Fermentation of Lactose in Direct-Acid-Set Cottage Cheese Whey.

Area of Science:

• Biotechnology
• Industrial Microbiology
• Biochemical Engineering

Background:

• Whey, a dairy byproduct, presents a significant disposal challenge.
• Utilizing whey for ethanol production offers a sustainable valorization strategy.
• Identifying robust microbial strains for efficient whey fermentation is crucial.

Purpose of the Study:

• To evaluate the suitability of Kluyveromyces fragilis for ethanol production from whey.
• To compare K. fragilis with other yeast strains, Candida pseudotropicalis and Kluyveromyces lactis.
• To determine optimal fermentation conditions for K. fragilis in whey.

Main Methods:

• Comparative fermentation trials using K. fragilis, C. pseudotropicalis, and K. lactis.
• Fermentation of direct-acid-set cottage cheese whey and heat-treated whey supernatant.
• Assessment of fermentation rates at various incubation temperatures (room temperature to 42°C) and inoculation levels.
• Measurement of specific gravity reduction and lactose conversion.

Main Results:

• Kluyveromyces fragilis demonstrated superior ethanol production suitability compared to C. pseudotropicalis and K. lactis.
• Fermentation rates were comparable between direct-acid-set whey and heat-treated whey supernatant.
• Optimal fermentation temperatures ranged from 35°C to 42°C, showing more rapid specific gravity reduction.
• Lactose conversion reached 83% in whey and 77% in whey supernatant.

Conclusions:

• Kluyveromyces fragilis is a highly suitable yeast for the bioconversion of whey into ethanol.
• Heat treatment of whey does not significantly impair fermentation efficiency by K. fragilis.
• Elevated temperatures (35-42°C) enhance the fermentation rate, leading to efficient lactose conversion.