The Studies On The Techniques Against Colour Variation And Precipitation Of Green Tea Drink

Nutritional, easy-to-drink, thirst-suppressing, Tea drinks are popular with consumers for its healthy effects, such as spirit-stimulation and refreshing. Nowadays tea drinks develop rapidly in our country, but in the market most of tea drinks are flavoring tea, pure tea drinks are rare, especially for pure green tea drinks. In terms of components in tea products, flavoring tea drinks don't show as much essence of tea as pure tea products, which attract more and more consumers. But pure tea drinks are easy to change their color and form sediment, because of high concentration, which prevent it being developed further. The stability of green tea drinks' color is studied by adjusting the pH of green tea liquor and adding the foreign materials such as Zncl2 Vc Cysteine and glucose oxidase. The degree of its change is judged by measuring the chromaticity of tea soup which has stored for a certain period. The result shows that the pH effect on green tea soup's color reaches noticeable level. The tea soup's color becomes deeper and the degree of its brightness becomes lower with the pH value rising. But the influence is unnoticeable when pH is below 5.5. Different foreign materials influence tea soup's color noticeably. By means of sensual judgment and analysis of variance, we find Amino acid and Glucose Oxidase, Zncl2 and Vc have better influence on the stability of green tea drink's color. Through adding 0.03%Zncl2 and 0.02%VC, adjusting the soup's pH to 5.0, the color of tea soup can remain well. The study of different enzymes effects on the precipitate of green tea soup. The result indicates that Tannase, Pectinase and Papain influence the tea soup's stability noticeably. The light transmittance of differently-handled tea soup lessens with different degree respectively after 20-day storage. In this case, polyphenol and coffeine decrease at different levels. Combining the analysis of variance with the tasting, the results show that the optimal effecting dose of Tannase is 4.0U/g and the optimal effecting time is 2 hours.Adopting HPLC to analyze the change of Catechins in the tea soup processed by Tannase .The result shows that the total Catechins of tea soup goes down and the light transmittance increases constantly, along with the increase of enzyme unit and effecting time. Research on the collaboration of β-CD, pectinase, papain and GOD with Tannase to tea soup respectively. The result shows that β-CD, pectinase and papain are effective in coordination of preventing precipitates. The effect of Glucose oxidase does not reach the noticeable standard.