| The research used by product of Fenghuang tea as raw material,The technology parameters of extraction,membrane clarification and membrane concentration,spay drying were studied.Both the characteristics and the aroma components of the tea powder were tested. With extraction rates of tea polyphenol,caffeine and free amino acids as indicators,the main factors influencing the extraction which included ratio of water to tea,extraction temperature,extraction time,extraction times,dosage of enzyme and ultrasonic power were studied by using water extraction,complex enzyme assisted extraction and ultrasonic assisted extraction,also the extraction technology were optimized.The experiments of both clarification and concentration were conducted by microfiltration and nanofiltration methods.The effects of different pressures and temperature on membrane flux and physical and chemical components of the tea infusion were studied.The optimal technology of spray drying were obtained by evaluation the effects of inlet temperature,outlet temperature,feed rate and souble solids on the yield and chromatic aberration L value.The properties of mobility,adhesion,caking and solubility of two kinds samples (both adding β-cyclodextrin tea powder and no β-cyclodextrin tea powder) which had different granularity were tested.The aroma components of tea powder were extracted and analyzed by simultaneous distillation extraction and gas-mass spectrometry methods.The results showed that the optimal parameters for water extraction were as follows:the ratio of water to tea1:15(m/F),extraction temperature80℃,extraction time40min,extraction times2.Under these conditions,the extraction rates of tea polyphenol was13.25%,extraction rates of free amino acids was0.44%,and the extraction rates of caffeine was0.22%.The optimal parameters of the complex enzyme assisted extraction were as follows:the composite enzymes (cellulases:pectinase=2:1g/g) was1.2%(E/S)hydrolysis temperature60℃,hydrolysis time90min and pH5.5.And the extraction rates of tea polyphenol was12.85%,extraction rates of free amino acids was1.04%,and the extraction rates of caffeine was0.25%.The optimum conditions of ultrasonic assisted extraction were as follows:the ultrasonic power550W,the ratio of water to raw material1:17(m/V),the ultrasonic temperature73℃,the ultrasonic time34min. Under these conditions,the extraction rates of tea polyphenol was16.13%,the extraction rates of free amino acids was0.40%,and the textraction rates of caffeine was0.33%.The optimal conditions of microfiltration were as the optimal conditions microfiltration were as follows:the membrane pore size0.1μm,the pressure0.2MPa and the temperature25℃, the yield of tea polyphenol, caffeine,free amino acids,pectin and soluble sugar were75.94%,84.69%,84.09%,41.18%and61.71%respectively.The optimal conditions of concentration were as follows:the membrane pore size300dal, the pressure0.5MPa and the temperature30℃, the soluble solids content increased from2.0%to11.9%; the optimum parameters of spray drying were determined as follows.the inlet temperature175℃,the outlet temperature75℃,the feed rate2.70L/h,the content of soluble solids12%;after granulation,the fluidity of the instant tea powder was maximum,the adhesiveness was minimum and the instant solubility achieved the best,the caking property of instant tea powder added with (3-cyclodextrin was minimum;the instant tea powder without adding β-cyclodextrinwere were identified51kinds of aroma components, and the relative content of the aroma components accounted for80.95%of total volatile components.The instant tea powder with adding β-cyclodextrinwere were identified61kinds of aroma substances,aroma components account for84.72%of the total volatile substances.the aroma material mainly included hydrocarbons,esters, alcohols,aldehydes, ketones,as well as a small amount of phenol and nitrogen-containing compounds.So β-cyclodextrin had certain effect on the reserves of aroma components. |
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