Structure variety and its effects on biological activity of tea polysaccharides

Tea polysaccharides(TPSs),one of the major bioactive ingredients in tea,have been widely studied due to their variety of biological activities,including antioxidant,cancer prevention,hypoglycemia,anti-fatigue,anti-coagulant,anti-obesity and immunomodulatory effect.The biological effectiveness of TPSs has direct relation with their structures such as monosaccharide composition,molecular weight,glycosidic linkages,conformation and others,which can be influenced by tea materials,processing methods,extraction and purification procedures among others.Comparing to the study of tea polyphenols,the exploration of TPSs in structural elucidation and biofunctionality is very preliminary.Yet several factors affecting the structural change of TPSs have been studied and identified.Consequently,the variation of some TPS biological activity brought by the change of TPS structures has been evaluated and preliminary correlation of structure activity relationship of TPSs has been performed.Therefore,this review aims to serve as a summary research report regarding the influencing factors on TPSs structures and consequential effects on the biological activities of TPSs.We hope to provide updated information and systematic references for future study and functional food development of TPSs.

Research on the Extraction Process of Pu-erh Tea Polysaccharide by Response Surface Analysis

[Objective] This study aimed to optimize the extraction process parameters of Pu-erh tea polysaccharide. [Method] Single-factor experiment was carried out to analyze the influences of three main factors, including extraction temperature, ex- traction duration and solid-liquid ratio, on the extraction yield of tea polysaccharide. Box-Behnken central composite design and response surface methodology were adopted to determine the optimal extraction process of Pu-erh tea polysaccharide. [Result] The results of response surface analysis showed that the optimal extraction process was solid-liquid ratio of 1：17, extraction temperature of 80 ℃ and extraction duration of 78.5 min, and the Pu-erh tea polysaccharide yield was 12.72%. [Conclu- sion] Using response surface methodology （RSM） is feasible for the optimization of Pu-erh tea polysaccharide extraction process, and the tea polysaccharide yield increased significantly.

Green tea polysaccharide conjugates and gelatin enhanced viability of L. acidophilus by layer-by-layer encapsulation

Adverse environments such as the gastrointestinal tract can affect the efficacy of probiotics.Therefore,the adequate protection of probiotics and their total effect exertion are probiotics application research hotspots.Green tea polysaccharide conjugate(gTPC),an anionic polymer,and gelatin as the encapsulation materials,and layer-by-layer self-assembly technology as the method,were applied to encapsulate Lactobacillus acidophilus.Microscopic results showed that with the increase in the number of deposited layers,the encapsulation was more complete.After continuous exposure to simulated gastrointestinal fluid for 120 min,the survival rate of unencapsulated cells was 53.26%,and encapsulated cells with different deposited layers were 66.00%,71.99%,76.94%,and 79.89%,respectively.In addition,Gel/gTPC bilayers can efficiently improve cell thermotolerance and freezing resistance.Results indicated that the more the number of Gel/gTPC bilayers,the more significant the protection is.Therefore,gTPC and Gel are viable materials to protect probiotics through microencapsulation by Layer-by-layer self-assembly.