title: Tuning Chocolate Flavor through Development of Thermotolerant Saccharomyces cerevisiae Starter Cultures with Increased Acetate Ester Production.
abstract: 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.
authors.affiliation: Laboratory for Genetics and Genomics, Centre of Microbial and Plant Genetics (CMPG), KU Leuven, Leuven, Belgium Laboratory for Systems Biology, VIB, Leuven, Belgium.
authors.forename: Esther
authors.initials: E
authors.lastname: Meersman
authors.affiliation: Laboratory for Genetics and Genomics, Centre of Microbial and Plant Genetics (CMPG), KU Leuven, Leuven, Belgium Laboratory for Systems Biology, VIB, Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Steensels
authors.affiliation: Laboratory for Genetics and Genomics, Centre of Microbial and Plant Genetics (CMPG), KU Leuven, Leuven, Belgium Laboratory for Systems Biology, VIB, Leuven, Belgium.
authors.forename: Nore
authors.initials: N
authors.lastname: Struyf
authors.affiliation: Laboratory for Genetics and Genomics, Centre of Microbial and Plant Genetics (CMPG), KU Leuven, Leuven, Belgium Laboratory for Systems Biology, VIB, Leuven, Belgium.
authors.forename: Tinneke
authors.initials: T
authors.lastname: Paulus
authors.affiliation: Laboratory for Genetics and Genomics, Centre of Microbial and Plant Genetics (CMPG), KU Leuven, Leuven, Belgium Laboratory for Systems Biology, VIB, Leuven, Belgium.
authors.forename: Veerle
authors.initials: V
authors.lastname: Saels
authors.affiliation: Barry Callebaut AG, Westpark, Zurich, Switzerland.
authors.forename: Melissa
authors.initials: M
authors.lastname: Mathawan
authors.affiliation: Barry Callebaut AG, Westpark, Zurich, Switzerland.
authors.forename: Leen
authors.initials: L
authors.lastname: Allegaert
authors.affiliation: Barry Callebaut AG, Westpark, Zurich, Switzerland.
authors.forename: Gino
authors.initials: G
authors.lastname: Vrancken
authors.affiliation: Laboratory for Genetics and Genomics, Centre of Microbial and Plant Genetics (CMPG), KU Leuven, Leuven, Belgium Laboratory for Systems Biology, VIB, Leuven, Belgium kevin.verstrepen@biw.vib-kuleuven.be.
authors.forename: Kevin J
authors.initials: KJ
authors.lastname: Verstrepen
mesh_terms: D000085:Acetates / Q000378:metabolism*; D002099:Cacao / Q000737:chemistry / Q000378:metabolism / Q000382:microbiology*; D004952:Esters / Q000737:chemistry / Q000378:metabolism*; D005285:Fermentation; D005421:Flavoring Agents / Q000737:chemistry / Q000378:metabolism*; D006358:Hot Temperature; D006801:Humans; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013649:Taste
chemical_list: D000085:Acetates; D004952:Esters; D005421:Flavoring Agents