Fruits and vegetables have high water content, but the epidermis protection tissue is poor, so they are vulnerable to mechanical damage and microbial invasion during harvesting, storage and transportation. In addition, fruits and vegetables are still a living body after harvest, which has respiration and transpiration, and will produce a lot of respiratory heat, which will raise the temperature of the surrounding environment and make the products lose water. Therefore, fruits and vegetables are easy to rot and deteriorate, losing commodity value and edible value. Packaging can buffer the adverse effects of too high and too low ambient temperature on products, prevent products from being polluted by dust and microorganisms, and reduce the spread of pests and diseases and the wilting of products due to dehydration. In the process of storage, transportation and sales, packaging can reduce the damage caused by friction, collision and extrusion between products, keep the products in good stability in circulation and improve the commodity rate.

In addition, packaging is also a trade aid, which can provide standard specification units for market transactions. The standardization of packaging is conducive to the mechanized operation of warehousing, reducing labor intensity, and the reasonable design of packaging is also conducive to making full use of warehousing space.

Second, the requirements of packaging containers

The packaging containers of fruits and vegetables have their special requirements. First of all, they should have sufficient mechanical strength to protect products from damage during loading, unloading, transportation and stacking. Secondly, they should have certain air permeability, which is conducive to eliminating the respiratory heat and gas exchange generated by the product. Packaging containers should be moisture-proof to prevent water absorption and deformation. In addition, the packaging container must be clean, pollution-free, odor-free, toxic chemicals-free, with smooth inner wall, beautiful appearance, light weight and low cost. The exterior of the packaging container shall be marked with trademark, product name, grade, weight, place of origin and packaging date.

Three. Types and specifications of packaging containers

Fruit and vegetable packaging containers can be divided into transportation packaging, storage packaging and sales packaging according to their uses. Suitable packaging containers for fruits and vegetables mainly include cartons, wooden cases, plastic boxes, etc. Some hard products can also be packaged in sacks, woven bags and net bags. The specification, size and capacity of packaging may vary depending on the type and variety of products, and the convenience of handling, stacking, handling, mechanization and palletizing should be considered at the same time. The length-width ratio of the packing box is1.5:1; The weight of general products plus packaging does not exceed 20kg. The products can be transported to the packaging shed in big wooden boxes after harvest, and can also be used for cold storage and modified atmosphere storage. In addition to the above-mentioned outer packaging, in order to prevent the product from losing water and reduce mechanical damage, the inner packaging should be added to the packing box, mainly various plastic films, paper or paper partitions.

Four, packaging methods and requirements

Fruits and vegetables should be fresh and clean, free from mechanical damage, pests and diseases, rot, freezing injury, frostbite, flooding and deformity. Before packaging, it should be trimmed and classified according to relevant international, national or local standards. Before packaging, the products should also undergo necessary post-harvest treatment, such as pre-cooling, cleaning, drying, drug treatment and waxing. Packaging should be carried out in a cold environment to avoid wind, sun and rain. In order to prevent the products from rolling and colliding with each other in the container and make full use of the space of the container to facilitate ventilation, the products should be packaged in bulk, positioned or bundled according to the characteristics and uses of the products, and leafy vegetables and stem vegetables should be bundled and packaged. The amount of packaging should be moderate, too much or too little will hurt the product. When packing fruits and vegetables that are not pressure-resistant, the packaging container should be supported and padded, such as paper or plastic trays and corrugated boards, which can reduce pressure, vibration and collision. For products that are easy to lose water, plastic lining or perforated plastic bags should be added to the packaging container. Handle with care when packing. When packing large boxes, the pressure resistance of the products should be considered to avoid the upper products crushing the lower products. A large box with the length and width of 1m× 1.2m, the maximum packing depth is onion, cabbage, potato 100cm, carrot 75cm, apple, pear 60cm, tomato 40cm and citrus 35cm.

Small packaging of fruits and vegetables can be carried out in wholesale or retail, and rotten and injured products should be eliminated when packaging. When selling small packages, transparent film bags, perforated plastic bags or net bags should be selected according to the characteristics of the products. We can also put the products on plastic trays or paper plates and wrap them with transparent film. The weight, name, price and date should be indicated on the sales package. Small packages should be attractive and easy to carry, which can prolong the shelf life.