Effect of fermentation on the physicochemical characteristics and sensory quality of Arabica coffee.

Abstract

This work aims to assess the physicochemical characteristics and final sensory quality of Yellow Catuai IAC 62 Arabica coffee fermented with Saccharomyces cerevisiae. For such a purpose, a Composite Central Rotational Design (CCRD) was performed to investigate how fermentation time,temperature and pH conditions, moisture content and concentration of sugars and organic acids affect its sensory quality on two different roast levels in accordance with Specialty Coffee Association (SCA) protocols. It was found that fructose concentration decreased from 12g/L to around 5g/L during fermentation, regardless of temperature condition. Furthermore, longer fermentation times and higher temperatures have lowered sucrose and glucose concentrations from 4 to 2g/L and 7g/L to zero, respectively. Glycerol concentration was higher as time and temperature increased, and optimal conditions ranged at temperatures between 24°C and 32°C from 35 to 45h of fermentation time. pH decreased as fermentation time elapsed, but there was a more significant reduction due to higher temperatures, starting at around pH 5 and, lower than 4 under extreme conditions. Contents of organic acids such as acetic, propionic, succinic, and lactic acids, were measured at the final stage of each fermentation process under studied conditions. It was observed that coffee samples achieved final scores ranging from 81 to 85 (SCA score), even in longer times and extreme temperature conditions, thus all samples have been classified as specialty coffees. This work described the initial step towards parameterizing fermentation processes, given that the response variables of temperature and fermentation time, were optimal and enhanced the sensory quality of coffee as beverage. Saccharomyces cerevisiae, a commercial product which has already been made available for producers, can ensure an increase in the sensory quality of coffee.