Functional yeast starter cultures for cocoa fermentation

Fermentation and its effect on the physicochemical and sensory attributes of cocoa beans in the Colombian Amazon

Cocoa (Theobroma cacao L.) is the basic raw material to produce chocolate and other derivatives such as cocoa butter, cocoa powder and cocoa liquor (cocoa paste), which requires a fermentation process that affects its chemical composition and sensory profile. The objective of this study was to monitor the biochemical, physical and sensory changes during fermentation of cocoa beans in cocoa bean processing plants in the department of Caquetá, Colombia. During fermentation, the temperature of the mass and the pH of the pulp and beans were monitored at the different cocoa bean processing plants (Sites ASOACASAN ASA, COMICACAO CMI, COMCAP COC). Also, at two points during fermentation (days 4 and 7), physical properties of the bean were determined, such as variables related to bromatological composition, polyphenolic compounds and antioxidant activity as sensory attributes at the different sites. An increase in dough temperature was found, however the pH of the cotyledon decreased during the fermentation process and the fat and moisture content varied with fermentation time. At the site level, total polyphenol content (TPC), total flavonoids (TF), 1,1-diphenyl-2-picrylhydrazil (DPPH) and ferric reducing antioxidant power (FRAP) contents were statistically different, with COC being different from the other sites. The TPC was higher at the COC site (507 mg gallic acid equivalent GAE/g Cocoa) with respect to the other sites (< 360 mg GAE/g Cocoa). The TF content followed a similar behavior to TPC, with significant differences between sites and differences between fermentation times for ASA. The TF was higher in COC (309.1 mg catechin/g cocoa) with respect to CMI (215.6 mg catechin/g cocoa) and ASA (185.7 mg catechin/g cocoa). Values in DPPH ranged from 5869.3 to 7781.8 μmol Trolox/g cocoa and for the FRAP assay ranged from 369.8 to 606.7 mg ascorbic acid AA/g cocoa among the sites. It was found that the time and management of the fermentation process has a significant impact on the parameters (biochemical, physical and sensory) of cocoa beans. Therefore, it is necessary to standardize the fermentation process to achieve a quality product that meets the needs of the market.

Investigating Key Volatile Compound Diffusion in Cocoa Beans during Yeast Fermentation-like Incubation

An experimental setup was devised to investigate the permeability of cocoa bean seed coat and pulp to key volatile compounds during fermentation. Four labeled compounds (ethyl acetate-d3, ethyl octanoate-d15, 2-phenylethanol-d5, linalool-d5) and 2 unlabeled (beta-damascenone, delta-decalactone) were chosen for the investigation. The beans (cotyledons), depulped beans, or pulped beans were immersed separately in a concentrated solution of these volatile compounds at 36 or 46 °C for durations ranging from 3 to 120 h. The imbibed beans were dissected, and the cotyledons were analyzed by SPME-GC/MS. The diffusion of volatile compounds from the external solution to the seed was categorized into three groups: (1) not diffusible (ethyl octanoate-d15); (2) semidiffusible (ethyl acetate); and (3) totally diffusible (2-phenylethanol-d5, linalool-d5, beta-damascenone, delta-decalactone). The impact of the yeast on volatile compound diffusion was also investigated by immerging the pulped beans into the same concentrated solution with a yeast starter. Results highlighted the positive role of yeast in the diffusion of volatile compounds. The starter positively contributed to volatile compound diffusion after a transition phase occurring at approximately 48 h of fermentation, enriching the cocoa beans with key aromatic volatile compounds.

Effect of Pod Storage and Drying Temperature on Fermentation Dynamics and Final Bean Quality of Cacao Nacional in Ecuador

The impact of pod storage (PS) and two drying temperatures of fermented cocoa beans was investigated in Ecuador. Therefore, four variations were simultaneously carried out three times at two locations, independently: 0, 3, and 5 days of PS, dried at 60 °C and 0 days of PS, dried at 80 °C. Pod weight during storage, pulp content, pH, temperature, microbial counts, total free amino acids, protein profiles, sugars, organic acids, cut-test, fermentation index, and sensory profiles were analyzed. Minor differences in fermentation dynamics and bean quality were found between variations with and without PS. A rather accelerated fermentation with pod-stored beans was observed (e.g., faster color change, slightly lower pH in cotyledon after 48 h), along with a significantly higher maximal temperature during 24-42 h (43.1 ± 3.2 °C compared to 39.2 ± 2.0 °C without PS). More well-fermented beans were reached with PS (52.3 ± 22.6%) than without (62.7 ± 9.2%). Differences during fermentation were observed between the locations (e.g., pH, acids, sugars), but sensory evaluation indicated that the impact of location was mitigated with PS. Drying at 80 °C showed no adverse effects, as evidenced by the results of the cut-test and fermentation index. However, sensory evaluations revealed significant differences between 80 °C and 60 °C, with the former exhibiting more bitter and astringent cocoa liquor.

