Since late August, walnut trees in our province have gradually entered the harvest period. In order to obtain high yield and good quality of harvested walnuts, the following work should be done:
1. Determine the correct harvest period. Different varieties of walnuts have different maturity stages. For example, Shangsong No. 6 in early real walnuts matures around August 28th, while Zhonglin No. 1 can not mature until mid-September. Some varieties such as fragrant walnuts mature in the middle or late September. In addition, even if the same variety is not the same in different regions, the Hongling walnut matures in late August in Shandong, matures in early September in Xingtai, and matures in late September in Shaanxi. Therefore, walnut ripening dates should be used in the form of Mature signs to determine the appropriate harvest period. The criteria for maturity of walnuts are as follows: The green skin turns yellow from green, cracks on the sides of some green peels, and peels from peels. The internal features are: full kernels, mature young embryos, hardened cotyledons, and strong aromas. Avoid early mining so as not to reduce walnut quality and yield.
2. Determine the order of rational harvesting. Different varieties were harvested in stages and one species was harvested before another. The order of harvesting on the tree is from top to bottom and from inside to outside so as not to damage the shoots and affect the next year's output.
3. Harvest method. In order to improve the appearance quality of nuts and facilitate the treatment of green peels, the method of manual picking of individual walnuts can also be used to pick up bamboo rafts or wooden poles with iron hooks to avoid damage to the green skin. Damaged and non-injurious bags of green skin were bagged separately during bagging.
4. Post-harvest treatment. After the fruit is harvested, it is dipped in a concentration of 0.3% to 0.5% ethephon solution for about 30 seconds and stacked in a cool place or room at a thickness of 50 cm. At a temperature of 30°C and a relative humidity of 80% to 95%, the peel rate can reach 95% in about 5 days. The duration of ethephon ripening and drug concentration are related to fruit maturity. The fruit has high maturity, low drug concentration and short ripening time. After ripening, the peels are peeled off by artificial peeling or peeling.
5. Wash nuts. Put the peeled nuts in a basket, stir it with a bamboo broom, and rinse it with running water. Thin-skinned walnuts are not bleached. The nuts used as seeds do not need to be washed after being peeled off, but can be directly dried and stored for later use.
6. The nuts are dry. Natural drying method: The washed nuts can be cloudy on the bamboo foil or sorghum stalk foil for a long time. After most of the water evaporates, they are then spread out on the dry mat or bamboo foil to dry, and they must not be exposed to the sun to prevent the core shell from breaking. Nuclear deterioration. The thickness of the nuts should not be more than 2 layers in order to prevent the kernel from being turned into yellow by the smooth surface. Take care to avoid rain and moisture at night. General sun 5 to 7 days can be. The criteria for judging the dryness are: the sound of the nut knocking sounds crisp, the diaphragm easily broken by hand, the skin color of the seed kernel changed from milky white to light yellowish brown, and the water content of the seed kernel does not exceed 8%.
In addition, the use of a low-temperature dryer to remove the nuts after peeling is the main drying method for modern large-scale production of walnuts.
7. Store nuts in storage. Ordinary indoor storage method: suitable for short-term storage. The dried nuts are put into a cloth bag or sack, stored in a ventilated, dry room or placed in a basket, and stored in a cool, dry, ventilated, and backlit place. In order to avoid moisture, it is better to isolate the material on the pile pad and prevent rat damage. A small amount of walnuts can be hung in a cloth bag. Low-temperature storage method: Long-term storage of walnuts should be stored at low temperatures. The large amount of storage can be packed in sacks and stored in a low temperature cold storage at 0°C to 1°C. Where there is no cold storage, it can be sealed and stored with plastic film. 0.2~0.23 mm thick polyethylene film is used to make the account. The size and shape of the account can be set according to the amount of storage and the condition of storage. The amount of oxygen in the account is less than 2%. If there is not much storage, nuts can be sealed in polyethylene bags and stored in refrigerators and freezers at 0°C to 5°C for over 2 years.
In northern North China, where winter temperatures are low and the air is dry, walnuts that are accounted for in the fall do not need to be sealed immediately. When the temperature rises in late February in the following year, they are sealed again. Sealing should be performed at low temperature and dry weather, so that the relative humidity of the air in the account is not higher than 50% to 60% to prevent mildew after sealing. For long-term storage of walnuts, the water content must not exceed 7%. Store walnut kernels at low temperatures (1.1°C to 1.7°C) for 2 years without rot. Walnut in the treasury to strengthen anti-mildew, anti-moth-eaten, anti-oil, anti-rat measures.