Use of starter culture on biotransformation processes of <i>Coffea arabica</i> (L.) from Southwestern Antioquia, Colombia

Recent advancements in coffee processing increasingly involve the use of isolated or native microorganisms, such as starter cultures, to enhance desired coffee characteristics and modulate sensory properties. This study employed a participatory research approach, collaborating with coffee producers to investigate the incorporation of homemade starter cultures into coffee bioprocessing. Coffee was processed using both wet and semi-dry methods, with three distinct starter cultures-lactic acid bacteria, yeast combined with fruit, and coffee pulp leachate-evaluated alongside respective controls. Parameters such as titratable acidity, antioxidant capacity, caffeine, trigonelline, theobromine content, and sensory profiles were assessed. Significant differences in antioxidant capacity were observed across the coffee processing methods; notably, coffee roasted using the wet method exhibited significantly higher antioxidant capacity compared to coffee roasted using the semi-dry method. However, no significant differences were found in caffeine content or titratable acidity levels across all methods. All bioprocesses resulted in variations in cupping profiles compared to their respective controls. Considering the specific conditions under which bioprocessing took place, the introduction of starter cultures led to notable changes in coffee transformation processes relative to their control treatments. For instance, the use of yeast and fruit inoculum increased the total score of washed coffee by seven points compared to its control. Similarly, the addition of lactic inoculum to honey-processed coffee led to a three-point increase relative to its control. These results indicate promising advancements in coffee bioprocessing. Importantly, all methods are scalable, cost-effective, and straightforward, offering significant potential for coffee producers.