Sensory attributes of fine flavor cocoa beans and chocolate: A systematic literature review

Fine flavor cocoa (FFC) is known for its unique flavor and aroma characteristics, which vary by region. However, a comprehensive overview of the common sensory attributes used to describe FFC beans and chocolate is lacking. Therefore, a systematic review was conducted to analyze existing literature and identify the most commonly used sensory attributes to describe FFC beans and chocolate. A systematic search of the Web of Science and Scopus databases was conducted in May 2023, and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines were followed to ensure transparency and reproducibility. This review summarizes the origins of cocoa and explores their unique flavor profiles, encompassing caramel, fruity, floral, malty, nutty, and spicy notes. Although some origins may exhibit similar unique flavors, they are often described using more specific terms. Another main finding is that although differences in sensory attributes are anticipated at each production stage, discrepancies also arise between liquor and chocolate. Interestingly, fine chocolate as the final product does not consistently retain the distinctive flavors found in the liquor. These findings emphasize the need for precise descriptors in sensory evaluation to capture flavor profiles of each origin. As such, the exploration of attributes from bean to bar holds the potential to empower FFC farmers and chocolate producers to effectively maintain quality control.

Electromagnetic fields effects on microbial growth in cocoa fermentation: A controlled experimental approach using established growth models

Understanding the effects of electromagnetic fields is crucial in the fermentation of cocoa beans, since through precise control of fermentation conditions the sensory and nutritional properties of cocoa beans could be improved. This study aimed to evaluate the effect of oscillating magnetic fields (OMF) on the kinetic growth of the core microbial communities of the Collections Castro Naranjal (CCN 51) cocoa bean. The data was obtained by three different models: Gompertz, Baranyi, and Logistic. The cocoa beans were subjected to different OMF strengths ranging from 0 mT to 80 mT for 1 h using the Helmholtz coil electromagnetic device. The viable microbial populations of lactic acid bacteria (LAB), acetic acid bacteria (AAB), and yeast (Y) were quantified using the colony-forming unit (CFU) counting method. The logistic model appropriately described the growth of LAB and Y under magnetic field exposure. Whereas the Baranyi model was suitable for describing AAB growth. The microbial populations in cocoa beans exposed to magnetic fields showed lower (maximum specific growth rate (μmax), values than untreated controls, with AAB exhibiting the highest average growth rate value at 5 mT and Y having the lowest average maximum growth rate value at 80 mT. The lower maximum specific growth rates and longer lag phases when exposed to magnetic fields compared to controls demonstrate the influence of magnetic fields on microbial growth kinetics.

Antimicrobial and Mycotoxin Reducing Properties of Lactic Acid Bacteria and Their Influence on Blood and Feces Parameters of Newborn Calves

The aim of this study was to evaluate the influence of in acid whey (AW) multiplied Lactiplantibacillus plantarum LUHS135 (L.pl135), Lacticaseibacillus paracasei LUHS244 (L.pc244), and their biomass combination on newborn calves' feces and blood parameters. Additionally, the antimicrobial and mycotoxin-reducing properties and the resistance to antibiotics of the tested lactic acid bacteria (LAB) strains were analyzed. In order to ensure effective biomass growth in AW, technological parameters for the supplement preparation were selected. Control calves were fed with a standard milk replacer (SMR) and treated groups (from the 2nd day of life until the 14th day) were supplemented with 50 mL of AWL.pl135, AWL.pc244, and AWL.pl135×L.pc244 (25 mL AWL.pl135 + 25 mL AWL.pc244) in addition to SMR. It was established that L.pl135 and L.pc244 possess broad antimicrobial activities, are non-resistant to the tested antibiotics, and reduce mycotoxin concentrations in vitro. The optimal duration established for biomass growth was 48 h (LAB count higher than 7.00 log10 CFU mL-1 was found after 48 h of AW fermentation). It was established that additional feeding of newborn calves with AWL.pl135, AWL.pc244, and AWL.pl135×L.pc244 increased lactobacilli (on average by 7.4%), and AWL.pl135 and AWL.pc244 reduced the numbers of Enterobacteriaceae in calves' feces. The tested supplements also reduced the lactate concentration (on average, by 42.5%) in calves' blood. Finally, the tested supplements had a positive influence on certain health parameters of newborn calves; however, further research is needed to validate the mechanisms of the beneficial effects.

