Kiwi fruit is a vine fruit that is rich in nutrients, especially high in vitamin C, and is called the "King of Fruits". Kiwi fruit is sweet and sour, with a unique flavor. In addition to being eaten fresh, it can also be processed into cans, jam, juice, fruit wine, etc.

Kiwi fruit is native to my country and is widely distributed. There are early-maturing and late-maturing varieties, and the fruits are divided into soft-haired and hard-haired fruits. Since the harvest period of kiwi fruit is from September to early October, which is the season with high temperatures, if effective preservation treatment is not carried out after harvest, it will easily soften and rot at room temperature. Therefore, storing it under suitable conditions as soon as possible after harvest and taking effective anti-corrosion and preservation measures is the key to extending storage.

Kiwi fruit is a storage-resistant fruit. If controlled well, the shelf life can be as long as 5-6 months. However, kiwi fruit also has a very special feature, which is that it softens very easily after harvesting. Its most outstanding feature is that the fruit softens easily under natural conditions. Once the fruit becomes soft, it means that its shelf life is about to end. Under the temperature of September-October, the fruits are hard when harvested. They become soft in only 5-6 days at room temperature, and soon become old and rotten, losing their commercial value. Kiwi fruit is a climacteric fruit. There is a sudden physiological change during the ripening process, and the respiration will suddenly rise. In a short period of time, the starch and protopectic substances in the fruit are converted into sugar and pectin, so the fruit quickly becomes soft and sweet. Therefore, there are two very important points in the preservation operation of kiwi fruits after other vegetables, namely rapid cooling and the elimination of the influence of ethylene.

(1) Varieties (strains) and harvesting

1. Varieties (strains)

Currently, the main cultivated and wild kiwifruit strains in my country are Chinese kiwifruit , soft date kiwi, dog date kiwi, etc. The cultivated kiwifruit introduced from New Zealand is Hiwatt. This variety matures late and is more resistant to storage and transportation.

2. Most of the kiwifruit harvested in my country used to be wild. In the past 20 years, the number of cultivated kiwifruit has gradually expanded, and a certain output has been formed. The most cultivated kiwifruit are Qinmei kiwifruit and Hiwatt kiwifruit, followed by Zhonghua kiwifruit. Kiwi fruit, the first two are more resistant to storage.

Attention should be paid to the following two aspects when harvesting:

(1) Late-maturing varieties are more resistant to storage, while early-maturing and mid-maturing varieties should be marketed in a timely manner.

(2) If harvested too late, the fruit will be fully mature. If used for storage, the storage tolerance will be significantly reduced, and the fruit will easily soften and rot. Therefore, kiwi fruits for storage should be picked appropriately early.

(2) Storage conditions and storage methods

1. Storage conditions

(1) Suitable storage temperature: 0℃～1℃;

(2) Relative humidity: 90% ~ 95%;

(3) Air conditioning index: oxygen 2% ~ 4%, carbon dioxide 5%;

(4) Storage period: 3 to 6 months.

2. Storage method Kiwi fruit is easily softened and rotted at normal temperature (higher temperature). Generally, good preservation effects can be obtained by refrigeration in mechanical refrigerators or controlled atmosphere warehouses (large air-conditioned tents and small film packaging bags). The cold storage and controlled atmosphere storage management measures can refer to the apple refrigeration and controlled atmosphere storage methods. Kiwi fruit is extremely sensitive to ethylene, so it is strictly forbidden to store it in the same storage warehouse as other fruits.

(3) Main problems and solutions

1. Softening of kiwi fruit is one of the main problems affecting storage and is also a factor causing fruit rot. The main measures to prevent fruit softening are:

(1) Timely pre-cooling after harvest. Pre-cooling is divided into strong wind cooling, ice water cooling and vacuum pre-cooling. Use forced cooling to lower the fruit temperature to 0°C within 8 to 12 hours after harvesting, and maintain a constant temperature before packaging. Mechanical refrigerated trucks or insulated trucks should be used for transportation. This is the most effective way to delay fruit softening.

(2) Small packaging boxes (or baskets) lined with polyethylene film bags. Pre-cooled kiwis are packaged in small packages (wooden boxes or corrugated boxes with holes in the box walls, 10kg to 15kg per box), lined with polyethylene film (thickness 0.04mm to 0.07mm) or with silicon windows for air conditioning. Packed in fresh-keeping bags, it can maintain high humidity and a certain proportion of oxygen and carbon dioxide. This facilitates rapid cooling and long-term storage.

(3) Place the ethylene blocker 1-MCP.

Kiwi fruit is extremely sensitive to ethylene. Even if the ethylene concentration is extremely low (0.1 mg/kg), even if it is refrigerated at 0°C, the fruit will soften and promote post-ripening and aging of the kiwi fruit. Therefore, placing ethylene absorbers (one piece per cubic meter of space for fumigation) in the cold storage or packaging box containing kiwi fruits can inhibit the ripening and aging of kiwi fruits for 4 to 6 months, which is the best way to control softening. Way.

(4) Controlled atmosphere storage. Kiwis can be stored for 3 to 6 months using large controlled atmosphere tents, small film packages and controlled atmosphere warehouses, but they must also be fumigated with the ethylene blocker 1-MCP to prevent softening caused by an increase in ethylene concentration.

2. Rot, wilting and mildew Rot and mildew of kiwi fruit are mainly caused by microorganisms. Mechanical damage, softening and aging of fruits are the main ways of bacterial infection. The prevention and control methods are as follows:

(1) Pre-harvest chemical treatment. Strengthen pre-harvest orchard management, especially the prevention and control of pests and diseases (such as powdery mildew, spray Cadozan 800 times at this time).

(2) Pre-cool in time and store at appropriate temperature. Lower the fruit temperature to 0°C as soon as possible after harvest and maintain constant temperature storage.

(3) Postharvest anti-corrosion treatment. Timely treatment with preservatives (such as Cardozan, etc.) after harvest can effectively inhibit fruit rot.