Chemical implications and time reduction of on-farm cocoa fermentation by Saccharomyces cerevisiae and Pichia kudriavzevii

Can Different Fermentation Boxes Improve the Nutritional Composition and the Antioxidant Activity of Fermented and Dried Floodplain Cocoa Beans in the Brazilian Amazon?

This study evaluated the impact of different fermentation boxes on the nutritional and antioxidant composition of dried lowland cocoa beans (Theobroma cacao L.), a characteristic product of some producers in the Amazon region. The analysis included ash content, moisture content, pH, titratable acidity, proteins, lipids, flavonoids, antioxidant activities (DPPH, ABTS, and FRAP), and mineral composition. Four types of fermentation boxes were assessed: a projected hexagonal box (PHB), square box (SB), basket (HP), and local square box (LSB). Statistical analyses included ANOVA, Tukey's test, and Fisher's LSD test to compare mean differences, while Principal Component Analysis (PCA) identified key contributors, including potassium and magnesium. Spearman correlation analysis revealed significant relationships between soil and almond nutrient profiles. The HP bed exhibited superior phenolic concentration, antioxidant activity, centesimal composition, and potassium and magnesium content. Despite its shorter fermentation period, the LSB bed met quality standards, while the PHB and SB showed intermediate results. Mineral analysis confirmed no toxicological risks, suggesting the beans are safe and enriched with floodplain minerals. These findings emphasize the importance of fermentation methods in determining cocoa bean quality and provide a framework for optimizing processes to enhance their nutritional and functional properties.

Exploring the potentials of indigenous Saccharomyces cerevisiae and Pichia kudriavzevii for enhancing flavour and aromatic characteristics in apricot wines

In this study, we investigated the oenological performance of key yeast populations previously identified from apricot wine fermentation, aiming to obtain indigenous starters suitable for apricot wine production. Twenty-one isolates were characterized physiologically, and two isolates each of Saccharomyces cerevisiae and Pichia kudriavzevii were selected for laboratory-scale fermentations. Results showed that S. cerevisiae S9 exhibited significantly higher sugar consumption than S2 and CECA strains, with the former demonstrating a fructophilic character. Mixed fermentations of P. kudriavzevii N11 and N12 resulted in lower citric acid content (decreasing by 12-25 %) and higher glycerol levels (increasing by 12-47 %) compared to pure fermentation. In the mixed fermentation, indigenous S. cerevisiae species supported the survival of P. kudriavzevii, effectively enhancing the fruity esters and terpenes content of apricot wine. This study provides technical support for screening specialized starters for apricot wine production.

Screening and characterizing indigenous yeasts, lactic acid bacteria, and acetic acid bacteria from cocoa fermentation in Hainan for aroma Development

Fermentation is crucial for inducing desirable flavor and aroma profiles in cocoa products. This research focused on identifying microbial strains isolated from spontaneous cocoa fermentation in Hainan through 16S and Internal Transcribed Spacer (ITS) sequencing. Pectinase activity was screened, and metabolic dynamics of sugars and organic acids were analyzed using high-performance liquid chromatography. Additionally, gas chromatography-mass spectrometry was employed for the quantification of volatile compounds. The fermentation potentials of isolated yeast, lactic acid bacteria, and acetic acid bacteria were analyzed from multiple perspectives. Pichia fermentans XY23.1 and Hanseniaspora uvarum XY23.1 exhibited significant pectinolytic activity, essential for breaking down pectin in cocoa pulp. Moreover, H. uvarum XY23.1, H. occidentalis XY23.1, Saccharomyces cerevisiae XY23.2, and P. fermentans XY23.1 were identified as producers of notable amounts of alcohols and esters, contributing sweet and floral notes to the fermentation profile. Furthermore, Levilactobacillus brevis exhibited strong fructophilicity, and Lactiplantibacillus plantarum strains showed high metabolic rates and lactic acid production abilities, crucial for enhancing fermentation efficiency. Assessment of growth rate and acid production performance revealed that Gluconobacter potus XY23.2 and Acetobacter oryzifermentans XY23.1 can produce less acid during rapid growth, avoiding flavor defects caused by excessive acidity. This study demonstrates the impact of various flavor compounds on the flavor characteristics of cocoa pulp. It highlights the potential of these microbial strains for use in starter culture cocktails, which can significantly improve the quality of cocoa products by enhancing desirable flavor and aroma profiles while maintaining balanced acidity. PRACTICAL APPLICATION: This study screened and characterized microorganisms isolated from the fermentation of Hainan cocoa (Trinitario) through a series of experiments, providing new insights for the future selection of cocoa fermentation starters.

