Fresh keeping and storage technology of the hottes

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Preservation and storage technology of Black Amber plum

Black Amber plum (Black Amber) is an early maturing large fruit black plum variety bred by the hybridization of Frair and queen rose. At present, it is planted in many provinces and regions in China. Yunhe County is the production area with the largest introduced cultivation area, the highest yield and the best fruit quality in Zhejiang Province. The cultivation area is more than 99000 mu, with an annual output of 6000 tons. The economic benefits are good, and the cultivation area continues to expand. However, because the fruit of Black Amber plum has high respiratory intensity, rapid post ripening, and the harvest time is in midsummer, the fruit is extremely intolerant to storage, vulnerable to microbial infection, and serious decay and loss. Industry inspectors believe that from 2002 to 2004, in cooperation with the Department of Horticulture of Zhejiang University and with the support of the Department of science and technology of Zhejiang Province, we completed the research on the subject of "research and development, promotion and application of storage and preservation technology of black plum (black amber variety)", and summarized a set of more suitable storage and preservation technology. After 60 days of storage, the rate of good fruit is as high as 98%

1. Prepare well before storage

produce high-quality fruits without diseases and pests. Pay attention to improving the ventilation and light transmission conditions of the tree; Strengthen pest control; Control nitrogen fertilizer and increase phosphorus, potassium and calcium fertilizer; Timely drainage after rain, reduce humidity and reduce pathogen infection; Harvest in time 2-3 days after sunny days

disinfect the warehouse. After the warehouse is cleaned, disinfect it by fumigation or spraying. Use 10-30 grams of sulfur per cubic meter of warehouse, add an appropriate amount of sawdust, ignite in piles, seal for 24 hours, and then ventilate. Or spray 3 kg of 1% formalin solution per 100 cubic meters of the reservoir, and then seal it for 24 hours before ventilation. Or fully stir with 4% bleach solution and keep it for 1 day and night, and then spray the cloth evenly

2. Harvest in batches in a timely manner without injury

plum fruit is harvested at the ninth maturity. At this time, there is fruit powder on the fruit surface, and the fruit has good color, aroma and taste. The best harvest index is the fruit hardness of 10.0-10.5 kg/cm2; The soluble solid content is more than 11%. The fruit surface is purplish red with fruit powder. Generally, it is collected in 2-3 times. There are many deformed fruits, disabled fruits and small fruits in the early mature fruits, which are generally not used for storage. It is best to choose the fruit harvested in the second batch, which is large and symmetrical, for storage. To harvest, it is necessary to strictly prevent bumping, crushing and stabbing, pinch the fruit with two fingers, minimize contact with the fruit surface, reduce the loss of fruit powder, and harvest the fruit with a handle. The harvesting sequence is from bottom to top, from outside to inside. The picking action should be light, and the fruit branches should not be damaged. The fruit should be handled with care. The harvested fruits should be placed in the shade to avoid sunburn. After harvest, it should be transported to the packaging site in time for pre cooling. During the handling process, it should be loaded and unloaded with care, and it is not necessary to dump the box at one time, so as to avoid mechanical damage. Each box of fruit weighs no more than 15kg, and the box should be padded with soft and light materials

3. Precooling in time

adopt warehouse precooling. The plum fruits collected in the field should be transported to the pre refrigeration warehouse that has been thoroughly disinfected and cooled to 0 ℃ on the same day, so that the fruits can be quickly cooled to 0-5 ℃. After the boxes are put into storage, they are stacked into stacks, and the base plates at the bottom of the stacks are 10-15 cm high. There should be gaps between stacks and between boxes. The fruits enter the pre cooling warehouse in batches, and the daily storage volume should not exceed 20% of the total storage capacity, so as to quickly reduce the fruit to the required temperature. The pre cooling time should be 24 hours

4. Use special fresh-keeping bags and graded packaging of preservatives

graded packaging is carried out in a specific cold storage, and the warehouse temperature is stable at 5-10 ℃. Fruits precooled to about ℃ shall be packed in grades. In the process of packaging, pick out the disabled, inferior, dirt and overripe fruits, and the rest of the commercial fruits are packaged according to the weight of each fruit. The whole process should be handled with care, and the box should not be emptied. Take the fruit with both fingers to minimize the loss of fruit powder

