Review on the storage and fresh-keeping technology

Review of grape storage and preservation technology (VII)

④ grape black spot. Grape black spot, also known as Alternaria, is a major postharvest disease of some varieties in the long-term storage process, belonging to Alternaria and Saccharomyces of the seminiferous division. The disease mainly occurs in the post harvest season. After rainfall in the later stage of growth, it begins to occur at the junction of the fruit stalk and the fruit grain, followed by brownish or dark brown decay around the fruit stalk, black molds on the surface of the disease spot, and seed drop

prevention and control measures of Grape Black Spot: A. because the disease mainly occurs before and after the harvest period, and each rainfall will lead to the occurrence and spread of the disease, ear bagging can prevent the rain from scouring the fruit grains and reduce the chance of disease; b. Spraying fungicides 3-4 times before harvest can inhibit the occurrence of diseases; c. Avoid harvesting in rainy and foggy weather, handle the harvested ears with care, and be extra careful in storage and transportation to avoid mechanical damage and the formation of infection channels; d. Refer to gray mold for post harvest treatment

⑤ grape scab. Grape scab, also known as grape bud branch mold or black pox, is a major disease of some grape varieties during the storage period, belonging to the subfamily of hemifungi. When the disease occurs, the fruit stalk produces black and hard rotten spots; The epidermis and shallow pulp of the fruit are hard and rotten. Stored at room temperature for a few days, the disease spots appear green to olive moldy. Can be latent and contact infection, wound invasion

prevention and control measures of grape scab: A. avoid mechanical damage and cut off the infection channel during picking, grading, storage and transportation; b. During the growth period of grapes, fungicides are sprayed every half a month to prevent latent infection. The main fungicides used are 65% zineb wettable powder 500 times or 64% alum 600-800 times or 50% carbendazim 800 times; c. The bacteria stopped growing at 34 ℃. The spread of scab can be well inhibited by treating the ears with 50-60 ℃ hot water for 20-30 minutes after harvest. d. Isolate the diseased ears in time and disinfect the healthy ears to prevent contact infection

⑥ Grape Black rot. When the disease occurs, the fruit grain appears purple brown spots. After the disease spot expands, its edge is brown, the middle is gray white, slightly sunken, and the fruit grain is soft and rotten. When the climate is dry, the diseased fruit loses water and shrinks into black stiff fruit. When the humidity is too high, the berries are rotten. Pathogenic bacteria can be infected circularly. Berries are susceptible to this disease at maturity and under high temperature and humidity

prevention and control measures of Grape Black Rot: A. clear the garden and disinfect to kill overwintering pathogens; b. Strengthen summer management, improve the scenery conditions of the shelf surface, reduce the humidity of the garden, and reduce the occurrence of diseases; c. Ear bagging to isolate disease infection; d. Chemical control during growth period

⑦ grape white rot. Grape white rot, also known as water rot and ear rot, is one of the main diseases of grape growth period and storage period. It is mainly harmful to fruits and cobs. At the initial stage of the disease, the fruit stalk showed water soaked brown spots and spread to the fruit grains; The stem of the fruit grain becomes light brown and soft rotten, and then the whole grain browning and rotten, and the fruit stem withers. About a week, the color of the diseased fruit deepened to black brown, and black and white small particles were dense under the peel, and then the diseased fruit lost water, dried, shrunk and stiffened. Rot under high humidity conditions. The disease has strong vitality (2-7 years), can be infected circularly, wound invasion, rain and water transmission, and high temperature and humidity are conducive to the occurrence and prevalence of the disease. Generally, after encountering storms and hail disasters, diseases are often caused. In places with sticky land, poor drainage, high groundwater level, low-lying and windy, the disease occurs more seriously

prevention and control measures of grape white rot: A. clearing the garden and disinfecting the warehouse. Spraying 0.4% potassium permanganate or lime water in the storehouse can directly kill overwintering pathogens; b. Keep fruits in high position to avoid rain splashing and water infection. Cover the ground with grass and film to prevent pathogen infection. Improve the scenery conditions, reduce the field humidity, and reduce the degree of berry disease; c. Fruit bagging; d. Chemical prevention and control, and spraying on the ground. In the early stage of the disease, use 1 part of thiram, 1 part of sulfur powder and 2 parts of calcium carbonate. After being evenly mixed, it can kill the overwintering pathogens under the surface of the frame. The dosage per hectare is 15-30kg, and the fungicide is sprayed every 10-15 days during the berry expansion period, 3-5 times continuously. The commonly used drugs are: 600-800 times of 50% ibuprofen, 400-500 times of 50% thiram, 500 times of 50% thiophanate methyl and 500 times of 50% chlorothalonil

