Walnuts – fruit knowledge

Walnut is one of the world's four major dried fruits (hazelnuts, walnuts, almonds, cashews), also known as walnuts, qiang peaches, long live seeds, peaches, etc., foreign called Persian walnuts or British walnuts. It is the seed nucleus of the fruit of the walnut tree, the surface of the core shell has concave grooves or dots, the fruit is round, oblong or oval, etc., and there are obvious sutures in the middle; there are brain-shaped seed kernels in the shell, and there are diaphragms between the seed kernels.

Walnuts are native to southeastern Europe and western Asia. China's ancient books record that "this fruit was originally out of Qianghu, and during the Han Dynasty, Zhang Qian made the western region first planted, planted in Qinzhong, and gradually reached the eastern soil, hence the name." ”

Walnut is a deciduous tree of the genus Walnut in the family Walnut family, up to 30 meters tall, more than 300 years old, the bark is gray, smooth, odd pinnate compound leaves, broadly ovoid or ovate, flowering between April and May, the fruit matures between August and September, shaped like a peach, the green flesh cannot be eaten, called "total bud", and there is a seed nucleus inside, that is, walnut.

Walnuts are nuts in horticultural classification and stone fruits in botanical terms. The size, shape, thickness of the shell, shell color, quality, etc. of walnuts vary depending on the region and variety. After 10 years of planting, it enters the full fruit stage, and the yield of adult trees is more than 100 catties.

Walnut trees are widely planted, in addition to China, the United States, Turkey, Iran, India, Italy, France, Russia, Britain, Yugoslavia, Romania, Greece, Bulgaria, Hungary and other countries have a large number of plantings.

Walnut kernel oil content of 65 ~ 83%, nutritional and medical value is very high, foreign countries have "Hercules food" known, China's walnut quality is excellent, is welcomed by the international market traditional export commodities.

Harvesting and processing. Walnut fruit varies according to the variety and region, and the ripening period is also inconsistent. Harvest times vary according to geographical location and climate, with the south in late August, the north in early September, and the cold areas as late as late September. When the total bud changes from dark green to pale yellow, there are fine spots of sesame seeds on the outside, individual fruits fall off, and some total buds are cracked ( 50% of the whole tree can be harvested). If harvested prematurely, the total buds are not easy to shed, and the core shell is dark yellowish brown, which affects the appearance; the kernels are tender, light in taste and slightly sweet. When harvested at the right time, the total buds can be naturally shed, the core shell is yellowish white, and the kernel aroma is thickened and the texture is crisp; the kernel yield and oil content can reach the highest height. If the harvest is too late, the fruit is easy to fall off, which will cause mold loss.

Harvesting method, China is mainly by hand picking or bamboo poles from the tree lateral knocking shock fall. The fruit of the lower tree should not be exposed to the sun, otherwise the total buds will not be easy to come out. Then pile up and sprinkle water, cover it with grass or reed mats, and after five to seven days, gently tap the buds with a wooden bouquet, rinse with water, and sun-dried or bake until dry. The core shell is not washed, and the residue is contaminated, affecting the shell color. Yun, Gui, Shaanxi and sichuan parts of the harvest is in the rainy season, mostly baked, shell color black brown, there are fireworks. The sun generally takes four to five days, until the dry and wet are moderate, if the sun is too dry, the kernel oil should be overflowing.

The standards for wet and dry moderation are: the sound is loud when the core shell is smashed, the color of the nucleus skin changes from milky white to golden yellow, and the space between the nucleus is crushed by rubbing with the hand.

Foreign countries use a dilute gas or a dilute fruit to ripen the fruit, so that the stone fruit out of the total bud. In some parts of the country, the aqueous solution of Ethali is used to remove the total buds, and the shell color is white and clean.

Export walnuts can also be bleached to make the shell color more white and pure, take the walnuts for peach kernels, remove the total buds, without rinsing, the peach kernels are light yellow and pleasing to the eye. If rinsed, it will make the peach dull yellow, affecting the quality.

Origin and variety. Most provinces in China have walnut production: Shandong and Hebei are famous for their high quality; in recent years, Shanxi and Shaanxi have the most production. The main origins are as follows.

