Fermentation Process Optimization for High 2-Phenylethanol Aroma Whisky.

Area of Science:

• Biotechnology and Fermentation Science
• Yeast Metabolism and Genetic Engineering

Background:

• 2-Phenylethanol (2-PE) is crucial for the rose-like aroma in brewed wines, but natural yeast production is typically low (<100 mg/L).
• Enhancing 2-PE levels is desirable for improving the sensory profile of fermented beverages like whisky.

Purpose of the Study:

• To increase 2-phenylethanol (2-PE) content in brewed wines using genetic modification of Saccharomyces cerevisiae.
• To optimize fermentation parameters for maximizing 2-PE yield in whisky production.

Main Methods:

• CRISPR-Cas9 gene editing was employed to delete the ARO8 gene in Saccharomyces cerevisiae SY.
• Single-factor experiments and Box-Behnken design were used to optimize fermentation conditions (sugar concentration, fermentation time, L-phenylalanine concentration).
• High-performance liquid chromatography (HPLC) was utilized to quantify 2-PE content.

Main Results:

• Deletion of the ARO8 gene in SY-A8 increased 2-PE content to 0.73 g/L, a 23.73% improvement over the original strain.
• Optimized fermentation conditions (46.30 g/L sugar, 6 days, 1.43 g/L L-phenylalanine) resulted in a 2-PE content of 3.68 g/L in a 1 L fermenter.
• The modified yeast strain and optimized process significantly enhanced 2-PE production for high-aroma whisky.

Conclusions:

• CRISPR-Cas9 mediated ARO8 gene deletion in Saccharomyces cerevisiae is an effective strategy for boosting 2-PE production.
• Fermentation process optimization further enhances 2-PE yield, offering a viable method for flavor improvement in whisky and other brewed beverages.
• This study provides a valuable research perspective for developing strategies to enhance the flavor profiles of fermented products.