Study On Physical And Chemical Properties And In Vitro Digestive Properties Of Ultramicro Tea Powder From Seabuckthorn Leaves

Seabuckthorn is a medicinal and edible homologous plants,which is rich in various nutrients and bioactive substances.China is the country with the most abundant natural seabuckthorn germplasm resources in the world and the largest area of artificial cultivation of seabuckthorn.As a by-product of seabuckthorn industry,most of the leaves are discarded due to technical and economic constraints,resulting in a serious waste of resources.Therefore,the study on seabuckthorn leaves products can not only realize the rational utilization and sustainable development of resources,but also maximize the efficacy of seabuckthorn leaves,which is of great significance for the development of seabuckthorn industry.In this study,the leaves of Seabuckthorn were used as raw material to investigate the physical and chemical properties and in vitro digestion of ultramicro tea powder of seabuckthorn.The main research and conclusions are as follows:(1)The coarse crushed seabuckthorn leaf tea powder(CST),dry ultrafine grinding of seabuckthorn leaf tea powder(DST)and wet ultrafine pulverized seabuckthorn leaf tea powder(WST)were prepared by high-speed multifunctional grinder and planetary mill.The powder structure,chemical composition and some food processing characteristics were compared.The results show that compared with the CST(967.50 nm),the DST particle size is significantly reduced to 830.43 nm.The value of ζ potential increases by 16.96% and the agglomeration of powders is weakened.Soluble dietary fiber(SDF)content increased significantly,tea polyphenol content also increased slightly.The brightness of the powder is significantly improved.Compared with CST,the diameter of WST decreases to 637.83 nm,and the value ofζ potential increases by 35.62%.SDF was significantly increased by 22.58%,the brightness of the powder was significantly increased,the water holding capacity and oil holding capacity were significantly increased by 22.32% and 5.24%,and the binding ability and flow performance of the powder with water and oil were greatly improved.In summary,ultramicro grinding can effectively improve the particle size,chemical composition and physical and chemical properties of sand buckthorn leaf tea powder,and the effect of wet ultramicro grinding is better than that of dry ultramicro grinding.However,considering the complex operation process,long time and high economic cost of wet ultramicro grinding in the process of powder preparation,dry ultramicro grinding,which is a relatively simple and fast method,can be selected.It will provide theoretical basis for the future development of seabuckthorn leaf tea industry.(2)Ultrafine tea powder from seabuckthorn leaves was prepared by different fermentation methods.The results showed that compared with the ultrafine tea powder of unfermented seabuckthorns leaves,the water and oil holding capacity of ultrafine tea powder of seabuckthorns leaves increased significantly after natural fermentation and Lactobacillus plantarum fermentation.The contents of flavonoids and tea polyphenols decreased significantly.Compared with the unfermented ultrafine tea powder,the L* value of ultrafine tea powder increased significantly after natural fermentation,the color of the powder was brighter,and the a* and b* values decreased significantly,which decreased by 20.10% and 4.46%,respectively.Protein content decreased;The SDF increased by 15.86%.The value of L* decreased significantly,and the value of a* and b* increased by 61.54% and 6.59%,respectively.Protein content significantly increased by 5.02%;SDF increased by 7.43%.In conclusion,fermentation effectively improved the physical and chemical properties of ultra-fine tea powder of seabuckthorn leaves,and the ultra-fine tea powder prepared by Lactobacillus plantarum was superior to that prepared by natural fermentation.(3)Through the simulation of gastrointestinal digestion in vitro,the contents of flavonoids,tea polyphenols,total antioxidant capacity and DPPH free radical scavenging ability in ultrafine tea powder of sea buckthorn leaves with different dosage during digestion were analyzed.The results showed that the contents of flavonoids,tea polyphenols,total antioxidant capacity and DPPH free radical scavenging capacity increased with the increase of ultrafine tea powder addition level in sea buckthorns leaves in the simulated in vitro digestion experiment.After 2hours of gastric digestion,flavonoid content in low dose seabuckthorn ultramicro tea powder group(LSP)increased by 50%;iron reduction capacity increased by 17.5%;DPPH free radical scavenging rate increased by 12.5%;flavonoid content in high dose seabuckthorn ultramicro tea powder group(HSP)was increased by 17.65%.Tea polyphenol content increased by12.33%.The contents of flavonoids and tea polyphenols of LSP,HSP,total antioxidant capacity and DPPH free radical scavenging capacity were decreased 2 h after intestinal digestion,and the release stability of HSP was stronger than LSP.In conclusion,the release of HSP in human digestion is more stable and more in line with the needs of human nutrition and health.