Effects Of Ultrasound On Extraction Rate,Structure And Biological Activity Of Polysaccharide From Large Yellow Tea

Tea has a long history of medicinal and dietary.Tea polysaccharide(TPS)is one of the main functional components in tea extract.So far,some studies have found TPS show various bioactivities and very beneficial to health.There are many common methods for extracting tea polysaccharides,the mainly used methods include hot water extraction and ultrasonic assisted extraction.Moreover,extraction method could effects on the structure,physicochemical properties and biological activity of YTPS.In this study,Large yellow tea was used as the material,response surface design was used to optimize the ultrasonic assisted extraction process of polysaccharides from Large yellow tea(YTPS).To study the effects of ultrasonic assisted extraction methods on the structure,antioxidant activity and regulating human intestinal flora of YTPS.Based on the influence of single factor on the extraction rate of YTPS.The aim was to improve the extraction rate of YTPS.The response surface optimization method was used to determine the optimal ultrasonic extraction conditions of YTPS,the extraction time was55 min,the ultrasonic power was 500 W,and the solid-liquid ratio was 1:35.At this point,the extraction rate of YTPS was 6.23%.Compared with hot water leaching method,the extraction rate of YTPS by ultrasonic wave is increased by 50.43%.UV and FT-IR analyses indicated partial degradation of YTPS treated with ultrasonibut the primary structure was not altered.Circular dichroism(CD)spectratomic force microscope(AFM)and scanning electron and microscopy(SEM)analysis further confirmed the breakdown of YTPS treated with ultrasound and the changes of YTPS surface morphology.Free radical scavenging activity showed that ultrasound irradiation could evidently enhance the antioxidant activities of YTPS-N,in which YTPS-7U exhibited the highest free radical scavenging activities among all the samples The IC50 values of DPPH,superoxide and hydroxyl radicals scavenging of YTPS-7U were 0.06 ±0.02 mg/ml,0.35 ± 0.02 mg/ml and 0.07 ± 0.004 mg/ml,respectively.The effects of ultrasonic assisted extraction of YTPS-U and hot water extraction of YTPS polysaccharides on the regulation of human intestinal flora were studied by in in vitro simulated gastrointestinal bionic system.The results showed that both polysaccharides adjusted the composition and promoted biodiversity of the intestinal flora and the production of short-chain fatty acids;YTPS-U can produced more total Bifidobacterium,more capable to inhibit Firmicutes proliferation.Conclusion: ultrasonic extraction can improve the yield,change the structure,enhancethe antioxidant activity of polysaccharides.Moreover,polysaccharides can produce more beneficial bacteria in fermentation broth and better regulate the structure of human intestinal flora.