Preservation of jujube

Jujube English is called Chinese date, belonging to Rhamnaceae and Zizyphus Jp. Our country of origin, so far has more than 3,000 years of cultivation history, widely distributed, latitude 19 degrees -43 degrees north, east 75 degrees -125 degrees, except in Heilongjiang, Tibet and other extremely cold areas, other provinces are cultivated, including Hebei Henan, Shanxi, Shandong and Shaanxi are the main producing areas. Jujube fruit is rich in nutrients, and it is determined that the sugar content in dried dates is 62.1%, 23.8% in fresh dates, 1.2%-3.3% in protein, 0.2%-0.4% in fat, and Fe, Ca, P, etc. The mineral elements and VA, VB Vc, VP, especially Vc most abundant, each 100g fresh dates up to 380-600mg, 12-20 times higher than the citrus. According to analysis, in the jujube fruit, it is also rich in cyclic adenosine monophosphate (CAMP), containing 50mg per 100g, CAMP has a strong role in the destruction and inhibition of cancer cells. In addition, it is found that jujube contains Rutin (Rodenyi), an effective ingredient for the treatment of hypertension. Jujube or traditional Chinese medicine tonic, spleen, blood and relieve drug function. At present, China produces more than 1.5 million tons of jujube annually, and 90% of it is used in dry-breeding and wine making. Vc loses 6,000 tons annually. The fresh dates are rarely available in the off season. In recent years, with the continuous improvement of people's living standards, the demand for fresh dates has grown rapidly, and fresh storage has become more and more important. At present, the solution to the supply of fresh jujube in off-season is to cultivate late-maturing and storage-resistant species, protected cultivation, and storage and preservation, but storage and freshness are the main ways to solve the problem of long-term supply of fresh jujube. First, the storage characteristics (a) varieties of varieties of jujube, different varieties of storage differences. The varieties used for storage must have both the characteristics of good commodity characteristics, storage and transportation, and storage resistance is the comprehensive performance of various traits. Generally, the late-ripening varieties are more resistant to storage than the early-maturing varieties, and the dry-fresh varieties are more resistant to storage than the fresh varieties, and the smaller fruit varieties are resistant to storage, and the crack-resistant varieties are more resistant to storage. Late maturing, smooth fruit surface, thick and tough peel, hard and crisp fruit quality, superior quality, and high dry matter content. Varieties with the above characteristics are resistant to storage. Storage-resistant varieties include: Mengyin Dazao, non-nuclear date, gold silk jujube, Zanhuang jujube, round bell date, gray date, Dunhuang jujube, Linze jujube, winter jujube, hajj date. (II) Postharvest physiological characteristics Fresh dates contain more sugar, strong metabolism, and strong respiration, belonging to non-climacteric fruits. At the same time, thin jujube and underprotected epidermis protect tissue, and water evaporates easily. It is difficult to store at room temperature. Generally, it can only be stored for 20-30 days. (C) Storage conditions 1. Jujube fruit moisture and relative humidity in the library. The water content of fresh jujube is one of the important indicators of freshness preservation. Jujube young fruit has 90% water content, 60% white ripening period and 45% full red period. The amount of water directly affects the activity of enzymes and the strength of respiration. The lack of moisture in the fruit, the balance of supply and transpiration, out of more than in, the fruit appears groove or shrinkage, lose the effect of preservation; water is too large, there will be fruit cracking phenomenon. The internal moisture of fresh jujube used for long-term storage is controlled at about 55%-60%, and the relative humidity of the storage reservoir is kept at 90%-95%. 2. Temperature. Controlling and adjusting the proper temperature is an important part of preservation. The freezing point temperature of the jujube and semi-red dates is -23°C and the full red period is -5°C. During storage, reduce the storage temperature as much as possible without chilling and maintain at -1 to 0°C. The temperature is too high, the respiration is strengthened, the metabolism is accelerated, the amount of consumed sugars and organic substances increases, fermentation occurs, the fruits are senescent, nutrients are lost, and the purpose of preservation is lost; low temperature damage occurs when the temperature is too low. 3. Gas composition. Oxygen and carbon dioxide have a better effect on the storage of jujube than the effect of refrigeration. Under certain high-oxygen and low-carbon dioxide concentrations, respiratory intensity can be reduced, respiration can be inhibited, and maturation and senescence can be postponed to reduce the consumption and degradation of internal sugars and other organic substances; at the same time, appropriate high oxygen and low carbon dioxide levels can also be achieved. The synthesis of ethylene can be suppressed; in addition, proper high oxygen, and low carbon dioxide: also has the effect of inhibiting the occurrence of certain physiological diseases and pathological diseases, reducing the loss of spoilage during storage. It is generally believed that the concentration of carbon dioxide is controlled at ∠2% and the oxygen concentration is controlled at 3%-5%. This kind of gas component has better storage effect. 4. Ethylene. Ethylene is a gas-phase plant hormone that promotes fruit ripening. The rise in ethylene content marks the ripening of fruit. Too much ethylene can make a large number of jujube dehydration, pectin material transformation, flesh crispness straight decline, loss of fresh food flavor, adverse storage. Therefore, for jujube preservation, should not use ethephon catalytic recovery, so as not to affect the quality of fresh fruit. 5. Enzymes and other plant hormones. The enzyme activity is significantly more active in mature jujube than in immature jujube. The enzyme is present in the mitochondria and directly affects the metabolism. When the fruit of jujube changed from green to red, the amount of pectinase in the fruit increased significantly, resulting in a decrease in jujube brittleness. Maintaining low temperatures during storage can inhibit enzyme activity and delay aging. Phytohormone played a dominant role in jujube maturation. Indole acetic acid oxidase, abscisic acid and ethylene content were the signs of fruit ripening, while 2.4-D had a stimulatory effect on the formation of ethylene and abscisic acid. In order to prolong the storage period, it can be sprayed with 10-20mg/kg of 2.4-D or gibberellin 10mg/kg, and 15mg/kg of nitric acid in the early stage of preharvest fruit coloring. II. Pre-harvest preparation The refrigeration equipment and electrical equipment shall be maintained and overhauled two months before the harvest, and then the warehouse shall be cleaned and disinfected. Storehouse tools or containers can be disinfected with 0.25% calcium hypochlorite solution soaked or brushed white, under conditions of exposure to sunlight; warehouse can be used 15g/m3-20g/m3 sulfur fumigation 24hr-48hr, or use 1% -2% Faw Malin, 84 disinfectant, 0.5% bleach and other disinfectants were sprayed on the wall and the ground; the temperature was lowered to -1°C one week before storage, and remained stable. III. Harvesting and post-harvest treatment (1) Determination of harvesting dates The dates are generally harvested in late September, and individual varieties are harvested in the middle of 10 and early November. The long-term storage was harvested at the brittleness and coloring of 25%-50%. At this point, the fruit begins to grow reddish with the stem and fruit shoulder. The flesh is brittle, the juice is numerous, the flesh is jade-white, and the peel is hardened and thickened. At this time, harvesting and storage are best. Prematurely affect quality, too late will shorten the storage period. (II) Harvesting method Because of thin and fragile jujubes, it is easy to form internal injuries during fruit picking and handling. It is difficult to distinguish them before storage, and it is easy to cause rot during storage. Therefore, it is forbidden to beat and shake the tree when picking, and it is necessary to pick it by hand so that it can be picked lightly and gently. Long-term storage of jujube fruit can not be ripened off by ethephon.

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