Changes in fatty acids profile and sucrose concentration of coffee beans during drying process

Abstract

Solar drying and forced convection of hot air (mechanical drying) are traditionally used for the drying process of coffee beans. This work describes the changes of the concentration of sucrose and 11 fatty acids contained in Castillo® variety coffee beans during the drying process using HPLC and CG MS. A single‐factor experimental design with three blocks was carried out like this: three solar and three mechanical drying. A phenomenological mathematical model was developed allowing to know the evolution of chemical compounds concentration over time by using a parameter called characteristic time, which can be experimentally measured. For the 18‐h mechanical drying, sucrose concentration increased by 14.55 ± 0.20 mg/g db, while palmitic and linoleic fatty acids decreased by 0.372 ± 0.013 mg/g dry basis (db). For solar drying of 94, 120, and 218 h the initial sucrose concentration was reduced by 24.81 ± 0.23, 29.28 ± 0.27, and 47.10 ± 0.21 mg/g db, likewise palmitic and linoleic fatty acids were reduced by 0.442 ± 0.010, 0.680 ± 0.012, and 1.088 ± 0.014 mg/g db. These results suggest that a short drying time leads to a higher concentration of the analyzed chemical compounds in the coffee beans.Practical ApplicationsThe coffee drying process impacts the concentration of chemical compounds that are of great interest in forming coffee aroma and flavor in the roasting process. This study highlights the impact of drying time on the concentration of sucrose and fatty acids in coffee beans. The main application of this research shows how in solar and mechanical drying variations organic compounds occur. The presence of these organic compounds in coffee beans is of great interest for the later coffee roasting process. The proposed phenomenological mathematical model allows a physical understanding in the effect of drying time on the concentration of sucrose and 11 fatty acids.

Implementation of fuzzy logic control algorithm for temperature control in robusta rotary dryer coffee bean dryer

“…Due to some of the negative consequences of drying coffee beans in conventional ways, it is needed to fix these problems by using a drying machine as an option [33] . Mechanical drying of coffee beans with air heated to 50°C achieves excellent coffee with better chemical and physical qualities than direct solar drying [34 , 35 , 36] . Furthermore, mechanical drying with machines contains more sucrose and less fatty acids than direct drying with sunlight, making it healthier than conventional drying [34] .…”

“…Mechanical drying of coffee beans with air heated to 50°C achieves excellent coffee with better chemical and physical qualities than direct solar drying [34 , 35 , 36] . Furthermore, mechanical drying with machines contains more sucrose and less fatty acids than direct drying with sunlight, making it healthier than conventional drying [34] .…”