Processing technology, packaging and storage of th

Processing technology, packaging and storage of dried fruit and vegetable products (3)

4 processing and packaging storage of dried products

4.1 processing of dried products

4.1.1 softening and softening, also known as moisture equalization, sweating or moisture balance, aims to balance the moisture content of each part through the transfer of internal and external moisture of dried products, and present a suitable soft state, so as to facilitate product processing, packaging and transportation. The time required for softening of dried products of different fruits and vegetables is also different, the less is 1 ~ 3 days, and the more is 2 ~ 3 weeks

4.1.2 pressed vegetables are bulky and bulky after drying, which is not conducive to packaging and transportation. Therefore, they need to be compressed, which is generally referred to as pressed vegetables. The briquetting of dehydrated vegetables must take advantage of the effects of water, heat and pressure at the same time. Generally, the temperature of vegetables in the final stage of dehydration is 60 ~ 65 ℃, and then they can be pressed immediately without softening. Otherwise, dehydrated vegetables will turn cold and crisp. Before briquetting, steam must be sprayed slightly to reduce the crushing rate. The moisture content of dried vegetables sprayed with steam after briquetting may exceed the predetermined standard and affect the storage resistance, so the final drying is required after briquetting. Quicklime can be used as desiccant. If the moisture of dehydrated vegetables after briquetting is about 6%, it can be stored with the same weight of quicklime. After 2 ~ 7 days, the moisture can be reduced to less than 5%

4.2 packaging of dry products

dry products can be packaged after necessary treatment and grading. The packaging container shall be able to cover, prevent insects and moisture. In recent years, dried fruits are packed with polyethylene, hydrochloric acid rubber, styrene, polypropylene and other products

4.3 storage of dry products

4.3.1 storage requirements the selection of dry raw materials and the treatment before drying are closely related to the storage resistance of dry products. The moisture content of dried products has a great influence on the preservation effect of dried products. Without damaging the quality of the finished product, the drier the product is, the lower the water content is, and the better the preservation effect is

low temperature is beneficial to the storage of dry products, because oxidation is related to temperature. Generally, the storage temperature should be 0 ~ 2 ℃ and not more than 10 ~ 14 ℃

the moisture content of dry products is low, and the relative humidity of the air must also be reduced accordingly. Otherwise, the increase of relative humidity will inevitably increase the equilibrium moisture of dry products, thereby increasing the moisture content

light can promote the pigment decomposition of dry products. Oxygen can not only cause the discoloration of dry products and destroy vitamin C, but also oxidize sulfite to sulfate, reducing the preservation effect of sulfur dioxide. Therefore, the storage of dried fruits and vegetables should be shielded from sunlight and reduce the supply of air

4.3.2 storage management in a certain storage environment, the quality of management is also closely related to the storage effect

requirements for the warehouse storing dry products are clear. 19. Safety device of the test bench: electronic limit protection, clean and sanitary, well ventilated and sealed, and equipped with rat prevention equipment. When storing dry products, do not store wet items at the same time. Pay attention to the stacking height to facilitate air flow, and leave a walkway in the center. Always pay attention to the management of temperature and humidity in the warehouse, and often check the quality of products to prevent pests and mildew

there are usually the following methods to control pests

(1) low temperature insecticidal use low temperature insecticidal the most effective temperature is below -15 ℃

(2) thermal insecticidal heating for several minutes at a suitable high temperature without damaging the quality can kill the hidden pests in the dried products

(3) fumigants kill insects in dried fruit and vegetable products. The commonly used fumigants are as follows:

carbon disulfide (CS2) fumigation carbon disulfide has a specific gravity of 1.29 at 0 ℃, volatilizes when placed in the air, boils at 46 ℃, and the gaseous carbon disulfide is heavier than the air. During fumigation, the container containing the fumigant should be placed high indoors to make it naturally volatilize and diffuse downward, Dosage concrete pressure testing machine is a frequently used testing instrument, which is about 100g per 1m3, and the fumigation time is 24h

the specific gravity of chloropicrin (ccl3no2) fumigation method is 1.66, and the boiling point is 112 ℃. It is a colorless liquid, insoluble in water, and volatilizes slower in air than carbon disulfide. The medicine is highly toxic and has a strong irritating odor. When the temperature is above 20 ℃, it is the most effective to kill insects. Therefore, it should be used in summer and autumn. The dosage is 17g per cubic meter, fumigated for 24h. Chloropicrin should not be in contact with metal. The containers used should be enamel or pottery. When the products are not completely dried, the use of this agent is prone to drug damage, and the products should be fumigated after being fully dried. During fumigation, the house must be tightly sealed without air leakage, and care must be taken to avoid danger

sulfur dioxide (SO2) fumigation method sulfur dioxide can only be used for dried fruits that have been fumigated with sulfur. The usage is the same as the sulfur treatment of the above raw materials, and the treatment time is 4 ~ 12h

methane bromide (CH3Br) fumigation method when using methane bromide, 1.7kg per 100m2 volume is required for fumigation for 24h

in addition, keep the packaging room and storage room clean, pay attention to cleaning up waste, and disinfect indoor and all appliances with chemicals

from food and 1. Drugs for experimental purposes (author/xuezhiyong)