Fresh cut fruit refers to fresh fruit raw materials, such as apples, pears, pineapples, mangoes, etc. by grading, cleaning, peeling, grooming, cutting, packaging and other processing for consumers to eat immediately or catering industry to use a new type of fruit processing products. Because it has nutrition, health, convenience, freshness, edible rate of up to 100% and other characteristics, and popular with consumers, market demand increases year by year. However, at the same time, due to peeling, cutting and other treatments on the fruit tissue mechanical damage, induced browning of fresh-cut fruit, resulting in discoloration, tastelessness, texture change and other quality problems, so that the difficulty of its preservation greatly increased. This paper tries to affect the quality of fresh-cut fruit factors and its preservation technology, to make a brief description, in order to provide reference for the application of production.

I, factors affecting the quality of fresh-cut fruit

1, physiological and biochemical factors fresh-cut fruit by peeling, cutting and other treatments no longer exist in a state of completion, the tissue is damaged, the injury signal will be respiratory, phenolics, ethylene and other metabolism have a significant impact. First of all, the regionalized structure of enzymes and substrates inside the tissue is destroyed, and the enzymes come into direct contact with the substrates, causing various physiological and biochemical reactions in the tissue. For example, polyphenol oxidase (PPO) catalyzes the oxidation reaction of phenolic substances, fat oxidation of this section catalyzes the membrane lipid reaction, cellulase catalyzes the decomposition reaction of the cell wall, etc., which leads to the browning of tissues, the destruction of cell membranes, the decomposition of the cell wall and the production of off-flavors. Secondly, after fruit peeling, cutting and other treatments, due to tissue damage, resulting in increased rate of ethylene release, the tissue itself to enhance the metabolism, respiratory strength, secondary metabolites, tissue wound healing will also change the appearance of the fresh cut fruit, and reduce its food value; and ethylene will promote the biosynthesis of the enzymes related to fruit ripening, such as ethylene induces phenylalanine ammonia lyase (PAL) activity increase, thus accelerating the fresh cut fruit activity increases, thus accelerating the aging and spoilage of fresh-cut fruits.

2, microbial factors Fresh cut fruit due to peeling, cutting and other treatments, resulting in tissue structure damage, the original protection system is destroyed, the fruit juice overflow, the larger surface and rich in nutrients for the microbial infestation provides favorable conditions. Therefore, microbial contamination and reproduction is the main factor leading to the decline in the quality of fresh-cut fruit.

3, the loss of nutrition Fresh cut fruit in the peeling, cutting and other processing and storage process, some nutrients, especially vitamins are very easy to lose, thus affecting the nutritional quality of cut fruit. At the same time, fresh cut fruit in the storage process, some unfavorable environmental conditions, such as unsuitable temperature, light, oxygen in the air and the organization of its own metabolic action will lead to the loss of fresh cut fruit nutrients.

Two, fresh cut fruit preservation technology

1, low-temperature cold chain storage Fresh cut fruit at room temperature respiration and metabolism exuberant, enzymatic browning is very easy to occur. Low temperature storage due to the inhibition of polyphenol oxidase and other enzyme activities, can slow down the process of browning, delay the oxidative decay of fruit, and can inhibit the growth and reproduction of microorganisms, nutrients consume less. Therefore, generally fresh cut fruits need to be refrigerated. Fresh fruit raw materials at low temperatures for peeling, cutting and other treatments, can be ethylene and respiration rate rise and other deterioration of physiological metabolism to a minimum, the freshness period can be greatly extended. Most studies have concluded that cut fruits are more suitable for storage at 0-5℃. In order to ensure the quality of fresh cut fruits, the temperature control of the processing place and the cold chain in the storage process is the key to the success or failure of freshness.

2, gas-conditioning preservation gas-conditioning preservation is based on cold storage to change the gas composition of the storage environment of a storage and preservation methods. Fresh cut fruit by gas-conditioning packaging combined with refrigeration, can effectively reduce respiration, inhibit the production of ethylene, reduce water loss, delay the aging of cut fruit, prolong storage time. In the process of gas-conditioned fresh storage, a low O2 and high CO2 environment should be created. However, low O2 or ultra-low O2 conditions are highly susceptible to anaerobic respiration, leading to the production of off-flavors, which is especially likely to occur when the temperature is not properly controlled. Therefore, fresh cut fruit packaging inside usually to maintain 2% -5% O2 and 2% -5% CO2, in order to help maintain its quality.O2 concentration is too low or CO2 concentration is too high will lead to low O2 or high CO2 injury to the fruit, resulting in low thanks to the disorders, the quality of the decline.

3, browning control The main quality problem of fresh-cut fruits is browning, which causes extremely poor appearance. Sulfite is the traditional browning inhibitor, but it will cause toxicity to human body and is banned. Therefore, for the inhibition of enzymatic browning, on the one hand, it should be done by cultivating new fruit varieties that are resistant to browning, improving cultivation and management techniques, reducing mechanical damage during harvesting, storage and transportation, and processing, and reducing the induction of phenylalanine deaminase activity, so as to control the formation of oxidizable phenolic substrates and delay browning of fresh-cut fruits. On the other hand, browning is controlled by controlling the property that polyphenol oxidase activity can be inhibited by heat, organic acids, certain phenols, sulfur, chelating agents, quinone coupling agents and other substances.

4, edible coating edible coating on fresh cut fruit enzymatic browning has a very good inhibition. On the one hand, it can reduce the water loss of fresh cut fruit, limit oxygen intake, reduce the impact of external gases and microorganisms, inhibit respiration, delay the production of ethylene to reduce the speed of physiological and biochemical reactions to prevent volatilization of aromatic components and can be entrapped in the delayed discoloration and inhibit the growth of microbial additives role. Such as the use of edible coating film on the permeability of oxygen, so that the oxygen concentration of the surface of the cut fruit is maintained at a low level, not only inhibits browning, but also reduces the respiration of the cut fruit and ethylene production, which is conducive to storage. On the other hand, adding antioxidants and anti-browning agents in the film-forming agent can reduce the aging and spoilage of the cut fruit tissues, and improve the quality and stability of fresh cut fruit.