Precursors of the Cocoa-Specific Aroma Components are Derived from the Vicilin-Class (7S) Globulin of the Cocoa Seeds by Proteolytic Processing

Impact of controlled fermentation on the volatile aroma of roasted cocoa

Abstract The study of controlled methods of cocoa fermentation on a small scale is important to assess the maintenance of heat generated in the last days of fermentation. The research aimed to study the impact of spontaneous fermentation in controlled fermentation systems on the quality and acceptability of fermented cocoa beans. A 2×3 complete factorial design used different controlled fermentation systems (jacket system, solar heater and wooden box) and pulp reduction as variables. Samples were analyzed for fermentation index and volatile aroma composition profile using Headspace-Solid Phase Microextraction (HS-SPME) and Gas Chromatography-Mass Spectrometry (GC-MS). The profile of volatile compounds is evaluated for the studied variables using a multivariate Principal Components Analysis (PCA). The results showed increasing fermentation times in the jacket system seeing that it raised the fermentation rate and accelerated it to five days of fermentation combined with pulp reduction. The PCA analysis showed differences in the chemical composition of volatile compounds that were mainly associated with the reduction of the pulping process than the type of controlled system in four days of fermentation.

The effect of fermentation and roasting on free amino acids profile in Criollo cocoa (Theobroma cacao L.) grown in Venezuela

Abstract The development of cocoa flavor and aroma is a complex phenomenon that depends on how the fermentation and roasting processes are carried out. During fermentation, the formation of some compounds so-called “aroma and flavor precursors” takes place, which are finally expressed during the roasting stage. Therefore, the evaluation of aroma precursors such as the amino acids formed during fermentation is crucial in order to determine the quality of the cocoa. In this context, we developed and validated a method for the study of these compounds in cocoa samples. The amino acids were quantitatively converted into their trimethylsilyl derivatives before their determination by gas chromatography with mass spectrometry detection. The results were verified performing precision and accuracy studies. The inter and intra assay coefficients of variation (C.V, n = 5) were lower than 4.7% and 4%, respectively. The analytical recoveries (95% to 108% with C.V < 4.2, n = 5) demonstrated the high performance of the extraction procedure. The method was successfully applied to the analysis of the amino acids in 110 samples of Venezuelan Criollo cocoa during the three days of fermentation and roasting (110 °C for 25 min). All samples had an appreciable content of free amino acids ranging between 3.87 and 5.97 g/kg in the absence of fermentation. We observed degradation of the acidic amino acids during the first day of fermentation, while the rest of amino acids increased progressively during the fermentation process with a predominance of the hydrophobic ones, mainly leucine, phenylalanine, valine, alanine and isoleucine. Additionally, during the roasting stage a fraction of the amino acids, especially the hydrophobic ones, was partially degraded through Maillard reaction to form the compounds associated with the cocoa aroma and flavor.

Microbial synergy between Pichia kudriazevii YS201 and Bacillus subtilis BS38 improves pulp degradation and aroma production in cocoa pulp simulation medium

Interactions between two major microorganisms from Ivorian cocoa fermentation, namely Bacillus subtilis BS38 and Pichia kudriazevii YS201, were investigated during fermentation in cocoa pulp simulation medium. The strains were mutually inhibitory, with Bacillus being more susceptible to this antagonistic effect than Pichia. However, both strains yielded different pulp-degrading enzymes, namely polygalacturonase (PG) from Pichia and pectate lyase (Pel) from Bacillus, that cooperate to efficiently breakdown pectin and vegetable pulp. The quantification of aromas from microbial cultures using Gas Chromatography-Mass Spectroscopy (GC-MS) coupled with headspace microextration (SPME) method, showed that P. kudriazevii produce mainly alcohols such as ethanol (63.165 g/L), phenylethanol (1.005 g/L), methylbutanol (0.138 g/L) and esters, notably ethyl acetate (0.037 g/L) and isoamyl acetate (0.032 g/L). The volatile fraction produced by Bacillus was dominated by butanediol (5.707 g/L), acetoin (1.933 g/L), phenylethanol (0.035 g/L) and acetic acid (0.034 g/L). In co-culture, Bacillus produced low levels of aroma compounds whereas a moderate decrease in the production of these compounds was observed in the yeasts strain. Thus, the dominant aromas present in the co-culture were mainly those from the yeasts strain; however, a 1.37 fold increase of ethanol production was observed in co-culture indicating a synergy between the strains. This study showed that cooperation between B. subtilis BS38 and P. kudriazevii YS201 leads principally to increasing pulp degradation and ethanol production, known as desirable properties for a well processing of cocoa fermentation.

RP-HPLC-DAD determination of free amino acids in cocoa samples during fermentation and roasting

Amino acids (AA) composition in cocoa beans can predict the synthesis of compounds which affect cocoa flavor. Thus, their determination is of great interest for the community implied in the commercialization and production of cocoa. In consequence, in this work, the analysis of AA produced during cocoa beans fermentation and roasting was carried out. A high-performance liquid chromatographic method with DAD detection at 254 nm was optimized and validated for their selective determination in six varieties of cocoa beans with different genotypes, all of them grown in Venezuela. AA were extracted by defatted milled cocoa powder ultrasonication using purified water at 70 ºC. Then, they were derivatized with phenyl isothiocyanate, and their derivatives were separated, using a reversed-phase column with gradient elution, achieving a satisfactory resolution among the peaks (greater than 1.0) in less than 29 min. 110 cocoa samples were analyzed. Results showed a significant content of free AA, ranging from 3.87 to 5.97 g/kg in absence of fermentation with a predominance of acidic AA. Moreover, there is a progressive increase in the AA content while fermentation process occurs, with a predominance of hydrophobic AA such as alanine, valine, isoleucine, leucine, phenylalanine, and tyrosine. On the other hand, all cocoa types showed a partial degradation of free AA during the roasting step, especially the hydrophobic ones.

