Study on caffeine in black tea by microwave-assisted extraction

This paper studies the solubilization characteristics of caffeine in black tea.The effect of the grinding degree,the ratio of solid to liquid,the extraction temperature,the extraction time,the pH value of the extraction liquid,the microwave powder,the microwave treatment time on the solubilization characteristics of caffeine in black tea were tested. Microwave-assisted extraction pro-cess for the caffeine from the black tea was studied by the orthogonal experiment.The result ofquantitative analysis of the extracting rate of caffeine indicates that the extracting rate of caffeine in black tea was more than 3.90% under the condition is: the tea not be grinded,the ratio of solid to liquid was 1∶30,the extractiontemperature was 90 ℃, the extraction time was 30 min,the pH value of the extraction liquid was 6,the microwave powder was 350 W,the microwave treatmenttime was 20 s.