Fresh-cut fruit processing should solve the problem of preservation. Processing methods of fresh-cut fruits are widely used in catering industry. Fresh-cut fruit refers to a new type of fruit processing product that uses fresh fruit raw materials such as apples, pears, pineapples and mangoes as raw materials, and is graded, cleaned, peeled, renovated, cut and packaged for consumers to eat immediately or used in catering industry. Because of its characteristics of nutrition, sanitation, convenience, freshness and high consumption rate of 100%, it is deeply loved by consumers and the market demand is increasing year by year. However, at the same time, peeling, cutting and other treatments cause mechanical damage to fruit tissues, induce browning of fresh-cut fruits, and lead to quality problems such as discoloration, taste change and deterioration, which greatly increases the difficulty of preservation. In this paper, the factors affecting the quality of fresh-cut fruits and their preservation techniques were briefly described in order to provide reference for production and application. 1. Factors affecting the quality of fresh-cut fruits 1. Physiological and biochemical factors Fresh-cut fruits no longer exist as finished products after peeling, cutting and other treatments. After their tissues are damaged, the damage signal will have a significant impact on respiration, phenol and ethylene metabolism. Firstly, the regionalized structure of enzymes and substrates in tissues is destroyed, and enzymes and substrates are in direct contact, causing various physiological and biochemical reactions in tissues. For example, polyphenol oxidase (PPO) catalyzes the oxidation of phenols, lipid oxidation catalyzes membrane lipid reaction, and cellulase catalyzes cell wall decomposition, which leads to tissue browning, cell membrane destruction, cell wall decomposition and odor generation. Secondly, after peeling and cutting, the tissue is damaged, which leads to the increase of ethylene release rate, metabolism and respiratory intensity of the tissue itself, and produces secondary metabolites. Tissue wound healing will also change the appearance of fresh-cut fruits and reduce their edible value; Moreover, ethylene can promote the biosynthesis of enzymes related to fruit ripening. For example, ethylene can increase the activity of phenylalanine ammonia-lyase (PAL), thus accelerating the senescence and decay of fresh-cut fruits. 2. Microbiological factors After fresh-cut fruits are peeled and cut, the organizational structure is destroyed, the original protection system is destroyed, and the juice overflows. Large surface area and rich nutrition provide favorable conditions for microbial infection. Therefore, microbial pollution and reproduction are the main factors leading to the decline of fresh-cut fruit quality. 3. Loss of nutrients During the processing and storage of fresh-cut fruits, some nutrients, especially vitamins, are easily lost, thus affecting the nutritional quality of cut fruits. At the same time, during the storage of fresh-cut fruits, some unfavorable environmental conditions, such as inappropriate temperature and light, oxygen in the air, and metabolism of tissues themselves, will lead to the loss of nutrients in fresh-cut fruits. Preservation technology of fresh-cut fruits 1. Fresh-cut fruits stored at low temperature have strong respiratory metabolism at room temperature and are prone to enzymatic browning. Low temperature storage can slow down the browning process, delay the oxidative decay of fruits, inhibit the growth and reproduction of microorganisms and consume less nutrients because it inhibits the activities of enzymes such as polyphenol oxidase. Therefore, fresh-cut fruits generally need to be refrigerated. Fresh fruit raw materials can be peeled and cut into pieces at low temperature, which can minimize the deterioration of physiological metabolism such as ethylene and increased respiratory rate, and the preservation period can be greatly extended. Most studies believe that cut fruits are suitable for storage at 0-5℃. In order to ensure the quality of fresh-cut fruits, the temperature control in the processing place and the cold chain during storage are the keys to the success or failure of preservation. 2. Modified atmosphere preservation Modified atmosphere preservation is a storage and preservation method that changes the gas composition in the storage environment on the basis of refrigeration. Modified atmosphere packaging combined with cold storage of fresh-cut fruits can effectively reduce respiration, inhibit the production of ethylene, reduce water loss, delay the senescence of cut fruits and prolong storage time. In the process of controlled atmosphere storage, a low O2 and high CO2 environment should be created. However, under the condition of low oxygen or ultra-low oxygen, especially improper temperature control, it is easy to lead to anaerobic breathing and odor. Therefore, 2%-5% O2 and 2%-5% CO2 should be kept in fresh-cut fruit packaging to maintain its quality. Too low O2 concentration or too high CO2 concentration will lead to the damage of low O2 or high CO2 to fruits, leading to low thank-you and quality degradation. 3. Browning control The main quality problem of fresh-cut fruits is browning, which leads to poor appearance. Sulfite is a traditional browning inhibitor, but it is banned because of its toxicity to human body. Therefore, to inhibit enzymatic browning, on the one hand, it is necessary to cultivate new varieties of fruit with browning resistance, improve cultivation management techniques, reduce mechanical damage during harvesting, storage, transportation and processing, and reduce the induction of phenylalanine ammonia-lyase activity, so as to control the formation of oxidizable phenols and delay the browning of fresh-cut fruits. On the other hand, controlling the activity of polyphenol oxidase can control browning through the inhibition of heat, organic acids, some phenols, sulfur, chelating agents, quinone coupling agents and other substances. 4. Edible coating Edible coating has a good inhibitory effect on enzymatic browning of fresh-cut fruits. On the one hand, it can reduce the water loss of fresh-cut fruits, limit the intake of oxygen, reduce the influence of external gases and microorganisms, inhibit breathing, delay the production of ethylene, slow down the speed of physiological and biochemical reactions, prevent the volatilization of aromatic components, and carry additives to delay discoloration and inhibit the growth of microorganisms. If the oxygen permeability of edible coating is used to keep the oxygen concentration on the surface of cut fruit at a low level, it can not only inhibit browning, but also reduce the respiration and ethylene production of cut fruit, which is beneficial to storage. On the other hand, adding antioxidants and anti-browning agents into the film-forming agent can reduce the aging and corruption of cut fruit tissues and improve the quality and stability of fresh-cut fruits. China Professional Fruit Forum Many people also want to open fruit shops. The investigation and planning of fruit shop opening, store name and location, operation and management, fruit preservation and loss control are all discussed. You can come and talk when you are free!

References:

/register.php？ fromuid=6978