Walnut peeling and rinsing after picking

  According to the determination, the moisture content of the walnut green skin after harvest is 40%~45%, and the moisture content of the kernel is 20%~25%. Such a high moisture content is easy to cause the walnut to rot and deteriorate after harvest. Therefore, walnut should be removed in time after harvest. The general methods of removing walnut green peel are stacking peeling method, chemical peeling method and mechanical peeling method.

  (1)Stacking peeling method This method is a traditional walnut peeling method in China. The technical key points are: after walnut harvest, it should be transported to outdoor shade or indoor in time, avoid insolation in sunlight, and then pile up according to the thickness of about 50 cm. If a layer of hay or dry leaves with thickness of about 10 cm is added to the fruit pile, the temperature in the pile can be increased, the nut ripening can be promoted, and the speed of de-aging can be accelerated. General heap retting 3~5 days, when the green peel from the shell or crack more than 50%, you can use a stick to knock peeling. Walnut green fruit without peeling can be retting a few days, until all peeling so far. When stacking, do not make green peel black, or even rotten so as not to pollute the kernel and reduce the quality of walnut nuts and commodity value.

  (2)Chemical peeling method because of the existence of a long peeling time, low efficiency, high fruit pollution rate shortcomings. Since 1970s, people began to study the technology of ripening and peeling with ethephon, and achieved success. The specific method is as follows: after walnut is harvested, it is dipped in ethephon solution of 3 000~5 000 mg/kg for about half a minute, and then stacked in a cool place or indoor according to the thickness of about 50 cm. Under the conditions of temperature of 30℃ and relative humidity of 80%~95%, after about 5 days, the peeling rate can reach more than 95%. If the stack is covered with a layer of hay about 10 cm thick, it will peel in about 2 days. The rate of first-grade fruit was 52% higher than that of retting method, and the rate of kernel deterioration was reduced to 1. 3%, and the fruit surface is clean and beautiful. The ripening time of ethephon was related to the concentration of ethephon and the ripening degree of fruit.

  (3)According to the kneading principle, the walnut with green peel is put between the rotating grinding disc and the hard wire brush for abrasion and kneading, so that the walnut green peel and nut are higher. If the walnut green peel has less moisture content, the kernel shrinks, and the picking force is strong, it is easy to damage the kernel when peeling the green peel. Therefore, when walnut peel is removed by mechanical peeling method, it must be removed within 1~2 days after harvest.

  2. After rinsing and removing the green skin of walnuts, the soil, residual rotten skin and branches on nuts can be removed by washing. Cleaning methods are manual cleaning and mechanical cleaning. The manual cleaning method is to load the peeled nuts into baskets, put the baskets into pools or flowing water, and stir them with bamboo brooms. When washing in the pool, the water should be replaced in time, each washing for about 5 minutes, the washing time should not be too long, so as not to infiltrate the dirty water into the shell to pollute the kernel. If you don't need bleaching, spread the washed nuts on foil to dry. Mechanical cleaning, its efficiency is 3~4 times that of manual cleaning, the yield will also increase by about 10%.

  Fruit growers often bleach walnuts after washing in order to make them smooth, clean and beautiful. The specific method is: in the ceramic jar (forbidden iron wooden container), first bleach (containing sodium hypochlorite 80%) 0.5 kg dissolved in warm water 3~4 kg, filter out the residue, then pour in the ceramic jar to clear water 30~40 liters to prepare bleach solution, then put the washed nuts into the bleach solution, stir with Mufu for 8~10 minutes, when the walnut nut shell surface turns white, immediately remove and wash with water twice, dry. As long as the bleach solution is not turbid, it can be used continuously. 25 kg of standard white powder can continue to rinse, each time can rinse 40 kg of walnut nuts.