12.3.8.3 use of preservatives

grapes have high sugar content, high environmental humidity, serious latent infection of pathogenic bacteria in the field, and strong resistance, which can complete high-speed and low-precision transformation and low temperature resistance. Therefore, pharmaceutical preservatives are an inevitable link in the preservation of fresh grapes. Sulfur dioxide is the most effective preservative in grape storage and preservation, and has been widely used in grape storage at home and abroad. Sulfur dioxide is a strong reductant, which can inhibit the activity of oxidase and microorganisms, so as to prevent food corruption, discoloration and vitamin loss. Sulfur dioxide in aqueous solution has strong toxicity to the spores and vegetative tissues of Botrytis cinerea and Alternaria

sulfur dioxide can kill all kinds of rot causing bacteria, especially Botrytis cinerea, Cladosporium, Rhizopus nigrum, Alternaria, etc. But in addition to grapes, there are few kinds of fruits and vegetables that can tolerate the concentration of sulfur dioxide to control disease decay. The pH value in grape pulp is 33d. The printing plastic material recycling system was sent into space by NASA 9-4.0. Sulfite is formed in the body after being treated with sulfur dioxide. Sulfur dioxide shows that its yield strength and tensile strength are higher than the predetermined value. When the area shrinkage and elongation are applied within the tolerance range, 30% of sulphurous acid forms a combined state with sugars and aldehydes, and the remaining non dissociated free sulphurous acid is the most effective for corrosion prevention. At present, SO2 and its complex are used for the preservation of fresh grapes in the following ways:

1 Sulfur dioxide fumigation preservative is used to fumigate the cellar, which has a good effect on the Botrytis cinerea bacteria that cause decay during storage. For example, 25 g/m3 sulfur is used for burning and disinfection three days before storage, and sealed for 24-48 hours. Once in the cellar, 4g/m3 sulfur is used for burning and fumigation for 30-60 minutes, and then fumigated once every 10 days. When the temperature is 0-1 ℃, fumigated once every 1 month. It should be pointed out that when using polyethylene film to store grapes and fumigating miscellaneous bacteria by burning sulfur, the account must be uncovered and ventilated after fumigation

2. The cylinder releases sulfur dioxide for fumigation. After harvest, stack the grape boxes (baskets) and cover them in a polyethylene film tent with a thickness of 0.1--2mm. The sulfur dioxide gas directly released from the steel cylinder is recorded in the account. The amount of sulfur dioxide is 0.5% of the volume in the account and fumigated for 20-30min. The amount of sulfur dioxide fumigated and the fumigation time can be appropriately reduced in the future. The concentration of sulfur dioxide is 0.1% - 0.3%, and the fumigation time is 20min

3. The fumigated grapes with SEC butylamine are treated with SEC butylamine preservative, and then put into polyethylene plastic substitute to seal and keep fresh. The specific usage is: every 500kg of grapes are fumigated with 25ml sec butylamine, then stored in a large film tent, and stored at a low temperature of 2.5-3 ℃ for 3 months. The good fruit rate can reach 98%, the weight loss rate is 2%, the fruit quality is normal, and the fruit stalk is green

4. Calcium peroxide preservative according to the Japanese patent tekong: put 20 clusters (ears) of Jufeng grapes into plastic bags with a width of 25cm and a length of 50cm respectively, clip 5g of calcium peroxide in the absorption paper with a length of 10cm, a width of 20cm and a thickness of 1mm, wrap it in a plastic bag and seal it, place it at 5 ℃. Its main function is to amplify the weak signal generated by the sensor, store it for 76 days, and the loss rate is 2.1%, while the control shows that the treatment is 10.3%; The threshing rate of berries was 4.3%, while that of the control was 82.2%. When calcium peroxide is wet, it decomposes into oxygen and reacts with ethylene to produce ethylene oxide, then reacts with water to produce ethylene glycol, and the rest is hydrated lime. It can eliminate the ethylene released during grape storage, so as to prolong the storage period. The medicament is safe and effective. If it is used together with fungicide, the effect is more remarkable

5. It is made of sulfites into tablets or powders, which are sealed and packed with plastic film (or non-woven fabric) outside. When in use, it is perforated to release SO2 when it meets water. In order to continuously release SO2 for a long time, different kinds of sulfites are used and mixed with different fillers to make quick release tablets and slow-release tablets

author/PAN Enmin (Senior Engineer of Jinan XINKEYUAN Storage Engineering Co., Ltd