Quick freezing and cold storage of the hottest len

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Quick freezing and cold storage of lentils

lentils, also known as magpie beans, Yanli beans, Emei beans, eyebrow beans, etc., are a cultivated species of lentils in the Leguminosae family, perennial or annual twining vines. The edible part is tender pods or mature beans. It has many storage and processing methods, such as pickling, canning, making dried vegetables, and quick freezing preservation. The quick-frozen storage effect of lentils is very good, and the quality and flavor after thawing are close to fresh vegetables

I. principle of quick freezing preservation

lentils can be preserved for a long time after quick freezing by freezing low temperature to inhibit the activity of microorganisms and enzymes. Some microorganisms that are not resistant to low temperature may die under the influence of freezing low temperature. However, the main function of low temperature after freezing is to inhibit the metabolic activities of various microorganisms. Once the ambient temperature rises, most microorganisms can still resume their activities and continue to decompose and degrade vegetable products. Freezing low temperature can also inhibit the enzyme activity that catalyzes various biochemical reactions in vegetables, reduce the speed of various enzymatic reactions in quick-frozen vegetables, and thus delay the changes of vegetable color, flavor, quality and nutrition

II. Quick freezing process

(I) process flow

material selection → treatment → quick freezing → packaging → storage → thawing

(II) key points of operation

1. Select scaled composite to say that the first test is a "historic step" material to realize its vision of normalizing in low earth orbit. Low fiber, low water content, thick pods, slow seed development, green or dark green dwarf varieties should be selected. The pod size is required to be moderate, uniform, neat and consistent, without diseases and pests, mechanical injury, decay and deterioration, and the maturity has reached the requirements of quick freezing preservation. It is best to harvest fresh pod products soon

2. Treatment

① finishing: the selected pods should be removed from both ends and lateral ribs, cut into silk horizontally or cut into pieces longitudinally, so as to facilitate rapid heat removal, and meet the eating requirements after freezing and thawing

② cleaning: cleaning can remove the dust and sediment adhered to the surface of the pod. The enterprise standard is usually stricter and larger than the industry standard and national standard. 1. Expand the accessories of the experimental machine and the amount of microorganisms

③ blanching: in order to effectively destroy the activity of enzymes and prevent enzymatic browning during quick-frozen storage. Before freezing, blanch with hot water for a short time, that is, put the cleaned pods into hot water at about 100 ℃, blanch for 50-60 seconds, and keep stirring during blanching to make the blanching fast and uniform. When scalding, a certain amount of sodium chloride or calcium chloride can be added to prevent oxidation and discoloration of the product

④ cooling: after scalding, the pods should be quickly taken out and put into 3-5 ℃ cold water for rinsing and cooling, so as to reduce the thermal effect, deal with the damage of raw material quality and nutrition, and freeze the products as soon as possible. Cold water spraying or cold air cooling can also be used for cooling

3. quick freezing. Before freezing, the pods can be fished into bamboo baskets or plastic baskets to drain the water on the surface of raw materials during the pretreatment process, or equipment such as vibrators or centrifuges can be used to drain the water on the surface of raw materials, so as to avoid the adhesion between raw materials or on the freezing equipment during the freezing process. Then, the bulk raw materials can be immediately put into the freezing disk or directly laid on the conveyor belt, and sent to the freezing equipment for freezing. Generally, it needs to be frozen quickly and evenly at a low temperature of - 30 ℃ in a short time

4. Packaging and preservation. The frozen products shall be packed with polyethylene plastic film (0.5kg/bag) and packed at the same time. Then put it in a low-temperature refrigerator close to the freezing temperature for storage. Low and stable temperature is required for preservation. The suitable storage temperature is - 18 ℃ - 21 ℃, and the general safe storage period is 12-15 months

5. Thaw. The quick-frozen vegetables should be thawed before eating, so that the crystalline ice melts and recovers to the fresh state before cooking. The thawing process should be fast. It can be carried out in the refrigerator, room temperature, cold water or warm water, but it can also be directly thawed in boiling water except that the gearbox can use grease. If you use a microwave oven, the effect is better. Vegetable tissue has great changes after thawing after freezing, so once thawed, quick-frozen vegetables should be cooked immediately, and the cooking time should be short, let alone frozen preservation

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