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

Whey, a primary byproduct of cheese production, is rich in organic content, largely due to its lactose concentration (45–60 g/L). Cheese production yields three types of residues: sweet whey (SW), acid whey, and ricotta whey (RW). Each has unique physicochemical properties that present challenges for small to medium-sized enterprises because of the expensive treatment required. One solution to this problem is fermenting these substrates to produce value-added products. This study aimed to assess the fermentation of the three RW types using Kluyveromyces marxianus ITD00262 for isoamyl acetate production, a compound that gives a banana-like aroma. Several factors were analyzed: cell growth, pH changes, lactose content reduction, ethanol production, and isoamyl acetate formation. Cell growth was consistent across all whey types. As for pH, there was a drop during the initial 48 h to roughly 4.3, after which it rose to near 7. In acid whey, 50.95 g/L of ethanol was produced by the 120-h mark. The peak isoamyl acetate concentration was observed at 24 h, registering 160 mg/L in YPL medium, while SW peaked at 124 mg/L at 72 h. Lastly, the highest lactose consumption was seen in SW, approximately 76% at 24 h, surpassing that of acid and ricotta whey, which fluctuated between 56 and 58%. Graphical Abstract