Multiomics analysis reveals microbial diversity and activity through spontaneous fermentation of Theobroma cacao

To gain insight into the active microbiota during spontaneous fermentation of Theobroma cacao L., this study assessed protein diversity during 120 h using a combined metabarconding and metaproteomics approach. During the first days of fermentation, most of the peptides were associated with T. cacao and yeast (0-72 h). Peptides associated with bacteria became more abundant after 72 h of fermentation, coinciding with a decrease in peptides associated with cocoa (96-120 h). In addition to the known microorganisms involved in fermentation, such as Saccharomyces, Lactobacillus and Acetobacter, novel genera were also metabolically active, including Microvirga, Inquilinus, Candolleomyces and Lasiodiplodia.. The results showed a consistency in the main genera detected by both techniques, but the identification of unexplored genera such as Inquilinus, Microvirga, Cyphellophora and Ashbya gossypii, among others, suggests that this omics approach needs to be used together for more comprehensive results on spontaneous fermentation. In conclusion, studies combining techniques such as metabarcoding and metaproteomics should be considered in fermentation studies, as a single technique would result in omissions regarding the activity of certain microorganisms that may be important for the course of spontaneous fermentation.

Exploring variations in quality parameters of Theobroma cacao L.beans from Eastern Amazonia

The cocoa tree (Theobroma cacao L.) is a native crop of the tropical forests of Central America and the Amazon. It plays an important role in the economy of producing regions; however, the infrastructure remains incipient, leading to inadequate processing practices and affecting the quality of the cocoa beans. Therefore, this research aimed to evaluate the quality of 55 samples of Amazonian cocoa beans produced in five regions of state of Pará (Lower Tocantins River, Northeast, West, Southeast, and Trans-Amazon) through physical and physicochemical evaluations (proteins, lipids, moisture, ash, pH, acidity, and water activity), and a questionnaire with producers about fermentation and drying practices. This was followed by physical, physicochemical, antioxidant capacity, quantification of total polyphenols, and bioactive compound evaluations. According to the physical evaluation, the samples met the acceptable commercial standard, but the cut test results showed a lack of standardization in the pre-processing of cocoa beans according to the International Cocoa Organization (ICCO). Among the physicochemical parameters, moisture was within the limit tolerated by legislation, and only lipids showed significant differences. Regarding antioxidant capacity, total polyphenols, and bioactive compounds, only the bioactive compounds showed significant differences, with the Lower Tocantins River region exhibiting higher values for all studied compounds. Inadequate processing practices, such as poor fermentation and drying, may lead to quality deficiencies in cocoa beans. Therefore, this study emphasizes the need for characterization of commercial cocoa beans, as well as standardization in the pre-processing of these beans. It also highlights potential variations in the quality of the beans among producing regions, owing to the vast territorial expanse of Pará, diverse cultivation conditions, variety of cocoa trees, and different methods of cocoa bean pre-processing.

Amino acid profile behavior during the fermentation of Criollo cocoa beans

The study investigated the behavior of seventeen amino acids during spontaneous (SF) and starter culture (SC) fermentation of Criollo cocoa beans from Copallín, Guadalupe and Tolopampa, Amazonas-Peru. For this purpose, liquid chromatography (UHPLC) was used to quantify amino acids. Multivariate analysis was used to differentiate the phases of the fermentation process. The percentage of essential amino acids during SC fermentation (63.4%) was higher than SF (61.8%); it was observed that the starter culture accelerated their presence and increased their concentration during the fermentation process. The multivariate analysis identified a first stage (day 0 to day 2), characterized by a low content of amino acids that increased due to protein hydrolysis. The study showed that adding the starter culture (Saccharomyces cerevisiae) to the fermentation mass increased the concentration of essential amino acids (63.0%) compared to the spontaneous process (61.8%). Moreover, this addition reduced the fermentation time (3-4 days less), demonstrating that the fermentation process with a starter culture allows obtaining a better profile of amino acids precursors of flavor and aroma.

