Optimal Fermentation Conditions and Storage Period of Fermented Beverages Made from Demineralized Whey Using Kluyveromyces marxians
Author(s): Naoki Yamahata, Yosuke Toyotake, Satomi Kunieda, Mamoru Wakayama
Fermented beverages made from demineralized whey (DMW) as a starting material have a higher sensory acceptability compared to those made from raw whey (RW). Here we investigated the optimal fermentation conditions, namely, temperature and initial pH, and storage period of fermented DMW-based beverages. The 20% w/v DMW solutions were fermented with pure cultured Kluyveromyces marxianus at various temperatures and initial pH values. Multiple sensory evaluations, such as an acceptance test, a descriptive test, and a preference ranking test, were conducted to determine the optimal initial pH and storage period. The final ethanol concentrations at selected fermentation temperatures were 9.6% v/v at 20°C, 9.6% at 25°C, 9.5% at 30°C, 5.8% at 35°C, and 3.6% at 40°C, and the fermentation rate was the highest at 30°C. No differences were observed in either fermentation or sensory characteristics at selected initial pH values (pH 7, pH 6, and pH 5). The optimal fermentation conditions were found to be a fermentation temperature of 30°C and an initial pH of pH 7. Although the preference for DMW-based beverages gradually decreased with storage, the storage period was assessed to extend to 4 weeks. These results indicate that approaches other than fermentation conditions, such as carbonation, aging, and serving temperature, should be used to improve the sensory preference of fermented whey-based beverages.