Study On Physicochemical Properties And In Vitro Digestion Of Green Tea Powder With Different Particle Sizes

As a new tea product,ultrafine tea powder retained the functional components of tea at maximum extent,and was widespread for its simpleness,convenience and abundant application mode.However,the particle size range of ultrafine tea powder was not standardized,its relative research was not continuous,and its production application was lack of reference basis.In this research,the green tea powder of different particle sizes were used as materials,and theirs physical and chemical properties,dissolution characteristics,and in vitro antioxidant activities were studied,hoping to provide experimental basis for the production application.The results are as follows:1?The characterization and physical property of green tea powder with different particle sizes prepared by a planetary ball mill were studied.The results showed that,with the prolonging of grinding time,the particle size of tea powder decreased significantly,the powders were distributed evenly,the angle of repose,swelling power and solubility of the powders were increased,the bulk density and the water-holding capacity were decreased,the oil-holding capacity showed a trend of increasing first and then decreasing,and their chromaticity values were improved.It was concluded that the physical properties of green tea powder(D50= 20.84 ?m)after 7 h of grinding was excellent,and the commercial value were enhanced.2.The component contents of Green tea powder with different particle sizes were studied.The results showed that there were significant difference among different sizes of green tea powder(except caffeine).With the decreasing of the particle size,the tea polyphenol(TP),amino acid,soluble sugar content showed a trend of increasing first and then decreasing,the tea polysaccharide(TPS)and water extract content increased significantly,and the catechins content were decreased.Especially,the green tea powder of 20.84 ?m had the highest TP content,the green tea powder of 74.85 ?m had the highest catechins content,the green tea powder of 15.10?m had the highest TPS content,the green tea powder of 34.62 ?m and 20.84 ?m had higher amino acid,soluble sugar and water extract content.3.The antioxidant activities of green tea powder with different particle sizes were studied.The results showed that with the decreasing of the particle size,the Ferric reducing antioxidant power(FRAP)increased,the Hydroxyl radical(·OH)scavenging power showed a trend of increasing first and then decreasing.The green tea powder of 15.10 ?m had the strongest FRAP,the green tea powder of 74.85 ?m had the strongest·OH scavenging power,the difference of the DPPH scavenging power of green tea powder with different particle sizes were not statistically significant.4.The dissolution characteristics of the compounds in green tea powder with different sizes at body temperature(370C)were discussed.The results showed that dissolution amount and dissolution rate of the compounds in tea powder were related to the particle size of tea powder and dissolution time.After 50 min of the dissolution,the dissolution amount of tea polyphenols in 15.10 ?m of tea powder was significantly higher than that in 564.24 ?m of tea powder,and the dissolution amount of soluble sugar and water extract in 15.10 ?m of tea powder was also significantly higher than that in all other particle sizes of tea powder.The dissolution rate of the compounds(except amino acid)in 15.10 ?m of tea powder was also higher than that in other tea powder in the late.5?The dissolution of main antioxidant component and antioxidant activities of green tea powder with different particle sizes in vitro digestion were studied.The results showed that with the prolonging of gastric digestion time,the dissolution of TP and TPS content were increased,so as the FRAP and the ·OH scavenging power were increased,and there were significant difference among different particle sizes of green tea powder.With the prolonging of intestinal digestion time,the dissolution of TP content were decreased,as well as the antioxidant capacity.But the dissolution of TPS content were increased.The different particle sizes of green tea powder were statistically significant.6.The physicochemical properties,dissolution characteristics and antioxidant activities after in vitro digestion of green tea powder with different particle sizes were analyzed to comprehensively evaluate its application value.The results showed that the functional activities of green tea powder of D50= 20.84 ?m were excellent.This particle size of green tea powder is suitble for production.