The Study On Preparation And Application Of Chinese Chestnut Powder

This research mainly studied the browning inhibition of Chinese chestnut, the preparation of Chinese chestnut powder and the production of instant Chinese chestnut powder. Taking catechol as the substrate, the Chinese chestnut polyphenoloxidase (PPO) existed isozyme. The optimum pH was 5.0 with a shoulder peak at pH 8.0 and the optimum temperature was 30℃. The Chinese chestnut polyphenoloxidase was stable in the range of alkalin and was heat-resisting. Chinese chestnut PPO was more sensitive to pH. The Chinese chestnut was not suitable for long-time heating in water for the serious browning. So Chinese chestnut powder was prepared by dry process.The inhibitors which chose through the single factor experiment were citric acid, ascorbic acid and cysteine (Cys). And on the base of orthogonal experiment, the optimum color-keeping condition was obtained as follows: the concentration of ascorbic acid for 3 mmol/L, the concentration of citric acid for 35 mmol/L, Cys for 0.75 mmol/L. Chinese chestnut kernel was dipped in the color-keeping solution .Along with the elevation of temperature, the drying rate of Chinese chestnut dried by hot-air was bigger. The drying rate of Chinese chestnut was smaller as the slice thickness. As reducing the thickness, the drying curves at 50, 60℃was more similar and the drying curves at 70, 80℃was closer. In order to reduce the drying time and obtain Chinese chestnut powder of high quality , the Chinese chestnut which was smaller than 0.3cm was dried at 50~60℃by hot-air for 6~8 h.The Chinese chestnut powder processed by different drying methods was different in the chemical composition, the physical and function properties, but the influence was not obvious. Therefore considering the drying cost and time, hot-air drying was suitable. All other chemical composition was similar besides the content of starch and reductive sugar. Chinese chestnut powder processed by different drying methods had favorable color, bad fluidity and high cohesiveness.The oil absorption and foaming property of Chinese chestnut powder dried by freeze was the highest and the water absorption capacity of powder dried by microwave vacuum was the best. The foaming stability of these three powder was the same.The instant Chinese chestnut powder which had favorable color and tasted delicious was made of Chinese chestnut powder, rice powder and degreased wheat embryo powder. The instant Chinese chestnut powder was produced as follows: Chinese chestnut powder 65%, rice powder 19.2%, degreased wheat embryo powder 15.8%, the extrusion moisture content 12.33%, the extrusion temperature 120℃.Monoglyceride and maltodextrin were added into the instant powder to improve the instant property. Monoglyceride reduced the agglomeration rate of the instant Chinese chestnut powder slightly and affect its viscosity greatly. After increasing the maltodextrin, the peak viscosity, the valley viscosity, the rupture value and the viscosity were declined. But the agglomeration rate was increased.The instant property of instant Chinese chestnut powder was improved with the addition of monoglyceride and maltodextrin for 0.3%,4% respectively.