Effect of mixed culture inoculation on chemical and sensory properties of aronia (Aronia melanocarpa)

The aim of this study was to investigate the effects of mixed inoculation on blocking astringency in aronia (Aronia melanocarpa) concentrates with respect to chemical and sensory properties. Mixed inoculation treatment included inoculation with four different ratios of mixed starter cultures (Lactobacillus bulgaricus, Streptococcus thermophilus, and Saccharomyces cerevisiae). The effect on astringency in aroina concentrates after mixed inoculation was demonstrated by three intimately reciprocal tests: bovine serum albumin precipitation, condensed tannin, and acetaldehyde analyses. After mixed inoculation, increased acetaldehyde components in aronia concentrates reacted with condensed tannin to form the modified tannin, resulting in decreased condensed tannin contents. This trend was supported by reduced aggregation of tannin-protein complex. Furthermore, sensory analyses (consumer testing and ranking descriptive analyses) showed moderated astringency perceptions after mixed inoculation. For consumer testing, the liking scores of all sensory attributes (overall liking, astringency, bitterness, sweetness, sourness, and berry taste) in mixed inoculated samples were slightly higher than those of non-inoculated aronia concentrate. The findings of ranking descriptive analysis indicated the significantly decreased scores at astringency attribute after mixed inoculation. In conclusion, these results suggested that mixed inoculation can be used to moderate astringency in aronia concentrates in both chemical and sensory aspects.