Physiological evaluation of yeast strains under anaerobic conditions using glucose, fructose, or sucrose as the carbon source

The aim of this study was to evaluate the physiology of 13 yeast strains by assessing their kinetic parameters under anaerobic conditions. They included Saccharomyces cerevisiae CAT-1 and 12 isolated yeasts from different regions in Brazil. The study aimed to enhance understanding of the metabolism of these strains for more effective applications. Measurements included quantification of sugars, ethanol, glycerol, and organic acids. Various kinetic parameters were analyzed, such as specific substrate utilization rate (qS), maximum specific growth rate (μmax), doubling time, biomass yield, product yield, maximum cell concentration, ethanol productivity (PEth), biomass productivity, and CO2 concentration. S. cerevisiae CAT-1 exhibited the highest values in glucose for μmax (0.35 h-1), qS (3.06 h-1), and PEth (0.69 gEth L-1 h-1). Candida parapsilosis Recol 37 did not fully consume the substrate. In fructose, S. cerevisiae CAT-1 stood out with higher values for μmax (0.25 h-1), qS (2.24 h-1), and PEth (0.60 gEth L-1 h-1). Meyerozyma guilliermondii Recol 09 and C. parapsilosis Recol 37 had prolonged fermentation times and residual substrate. In sucrose, only S. cerevisiae CAT-1, S. cerevisiae BB9, and Pichia kudriavzevii Recol 39 consumed all the substrate, displaying higher PEth (0.72, 0.51, and 0.44 gEth L-1 h-1, respectively) compared to other carbon sources.

Evaluation of stress tolerance and design of alternative culture media for the production of fermentation starter cultures in cacao

Ecuador is one of the world's leading producers of cacao beans, and Nacional x Trinitario cacao represents one of the most distinctive varieties due to its flavor and aroma characteristics. This study aimed to evaluate the effect of the starter culture isolated from microbial diversity during the spontaneous fermentation of Nacional x Trinitario cacao. A total of 249 microbial isolates were obtained from spontaneous culture, with Lactiplantibacillus (45 %), Saccharomyces (17 %), and Acetobacter (2 %) being the most relevant genera for fermentation. Tolerance tests were conducted to select microorganisms for the starter culture. Lactiplantibacillus plantarum exhibited the highest tolerance at pH 5 and 6 % ethanol and tolerated concentrations up to 15 % for glucose and fructose. Acetobacter pasteurianus grew at pH 2 and 6 % ethanol, tolerating high sugar concentrations of up to 15 % for glucose and 30 % for fructose, with growth observed in concentrations up to 5 % for lactic and acetic acid. Subsequently, a laboratory-scale fermentation was conducted with the formulated starter culture (SC) comprising S. cerevisiae, L. plantarum, and A. pasteurianus, which exhibited high tolerance to various stress conditions. The fermentation increased alcoholic compounds, including citrusy, fruity aromas, and floral notes such as 2-heptanol and phenylethyl alcohol, respectively 1.6-fold and 5.6-fold compared to the control. Moreover, the abundance of ketones 2-heptanone and 2-nonanone increased significantly, providing sweet green herbs and fruity woody aromas. Cacao fermented with this SC significantly enhanced the favorable aroma-producing metabolites characteristic of Fine-aroma cacao. These findings underscore the potential of tailored fermentation strategies to improve cacao product quality and sensory attributes, emphasizing the importance of ongoing research in optimizing fermentation processes for the cacao industry.

Food yeasts: occurrence, functions, and stress tolerance in the brewing of fermented foods

With the rapid development of systems biology technology, there is a deeper understanding of the molecular biological mechanisms and physiological characteristics of microorganisms. Yeasts are widely used in the food industry with their excellent fermentation performances. While due to the complex environments of food production, yeasts have to suffer from various stress factors. Thus, elucidating the stress mechanisms of food yeasts and proposing potential strategies to improve tolerance have been widely concerned. This review summarized the recent signs of progress in the variety, functions, and stress tolerance of food yeasts. Firstly, the main food yeasts occurred in fermented foods, and the taxonomy levels are demonstrated. Then, the main functions of yeasts including aroma enhancer, safety performance enhancer, and fermentation period reducer are discussed. Finally, the stress response mechanisms of yeasts and the strategies to improve the stress tolerance of cells are reviewed. Based on sorting out these related recent researches systematically, we hope that this review can provide help and approaches to further exert the functions of food yeasts and improve food production efficiency.