4.1 use of preservatives and fresh-keeping bags

special preservatives are compound preservatives that can absorb harmful gases, inhibit respiration and prevent corrosion. The special fresh-keeping bag is a plastic film bag with specific additives. The gas in the bag can be exchanged with the outside world, playing a better role in air conditioning. Because the special fresh-keeping bags have good strength, each bag can store 10-15 kg of fruit crystals. During grading packaging, the special fresh-keeping bag shall be padded on the inner wall of the outer packaging box, and then the fruits of different specifications shall be sorted and packed into the fresh-keeping bag. When the specified weight is reached, the special fresh-keeping agent shall be placed on the fruit, and one package (15g) of the agent shall be placed every 5kg of fruit. Put a piece of paper between the special preservative and the fruit to avoid direct contact between the preservative and the fruit surface. Put the preservative in place, and immediately tie the mouth of the bag with a rope or rubber strip

4.2 select the outer packing box

make institutional arrangements for the risk control and sharing of the utilization demonstration of new materials that enter the sales channel immediately. Fruits can be directly packaged in the packaging box of finished products on the market, with quantitative packaging, and full consideration of the ventilation, moisture resistance and pressure resistance of the box. Finished products can be packed in wooden boxes, plastic boxes and special refrigerated cartons. The wooden box we use is environmentally friendly and strong, with a shape specification of 465mm × 300 mm × 165 mm, with a net fruit weight of 9.0-10.0 kg per box. For fruits that need to be stored for a long time (such as more than 7 weeks), they can be stored in plastic transfer boxes. When selling fruits, open the fresh-keeping bags, remove the softened and rotten fruits, and then pack them and transport them to the market in time

5. Strengthen the inspection and do a good job in the warehouse management during the storage period

after the graded packaging of fruits, they should be sent to the special storage and fresh-keeping cold storage in time, and the storage temperature should be controlled at 1 ± 1 ℃. Stable storage temperature is one of the keys to the success or failure of Black Amber plum storage. Pay attention to adjusting the temperature of different parts in the warehouse to make it balanced and stable, so as to prevent mildew caused by water in the bag due to unstable warehouse temperature. The fruit box on the top floor is 50-80 cm from the ceiling of the cold storage, and 120 cm is used for each stack of fruit boxes × The base plate frame of L20 cm is 10-15 cm high. There is a gap between boxes through which cold air passes. There is a gap of l0cm between stacks, and the distance between stacks and the four walls of the cold storage is not less than l0cm, so as to ensure the smooth flow of cold air in the storage. At the same time, according to the operation needs, a 50-200 cm wide operation track is reserved

after fruits are put into storage, first, check the temperature and humidity in the warehouse; Second, check the quality of fruit preservation. Place thermometers and hygrometers in different parts of the warehouse, and regularly check the changes of temperature and humidity twice a day. The temperature difference in the warehouse is controlled at about 1 ℃ and the humidity is controlled at 85% - 95%. Select observation boxes at different parts of the stack, and regularly check the fruit hardness, color and sugar content of the pulp. If the pulp becomes soft (the fruit hardness is less than 8.0 kg/cm2), the meat color turns brown (the part near the core turns brown first), and the fruit loses water, it should be handled in time to avoid causing large losses

6. Discussion

6.1 operation process

for large-scale storage and preservation of Black Amber plum, pre cooling warehouse, graded packaging warehouse and storage warehouse must be set up separately to meet the needs of harvesting → pre cooling → graded packaging → storage → ex warehouse, which can reduce the loss of cooling capacity, improve processing capacity and reduce costs. In case of small batch storage, the following process can be followed: harvesting → graded packaging → bag opening and pre cooling → fresh storage → ex warehouse. Pre cooling warehouse and storage warehouse can be shared or set separately

6.2 fresh keeping bags

using polyethylene or non-toxic polyvinyl chloride film bags with fo as the lower limit frequency (Hz) of 0.025-0.04 mm to replace special fresh keeping bags also has a certain fresh-keeping effect, but the fresh-keeping effect is slightly inferior, which shows that the pulp softens and ages in advance, especially when the storage temperature is unstable, the ordinary film wall is easy to produce a large number of water droplets, The influence focused on the appearance of fruit packaging, the landmark achievement of 25 sets of major technical equipment, which is prone to fruit mildew

6.3 storage and fresh-keeping cost

production storage and fresh-keeping costs are relatively low due to large storage volume. Based on the 30 day storage and preservation of each ton of fruit, the expenditure of cold storage is 100 yuan, the expenditure of special preservative is 130 yuan, and the expenditure of special fresh-keeping bag is 70 yuan. The total storage and preservation cost of each ton of fruit is 300 yuan, and the estimated loss of fruit is 3%

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