Enzymatic synthesis optimization of isoamyl butyrate from fusel oil

Many food, cosmetic and pharmaceutical industries have increased their interest in short-chain esters due to their flavor properties. From the industrial standpoint, enzyme reactions are the most economical strategy to reach green products with neither toxicity nor damage to human health. Isoamyl butyrate (pear flavor) was synthesized by isoamyl alcohol (a byproduct of alcohol production) and butyric acid with the use of the immobilized lipase Lipozyme TL IM and hexane as solvents. Reaction variables (temperature, butyric acid concentration, isoamyl alcohol:butyric acid molar ratio and enzyme concentration) were investigated in ester conversion (%), concentration (mol L-1) and productivity (mmol ester g-1 mixture . h), by applying a sequential strategy of the Fractional Factorial Design (FFD) and the Central Composite Rotatable Design (CCRD). High isoamyl butyrate conversion of 95.8% was achieved at 24 hours. At 3 hours, the highest isoamyl butyrate concentration (1.64 mol L-1) and productivity (0.19 mmol ester g-1 mixture . h) were obtained under different reaction conditions. Due to high specificity and selectivity of lipases, process parameters of this study and their interaction with the Lipozyme TL IM are fundamental to understand and optimize the system so as to achieve maximum yield to scale up. Results show that fusel oil may be recycled by the green chemistry process proposed by this study.

A cost effective fermentative production of glutathione by Saccharomyces cerevisiae with cane molasses and glycerol

This work aimed to evaluate the effect of sugar cane molasses and glycerol on glutathione (GSH) fermentation by Saccharomyces cerevisiae ATCC 7754 in flask culture using response surface methodology. Under optimized conditions (80 g/L of molasses and 60 g/L of glycerol), the highest GSH and biomass concentration achieved were 119.6 mg/L and 25.3 g/L, respectively. Further studies done in 5 L bioreactor resulted 241.3 mg/L GSH after 96 h in batch fermentation without amino acids addition and the concentration of biomass was 12.1 g/L. In batch fermentation with the addition of the three amino acids (4 mM cysteine, glycine and glutamic acid at 32 h), biomass reached to 25 g/L and GSH, 236.1 mg/L at 96 h of fermentation. The strategy of precursor amino acids addition is a key aspect in increasing the synthesis of GSH.