Microbial composition and metabolic profiles during machine-controlled intra-factory fermentation of cocoa beans harvested in semitropical area of Japan

Cocoa bean fermentation is typically performed in a spontaneous manner on farms in tropical countries or areas and involves several microbial groups. Metabolism by microbes markedly affects the quality of cocoa beans fermented and the chocolate produced thereof. The present study characterized the microbiota and their metabolic profiles in temperature- and humidity-controlled intra-factory cocoa fermentation in a semitropical area of Japan. Although environmental factors were uniform, the microbiota of cocoa beans subjected to intra-factory fermentation was not stable between tests, particularly in terms of the cell count levels and species observed. Fermentation was sometimes delayed, and fermenting microbes were present at very low levels after 24 hr of fermentation. Due to the unstable microbiota, the profiles of water-soluble compounds differed between tests, indicating the unstable qualities of the fermented cocoa beans. These results suggest the necessity of starter cultures not only in on-farm fermentation but also in machine-controlled intra-factory cocoa fermentation.

Yeast strains do have an impact on the production of cured cocoa beans, as assessed with Costa Rican Trinitario cocoa fermentation processes and chocolates thereof

The microbiological and metabolic outcomes of good cocoa fermentation practices can be standardized and influenced through the addition of starter culture mixtures composed of yeast and bacterial strains. The present study performed two spontaneous and 10 starter culture-initiated (SCI) cocoa fermentation processes (CFPs) in Costa Rica with local Trinitario cocoa. The yeast strains Saccharomyces cerevisiae IMDO 050523, Hanseniaspora opuntiae IMDO 020003, and Pichia kudriavzevii IMDO 060005 were used to compose starter culture mixtures in combination with the lactic acid bacterium strain Limosilactobacillus fermentum IMDO 0611222 and the acetic acid bacterium strain Acetobacter pasteurianus IMDO 0506386. The microbial community and metabolite dynamics of the cocoa pulp-bean mass fermentation, the metabolite dynamics of the drying cocoa beans, and the volatile organic compound (VOC) profiles of the chocolate production were assessed. An amplicon sequence variant approach based on full-length 16S rRNA gene sequencing instead of targeting the V4 region led to a highly accurate monitoring of the starter culture strains added, in particular the Liml. fermentum IMDO 0611222 strain. The latter strain always prevailed over the background lactic acid bacteria. A similar approach, based on the internal transcribed spacer (ITS1) region of the fungal rRNA transcribed unit, was used for yeast strain monitoring. The SCI CFPs evolved faster when compared to the spontaneous ones. Moreover, the yeast strains applied did have an impact. The presence of S. cerevisiae IMDO 050523 was necessary for successful fermentation of the cocoa pulp-bean mass, which was characterized by the production of higher alcohols and esters. In contrast, the inoculation of H. opuntiae IMDO 020003 as the sole yeast strain led to underfermentation and a poor VOC profile, mainly due to its low competitiveness. The P. kudriavzevii IMDO 060005 strain tested in the present study did not contribute to a richer VOC profile. Although differences in VOCs could be revealed in the cocoa liquors, no significant effect on the final chocolates could be obtained, mainly due to a great impact of cocoa liquor processing during chocolate-making. Hence, optimization of the starter culture mixture and cocoa liquor processing seem to be of pivotal importance.

Chemical Composition and Sensory Profiles of Fermented Cocoa Beans Obtained from Various Regions of Indonesia

The chemical composition and sensory profile of cocoa beans are essential factors determining the quality of cocoa-based products. In this study, cocoa bean samples were collected from various regions of Indonesia, including Aceh, Banten, Bali, East Java, West Sumatra, West Sulawesi, East Kalimantan, and Yogyakarta. The cocoa beans were fermented and sun-dried according to the producers' protocols and local practices. The sensory profile, fat content, total phenolic content, and the composition of sugars, organic acids, and amino acids of the cocoa bean samples were analyzed. The results revealed that the chemical composition and sensory profiles of the samples were diverse. The sensory profiles of cocoa liquor samples were described by low intensities of cocoa notes with the occurrence of fruity, floral, spicy, and sweet notes. The concentration of acetic acid, lactic acid, and some amino acids (glutamic acid, proline, and methionine) was associated with fresh fruit, browned fruit, and roasted note of the cocoa liquor, respectively. The variation in the environmental conditions and postharvest practices contributed to the diversity of cocoa beans' chemical and sensory characteristics.

