Introduction of potato refrigeration technology

First, storage characteristics

Potatoes generally have a dormant period of 2 to 4 months after harvest, and the length of the dormancy period varies from species to species. Late maturing varieties have a short dormancy period, and early maturing varieties have a long dormancy period. Different maturity also has an effect on the length of the dormant period. The maturity of the immature potato tubers is longer than that of the mature ones. The storage temperature also affects the length of the dormancy period. The potato tubers stored at a relatively low temperature have a long dormancy period, especially the low temperature at the initial stage of storage is beneficial to prolong the dormancy period.

Potatoes are rich in starch and sugar, and starch and sugar can be converted into each other during storage. When the temperature drops 0°C At the time, the activity of starch hydrolase is increased, the monosaccharide in the potato block is accumulated, the potato pieces are sweetened, the eating quality is not good, and the processed product is browned. If the storage temperature rises, the monosaccharide will synthesize starch. When the temperature is higher than 30 ° C And below 0°C When the potato heart is easy to turn black.

Second, variety and harvest

The selection of potato varieties with long dormancy can prolong the storage period. Early maturing varieties, cultivated varieties in cold regions or long-term dormancy of potato in autumn are conducive to storage. Potato can not be flooded in the late growth stage, and the application of phosphorus and potassium fertilizer can improve the storability and disease resistance of the potato. Potatoes in the spring of northern China are mostly harvested before the rainy season in July; most of the summer and autumn sowings are harvested in mid-September. Potatoes can be harvested when the upper part of the potato leaves turns yellow, lodging and withering. The harvest should be carried out on a sunny day. The potato pieces are dried on the spot for about half a day, and some of the water is released to make the potato skin dry, so as to reduce the incidence in storage.

Third, storage conditions

Suitable storage temperature for potatoes is 3~ 5 ° C But potatoes used as fried potato chips or fried fries should be stored in 10~ 13 ° C Under conditions.

Why are the potatoes used for cooking and the potatoes used for processing different in temperature?

This is because the starch in the potato is converted to sugar at low temperatures. The suitable relative humidity of the potato is 85%-90%. If the humidity is too high, the rot will increase, the moisture will be too low, the water will increase, and the potato will shrink. Another problem to be aware of in potato storage is that it needs to be stored away from light, as light can cause it to germinate. Increase the content of solanine in the potato tubers. The content of solanine in the normal potato block does not exceed 0.02%, but after the potato block shines or germinates, the solanine content is sharply increased, which has a toxic effect on humans and animals, so the potato should be stored in the dark.

Fourth, storage methods and management

1. Trench

The potatoes were harvested in mid-July and pre-stored in a shed or empty house after harvest until they were stored in the ditch in October. Ditch depth 1~ 1.2m , width 1 -1.5m The length of the ditch is not limited. The thickness of the potato block is 40-50 cm, and the thickness of the cold area can reach 70-80 cm. The upper part is covered with soil insulation, and it should be covered with the temperature drop. The potato pile in the ditch should not be too thick, otherwise the temperature at the bottom of the ditch and the middle of the ditch will tend to be too high, and the potato block will cause decay due to heat.

2, cold storage

After the dormant period, the potatoes are transferred to the cold storage for storage, which can control the germination and water loss well. It can be piled up in the cold storage or packed in the yard. Control the temperature at 3~ 5 ° C The relative humidity is 85-90%.

The potato is easy to germinate in the later stage of storage, and the potato pieces become shrunk. How to control its germination? In order to control its germination, in addition to low temperature, it can also be controlled by drugs.

3, drug treatment

Chlorobenzoate (CIPC) is a post-harvest bud inhibitor. The dosage of powder is 1.4. -2.8 grams /kg, when used, the powder is sprinkled on the potato heap, and the cover is covered with plastic film or canvas. After 24 to 48 hours, the treated potato will not germinate at room temperature. However, it should be noted that the bud inhibitor must be used after the callus of the potato. Otherwise, it will interfere with the callus of the potato and cause the potato to rot during storage. The potato before the dormancy period is better to use the bud inhibiting effect, and is used after the dormant period, and the bud inhibiting effect is obviously weakened. In addition, the effect of treating the potato with α-naphthylacetate or α-naphthalene ethyl acetate is also good. The dosage of each 10 tons of potato chips is 0.4~05 kg, and the powder is evenly mixed with 15~30 kg of fine soil. The ground is scattered in the potato pile. Should be carried out in the middle of dormancy, not too late, otherwise it will reduce the efficacy. MH (green freshener) also has a bud-inhibiting effect on potatoes, but it needs to be sprayed in the field 3-4 weeks before the potato chips are harvested. The concentration of the drug is 0.3%-0.5%, and it should be re-sprayed in case of rain.

4, radiation treatment

Irradiation of the potato with radiation has obvious bud inhibition effect, and the effect is more obvious at the same dose and higher dose rate. The irradiated potato can be stored well for several months at room temperature, but browning may occur around the vascular bundle of the potato stalk after irradiation.