Comparison of different drying technologies for coffee pulp tea: Changes in color, taste, bioactive and aroma components.

Drying is a crucial process in the production of tea. The effects of sun drying (SD), hot air drying (HAD), microwave drying (MD), vacuum drying (VD) and freeze drying (FD) on the color, taste, bioactive, and aroma of coffee pulp tea (CPT) were evaluated systematically. The results showed that FD could better retain the original color, total phenolics (4.75 mg/mL), trigonelline (0.31 mg/mL), chlorogenic acid (0.067 mg/mL), protocatechuic acid (0.81 mg/mL), and total soluble sugars (24.33 mg/mL) of CPT, but its drying time was longer (32.56 h), and the taste and flavor were the worst. HAD and SD displayed the highest loss rates of most bioactive components, exceeding 40%. In contrast, MD can better improve the quality of CPT, giving it a better color, superior retention of bioactive components, and the most attractive taste and aroma, and decrease the drying time by 66.1% and 96.5%, respectively. Overall, MD is a promising production method for obtaining high-value-added CPT products. [Display omitted] • FD can keep coffee pulp tea's color and phytochemical profiles considerably. • The volatile components of coffee pulp tea were modeled using OPLS-DA. • MD-dried coffee pulp tea had a better attractive aroma under shorter drying times than other drying. • MD was more suitable to produce dried coffee pulp tea on an industrial scale. [ABSTRACT FROM AUTHOR]