Exploring coffee processing stages: Wet fermentation with and without Saccharomyces cerevisiae vs. Conventional...

Area of Science:

• Food Science
• Microbiology
• Agricultural Science

Background:

• Wet coffee processing is crucial for beverage quality.
• Traditional methods can lead to undesirable flavor profiles.
• Optimizing fermentation is key to enhancing coffee characteristics.

Purpose of the Study:

• To evaluate the impact of self-induced anaerobic fermentation (SIAF) with and without Saccharomyces cerevisiae inoculation on wet coffee quality.
• To compare SIAF with a conventional coffee processing method.
• To analyze the biochemical and sensory changes during coffee fermentation and drying.

Main Methods:

• Ripe coffee fruits underwent SIAF with or without S. cerevisiae CCMA 0543 inoculation.
• A conventional direct drying process was used as a control.
• Analyses included yeast population (qPCR), carbohydrates/organic acids (HPLC), protein profiles (2-D SDS-PAGE), and volatile compounds (GC-MS).
• Sensory analysis was conducted by certified Q-Graders.

Main Results:

• S. cerevisiae inoculation efficiently consumed sugars, reducing glucose and fructose levels.
• Inoculated coffee showed higher lactic acid and lower acetic acid concentrations compared to conventional processing.
• Proteomic analysis revealed distinct protein expression in the inoculated treatment.
• Fermented and roasted coffee from the inoculated treatment exhibited a higher abundance of desirable volatile compounds (esters, aldehydes, alcohols, acids, furans, pyrazines).
• Only the inoculated SIAF coffee achieved specialty coffee classification (score 85.00).

Conclusions:

• Inoculation with S. cerevisiae using the SIAF method significantly enhances wet coffee quality.
• This method produces consistent, high-quality coffee beverages meeting specialty standards.
• SIAF with S. cerevisiae offers a promising approach for improving coffee flavor and aroma profiles.