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Applied and Environmental Microbiology Jan 2016Microbial starter cultures have extensively been used to enhance the consistency and efficiency of industrial fermentations. Despite the advantages of such controlled...
Microbial starter cultures have extensively been used to enhance the consistency and efficiency of industrial fermentations. Despite the advantages of such controlled fermentations, the fermentation involved in the production of chocolate is still a spontaneous process that relies on the natural microbiota at cocoa farms. However, recent studies indicate that certain thermotolerant Saccharomyces cerevisiae cultures can be used as starter cultures for cocoa pulp fermentation. In this study, we investigate the potential of specifically developed starter cultures to modulate chocolate aroma. Specifically, we developed several new S. cerevisiae hybrids that combine thermotolerance and efficient cocoa pulp fermentation with a high production of volatile flavor-active esters. In addition, we investigated the potential of two strains of two non-Saccharomyces species that produce very large amounts of fruity esters (Pichia kluyveri and Cyberlindnera fabianii) to modulate chocolate aroma. Gas chromatography-mass spectrometry (GC-MS) analysis of the cocoa liquor revealed an increased concentration of various flavor-active esters and a decrease in spoilage-related off-flavors in batches inoculated with S. cerevisiae starter cultures and, to a lesser extent, in batches inoculated with P. kluyveri and Cyb. fabianii. Additionally, GC-MS analysis of chocolate samples revealed that while most short-chain esters evaporated during conching, longer and more-fat-soluble ethyl and acetate esters, such as ethyl octanoate, phenylethyl acetate, ethyl phenylacetate, ethyl decanoate, and ethyl dodecanoate, remained almost unaffected. Sensory analysis by an expert panel confirmed significant differences in the aromas of chocolates produced with different starter cultures. Together, these results show that the selection of different yeast cultures opens novel avenues for modulating chocolate flavor.
Topics: Acetates; Cacao; Esters; Fermentation; Flavoring Agents; Hot Temperature; Humans; Saccharomyces cerevisiae; Taste
PubMed: 26590272
DOI: 10.1128/AEM.02556-15 -
Journal of Applied Microbiology Sep 2015To determine the starter culture and multifunctional potentials of yeast strains from some cereal-based Nigerian traditional fermented food products.
AIMS
To determine the starter culture and multifunctional potentials of yeast strains from some cereal-based Nigerian traditional fermented food products.
METHODS AND RESULTS
Yeast isolates were screened for enzyme production and identified by sequencing the D1/D2 region of 26S rDNA. Pichia kluyveri LKC17, Issatchenkia orientalis OSL11, Pichia kudriavzevii OG32, Pichia kudriavzevii ROM11 and Candida tropicalis BOM21 exhibited the highest protease, lipase and phytase activity. They were selected and further evaluated for gastrointestinal survival and adherence ability. Although strain-specific, they retained viability at 37°C and showed survival at pH 2·0., I. orientalis OSL11 showed the highest survival at 2% bile salts concentration and P. kudriavzevii ROM11 showed the least survival. The yeast strains showed strong autoaggregation ability (81·24-91·85%) and hydrophobicity to n-hexadecane (33·61-42·30%). The highest co-aggregation ability was detected for P. kudriavzevii OG32 and Escherichia coli (71·57%). All the yeast strains removed cholesterol in the range of 49·03-74·05% over 48 h and scavenged for free radicals in methanol reaction system.
CONCLUSIONS
In this study, we isolated new yeast strains with multifunctional potentials that can be used as functional starter cultures to produce cereal-based probiotic products.
SIGNIFICANCE AND IMPACT OF THE STUDY
The development of probiotic yeast strains as starter culture to improve the quality attributes and confer functional value on cereal-based traditional fermented foods is beneficial.
Topics: Cholesterol; Edible Grain; Fermentation; Food Microbiology; Molecular Sequence Data; Nigeria; Probiotics; Yeasts
PubMed: 26095794
DOI: 10.1111/jam.12875