The impact of yeast starter cultures on the microbial communities and volatile compounds in cocoa fermentation and the resulting sensory attributes of chocolate

Abstract

Theobroma cacao seeds are the main raw material for chocolate production. During their fermentation, a succession of microorganisms are responsible for the physicochemical changes occurring in the pulp and inside the beans. The aim of this study was to investigate the effects of yeast inoculation (Saccharomyces cerevisiae UFLA CA11, Pichia kluivery CCMA0237, and Hanseniaspora uvarum CCMA0236) on the profile of the volatile compounds and microbial communities in cocoa fermentation. The resulting chocolate was also evaluated by temporal dominance of sensations (TDS) analyses. The dominant microorganisms during spontaneous fermentation were S. cerevisiae, H. uvarum, H. guilliermondii, Lactobacillus fermentum, Pediococcus sp., and Acetobacter pasteurianus. Similarly, S. cerevisiae, P. kluyveri, Candida sp., Pediococcus sp., and A. pasteurianus were the predominant microorganisms assessed by Denaturing Gradient Gel Electrophoresis (DGGE) in inoculated fermentation. Sixtyseven volatile compounds were detected and quantified by gas chromatography/mass spectrometry (GC/MS) at the end of fermentation and chocolates. The main group of volatile compound found after the inoculated and spontaneous fermentations was esters (41 and 39 %, respectively). In the chocolates, the main group was acids (73 and 44 % from the inoculated and spontaneous fermentations, respectively). The TDS analyses showed a dominance of bitter and cocoa attributes in both chocolates. However, in the inoculated chocolate, lingering fruity notes were more intense, while the chocolate produced by spontaneous fermentation was more astringent. Thus, the inoculation of yeast influenced the microbial profile, which likely affected the volatile compounds that affect sensory characteristics, resulting in chocolate with dominant bitter, cocoa, and fruity attributes.

Fine Resolution Analysis of Microbial Communities Provides Insights Into the Variability of Cocoa Bean Fermentation

“…Some of the microorganisms we observed in our study have been suggest as microbial starters (Schwan, 1998;Papalexandratou et al, 2013;Magalhães da Veiga Moreira et al, 2017), such as Acetobacter pasteurianus and Lactobacillus fermentum (Papalexandratou et al, 2013;Illeghems et al, 2016), additionally, some of the yeasts groups (Hanseniaspora opuntiae and Picha sp.) have been reported in the fermentation process from other countries (Schwan et al, 2014) and some have been used as culture starter (Batista et al, 2016). The dominance patterns suggest that to design starter cultures, only a few isolates of each group might be necessary; however, experiments are needed to elucidate the importance of non-dominant bacteria in the fermentation and the generation of chemical precursors of cocoa quality Future perspectives, will direct these studies toward the design of family-specific molecular markers, e.g., phyloTAGs (Caro-Quintero and Howard, 2015), that provide higher resolution than 16S rRNA gene allowing monitoring of starter cultures in controlled and spontaneous conditions, and to understand the mechanisms for higher dominance of specific populations.…”

Genome Sequences of Three Species of Hanseniaspora Isolated from Spontaneous Wine Fermentations

“…Besides a role in grape wine fermentation, Hanseniaspora species have been used as starter cultures in the fermentation of fruit wines, ciders, and spirits (2–5) and cocoa (6, 7). …”

Key Aroma Compounds of Dark Chocolates Differing in Organoleptic Properties: A GC-O Comparative Study

“…However, all of them have been previously described in foodstuffs or beverages. Thus, 3-ethyl-4-methylpentan-1-ol (OA n • 37) was previously described in brandies [54]; 3-hydroxybutanoic acid (42) was described in various fruits, wine and honey [54]; methyl 2-methylpentanoate (48) in potato and tea [54]; 3-hydroxypropyl acetate (50) in bread and wines [54]; δ-pentalactone (53) in various foods and beverages [54]; dihydromaltol (57) in milk products and wine [54]; isopropyl palmitate (82) in various food products [54]; 3-hydroxy-4-phenylbutan-2-one (84) in honey and wines [54]; 2-phenylethyl lactate (86) in cheddar cheese [54]; dihydroactinidiolide (87) in a lot of foodstuffs, beverages, and seeds [54]; farnesol (88) in a lot of foods and beverages [54]; 5-(oct-2-en-1-yl)dihydrofuran-2(3H)-one (90) in chicken [54]; and octadecan-1-ol (95) in a lot of products, including milk products, fruits, and tea [54].…”

“…Some important heterocycles were also found amongst the 73 discriminant odorants: The furanones furaneol (4-hydroxy-2,5-dimethylfuran-3(2H)-one, OA n • 70), a key aroma of dark chocolate; dihydroactinidiolide (4,4,7a-trimethyl-5,6,7,7a-tetrahydro-1-benzofuran-2(4H)-one, OA n • 87), found as a new dark chocolate key odorant; and 5-[(2Z)oct-2-en-1-yl]dihydrofuran-2(3H)-one (90), newly described as a key aroma of a cocoa product. Pyrans and pyranones were also part of the discriminant odorants, together with some pyrroles: The pyranol trans-linalool-3,7-oxide (6-ethenyl-2,2,6-trimethyltetrahydro-2H-pyran-3-ol, OA n • 51); the pyranones maltol (OA n • 63, 3-hydroxy-2-methyl-4H-pyran-4-one), 3-hydroxy-2,3-dihydromaltol (85), newly cited in dark chocolate's key compounds; dihydromaltol (57), newly determined in a cocoa product; and the pyrroles 2-acetylpyrrole (OA n • 64), 5-methyl-1H-pyrrole-2-carbaldehyde (73), and 1H-indole (91), all three already described as key odorants of dark chocolate (Table 1).…”