Reduction in the Cocoa Spontaneous and Starter Culture Fermentation Time Based on the Antioxidant Profile Characterization

In current systems, the fermentation spontaneous process produces fermented beans of heterogeneous quality due to the fermentation time. This study demonstrated that the fermentation time should be reduced. For this purpose, the physicochemical parameters, antioxidant profile, and volatile compounds were characterized in two types of fermentation (spontaneous and starter culture) for 168 h in cocoa from three altitude levels. Multivariate analysis (cluster and PCA) was used to discriminate the fermentation stages. We found three stages in all fermentations, where the first two stages (0 h to 96 h) were characterized by a higher antioxidant potential of the cocoa bean and the presence of desirable volatile compounds such as acids, alcohols, aldehydes, ketones, and esters, which are precursors of cocoa aroma; however, prolonged fermentation times affected the antioxidant profile of the bean. In addition, the use of a starter culture facilitates the release of compounds in a shorter time (especially alcohols and esters). It is concluded that it is necessary to reduce the fermentation time under these conditions in the region of Amazonas.

Advances in the Application of the Non-Conventional Yeast Pichia kudriavzevii in Food and Biotechnology Industries

Pichia kudriavzevii is an emerging non-conventional yeast which has attracted increased attention for its application in food and biotechnology areas. It is widespread in various habitats and often occurs in the spontaneous fermentation process of traditional fermented foods and beverages. The contributions of P. kudriavzevii in degrading organic acid, releasing various hydrolase and flavor compounds, and displaying probiotic properties make it a promising starter culture in the food and feed industry. Moreover, its inherent characteristics, including high tolerance to extreme pH, high temperature, hyperosmotic stress and fermentation inhibitors, allow it the potential to address technical challenges in industrial applications. With the development of advanced genetic engineering tools and system biology techniques, P. kudriavzevii is becoming one of the most promising non-conventional yeasts. This paper systematically reviews the recent progress in the application of P. kudriavzevii to food fermentation, the feed industry, chemical biosynthesis, biocontrol and environmental engineering. In addition, safety issues and current challenges to its use are discussed.

Metabolomics during the spontaneous fermentation in cocoa (Theobroma cacao L.): An exploraty review

Spontaneous fermentation is a process that depends on substrates' physical characteristics, crop variety, and postharvest practices; it induces variations in the metabolites that are responsible for the taste, aroma, and quality. Metabolomics makes it possible to detect key metabolites using chemometrics and makes it possible to establish patterns or identify biomarker behaviors under certain conditions at a given time. Therefore, sensitive and highly efficient analytical techniques allow for studying the metabolomic fingerprint changes during fermentation; which identify and quantify metabolites related to taste and aroma formation of an adequate processing time. This review shows that studying metabolomics in spontaneous fermentation permits the characterization of spontaneous fermentation in different stages. Also, it demonstrates the possibility of modulating the quality of cocoa by improving the spontaneous fermentation time (because of volatile aromatic compounds formation), thus standardizing the process to obtain attributes and quality that will later impact the chocolate quality.

Effect of spontaneous fermentation location on the fingerprint of volatile compound precursors of cocoa and the sensory perceptions of the end-chocolate

