红茶氨基酸、茶多酚、咖啡因的低强度多频超声浸取特性

用DPS系统建立了包括温度、茶水质量比、时间、超声强度和超声频率(28 kHz和40 kHz)等因素的均匀设计实验方案,探索水为溶剂,低强度(低于0.6 W.cm-2)单频、双频复合和双频交变超声浸取红茶氨基酸、茶多酚、咖啡因的浸取特性;以质量浓度、浸取率为指标,用偏最小二乘法处理实验数据,以标准化回归系数评价各因素的影响程度。结果表明,与单频超声场相比,双频超声场降低了超声作用强度54%~67%,提高了温度、茶水质量比等其他单因素作用强度34%~143%;双频交变超声场的这种作用最强。双频交变超声场降低了除温度-茶水质量比之外所有双因素的作用强度12%~75%;而双频复合超声场提高了与超声强度有关的双因素作用强度19%~1 350%,降低了与超声场无关的双因素作用强度47%~75%。90℃0.3 W.cm-23种超声场浸取5 m in,红茶3种成分浸取特性有明显差异,双频复合超声浸取氨基酸的质量浓度和浸取率最高(分别为369.4mg.L-1和55.0%);双频交变浸取茶多酚、咖啡因最好,质量浓度分别为11.4、2 749.52 mg.L-1,浸取率为39.8%、49.8%,单频超声浸取效果最差。

Extration of Amino Acid, Polyphenol and Caffeine from Black Tea by Low Intensity and Multi-frequenciy Ultrasound

The experimental plan of various experimental conditions,such as temperature,mass ratio of tea and water(MR),intensity,time and frequency(28 kHz and 40 kHz),were done according to uniform design by DPS to investigate the extraction of black tea amino acid,polyphenol and caffeine with water by single-frequency ultrasonic extraction(SFU),dual-frequency-complex ultrasonic extraction(DCU) and dual-frequency-alternant ultrasonic extraction(DAU) at two ultrasonic frequencies in low ultrasonic intensities(up to 0.6 W·cm~(-2)) for getting the extraction characteristic of the black tea compositions.The data were processed with PLS procedure and the effect of the factors on mass concentration and extract content was confirmed by the standard regression coefficient.The result shows that the dual-frequency-ultrasound weakens the effect of the ultrasonic intensity by 54%～67% as compared with SFU,but strengthens the effect of other single factors,such as temperature,MR and time,by 34%～143%,and the action of DAU is stronger than DCU.DAU weakens the effects of every other dual factors than temperature-MR by 12%～75%,but DCU strengthens the effect of dual factors containing ultrasonic intensity by 19%～(1 350)%,and weakens the effect of dual factors containing no ultrasonic factor by 47%～75%.With three kinds of ultrasonic extraction of 0.3 W·cm~(-2) for 5 min at 90 ℃,there are obvious different results for three kinds of black tea compositions:DCU gives the best result of high concentration and high extraction rate of amino acid(369.4 mg·L~(-1) and 55.0% respectively);DAU gives the best result in extracting polyphenol and caffeine,the concentrations and extration rates being 11.4 mg·L~(1),(2 749.52) mg·L~(-1) and 39.8%,49.8% respectively.The lowest is in SFU.