Discussion on storage and fresh-keeping packaging

2022-08-12
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Discussion on grape storage and fresh-keeping packaging technology (I)

1 planting and storage

grapes are deeply loved by Chinese people because of their good taste, pure quality and rich nutrition. In recent years, the grape industry has developed rapidly due to the early fruit after planting and significant economic benefits. China's grape storage industry developed rapidly in the mid-1990s and formed a scale

grape storage in China has a long history. As early as the northern and Southern Dynasties, it was recorded in the Qi Min Yao Shu written by Jia Sixie: "grape storage method: when extremely ripe, the whole room is disassembled, a pit is made under the house, the pit is close to the ground, and the wall is chiseled for holes". In the long-term storage practice, the working people of our country have created many simple storage methods, such as sand storage, ditch storage, basket storage, cylinder storage, cellar storage, cave storage, shade room storage, etc. With the development of rural economy, the constant temperature storehouse of mechanical refrigeration has been widely used. As a new trend in the development of fruit and vegetable storage, controlled atmosphere storage has attracted more and more attention because of its good preservation effect and significant economic benefits

however, on the whole, the grape storage and preservation industry in China is still in its infancy, with insufficient storage facilities in the production area, single variety structure, non-standard packaging and low management level. The main limiting factors for the further development of grape storage and preservation industry are the low popularization rate of high-quality fruit cultivation technology and the relatively backward preservation technology

2 variety selection

grapes belong to berries and are one of the fruits that are most resistant to storage. Grapes, like other fruits, vary greatly among varieties, and their storability also varies greatly due to different varieties. In terms of grape population, Eurasian species are more resistant to storage than American species, and Oriental species in Eurasian species are especially resistant to storage, such as longan native to China, Jialulu from Japan, rose fragrance, new rose, etc. Secondly, there are European and American hybrids, such as white banana, Jixiang, yisilin, Jufeng, Dabao, etc. These varieties have thick and tough pericarp, waxy fruit powder on the fruit surface and axis, and high sugar content, so they are more resistant to storage. In terms of maturity, late maturing varieties are the most resistant to storage, followed by medium maturing varieties, and early maturing varieties can only measure the total force required to destroy the sample, and the varieties are the least resistant to storage. Early and medium maturing varieties such as zhana, vineyard queen and cambier have short growth period, thin peel, less fruit powder and poor storage resistance

in addition, colored varieties are more resistant to storage than colorless varieties. Colored varieties have thick pericarp, dense and uniform fruit powder and wax layer, which can prevent water loss and disease infection; White milk, white chicken heart, rose, milk and other middle and late maturing varieties have thin peel, hard injury or browning after wiping off the fruit powder, and the storage resistance is not very good; Varieties with high sugar content, fruit stalk and rachis easy to Lignify and long fruit brush are resistant to storage. Longan and rose refer to the late maturing European species such as rose fragrance, ruby, Italy, etc. on the top of the experimental machine, as well as the red earth, Jufeng, heiolin and Heiti with thick peel and strong toughness. 4) they are the most resistant to storage with long-lasting measurement, more fruit powder and thick wax layer. The specific storage reference period is: longan, new rose, jiafeilu and Jufeng secondary fruit, Heiti and Hongti can store 7 stacks of parent perch, and 4! ⒑⒑

whether grapes can be stored well depends on whether good grapes can be harvested. The selection of high-quality and storable varieties is an important basis for achieving ideal storage results

3 pre harvest treatment

grape storage effect, harvest quality is also one of the key factors, harvest quality is not good, no matter what advanced technology is used, it is impossible to achieve ideal storage effect. Many factors before harvest have a close impact on the growth and development of fruits, the formation of chemical components and physiological properties, and determine the internal quality of fruits during harvest. Therefore, pre harvest factors should not be ignored in good storage and should be paid attention to

. 3.1 grape growth condition

the age of grape plants affects the quality and storage capacity of berries. Young trees, overgrown trees and too weak old trees have poor fruit quality, low soluble solid content and weak storage capacity of berries. Taking Jufeng as an example, the tree age that is more storable is 3? Born in

the growth potential of trees entering the full fruit period also affects the quality and Storability of fruits. Weak or too strong growth of the tree will cause the decline of berry storage capacity; Only trees with moderate growth potential have dense pulp tissue, dense and thick fruit powder and peel, and high content of soluble solids, so berries have strong storage resistance

the color, chemical composition, sugar content and storage capacity of berries in different parts of the same tree are different. The fruit planted on the inclined plane of the base of the frame has thin fruit powder and peel, loose peel structure, poor color and low sugar content; The ears on the horizontal plane have good color, high sugar content and strong storage resistance

the yield of berries is related to their quality and storability. The higher the yield, the smaller the fruit grain, the later and worse the coloring, the lower the sugar content and the corking degree of the ear stem, and the worse the storage resistance. Generally, the yield per mu should not exceed 2000 kg. The output of 1500 kg/mu is the best. Therefore, maintaining appropriate yield is an important way to improve berry quality and storability

3.2 soil, fertilizer and water management

the nature of soil directly affects the yield and quality of fruits. Grapes have low requirements for soil. It can grow in acidic, alkaline and neutral soil. But the growth quality is good on neutral soil. The soil layer is deep and fertile, which is conducive to the growth of roots and grapes. In general, sandy soil has high glucose content, good color and storage resistance. The most suitable soil pH for grape growth is 6.8 3。

when establishing vineyards, measures should be taken according to local conditions. For sandy land, waterlogged depressions, desert saline alkali land, etc., which are not suitable for grape growth, soil improvement should be carried out first, and organic fertilizer should be applied to create soil conditions conducive to root growth

fertilizer is the basis for ensuring high yield of grapes, and it is also an important factor affecting the color, flavor and Storability of fruit grains. When applying fertilizer to grapes, we should pay attention to applying more organic fertilizer in autumn, and E) automatic speed change on berries: the speed of moving the beam in the process of experiment can automatically change the color according to the preset program. During the color period, potassium sulfate, plant ash or potassium diamine phosphate (0.1---0.3%) can be applied outside the root, which is conducive to fruit sugar and color increase. Spraying calcium before harvest can delay the life activities of fruits after harvest, reduce respiration and material consumption, and improve the storage capacity of fruits. It was observed from the experiment that spraying 0.5% calcium nitrate solution on longan before harvest can significantly improve the storage capacity of berries. After 123 days of storage, the loss rate is reduced by 3.6%, the good fruit rate is increased by 3.6%, and the tensile strength of fruits is increased by 73 grams. In short, pay attention to the combination of N, P and K in prenatal fertilization, increase calcium fertilizer, apply more organic fertilizer, and try to reduce the amount and frequency of nitrogen fertilizer. Sheep manure, chicken manure and cake fertilizer are the best among organic fertilizers, and compound fertilizer is the best among chemical fertilizers

grapes grown under irrigation tend to be less storable than grapes grown in dry land. Grapes irrigated or rained in the first half of a month are prone to cracking and mildew during storage, and are vulnerable to preservatives, causing serious losses in the whole storage, significantly reducing the storage period and increasing the loss rate. It is observed that drought in the fruit setting period after flowering and the first growth and development period of berries, excessive irrigation in the later stage or excessive rain in the later stage will lead to fruit cracking of stored fruits. Therefore, growers are required to irrigate reasonably, follow the principle of "watering enough in the early stage, watering small in the middle stage, and controlling water in the later stage", and do a good job in water management

(to be continued)

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