The Study Of Tea Polyphenols Components Analysis And Its Interaction With Soybean Protein Isolate

Tea polyphenols is a natural antioxidant extracted from tea, including flavanols(catechins), flavonoids and flavonoid glycosides, anthocyanins and phenolic acids such four categories, and the specific composition of these four categories has not been reported. At present, most research of tea polyphenols extract concentrate on the determination of polyphenols, but the purity of tea polyphenols final product is hard to reach 100%, and the specific composition of other ingredients except polyphenols has not been systematically analysis. In this paper, we conduct a comprehensive analysis on the composition of tea polyphenols by using modern analysis methods. At the same time, we investigate the interaction between tea polyphenols and soybean protein isolated and the effect on its functional properties. Not only provide guidance for better purification of tea polyphenols, but also provide a scientific basis for the rational use of tea polyphenols products. The main content of this research is as follows:One method which could simultaneously determine the main kinds of tea polyphenols in three sizes of TP, such as catechins, flavonoids, anthocyanins, phenoic acids, was established by HPLC-MS. The content of catechins increase with the improvement of purity, in which content of EGCG is the highest,and ECG、EC、EGC are inferior to EGCG,and the content of C is the least. The contents of three others kinds of polyphenols are low and it increase with the improvement of purity then decrease. The study determined the content of non-polyphenols of tea extracts which are different sizes, such as moisture, ash, protein, amino acid, tea polysaccharide, γ- aminobutyric acid, theanine, heavy metals and other indicators. It compares the change value of contents of composition after separation and purification.It examines the factors which can influence the interaction between TP and SPI. When the mass ratio of SPI and TP is 0.8, the precipitation rate is maximum; When the temperature is 40 ℃, the precipitation rate reach the maximal value; when p H range from 3.5 to 5.5,the precipitation rate is also maximum.In this paper, it also compares the ability of interaction between three sizes of TP and SPI,the result shows that the overall trend is firstly go up then down. The interaction ability order of three sizes of TP and SPI is that: TP98>TP80>TP50. The change value of EGCG reached 4.79mg(TP50), 5.02mg(TP80), and 5.86mg(TP98) respectively before and after reaction of three sizes of TP, which has main contribution to precipitation of TP and SPI. The rest of classification including three kinds of catechins and flavanols,anthocyanins,phenolic acids, which has a small change value.It also identify the concentration of TP which is between 0~0.12% has little effect of pepsin activity, and test the variation of SPI in vitro digestion which complexing with TP in this concentration range. Results show that the TP50 has the bigger impact on SPI in vitro digestion, TP98 followed, TP80 is the least effect.It also systematically discusses the effect of TP98 on the functional characteristics of SPI. The result shows that : when TP content is 0.10%, the solubility of SPI is maximum; when TP content is 0.16 g, SPI’s water-keeping rate reach its maximum value-450%,which is 12.5% higher than non-TP; when TP content is 0.02 g, SPI’s oil-keeping rate reach a maximum value that is 200%,which is 25% more than non-TP; SPI’s emulsification increase when the range of TP concentration is 0~0.1%,decrease in the range of 0.1%~0.4%. when the concentration of TP is 0.8%,which is 2.7% higher than non-TP, emulsion stability also increase; when the addition of TP is 0.50%(w/v), SPI’s gel strength increase by 56% than its control group, to 170.08 g. In contrast,the water-keeping rate of SPI gel decrease with the increase of TP;TP has improvement on the SPI’s foam expansion,when the concentration is 0.1%, the ability of foam expansion is maximum,higher 30% than its control group. However, the stability of foam only increase at the beginning, then decrease with the increase of the concentration of TP.