A novel approach for the production of natural aroma compounds using agro-industrial residue

Abstract

 Experiments were carried out to study the production of aroma compounds from coffee husk by a fungal culture of C. fimbriata in solid state fermentation. Hot water treated coffee husk seemed to be useful substrate for aroma production in comparison to whole coffee husk or its water extract. Raw data were integrated in order to calculate the total volatiles (TV) accumulated during the fermentation using the Gompertz model. Glucose addition between 20–35% increased significantly the yields of aroma compounds. Supplementation of leucine further improved the TV production significantly (about 58%), specially the esters. When soybean oil was added, TV production was similar to the control, showing that the fungus was not able to use soybean oil for its primary metabolism, nor it acted as precursor for the synthesis of methyl ketones as reported for other fungi. Addition of saline solution drastically decreased the volatile production. Under optimized conditions, a total of 13 compounds were produced which included alcohols (2), aldehyde (1), ketones (2) and esters (8). Ethyl acetate was the prominent compound, followed by ethanol.