Cocoa pod-opening delay and bean fermentation promote the organoleptic quality of chocolate. The present research investigated the changes in the volatile fingerprint of cocoa harvested at a traditional plantation. Cocoa beans extracted from 2-days pod-opening delay were simultaneously fermented for 5 days using container and then sun-dried to 7-8% moisture content at five different locations: Akoupé, San Pedro, Soubré, Djekanou and Daloa. The aromatic analysis were done on cocoa using the HS-SPME-GC/MS technique. Professional panelists evaluated the sensory perceptions of the chocolate. The results shows that cocoa fermented in both Daloa and Soubré regions were differentiated by 2,3-butanediol while those processed in other regions presented highest acetoin content. However, fermented cocoa from Soubré region exhibited most amount of 2,3-butanediol, diacetate A whereas 2,3,5,6-tetramethylpyrazine differentiated those from Daloa region. Sensory properties of chocolate were not linked to the aromatic compound precursors profile of beans. The fermentation performed in San Pédro region promote both the generation of more desirable aromatic compounds of cocoa and sensory attributes of the finished chocolate. The fermentation location generates a greater differentiation of the volatile fingerprint of cocoa and the sensory perceptions of the finished chocolate.

Traditional Fermented Foods from Ecuador: A Review with a Focus on Microbial Diversity

The development of early civilizations was greatly associated with populations’ ability to exploit natural resources. The development of methods for food preservation was one of the pillars for the economy of early societies. In Ecuador, food fermentation significantly contributed to social advances and fermented foods were considered exclusive to the elite or for religious ceremonies. With the advancement of the scientific research on bioprocesses, together with the implementation of novel sequencing tools for the accurate identification of microorganisms, potential health benefits and the formation of flavor and aroma compounds in fermented foods are progressively being described. This review focuses on describing traditional fermented foods from Ecuador, including cacao and coffee as well as less popular fermented foods. It is important to provide new knowledge associated with nutritional and health benefits of the traditional fermented foods.

Kinetics Crystallization and Polymorphism of Cocoa Butter throughout the Spontaneous Fermentation Process

The spontaneous fermentation process of Criollo cocoa is studied for its importance in the development of chocolate aroma precursors. This research supports the importance of spontaneous fermentation, which was studied through the crystallization behavior and polymorphisms of cocoa butter (CB), the most abundant component of chocolate that is responsible for its quality physical properties. The k-means technique was used with the CB crystallization kinetics parameters to observe the division of the process during the first stage (day 0–3). The experimental crystallization time was 15.78 min and the second stage (day 4–7) was 17.88 min. The Avrami index (1.2–2.94) showed that the CB crystallizes in the form of a rod/needle/fiber or plate throughout the process. CB produced metastable crystals of polyforms β1′ and β2′. Three days of fermentation are proposed to generate Criollo cocoa beans with acceptable CB crystallization times.

Identification of Lactic Acid Bacteria on Raw Material for Cocoa Bean Fermentation in the Brazilian Amazon

The prevalent microbiota during cocoa fermentation is one of the main factors responsible for the chemical and biochemical changes that lead to desirable chocolate characteristics. However, the microbiota can be affected by several factors, including the edaphoclimatic conditions, which are typical of the production region. The objective of this study was to identify LAB in Amazonian cocoa prior to fermentation. LAB were isolated using MRS agar. By sequencing the 16S region of isolated LAB in MRS agar, it was possible to identify five LAB species that were registered in the GenBank database (accessions from MT117900 to MT117915). They included Pediococcus acidilactici, which was the most prevalent, followed by Lactobacillus farraginis, L. parafarraginis, L. zeae, and L. casei. Studies are needed to ascertain their specific roles and impact on cocoa quality. It is likely that they can be available as starter cultures to enhance the quality characteristics of chocolate.

Functional yeast starter cultures for cocoa fermentation

The quest to develop a performant starter culture mixture to be applied in cocoa fermentation processes started in the 20th century, aiming at achieving high‐quality, reproducible chocolates with improved organoleptic properties. Since then, different yeasts have been proposed as candidate starter cultures, as this microbial group plays a key role during fermentation of the cocoa pulp‐bean mass. Yeast starter culture‐initiated fermentation trials have been performed worldwide through the equatorial zone and the effects of yeast inoculation have been analysed as a function of the cocoa variety (Forastero, Trinitario and hybrids) and fermentation method (farm‐, small‐ and micro‐scale) through the application of physicochemical, microbiological and chemical techniques. A thorough screening of candidate yeast starter culture strains is sometimes done to obtain the best performing strains to steer the cocoa fermentation process and/or to enhance specific features, such as pectinolysis, ethanol production, citrate assimilation and flavour production. Besides their effects during cocoa fermentation, a significant influence of the starter culture mixture applied is often found on the cocoa liquors and/or chocolates produced thereof. Thus, starter culture‐initiated cocoa fermentation processes constitute a suitable strategy to elaborate improved flavourful chocolate products.

