Study On The Control Technique Of The Sediments In Green Tea Concentrate

Formation of tea sediments is a big problem in tea beverage industry, which can affect organoleptic quality of tea beverage. It is lack of efficient method to control the formation of sediments. The present study aims on reducing the sediments in green tea concentrate by adding sugars and enzymes in the concentrate.Four sugars (fructose, sucrose, maltose and glucose) were tested for reducing the sediments in green tea concentrate. The results showed that the4sugars had potential of reducing tea sediments in green tea concentrates with30%of soluble solids. The4sugars exhibit ability of reducing tea sediments according to fructose>sucrose>maltose≈glucose. With the increase of the concentration of the sugars, tea sediments were reduced significantly. Tea sediments in green tea concentrate were reduced more than80%compared to the control after adding20g/100mL fructose or40g/100mL sucrose. But adding50g/100mL maltose or glucose, the sediments were only reduced about50%. CMC, Xanthan gum and Carrageenan couldn’t inhibit the formation of tea sediments. The change of viscosity of green tea concentrate by adding of the4sugars or food gums did not relate to the formation of sediments. The ratio of total sugars/tea sediments increased with the added amount of the sugars, which suggested that the sugars competitively replace some tea compounds to participate in the formation of tea sediments by reducing tea compounds to enter the tea sediments, and increasing the steric hindrance between the compounds that participate in the formation of tea sediments.The effect of three enzymes including tannase, protease and pectinase on degrading the tea sediments were investigated. The efficacy of tannase was much bigger than protease and pectinase. Tannase could reduce tea sediments by hydrolyzing galled catechins to non-galled catechins with an optimum process, i.e. time120min, temperature35℃, additive amount0.05g/100mL. Tea sediments could be recycled to use for tea concentrate by treatment of tananse. The taste of tea infusion made of the mixture of supernatant and tannase-treatment sediment solution was better than the control.Compared the above two methods of reducing sediments, the method of treating with tannase was more effective than that of treating with fructose. Tannase treatment and fructose treatment both had influence on the taste of green tea concentrates. A sensory evaluation showed that tea infusion with only treated by tannase got higher scores than that of treating with fructose. But for some cases, it is also suggested that flavor tea beverage concentrate could be treated with fructose solutions in order to get the sweet taste.