Effect of post-harvest drying process on chlorogenic acids, antioxidant activities and CIE-Lab color of Thai Arabica green coffee beans

Drying process affected the qualitative indicators of green coffees; chlorogenic acid (CGAs), total phenolic content (TPC), antioxidant activities and CIE-lab color to varying degrees. Sun drying and heat pump drying resulted in comparable levels of CGAs and antioxidant activities in green coffees; however, color parameters, especially lightness (L*), differed. Correlation analyses indicated a relationship between specific CGAs, antioxidant activities and color parameters among coffees. PLS analysis revealed that the high contents of 5-caffeoylquinic acid in green coffees did not correlate with antioxidant activities. Results from CGAs contents and PCA analysis provided a linkage to previous research relating important components and quality indices of both green and roasted coffees as affected by postharvest drying. Results indicated that heat pump drying at 50 degrees C is a viable alternative and possibly superior to sun drying for preserving certain desirable chemical and physical characteristics of green coffee.

Automated summary

The drying process affects the qualitative indicators of green coffees to varying degrees, with sun drying and heat pump drying resulting in comparable levels of CGAs and antioxidant activities. Specific CGAs, antioxidant activities, and color parameters are correlated among coffees. Heat pump drying at 50 degrees C is a viable alternative and possibly superior to sun drying for preserving certain desirable chemical and physical characteristics of green coffee, according to results from CGAs contents and PCA analysis.