An overview of the physical and biochemical transformation of cocoa seeds to beans and to chocolate: Flavor formation

Chocolate is a widely consumed product worldwide due to its exquisite flavor, which comes from the unique and fascinating cocoa flavor. This flavor depends on little controllable variables such as the genotype and the agroecological niche, and on the other side, on postharvest operations: (1) cocoa transformation from seeds to beans that comprises cocoa seeds preconditioning, fermentation, and drying, and (2) the production of chocolate from the bean in which roasting is highlighted. Postharvest transformation operations are critically important because during these, cocoa flavor is formed, allowing the differentiation of two categories: bulk and specialty cocoa. In this sense, this article presents an overview of cocoa postharvest operations, the variables and phenomena that influence and control the physical and biochemical transformation from seeds to cocoa beans, and their relation to the formation of chocolate flavor. Moreover, research perspectives in terms of control and management of postharvest practices in order to obtain cocoa with differentiated and specialty characteristics "from bean to bar" are discussed.

Cocoa Bean Proteins-Characterization, Changes and Modifications due to Ripening and Post-Harvest Processing

The protein fractions of cocoa have been implicated influencing both the bioactive potential and sensory properties of cocoa and cocoa products. The objective of the present review is to show the impact of different stages of cultivation and processing with regard to the changes induced in the protein fractions. Special focus has been laid on the major seed storage proteins throughout the different stages of processing. The study starts with classical introduction of the extraction and the characterization methods used, while addressing classification approaches of cocoa proteins evolved during the timeline. The changes in protein composition during ripening and maturation of cocoa seeds, together with the possible modifications during the post-harvest processing (fermentation, drying, and roasting), have been documented. Finally, the bioactive potential arising directly or indirectly from cocoa proteins has been elucidated. The “state of the art” suggests that exploration of other potentially bioactive components in cocoa needs to be undertaken, while considering the complexity of reaction products occurring during the roasting phase of the post-harvest processing. Finally, the utilization of partially processed cocoa beans (e.g., fermented, conciliatory thermal treatment) can be recommended, providing a large reservoir of bioactive potentials arising from the protein components that could be instrumented in functionalizing foods.

Volatile compounds and protein profiles analyses of fermented cocoa beans and chocolates from different hybrids cultivated in Brazil

Cocoa beans from different geographical and genetic origins show distinct fermentation dynamics which result in different chocolate qualities. In order to understand the effects of genetic improvement of cocoa plants, in this work volatile compounds and proteins profiles of beginning and end of the fermentation from different cocoa hybrids (CEPEC2004, PH15, PS1319, SJ02) were searched. Moreover, sensorial characterization of the produced chocolate from these hybrids was performed. According to the results obtained, different volatile compounds were identified in fermented beans and in the chocolate produced. Chocolate from CEPEC2004 was the most accepted by judges and correlated with sweet and bitter taste which can be explained by the presence of desired flavor compounds, such as 2,3-butanediol and 2-methyl-1-butanol. A higher presence of acids (undesirable compounds) was observed in chocolates samples from PS1319 hybrid, that have resulted in the low acceptance by judges. In addition, MALDI-TOF MS analysis showed that during fermentation the protein profile was different among the hybrids, which indicates this kind of compounds also contributes to the cocoa-specific flavor.

Food Evolution: The Impact of Society and Science on the Fermentation of Cocoa Beans

Cocoa is part of the cultural heritage in many areas of South and Central America and has played an important role in the history of human culture there. The modern methods of cocoa bean production for the purpose of the manufacture of modern chocolate are tied to the origin and development of cocoa bean fermentation and processing methods and the science of microbiology. To date, however, there has not been a study that discusses the impacts of both science and culture on the evolution of cocoa beans and cocoa bean processing. This work provides both a detailed overview of the evolution and historical development of cocoa, from its earliest forms to modern chocolate manufacturing, an in-depth discussion of the biochemistry of cocoa bean fermentation, as well as a compilation of primary research studies with details on fermentation methods, the scientific bases of interactions in microbial fermentations, and methods for their investigation, as well as metabolites that are produced. As a result, we present here the major microorganisms among all the ones that have been identified in previous studies. This database will aid researchers seeking standardized inoculants to drive cocoa bean fermentation, as well as serve as a guide for inventorying and assessing other food evolution-related studies regarding traditional and artisanal-based food systems.

Flavor formation and character in cocoa and chocolate: a critical review

Chocolate characters not only originate in flavor precursors present in cocoa beans, but are generated during post-harvest treatments and transformed into desirable odor notes in the manufacturing processes. Complex biochemical modifications of bean constituents are further altered by thermal reactions in roasting and conching and in alkalization. However, the extent to which the inherent bean constituents from the cocoa genotype, environmental factors, post-harvest treatment, and processing technologies influence chocolate flavor formation and relationships with final flavor quality, has not been clear. With increasing speciality niche products in chocolate confectionery, greater understanding of factors contributing to the variations in flavor character would have significant commercial implications.