Ghanaian Cocoa Bean Fermentation Characterized by Spectroscopic and Chromatographic Methods and Chemometrics

Abstract: Export of cocoa beans is of great economic importance in Ghana and several other tropical countries. Raw cocoa has an astringent, unpleasant taste, and flavor, and has to be fermented, dried, and roasted to obtain the characteristic cocoa flavor and taste. In an attempt to obtain a deeper understanding of the changes in the cocoa beans during fermentation and investigate the possibility of future development of objective methods for assessing the degree of fermentation, a novel combination of methods including cut test, colorimetry, fluorescence spectroscopy, NIR spectroscopy, and GC-MS evaluated by chemometric methods was used to examine cocoa beans sampled at different durations of fermentation and samples representing fully fermented and dried beans from all cocoa growing regions of Ghana. Using colorimetry it was found that samples moved towards higher a* and b* values as fermentation progressed. Furthermore, the degree of fermentation could, in general, be well described by the spectroscopic methods used. In addition, it was possible to link analysis of volatile compounds with predictions of fermentation time. Fermented and dried cocoa beans from the Volta and the Western regions clustered separately in the score plots based on colorimetric, fluorescence, NIR, and GC-MS indicating regional differences in the composition of Ghanaian cocoa beans. The study demonstrates the potential of colorimetry and spectroscopic methods as valuable tools for determining the fermentation degree of cocoa beans. Using GC-MS it was possible to demonstrate the formation of several important aroma compounds such 2-phenylethyl acetate, propionic acid, and acetoin and the breakdown of others like diacetyl during fermentation. Practical Application: The present study demonstrates the potential of using colorimetry and spectroscopic methods as objective methods for determining cocoa bean quality along the processing chain. Development of objective methods for determining cocoa bean quality will be of great importance for quality insurance within the fields of cocoa processing and raw material control in chocolate producing companies.     

Solid Fat Content,Pre-Crystallization Conditions,and Sensory Quality of Chocolate with Addition of Cocoa Butter Analogues

The objective of this study was to determine how the addition of two cocoa butter equivalents and cocoa butter improver affect the physical and sensory properties of chocolate. The laboratory-made chocolate samples were tempered at three different pre-crystallization temperatures (25, 27, and 29°C), using different concentrations (3, 5, and 7%) of two commercial cocoa butter equivalents as well as commercial cocoa butter improver of the chocolate. The nucleation time of the chocolate mass primarly depended on pre-crystallization temperature while the value of maximum torque of chocolate mass were influenced by both, pre-crystallization temperature and concentration of fats. Sensory evaluation revealed that cocoa butter equivalents were acceptable in chocolate formulation without producing a negative impact on the sensory quality, while usage of improver required adjustment of raw formulations or process parameters. The results of the instrumentally measured hardness revealed that addition of cocoa butter improver significantly (p > 0.05) increased hardness of chocolate samples.     

A comparison of antioxidant properties between artisan‐made and factory‐produced chocolate

The antioxidant capacities and the total phenolic content in cocoa liquor directly manufactured chocolate from an artisan manufacturer were measured using different in vitro methods (BR, TEAC, and Folin–Ciocalteu Reagent). These parameters were then compared with those of a chocolate made by a leading manufacturing company producing chocolate and cocoa‐containing products. A statistical analysis of the collected data showed that the antioxidant properties of the artisan‐made chocolate are significantly better than those of the factory‐produced one. These results were ascribed to the fact that all the bioactive components in the cocoa beans are better preserved in the artisan‐made chocolate.     

Improving chocolate flavor in poor-quality cocoa almonds by enzymatic treatment

Abstract: This paper proposes a method to enzymatically treat poor‐quality cocoa almonds (known as “slate”) to ensure the formation of chocolate flavor precursors. The production of flavor precursors improves the quality of these almonds, which are usually responsible for the low quality of the liquor produced. Proteases and carboxypeptidases from different sources were tested under various conditions. The different treatments were evaluated by chemical analysis (hydrolysis efficiency) and sensory analysis of the treated material compared to good‐quality cocoa almonds. The results show that it is possible, through the use of microbial enzymes, to generate the mixture of compounds that will release, after roasting, the characteristic chocolate flavor in poor‐quality almonds. However, it is necessary to optimize the conditions of enzymatic treatment to obtain better results and thus establish a process that can be used for industrial purposes for manufacturing cocoa and chocolate. Practical Application: The basidiomycete Moniliophtora perniciosa is the causative agent of witches’ broom disease (WBD) of the cocoa tree, whose seeds are the source of chocolate. It is the most important phytopathological problem of cocoa‐producing areas of the American continent, and has decimated the Brazilian cocoa industry. In Bahia (Brazil), M. perniciosa was identified in 1989 and, as a consequence of its spreading, the annual production of cocoa almonds dropped from 450000 to 90000 tons within 12 y, reducing export values from an all‐time high of about US$ 1 billion to 110 million. The high incidence of WBD incapacitates Brazil to produce enough cocoa almonds even for the internal market, leading the country to import low‐quality cocoa almonds mainly from African countries. Our work proposes an enzymatic treatment to increase the quality of that cocoa almonds and, consequently, to improve the quality of the chocolate produced and consumed in the country.     

