Processing optimization and quality evaluation of black tea crisp cake

【Objective】The processing of black tea crisp cake was optimized and its quality was evaluated,in order to provide scientific basis for industrialization of black tea crisp cake and black tea Chinese pastry. 【Method】Black tea crisp cake was prepared with ultrafine black tea powder as main raw material. The sensory evaluation method was used to optimize the process conditions through single-factor tests combined with orthogonal tests,and the quality of black tea crisp cake was evaluated in terms of functional components,storage properties and digestive characteristics. 【Result】The factor affecting sensory score of black tea crisp cake were ranked as follows:ultrafine black tea powder dosage>baking temperature>baking time. All three factors had extremely significant effects on the sensory score of black tea crisp cake(P<0.01).The optimum processing conditions were ultrafine black tea powder dosage of 4% of flour mass,baking temperature of 175 ℃,and baking time of 16 min. Under the optimized conditions,the sensory score of black tea crisp cake reached up to 92.84 points,which had the unique taste and color of black tea. The retention rate of functional components in black tea crisp cake after processing were above 80.00%,and the retention rate from large to small were caffeine>theabrownin>thearubigin>theaflavin>amino acids>tea polyphenols. Compared with ordinary crisp cake,black tea crisp cake had stronger antioxidant activity. When stored to the 16^th day,the peroxide value(0.26 g/100 g) and acid value(5.1 mg/g) exceeded the upper limit of the national standard peroxide value(calculated with fat) ≤0.25 g/100 g,acid value(calculated with fat)(KOH) ≤5 mg/g. At the same time,the ^{in vitro} anti-starch digestion ability of black tea crisp cake was also greatly enhanced,in which the resistant starch content was elevated by 68.57%,the fast digestible starch content was reduced by 7.49%,and the slow digestible starch content was reduced by 20.29%. In addition,the glycaemic index of black tea crisp cake(66.98) was obviously reduced,which was 16.08% lower than that of ordinary crisp cake(79.81). 【Conclusion】Under the above optimum processing conditions,the sensory quality and functional component retention rate of black tea crisp cake are high,and it has strong storage properties and digestion characteristics. Therefore,the optimized processing technique can be applied in actual production.