Concurrent inoculations of Oenococcus oeni and Lachancea thermotolerans: Impacts on non-volatile and volatile components of spent coffee grounds hydrolysates

Abstract

This work investigated the impact of co-fermentations of Oenococcus oeni and Lachancea thermotolerans on chemical constituents of spent coffee grounds (SCG) hydrolysates with added yeast extract. O. oeni Lalvin 31 and L. thermotolerans grew well in co-cultures, but the yeast died early in two co-cultures with O. oeni Enoferm Beta and O. oeni PN4. Compared with the monoculture of yeast only, co-inoculation with O. oeni did not significantly affect sugar consumption but reduced ethanol production. In addition, co-fermentation significantly altered organic acids profiles. Furthermore, the fermented SCG hydrolysates from co-culture of L. thermotolerans and O. oeni Lalvin 31 retained more alkaloids (e.g. theophylline and trigonelline) and had higher amounts of ethyl acetate, methyl acetate and acetoin as compared with those of control. Hence, simultaneous malolactic fermentation by selected O. oeni and alcoholic fermentation by L. thermotolerans may provide a new strategy to valorize SCG for developing novel alcoholic beverages.