline of soluble solids and titratable acid content, inhibit the increase of fruit hardness and core browning, reduce the occurrence of fruit decay, and thus prolong the storage period. The study found that calcium chloride combined with cold storage can also prolong the storage period of loquat. Soaking in 0.5% calcium chloride solution for 30 minutes and storing at 5 ℃ for 25 days has the lowest decay index and the best effect. Experts believe that the thickness of 20 μ M polyethylene film packaging, stored at 5 ℃ for 60 days, the fruit quality remained good. An Italian study showed that at 8 ℃, packed in polyethylene bags, the fruit could be stored for 30 days without changing its appearance and flavor

2. Controlled atmosphere storage the temperature of loquat controlled atmosphere storage is 5 ± 1 ℃, the relative humidity is 90% - 95%, the oxygen content is 10% - 12%, and the carbon dioxide is 4% - 6%. Under these conditions, the fruit loss rate is more than 50 days, but everyone knows that lactic acid bar is 3.14%, the good fruit rate is more than 96%, and the fruit appearance is plump, bright color, and easy to peel. However, the relative concentration of carbon dioxide and oxygen must be paid attention to when using this method. It is reported that when the carbon dioxide content is 12% and the oxygen content is 2%, the fruit will be browning inside and brown spots will appear on the outer skin after 5 days of storage, and the longer the time, the more obvious the symptoms. The reason may be that high concentration of carbon dioxide promotes the phenol metabolism in the fruit

reprinted from: China Agriculture

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