Phenolic content analysis of coffee leaves subjected to htst and convective drying

Abstract

As a potential beverage, coffee leaf tea may possess both qualities of brewed coffee and regular tea . Thus, making it an attractive beverage in years to come. One of the main qualities is the leaf’s phenolic content, which is chiefly attributed with health benefits. However, the leaf’s total phenolic content may be adversely affected by heat during the drying process. Coffee leaves were dried using a combined drying process, high-temperature short-time (HTST) and convective drying, to assess the optimal drying parameters for both total phenolic content preservation and drying time reduction. To reach conclusions, a central composite rotational design (CCRD) was employed. With both temperature and thickness as independent variables, a response surface using time as dependent variable was generated . The temperature ranged from 80°C to 110°C and the thickness from 1cm to 3cm . Results indicate that the HTST pretreatment significantly reduced the drying time without affecting the total phenolic content; that is, the CCRD analysis on the effect of the HTST pretreatment on the total phenolic content did not yield statistically significant results.