Quality differentiation of cocoa beans: implications for geographical indications

Geographical indications may stimulate collective actions of governance for quality control, trade and marketing as well as innovation based on the use of local resources and regional biodiversity. Cocoa production, however, dominated by small family agriculture in tropical regions, has rarely made use of such strategies. This review is aimed at understanding major research interests and emerging technologies helpful for the origin differentiation of cocoa quality. Results from literature search and cited references of publications on cocoa research were imported into VOSviewer for data analysis, which aided in visualizing major research hotpots. Co-occurrence analysis yielded major research clusters which guided the discussion of this review. Observed was a consensus recognizing cocoa quality resulting from the interaction of genotype, fermentation variables and geographical origin. A classic view of cocoa genetics based on the dichotomy of 'fine versus bulk' has been reexamined by a broader perspective of human selection and cocoa genotype evolution. This new approach to cocoa genetic diversity, together with the understanding of complex microbiome interactions through fermentation, as well as quality reproducibility challenged by geographical conditions, have demonstrated the importance of terroir in the production of special attributes. Cocoa growing communities around the tropics have been clearly enabled by new omics and chemometrics to systematize producing conditions and practices in the designation of specifications for the differentiation of origin quality. © 2021 Society of Chemical Industry.

How Climatic Seasons of the Amazon Biome Affect the Aromatic and Bioactive Profiles of Fermented and Dried Cocoa Beans?

In addition to the vast diversity of fauna and flora, the Brazilian Amazon has different climatic periods characterized by periods with greater and lesser rainfall. The main objective of this research was to verify the influence of climatic seasons in the Brazilian Amazon (northeast of Pará state) concerning the aromatic and bioactive profiles of fermented and dried cocoa seeds. About 200 kg of seeds was fermented using specific protocols of local producers. Physicochemical analyzes (total titratable acidity, pH, total phenolic compounds, quantification of monomeric phenolics and methylxanthines) and volatile compounds by GC-MS were carried out. We observed that: in the summer, the highest levels of aldehydes were identified, such as benzaldehyde (6.34%) and phenylacetaldehyde (36.73%), related to the fermented cocoa and honey aromas, respectively; and a total of 27.89% of this same class was identified during winter. There were significant differences (p ≤ 0.05, Tukey test) in the profile of bioactive compounds (catechin, epicatechin, caffeine, and theobromine), being higher in fermented almonds in winter. This study indicates that the climatic seasons in the Amazon affect the aromatic and bioactive profiles and could produce a new identity standard (summer and winter Amazon) for the cocoa almonds and their products.

Profile of Volatile Compounds of On-Farm Fermented and Dried Cocoa Beans Inoculated with Saccharomyces cerevisiae KY794742 and Pichia kudriavzevii KY794725

This study aimed to identify the volatile compounds in the fermented and dried cocoa beans conducted with three distinct inoculants of yeast species due to their high fermentative capacity: Saccharomyces cerevisiae, Pichia kudriavzevii, the mixture in equal proportions 1:1 of both species, and a control fermentation (with no inoculum application). Three starter cultures of yeasts, previously isolated and identified in cocoa fermentation in the municipality of Tomé-Açu, Pará state, Brazil. The seeds with pulp were removed manually and placed in wooden boxes for the fermentation process that lasted from 6 to 7 days. On the last day of fermentation, the almonds were packaged properly and placed to dry (36 °C), followed by preparation for the analysis of volatile compounds by GC-MS technique. In addition to the control fermentation, a high capacity for the formation of desirable compounds in chocolate by the inoculants with P. kudriavzevii was observed, which was confirmed through multivariate analyses, classifying these almonds with the highest content of aldehydes, esters, ketones and alcohols and low concentration of off-flavours. We conclude that the addition of mixed culture starter can be an excellent alternative for cocoa producers, suggesting obtaining cocoa beans with desirable characteristics for chocolate production, as well as creating a product identity for the producing region.