| Coix seed is the dry and mature seed of Coix lacryma-jobi L.var.ma-yuen(Roman.)Stapf which was first listed as the top grade in “Shen Nong’s Herbal Classic”.It is also one of 87 kinds of medicinal and edible homologous Chinese herbal medicines published in weifajianfa [2002] No.51 “general notice of the Ministry of health on further standardizing the management of health food raw materials”.It mainly contains polysaccharides,flavonoids,phenols,proteins and amino acids,inorganic elements,fatty oils and fatty acids.Coix seed is widely distributed in China,mainly in Guizhou,Yunnan,Fujian,Guangxi and other provinces,and also in Vietnam,Myanmar,Laos and other places.There are few studies on the chemical constituents of Coix seed,such as polysaccharides,flavonoids,phenolic acids,amino acids,inorganic elements and so on.Coix seed is easy to get moldy and insect eaten during storage.Market research shows that Coix seed is usually placed in the medicinal materials market or warehouse,most of which have no ventilation and temperature control device,and there are some problems,such as irregular management,disordered storage conditions and so on.Every year,a large number of Coix seed are lost due to storage deterioration.In this dissertation,the herbal research and modern research progress of Coix seed were systematically reviewed;A method for the determination of amino acids in Coix seed was established by high performance liquid chromatography(HPLC);The water activity theory was introduced to study the isothermal adsorption law of Coix seed,and the safe water content of Coix seed during storage was successfully predicted;The storage characteristics of Coix seed in 18 months were studied.The changes of polysaccharide,flavone and phenolic acid contents in Coix seed under different temperature and humidity conditions were analyzed.The optimal storage conditions of Coix seed were discussed,so as to provide scientific basis for scientific storage and maintenance of Coix seed.The research contents are as follows:1 Comparative Study on Chemical Constituents of Coix Seed from Different Habitats1.1 Comparative Study on the Contents of polysaccharides,flavonoids and phenolic acids in Coix Seed from Different AreasIn this study,Spectrophotometric method is spectrophotometer was used to detect the contents of total polysaccharides,total flavonoids and total phenols in 33 batches of Coix seed samples from different habitats.The results showed that there were significant differences among the three kinds of active substances in Coix seed samples from different habitats.The contents of total polysaccharides were 20.22 %and 19.4 % respectively in Xingren of Guizhou and Ninghua of Fujian.The contents of total flavonoids were 20.22 % and 19.4 % respectively in Xingren of Guizhou and Ninghua of Fujian Xianyou was the highest,0.95 % and 0.84 % respectively;the total polyphenols in Xingren of Guizhou and Ninghua of Fujian were the highest,both0.46 %;taking the total amount of three kinds of active ingredients as the standard,the Coix seed from Xingren of Guizhou Province was the best.1.2 Comparative Study on Amino Acid Content of Coix Seed from Different Producing AreasIn this study,the amino acids of Coix seed were pre-column derivatized with phenyl isothiocyanate The amino acid composition and content of Coixseed from 33 producing areas were analyzed by high performance liquid chromatography.The results showed that the established method was simple and practical,and could accurately detect 17 kinds of amino acids in coix seed,which provided a new method for the determination of amino acids in coix seed and the quality evaluation of Coix seed.The results showed that there were 17 kinds of amino acids in coix seed,including 7 kinds of essential amino acids: lysine,phenylalanine,methionine,isoleucine,leucine,valine and threonine.The content of isoleucine was the highest,with an average of 58.43 μg/g.The other 10 kinds of amino acids are non essential amino acids for human body,and the content of tyrosine is the highest.Taking the total content of amino acids as the index,the quality of Coix seed from Xingren County of Guizhou Province was the best,reaching274.0 μg/g.1.3 Comparative Study on Nutrient Index of Inorganic Elements and Heavy Metal Pollution of Coix Seed from Different Producing AreasMicrowave digestion combined with inductively coupled plasma atomic emission spectrometry was used in this study,The contents of six heavy metal elements(Cu,As,Hg,Cr,Cd,Pb)and eight essential trace elements(Mn,Fe,Cu,Zn,Co,Ni,Se,Cr)in coix seed from different habitats was determined by ICP-AES,NPI was used to analyze the nutritional index and evaluate the heavy metal pollution of the above eight essential trace elements and six heavy metal harmful elements in coix seed.The results showed that the average contents of 12 inorganic elements in coix seed were 0.0153,0.0021,0.0032,0.0644,0.3416,0.1429,0.4824,0.3966,0.1990,0.1080,0.9196 and 1.127mg/kg respectively.The content of Microelements in coix seed from different areas was significantly different,and the total content of Microelements in Liaoning and Fujian was the highest.The INQ values of Cr,Co and Se in coix seed were all greater than 1 by INQ analysis.According to the INQ evaluation index,coix seed can be used as an excellent nutritional supplement for human intake of Cr,Co and Se.The results showed that the pollution of six heavy metal elements in coix seed was good,except for a batch of coix seed sample from Zhejiang Province,the rest of them did not exceed the standard.The comprehensive pollution order of each single heavy metal element was Cr>Pb>Hg>Cd>As>Cu.The results of nemerol comprehensive pollution evaluation method showed that all batches of coix seed samples was almost safe.The results can provide experimental basis and scientific ideas for the safety evaluation of coix seed and the development of comprehensive nutrition and health products.2 Study on Isotherm Adsorption Curve of Coix SeedThe growth and reproduction of moldy microorganisms are closely related to water activity.In this study,the isotherm adsorption curve was applied to coix seed for the first time.By studying the isotherm adsorption curve of coix seed samples under the conditions of water activity of 0.11～0.90 and storage temperature of 15 ℃,25 ℃and 35 ℃,the safe water content of coix seed during storage was predicted.The results showed that: the equilibrium moisture content of coix seed increased gradually with the increase of water activity at different temperatures,the isotherm adsorption curve of coix seed belonged to the third type,and the fitting degree of ferro Fontan equation for the isotherm adsorption curve of coix seed at different temperatures was the best.The absolute safe water content of coix seed at 15 ℃,25 ℃ and 35 ℃ is6.55 %,6.73 % and 6.98 %,and the relative safe water content is 13.46 %,13.86 % and13.48 %,which is consistent with the "water content can not exceed 15.0 % under the item of" inspection "of coix seed in Chinese Pharmacopoeia(2020 Edition).3 Study on the Changes of Chemical Components in Coix Seed under Different Storage ConditionsIn this study,The contents of polysaccharide,flavone and phenolic acid in coix seed were determined by spectrophotometry under different storage conditions.The results showed that the contents of polysaccharides,flavonoids and phenolic acids in three batches of coix seed decreased under nine storage conditions.With the increase of storage temperature and humidity,the decrease rate increased,and the decrease rate was the fastest at 35 ℃-80 %.In other words,the higher the temperature and humidity,the more the content of polysaccharides,flavonoids and phenolic acids in coix seed lost during storage.The lower the temperature and humidity,the less the loss of chemical components in coix seed.and the more conducive to the preservation of coix seed. |
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