| Since the 21st century,the fast-paced life has attracted people’s attention to improving sleep and quality of life.The market demand of sour jujube kernel has been increasing because of its remarkable curative effect and no side effects.At the same time,it has also exposed the problems of chaotic market circulation,uneven quality and lack of high-quality resources.In order to improve the quality control and comprehensive utilization level of wild jujube kernel,the appearance properties,moisture,total ash,water-soluble extract,spinozin content and wild jujube kernel saponin A content of 19 batches of wild jujube kernel pieces from different producing areas were determined,and the coefficient of variation and correlation analysis were carried out on the index data of each batch of samples by using statistical software,The specification grade standard of sour jujube kernel based on the correlation between Appearance Traits and internal content was preliminarily formulated;Taking wild jujube in Yan’an area as an example,five harvest time points in the"rush for green"harvest period from mid August to mid October and the traditional harvest period were selected for self collection,and their related indexes were measured.The quality of wild jujube kernel in different harvest periods in the same producing area was comprehensively evaluated,and the quality differences and change trend of wild jujube fruit and medicinal materials in different harvest periods were clarified;The effects of temperature,humidity and oxygen content on the accumulation of effective components and the indexes of water,total ash and water-soluble extract were investigated,The effects of environmental factors on the synthesis and accumulation of metabolites during storage of wild jujube kernel were further analyzed.The main conclusions are as follows:1.Five indexes including spinosin content,jujube kernel saponin A content,100 grain mass,density and water-soluble extract were selected as the quality evaluation and grading indexes of jujube kernel.According to the cluster analysis results of the five indexes,they were divided into five specifications.The specific standards are as follows:the first-class jujube kernel spinozin content≥0.1171%,jujube kernel saponin A content≥0.0736%,100grain mass≥3.71 g,Density≥0.86 g·cm-3,water-soluble extract content≤20.21%;The content of spinozin in the second-class jujube kernel is≥0.0879%,the content of jujube kernel saponin A is≥0.0442%,the mass of 100 grains is≥3.22 g,the density is≥0.76g·cm-3,and the content of water-soluble extract is≤20.42%;The content of spinozin in the third grade wild jujube is≥0.0806%,the content of jujube saponin A is≥0.0508%,the mass of 100 grains is≥2.63 g,the density is≥0.72 g·cm-3,and the content of water-soluble extract is≤22.60%;The content of spinozin and Jujuboside A of the fourth grade product should be higher than the standard specified in the Chinese Pharmacopoeia 2020 edition,and the quality,density and content of water-soluble extract of 100 Capsules should be the same as that of the third grade product;The rest are classified as nonconforming products.The HPLC-ELSD fingerprints of 19 batches of wild jujube kernel from different sources were established.The peak area cluster analysis results of common peaks were similar to the proposed grading standard.It was considered that the standard could preliminarily predict the quality of wild jujube kernel samples,and the quality evaluation results were more reliable.2.The appearance characters of wild jujube fruit and wild jujube kernel collected from mid August to mid October in Yan’an area as an example were significantly different.The pericarp changed from cyan to red and finally to dark red,and the pulp texture became soft to shrink;Jujube kernel gradually plump,kernel thickness and quality gradually increase,and the changes of width and length first increase and then decrease,and the ratio of width to thickness,length to thickness,length to width are gradually close to 1.The color measurement results showed that during the harvest test,the L*value and a*value gradually increased and the B*value gradually decreased,indicating that with the delay of harvest time,the brightness of jujube kernel gradually increased and the color gradually changed to dark red or purple.The content of water-soluble extract was positively correlated with the harvest time,indicating that the metabolites of wild jujube kernel were still accumulating during the harvest period;The content of active components in Zizyphus jujuba kernel increased significantly.The content of Zizyphus jujuba saponin A in Zizyphus jujuba kernel harvested in mid October was more than 3 times that of the sample harvested in mid August,indicating that the harvest time had a significant impact on the quality index of Zizyphus jujuba kernel.HPLC-ELSD fingerprints of wild jujube kernel at different harvest periods in Yan’an area were established.The results of cluster analysis and principal component analysis of common peak area were also consistent to a high extent,which reflected the dynamic accumulation differences of main chemical components of wild jujube kernel in different harvest periods in Yan’an area to a certain extent.3.The treatment groups with the largest increase of spinozin and jujuba saponin A content were 15℃treatment group and 20℃treatment group respectively,suggesting that15℃～20℃may be the most suitable temperature for the synthesis of secondary metabolites of jujube kernel.The jujube kernel was dehumidified in the first,third and may of storage,and hygroscopic in the second,fourth and June,The equilibrium moisture content is significantly affected by temperature;In the humidity range of 33.07%～75.47%,the contents of spinozin and jujuba saponin A in jujube kernel during storage were positively correlated with humidity.With the increase of humidity,the content of effective components in jujube kernel increased,indicating that higher environmental water content was conducive to the accumulation of secondary metabolites in jujube kernel,and the water determination results showed an upward trend with the increase of humidity;Among the five packaging treatments,the growth rate of effective component content in PE40 film bag packaging was the highest.The moisture content of treatment groups with different packaging thickness increased in varying degrees,and the overall change trend was negatively correlated with the packaging thickness.Based on the single factor experimental results,the multiple linear regression models of different temperature and humidity treatments and different packaging treatments were established.The results of multiple linear regression analysis of different temperature and humidity showed that the influence degree of spinozin was as follows:storage time>temperature>humidity;The influence degree of jujube saponin A was as follows:storage time=temperature>humidity;After weighting the spinozin and jujube saponin A model,the influence degree of each influencing factor on the overall quality of jujube kernel was as follows:storage time>temperature=humidity;The contents of spinozin andjujube saponin A in jujube kernel packed with PE40 were significantly higher than those in other packages（P<0.05）. |
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