Shandong: Licheng, Zhangqiu, Changqing, Yidu, Linqu, Shouguang, Yiyuan, Cangshan, Tancheng, Tai'an, Laiwu;

Hebei: Changli, Lulong, Funing, Zunhua, Qian'an, Laishui, Lincheng, Yixian, Luanxian, Xiangxian, Wu'an, Pingshan, Zanhuang, Yuelu;

Shanxi: Fenyang, Xiaoyi, Jiaokou, Lishi, Zuoquan, Licheng, Anze, Luxian, Lingchuan, Lingshi;

Shaanxi: Shang County, Luonan, Danfeng, Ningqiang, Luoyang, Ankang, Yijun, Nanzheng, Mian County;

Henan: Lushi, Lingbao, Luyi, Huixian, Jiyuan, Songxian, Anyang, Linxian;

Guizhou: Weining, Bijie, Hezhang, Xingyi, Xingren, Anshun, Meize, Qianxi, Dafang, Shuicheng;

Yunnan: Yangpi, Qiaojia, Qujing, Ludian, Changning, Dayao, Nanhua, Chuxiong;

Gansu: Tianshui, Wuwei, Qingyang;

Hubei: Xun County, Enshi, Yichang;

Xinjiang: Aksu, Kucha;

Beijing: Huairou, Changping, Miyun, Tongxian;

Tianjin: Jixian County;

Sichuan: Guangyuan.

In addition, Qinghai, Liaoning, Jiangsu, Zhejiang, Anhui, Jiangxi, Tibet and other provinces and regions also have some production.

There are twelve varieties of walnuts cultivated in China. As a commodity according to commercial habits divided into three categories, its main features are.

Pickled walnuts: thin shell, shallow grooves on the shell surface, full of seed kernels, easy to remove.

Pinch walnuts: thicker shells! The outer grooves are deep, and the seed kernels are embedded in the recesses of the well-developed inner fold wall, which are difficult to remove and the individuals are heavier.

Iron walnut: the shell is extremely thick, the shell has a black rust color, the groove is deep, and the seed kernel is deeply embedded in the recess of the developed inner fold wall, which is extremely difficult to remove, and the individual is very heavy.

There are many traditional excellent varieties of walnuts in China, such as the famous Shimen walnut in Hebei Province, the walnut in the iron factory (named after the distribution in Shimen and the iron factory), the southern walnut in Shandong Province, the thin-shell walnut in Xinjiang, and the yangbi walnut in Yunnan. Among the walnut kernels are Xishan peach kernels in the suburbs of Beijing, Jinan peach kernels in Shandong, Fenyang peach kernels in Shanxi, and Longjuzhai peach kernels in Shaanxi.

Walnuts in China are widely planted, and due to the long-term use of solid breeding, varieties and types are mixed. The group of excellent varieties can be summarized into the following four types:

Dew kernel walnuts or paper-skin walnuts, cotton walnuts or thin-shelled walnuts, spike-shaped walnuts, alternate year walnuts.

Foreign good breeds include the American "Hartley", the French "Frankotti", the Russian "ideal" and so on.

Grade specifications. Clips and iron peaches should not be sold as dried fruits, and most of them are pressed for oil. The grade specifications of pickled peaches vary slightly from place to place. According to the regulations of the former headquarters, the diameter of the first class single is more than 30 mm, the second class is more than 28 mm, and the third class is more than 26 mm. The specifications for the acquisition of the main origin are as follows:

Grade 1: produced in the same year, dry goods, full of kernels, yellow and white, less than 40 per kilogram, half flower skin (slight black skin) does not exceed 5%.

Grade II: produced in the current year, dry goods, full of kernels, yellow and white, half-flower skin does not exceed 10%, less than 50 per kilogram.

Grade III: produced in the current year, dry goods, full of kernels, yellow and white, less than 60 per kilogram, half flower skin does not exceed 5%.

The sales land is generally divided into grades based on the place of origin or the white color of the shell, and then divided into one, two or three levels according to the size, and the empty and bad rate of any level should not exceed 8%, and the rate of benevolence should be more than 40%, and the price according to the quality should not be reached.

The grade specifications for walnut kernels are as follows:

1. Peach ball, folio positive grade: the whole into a spherical shape or folio piece (for half of the peach ball, commonly known as butterfly piece or head road) is only large and uniform, dry and fat, pale yellow, no mold and oil only black flakes, dehumanded diaphragm, shell does not exceed 0.5%.

2. Peach ball, folio sub-level: only the size of the slices is uneven, the meat is average, and other standards are the same as the positive grade.

3. Four-open positive grade: it is a quarter of the peach ball, (also known as the second way) the sheet is neat, the body is dry and fertile, the color is pale yellow, there is no mold and moth and oil black flakes, the de-kernel partition, the shell does not exceed 0.5%.

4. Four-open sub-level: the color is light yellow, the kernel meat is general, the eight-open piece is not more than 10%, and other standards are the same as the positive level.

5. Four or eight open positive grade: (eight open is one eighth of the peach ball, also known as three roads) of which four open pieces are more than 60%, the rest is eight open pieces, the body is dry and fat, the color is light yellow, no mold and oil black flakes, dehumandrium, shell does not exceed 0.5%.

