The main cause of fruit and vegetable deterioration
1. Physiological effects of fruits and vegetables themselves
Fruits and vegetables will continue to breathe after picking, decomposition of organic matter in the body, in order to maintain its own life metabolic activities. The respiration of fruits and vegetables is a slow oxidation process with the participation of oxygen and enzymes. In this process, the nutrient glucose in the body is consumed, which will constantly change the shape, quality, color and flavor of fruits and vegetables. Finally, they will wither, rot and deteriorate, lose their edible value and shorten their storage period. Moreover, fruits and vegetables under the action of respiration will produce heat and continue to accumulate, such as not timely emit, often accelerate the deterioration of fruits and vegetables. At the same time, fruits and vegetables will decompose water due to respiration, which not only provides good conditions for the growth and reproduction of harmful microorganisms, but also speeds up the mildew of fruits and vegetables.
2. Infection of pathogenic microorganisms
- The loss caused by fungi and bacteria before and after fruit and vegetable harvest is much serious, especially in tropical and subtropical areas, because high temperature, and high temperature is conducive to the growth and reproduction of microorganisms, will make fruits and vegetables quickly rotten. And rotting fruit and vegetable pathogens will attack other good fruit and vegetable products, so that more products rot, forming a vicious cycle.
- There are three main ways for various pathogens to invade fruits and vegetables: one is through directly penetrating the skin of fruits and vegetables; Secondly, it invades from natural orifice such as stoma and water orifice. The third is invasion from mechanical wound. In general, bacterial pathogens are mostly infected by wounds, and only a few bacteria can invade from natural pores.
3. Harvesting and mechanical damage after harvesting
Fresh fruits and vegetables are generally artificially harvested. When harvesting personnel use auxiliary tools, they may cause mechanical damage to fruits and vegetables and form wounds. If pathogenic microorganisms are carried on the tools, they will cause bacterial contamination to the wounds and accelerate deterioration. In addition, fruits and vegetables in the classification, packaging, transportation, loading and unloading and storage process often encounter extrusion, collision, stabbing and other external damage, in this case, the strength of fruit and vegetable respiration, accelerate the fruits and vegetables after ripening and aging, but also by mechanical damage of fruits and vegetables, it is easy to be infected by bacteria and cause decay.
4.Biological factors: microbial action
- Microorganisms can be divided into beneficial microorganisms, corrupt microorganisms and pathogenic microorganisms.
- There are many kinds of microorganisms that cause the spoilage of fruits and vegetables, which can be generally divided into bacteria, yeasts and molds. Bacteria are generally more dominant than yeasts .
- Microorganisms play an important role in the spoilage and deterioration of fruits and vegetables. If certain fruits and vegetables are thoroughly sterilized or filtered for sterilization, they can have a long shelf life. On the other hand, if certain fruits and vegetables are contaminated with microbes, they can cause spoilage if conditions are right.
5.Physical factors: temperature, moisture and light
Physical factors are the causes of food deterioration caused by chemical reactions and microbial activities.
- Temperature: it affects the chemical changes of fruits and vegetables, the biochemical reaction speed catalyzed by enzymes and the growth and development degree of microorganisms, etc.
- Moisture: by affecting the growth and development of microorganisms caused by food deterioration.
- Light: light irradiation can promote chemical reactions. 6. Impact of storage and transportation environment
6.Impact of storage and transportation environment
- After fruit and vegetable picking, the breath of fruits and vegetables will continuously release ethylene, which gradually increases the concentration of ethylene gas in the logistics and storage environment. Ethylene gas in turn promotes the respiration and metabolism of fruits and vegetables, accelerates the ripening of fruits and vegetables, leading to accelerated aging of fruits and vegetables.
- The temperature of storage and transportation environment is an important factor affecting the deterioration rate of fruits and vegetables. Temperature will affect the respiration of fruits and vegetables and the life activities of microorganisms. Within a certain temperature range, the respiration intensity of fruits and vegetables will be doubled every time the temperature increases by 10℃, and the intensity of ethylene release will increase accordingly.
- too low temperature will cause cold injury or freezing injury of fruit and vegetable organisms, so that the aging process is accelerated, the resistance is decreased, vulnerable to pathogen invasion, easy to decay; At the same time, the internal organization of fruits and vegetables will change, greatly shortening the storage life of fruits and vegetables.
- Normal temperature or refrigerated storage and transportation: lemon, pineapple, grape, orange, olive, date, apple, watermelon, orange, coconut, grapefruit, sugar cane, etc.
- Must be refrigerated storage and transportation: peaches, mulberries, plums, cherries, chestnuts, guava, grapes, pears, strawberries, melons, grapefruit, etc.
- Storage and transportation without refrigeration: bananas, star fruit, loquat, pitaya, mango, litchi, longan, papaya, rambutan, etc.
fruit and vegetable storage and maintenance scheme
- Implement fine harvesting to avoid mechanical damage to fruits and vegetables caused by harvesting work.
- After fruit and vegetable harvesting, screening work is carried out to screen out damaged individuals.
- Timely antisepsis and disinfection treatment after vegetables, to avoid the infection of pests and microorganisms.
- Pre-cooling and fresh packaging, control the preservation temperature of fruits and vegetables, isolation of water and light.
- Ethylene absorbent is placed in fruit and vegetable bags to absorb and decompose the ethylene constantly released in the process of storage and transportation of fruits and vegetables to prevent fruit and vegetable aging after ripening.