Early harvest is good for storage, but the peel color, flesh flavor and taste are poor. The flesh harvested too late has good flavor but is not resistant to storage, so the Pitaya with high maturity can only be sold locally, and cannot be sold and stored in distant markets. Generally, the best harvest time of Pitaya is 25-28 days after flower, and the best harvest time for local market is 29-30 days after flower. At present, the methods of preserving pitaya at home and abroad mainly include low-temperature preservation, coating preservation, chemical preservation and so on. Although the fresh-keeping methods used are different and the emphasis is different, they are all physiological and metabolic regulation that plays a key role in fruit storage and fresh-keeping.

Low temperature storage

Low temperature cold storage is one of the main forms of tropical fruit storage, which is widely used in Vietnam. So far, the main storage method of Pitaya is cold storage. Low temperature storage can effectively control the growth and reproduction of microorganisms and inhibit the activities of browning related enzymes, thus delaying aging and spoilage. Some studies have shown that the quality deterioration of pitaya fruit during storage can be significantly delayed after it is fumigated with 1-methylcyclopropene and stored in a constant temperature cold storage at 10 ° C. In addition, pitaya can be refrigerated at 4-8 ° C and 85% - 95% humidity, with a shelf life of 20-25 days. It can be stored for 40 days at 5 ° C and 90% relative humidity. Although low-temperature storage is not the lowest cost, it is the most effective and ideal collaborative fresh-keeping method, which is widely used in commerce.

Commonly used for family preservation: the collected pitaya fruit belongs to the fruit with low respiration rate, and is extremely resistant to storage and transportation due to its thick skin and waxy protection. In the low temperature of 5-9 ℃, the freshly picked pitaya can be stored for more than one month without extrusion and collision; At room temperature of 25-30 ℃, the shelf life can exceed 2 weeks.

As pineapple is a non climacteric fruit, early harvest will lead to poor quality and flavor of the fruit; Too late is easy to cause fruit rot. The maturity of pineapple fruit is mainly determined by the color of the peel. Pineapple is a kind of tropical fruit sensitive to low temperature. Generally, cold damage will occur below 6 ℃. Among them, black heart disease is the most common physiological disease in pineapple storage, which is mainly caused by low temperature during fruit growth, storage and transportation.

1. Low temperature storage method

It is mainly to reduce the temperature to inhibit respiration and achieve the purpose of storage and preservation. The reaction of pineapple fruit to storage temperature is related to the maturity of pineapple fruit. If all green fruits without any yellow color are stored at 10 ℃, it is very easy to produce cold damage. According to the test results in Hawaii, the maximum storage life is four weeks at 7 ℃, the suitable temperature for storage and transportation recommended by India is 8 ℃, and that recommended by South Africa is 8.5 ℃.

2. Controlled atmosphere storage method

It is mainly through reducing the oxygen content in the storage and appropriate low temperature to inhibit the respiration to achieve the purpose of fresh-keeping. According to the research of the University of Hawaii, the fresh-keeping period of pineapple can be prolonged under the temperature of 7.2 ℃ under the atmosphere composed of 2% oxygen and 98% nitrogen.

3. Drug preservation method

It is reported that half mature pineapple can be kept fresh for 6-14 days at normal temperature after soaking in 100ppm2, 4,5-t solution. It is also reported that only 50% of the small fruits of 25% of the pineapple turned yellow after being soaked with 100ppm sodium naphthylacetate solution and stored at room temperature for 9 days can maintain the unique flavor of pineapple and the normal structure of the pulp tissue. The fresh cut of fruit stalks soaked with 300 ppm benlaite can effectively prevent various bacteria from invading from the cut

Commonly used by families: the pineapples bought are not ready to eat for the time being. You can try to keep them fresh by putting them in a pineapple basket or similar ventilated container, and it is better to lay some bamboo leaves or shredded paper inside. Then store it in a cool and ventilated place. The recommended temperature is about 11-13 ℃. Because pineapple has not been cut, it can be stored for a long time according to this method.