6. Four or eight open sub-grades: the color of the old belt wilts, the meat is general, and other standards are the same as the positive level.

Pomegranate seeds (also known as four-way) slices are slightly less than eight open, dry evenly, without mold and oil black grains, diaphragm, shell does not exceed 0.5%.

Quality inspection. Pickled walnut quality requirements: dry body, large, thin shell, white net shiny, the inner fold wall is not developed, the kernel coat is light yellow, the kernel is fat, crisp and slightly sweet. The key points of the sensory test are as follows:

1. Dry humidity: The water content of walnut kernels should be 5 to 6%. The identity is dry, the sound is crisp and fragile when knocking on the shell, the kernel color is consistently milky white; the tide, the shell is not easy to break, the sound is heavy and turbid when tapping, the kernel and the kernel are easy to separate, break the kernel meat, and there is a small piece of snow white at the junction of the two pieces.

2. Shape: "It is better to be round and uniform in size." Divide in two from the suture and measure its diameter, the larger one is more than 30 mm in diameter and the middle only has a diameter of more than 26 mm.

3. Core shell: the shell surface is smooth, no residual dirt, the color is white or light yellow, and it is good to have natural luster. The shell surface grooves and points are less and shallow, the shell is thin, the inner fold wall is not developed, and it is easy to take kernels (but pay attention to the rate of shell fragmentation). The shell surface groove is thick, the inner fold wall is developed, and the nucleus is deeply embedded in it, making it difficult to take the kernel. Those with oily marks on the shell surface have deteriorated.

4. The color of the kernel coat is light yellow, followed by dark yellow, and the yellowish brown or dark brown markings (also known as tiger skin peach kernel) is poor. Breaking the kernel by hand, the flesh is milky white, and the two pieces with oily yellow signs at the junction are "chrysanthemum hearts" that have begun to deteriorate. All oily, sticky hands, peach flesh is yellow-brown, the smell of ha la has been seriously deteriorated, for fat oxidation rancidity, the industry is called stuffy oil, can not be eaten. The benevolent and fat are good, and the skinny are poor. Old goods should pay attention to whether there are insects and moths, mold.

5. The flavor is crisp and slightly sweet, the bitter taste is poor, and the smelly oil (that is, the harrah) is stuffy and the oil has only deteriorated.

Inspect the whole batch of walnuts, you can use the hand bag corner, feel the weight is moderate (ordinary sack 90 ~ 100 pounds), the outside of the bag is patted, the sound is crisp and crisp is the peach, such as the amount of heavy or the bag makes a heavy turbid sound, there are clamps, iron peaches mixed in; if the amount is too light, there will be more empty shell sounds. The whole batch should be measured by sampling and determination:

First, the proportion of clamps and iron peaches; second, empty, bad only the proportion (empty only refers to the fleshless, bad only includes mold, moth, stuffy oil only); third, the rate of ren.

Sale and Use. Walnuts are sold well in the southeast coastal provinces, with the largest sales from the winter solstice to the spring. In some local stores, retail stores have a traditional "knocking peach" method, that is, after the customer buys walnuts, the salesman knocks the shell for free, and the spoiled goods are exchanged immediately according to the regulations, so as to avoid consumers from being undue losses.

A small amount of walnuts can be mixed into dry yellow sand and sealed in a jar or altar. If the kernel is not exposed to moisture to prevent the oil from spilling out, it can be slowly dried over a low heat.

If walnuts attract insects and moths, you can turn to the professional fumigation team of the grain storage department to kill insects, which can ensure that the quality of walnuts is not affected.

Walnuts are rich in nutrients, and our country has been used as a tonic since ancient times. The Tang Dynasty "Dietary Therapy Materia Medica" said: "Regular service makes people edible, the flesh and bones are delicate and smooth, the hair must be black, the blood veins are moist, and the old hemorrhoids are cut in yangli." Modern medical scholars believe that asthma, waist and leg pain, kidney deficiency, urinary stones, constipation, otitis media, rosacea, etc. have a certain effect, but because of its hot slippery intestine, the medication should be supplemented by drugs to comply with medical advice. Folk in the winter season, more as a tonic, a variety of food methods; in addition to raw food or fried food, there are also added sugar mashed into crumbs, steamed, each time two spoons with hot rice wine or soy milk to serve; mashed into ejiao, turtle plate glue, tiger bone glue and other high-quality rice wine, rock sugar steamed. When eating, stew in water and take it with heat; cook porridge with walnut kernels and rice, add sugar to eat; core kernels are fried in a frying pan, mixed with sugar or stir-fried in noodle sauce, and can also be used as dishes, such as the famous dish peach kernel chicken breast.

conscience

September 1, 2021