Comparative Analysis of Three Types of Whey as Substrate for Fermentation by Kluyveromyces marxianus and its Influence on Isoamyl Acetate Synthesis

Abstract

Abstract Whey, the main byproduct in cheese manufacturing, has a high organic content, predominantly due to its lactose amount (45-60 g/L). There are three types of residues coming from cheese production: sweet whey (SW), acid whey (AW), and ricotta whey (RW). Each one presents physicochemical particularities that pose challenges when handled by small and medium enterprises, due to their costly treatment. An alternative to address this issue is the fermentation of such substrates to obtain value-added products. The goal of this research was to evaluate the fermentation with Kluyveromyces marxianus in the three types of raw whey for the production of isoamyl acetate, a compound responsible for the banana aroma. Several factors were analyzed: cellular growth, pH variations, reduction in lactose content, ethanol production, and isoamyl acetate generation. Cellular growth showed no significant differences between the three types of whey. Regarding pH, a decrease was recorded during the first 48 hours down to an approximate value of 4.3, then it increased to reach values close to 7. In acid whey, 50.95 g/L of ethanol was obtained at 120 hours. On the other hand, the maximum observed production of isoamyl acetate was 160 mg/L. Finally, the maximum lactose consumption was observed in sweet whey, with an approximate percentage of 76% at 24 hours, higher than that of acid and ricotta whey, which ranged between 56 and 58%.