Use of microencapsulated starter cultures by spray drying in coffee under self-induced anaerobiosis fermentation (SIAF)

Using starter culture in liquid form is not economically viable in the coffee fermentation process. This work aimed to compare the fermentative performances of fresh and microencapsulated yeasts in coffee under selfinduced anaerobic fermentation (SIAF). The inoculum permanence was monitored, and sugars, alcohols, acids, and volatile compounds were analyzed by chromatography. In addition, sensory analysis was performed on roasted beans. After 180 h of fermentation in the natural process, microencapsulated Torulaspora delbrueckii (MT) (7.97 x 107 cells/g) showed a higher population than fresh Torulaspora delbrueckii (FT) (1.76 x 107 cells/g). The same acids and volatile compounds were detected in coffees with fresh and microencapsulated yeast. However, the yeast state influenced the concentration of the compounds. In pulped coffee, the coffee inoculated with microencapsulated Saccharomyces cerevisiae (MS) obtained the highest concentration of alcohols, esters, pyrazines, and others compared with fresh Saccharomyces cerevisiae (FS), with an increase of up to 47%. Furthermore, the coffee inoculated with MT obtained the highest concentration in almost all chemical classes in both processes compared with FT. These differences ranged up to 55%. Regarding sensory analysis, coffees inoculated with MS showed dominant notes of fruity, caramel, and nuts in the natural process. Otherwise, in pulped process, coffees inoculated with MT showed caramel, honey, and nuts. Therefore, the microencapsulated yeasts were metabolically active and may be considered with commercial potential. Considering the parameters analyzed, the most suitable yeast for natural and pulped processing would be MS and MT, respectively.

Automated summary

This study compared the fermentative performances of fresh and microencapsulated yeasts in coffee fermentation. After 180 hours of fermentation, microencapsulated Torulaspora delbrueckii (MT) had a higher cell population than fresh Torulaspora delbrueckii (FT). The same acids and volatile compounds were detected in both fresh and microencapsulated yeast coffees. However, the yeast state influenced the concentration of these compounds. In pulped coffee, the coffee inoculated with microencapsulated Saccharomyces cerevisiae (MS) obtained the highest concentration of alcohols, esters, pyrazines, and others compared with fresh Saccharomyces cerevisiae (FS), with an increase of up to 47%. Furthermore, the coffee inoculated with MT obtained the highest concentration in almost all chemical classes in both processes compared with FT. These differences ranged up to 55%. Sensory analysis showed that the coffees inoculated with MS had dominant notes of fruity, caramel, and nuts in the natural process, while the coffees inoculated with MT had caramel, honey, and nuts in the pulped process. Therefore, microencapsulated yeasts were metabolically active and had commercial potential. Considering the analyzed parameters, MS and MT were the most suitable yeasts for natural and pulped processing, respectively.