Ecology and population dynamics of yeast starter cultures in cocoa beans fermentation

This study aimed to investigate controlled fermentation of cocoa beans with selected yeasts as starter cultures via integrating microbiological, biochemical, and chromatographic analyses. The steps involved in the yeast starter culture test were of the following order: 1) counting, isolation, purification, and biochemical identification of yeasts, 2) selection of ethanol-producing yeasts, 3) selection of thermotolerant yeasts, and 4) evaluation of physicochemical parameters of the selected yeasts in controlled fermentation of cocoa (F1 - Saccharomyces ssp. and Hanseniaspora ssp. and F2 - spontaneous fermentation - control). A total of 32 yeasts were isolated from three sampling points (M1, M2, and M3), which comprised 50% Candida ssp., 9.4% Rhodotorula ssp., 18.8% Saccharomyces ssp., and 18.8% Hanseniaspora ssp. The yeasts identified as Saccharomyces ssp. (n = 6) were subjected to the ethanol production test. Saccharomyces spp. CLV09 showed the highest concentration of ethanol in the simulated cocoa medium (3.5% v/v). Hanseniaspora spp. CVL20 and CVL19 strains showed the highest thermotolerance at 42°C after 72 h of growth. The starter cultures with Saccharomyces ssp. and Hanseniaspora ssp. showed a similar growth rate of the mesophilic aerobic population in both F1 and F2. Fermentation of the starter culture showed a higher production of organic acids than spontaneous fermentation (F2). Thus, Saccharomyces ssp. and Hanseniaspora ssp. can be used as a starter culture in cocoa fermentation.

Phylogenomics of a Saccharomyces cerevisiae cocoa strain reveals adaptation to a West African fermented food population

Various yeast strains have been proposed as candidate starter cultures for cocoa fermentation, especially strains of Saccharomyces cerevisiae. In the current study, the genome of the cocoa strain S. cerevisiae IMDO 050523 was unraveled based on a combination of long- and short-read sequencing. It consisted of 16 nuclear chromosomes and a mitochondrial chromosome, which were organized in 20 contigs, with only two small gaps. A phylogenomic analysis of this genome together with another 105 S cerevisiae genomes, among which 20 from cocoa strains showed a geographical distribution of the latter, including S. cerevisiae IMDO 050523. Its genome clustered together with that of a West African fermented food population, indicating a wider adaptation to West African food niches than cocoa. Furthermore, S. cerevisiae IMDO 050523 contained genetic signatures involved in sucrose hydrolysis, pectin degradation, osmotolerance, and conserved amino acid changes in key ester-producing enzymes that could point toward specific niche adaptations.

Yeasts as Producers of Flavor Precursors during Cocoa Bean Fermentation and Their Relevance as Starter Cultures: A Review

During the fermentation of cocoa beans, the yeasts produce volatile organic compounds (VOCs). Through reactions associated with amino acid metabolism, yeasts generate important aroma precursors as acetate esters and fatty acid ethyl esters are essential in developing fruity flavors and aromas in the final product (usually chocolate). In addition, some yeasts may have pectinolytic and antifungal activity, which is desirable in the post-harvest process of cocoa. The main yeast species in cocoa fermentation are Saccharomyces cerevisiae, Pichia kudriavzevii, and Hanseniaspora opuntiae. These produce higher alcohols and acetyl-CoA to make acetate–esters, compounds that produce floral and fruity notes. However, there are still controversies in scientific reports because some mention that there are no significant differences in the sensory characteristics of the final product. Others mention that the fermentation of cocoa by yeast has a significant influence on improving the sensory attributes of the final product. However, using yeasts as starter cultures for cocoa bean fermentation is recommended to homogenize sensory attributes such as notes and flavors in chocolate.

Microbiomes Associated With the Surfaces of Northern Argentinian Fruits Show a Wide Species Diversity

The fiber, vitamin, and antioxidant contents of fruits contribute to a balanced human diet. In countries such as Argentina, several tropical fruits are witnessing a high yield in the harvest season, with a resulting surplus. Fruit fermentation using autochthonous starter cultures can provide a solution for food waste. However, limited knowledge exists about the microbiota present on the surfaces of fruits and the preceding flowers. In the present exploratory study, the microbiomes associated with the surfaces of tropical fruits from Northern Argentina, such as white guava, passion fruit and papaya were investigated using a shotgun metagenomic sequencing approach. Hereto, one sample composed of 14 white guava fruits, two samples of passion fruits with each two to three fruits representing the almost ripe and ripe stage of maturity, four samples of papaya with each two to three fruits representing the unripe, almost ripe, and ripe stage of maturity were processed, as well as a sample of closed and a sample of open Japanese medlar flowers. A considerable heterogeneity was found in the composition of the fruits’ surface microbiota at the genus and species level. While bacteria dominated the microbiota of the fruits and flowers, a small number of the metagenomic sequence reads corresponded with yeasts and filamentous fungi. A minimal abundance of bacterial species critical in lactic acid and acetic acid fermentations was found. A considerable fraction of the metagenomic sequence reads from the fruits’ surface microbiomes remained unidentified, which suggested that intrinsic species are to be sequenced or discovered.