Storage and fresh-keeping Technology of Potato

The edible part of potato (potato) is tuber, which contains a lot of carbohydrates and rich mineral elements. The potato is resistant to storage and transportation and can be supplied year-round. It is a kind of raw material for fresh vegetables and processed products to adjust the weak market and popular.

I. Storage and characteristics

Potatoes generally have a dormant period of 2-4 months after harvest, and the length of dormant period varies with different varieties. The dormancy period of late-maturing varieties is short, while that of early-maturing varieties is long. Different maturity also affected the length of dormancy period, and the dormancy period of immature potato stem was longer than that of mature potato stem. The storage temperature also affects the long dormancy period, especially the low temperature at the initial stage of storage is very beneficial to prolong the dormancy period.

Potato is rich in starch and sugar, which can be transformed into each other during storage. When the temperature dropped to 0 ℃, the hydrolysis activity of starch increased, monosaccharides accumulated in the potato, sweet potato became sweet, the edible quality was poor, and the processed products browned. If the storage temperature increases, the monosaccharide will synthesize starch. When the temperature is higher than 30 ℃ and below 0 ℃, the potato heart is easy to turn black.

II. Varieties and harvests

The selection of potato varieties with long dormancy period can prolong the storage period, while early-maturing varieties, varieties cultivated in cold areas or autumn potatoes have a long dormancy period, which is beneficial to storage. Potato should not be irrigated too much in the later stage of growth, and the application of phosphorus and potassium fertilizer can improve the storage and disease resistance of potato. Most of the potatoes planted in spring in northern China are harvested before the rainy season in July, while those sown in summer and autumn are mostly harvested in mid-September. Potatoes can be harvested when the aboveground stems and leaves turn yellow, lodge and wither. The harvest should be carried out on a sunny day, and the potato pieces should be dried on the spot for about half a day, giving off some moisture to dry the potato skin, so as to reduce the incidence during storage.

III. Storage conditions

The suitable storage temperature of fresh potato is 3-5 ℃, but the potato used as fried potato chips or French fries should be stored at 10-13 ℃. The suitable relative humidity for storage is 85% RHI 90%, too high humidity is easy to increase decay, too low humidity increases water loss, and potato pieces shrink. Light can promote potato germination and increase the content of solanine glycosides in potato pieces. The content of solanine glycosides in normal potato pieces does not exceed 0.02%, which is harmless to human beings and animals, but after the potato pieces are illuminated or germinated, the content of solanine glycosides increases sharply, which is toxic to both human beings and animals. Therefore, potatoes should be stored away from light.

Fourth, storage methods and management

1. Gully hiding. Potatoes were harvested in mid-July and stored in shade sheds or empty houses until they were stored in ditches in October. The ditch is 1-1.2 m deep and 1-1.5 m wide, and its length is unlimited. The potato pieces are 40-50 cm thick and 70-80 cm thick in cold areas. they are covered with soil and should be covered step by step as the temperature drops. The pile of potatoes in the ditch should not be too high. Otherwise, the temperature at the bottom and middle of the ditch is easy to be on the high side, and the potato pieces will rot when they are heated.

2. Cellar. Use well cellar or kiln cellar to store potatoes, each cellar can store 3000-3500 kg, because only use the pit mouth ventilation to adjust the temperature, so the heat preservation effect is better. However, it is not easy to cool down at the initial stage of entering the cellar, so the potato can not be filled too full, and pay attention to the opening and closing of the cellar. As long as it is properly managed, the storage effect of potatoes is very good. When using the shed cellar for storage, the top cover of the cellar should be thickened and the cellar body should be deepened to avoid freezing damage. The height of the potato pile in the cellar is less than 1.5m, otherwise it is easy to sprout and rot due to heat at the initial stage of entering the cellar.

3. Ventilation storage. Generally, the height of the reactor is not more than 2m, and a ventilator is installed in the reactor. Basket palletizing and storage, it is more convenient to manage and improve the storage capacity. No matter which storage method is used, there should be a certain gap around the potato pile to facilitate ventilation and heat dissipation.

4. Refrigerate. After dormant period, potatoes can be transferred to cold storage to control germination and water loss, which can be stored in cold storage or packed in boxes. Control the temperature at 3-5 ℃ and the relative humidity at 85% Murray 90%.

5. Drug treatment. Chlorpheniramine (CIPC) is a kind of postharvest sprouting inhibitor. The dosage of the powder is 1.4g / kg / kg. The powder is sprinkled into the potato pile and covered with plastic film or canvas. After 24-48 hours, the treated potato will not germinate at room temperature. The sprouting inhibitor must be used after potato callus, otherwise it will interfere with potato callus and cause potato to rot during storage. The effect of sprouting inhibition of potato before dormancy period is good, and the effect of sprouting inhibition is obviously weakened when it is used after dormancy period. The sprouting inhibition effect of potato treated with methyl a-naphthylacetate or ethyl a-naphthyl acetate is good. The dosage is 0.4-0.5 kg for every 10 tons of potato, and 15-30 kg of fine soil is made into powder in the potato pile. Should be carried out in the middle of dormancy, not too late, otherwise the efficacy will be reduced. MH (penicillin) also has a sprouting inhibition effect on potatoes, but it should be sprayed in the field 3-4 weeks before the potato is harvested, with a concentration of 3% Mel 5%, and should be re-sprayed in case of rain.

6. Radiation treatment. The potato irradiated with 8-15kR r-ray has obvious bud inhibition effect, and the irradiated potato can be stored well for several months at room temperature.