Combination of the Simple Additive (SAW) Approach and Mixture Design to Determine Optimum Cocoa Combination of the Hot Chocolate Beverage

Physicochemical (pH, brix, and color), sensory (color, taste, odor, mouthfeeling, consistency, bitter flavor, and general acceptability), and rheological properties of the hot chocolate beverages including different cocoa combinations were investigated in the present study. Cocoa type significantly affected all of the properties. Simple additive weighting approach was applied to obtain one score from seven different sensory parameters and simple additive weighting score was used in mixture design to determine optimum cocoa type or cocoa combination. Ostwald de Waele model described the flow behavior of the hot chocolate beverage samples with R² values ranged between 0.818 and 0.999. The consistency coefficient (K) and apparent viscosity at shear rate 50 s^?1 (η₅₀) were significantly affected by cocoa type found in the formulation of the beverage. The mixture design approach was performed in order to determine variation of the responses (physicochemical, sensory, and rheological parameters) as a function of cocoa concentration. Simple additive weighting scores were satisfactorily described by established equation as a function of cocoa concentration to be used in the formulation of the hot chocolate beverage (R² = 0.8645).     

Theobroma cacao L., "The food of the Gods": quality determinants of commercial cocoa beans, with particular reference to the impact of fermentation

The quality of commercial cocoa beans, the principal raw material for chocolate production, relies on the combination of factors that include the type of planting material, the agricultural practices, and the post-harvest processing. Among these, the fermentation of the cocoa beans is still the most relevant since it is the process whereby the precursors of the cocoa flavor arise. The formation of these precursors depends on the activity of different microbial groups on the beans pulp. A comparison of fermentations in different countries showed that a well-defined microbial succession does not always take place and that the role of Bacillus spp. in this process remains unclear. Considering the overriding importance of the fermentation to achieve high quality commercial cocoa beans, we discuss the need of addressing the impact of the farming system, the ripeness state of the pods, and the role of microbial interactions on the fermentation in future research. In addition, the problem of high acidification cocoa beans, aspects dealing with the volatile fraction of the flavor, and the cocoa butter properties, all were identified as critical aspects that need further investigation. The standardization of the microbiological methods and the application of metagenomic approaches would magnify the knowledge in this domain.     

Precursors of Chocolate Aroma: Studies in the Degradation of Amino Acids during the Roasting of Accra Cocoa Beans

SUMMARY— A preliminary study of the Strecker degradation of amino acids by reducing sugars in cocoa beans has revealed an unexpected temperature effect on the extent of the reaction which might influence the flavor of the product. Model amino acid/sugar systems were studied and the results support the hypothesis that there exists a relationship between the temperature of reaction, the extent of amino acid degradation and the production of flavor volatiles during the roasting of cocoa beans. A factory experiment, in which Accra cocoa beans were roasted at three different temperatures, provided supporting evidence of the influence of temperature on total flavor and on the strength of basic chocolate flavor.     

Bioactive and Sensory Properties of Herbal Spirit Enriched with Cocoa (Theobroma cacao L.) Polyphenolics

In the Southeast European and Mediterranean regions, consumption of various alcoholic beverages in the form of plain and aromatized spirits and liqueurs is an important part of traditional local gastronomy. Especially herbal spirits and liquors are widely spread and consumed. The objective of this study was to evaluate the potential of using cocoa raw materials (cocoa beans, cocoa nibs or cocoa liquor) in order to enhance the bioactive profile of traditional herbal liqueur, and to produce an appealing cocoa-flavoured alcoholic beverage. Therefore, the polyphenolic profile, antioxidative and sensory properties of herbal liquors containing the macerated cocoa raw materials were monitored during 6 months, in order to evaluate the kinetics of cocoa polyphenols release and optimise the maceration procedure for obtaining the best cocoa-enriched herbal spirit. Compared to plain herbal liquor without the additions, the obtained herbal liqueurs exhibited significantly higher content of polyphenolic antioxidants. Among the used cocoa raw materials for the maceration, cocoa nibs were evaluated as the best source of polyphenolic compounds (herbal liqueur containing cocoa nibs, 3,081.82 mg GAE/L), followed by cocoa liquor (1,897.73 mg GAE/L) and cocoa beans (1,358.64 mg GAE/L). Prolonged maceration time (up to 6 months) resulted with an increase in the content of polyphenolic compounds and the antioxidant capacity of herbal liqueurs. Herbal liqueurs containing the cocoa raw materials of bigger particle size (cocoa beans and cocoa nibs) exhibited better sensory properties (overall acceptability and chocolate-like flavour) than herbal liqueur containing cocoa liquor.     

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.     

Cocoa Agronomy,Quality, Nutritional,and Health Aspects

The history of cocoa and chocolate including the birth and the expansion of the chocolate industry was described. Recent developments in the industry and cocoa economy were briefly depicted. An overview of the classification of cacao as well as studies on phenotypic and genetic diversity was presented. Cocoa agronomic practices including traditional and modern propagation techniques were reviewed. Nutrition-related health benefits derived from cocoa consumption were listed and widely reviewed. The specific action of cocoa antioxidants was compared to those of teas and wines. Effects of adding milk to chocolate and chocolate drinks versus bioavailability of cocoa polyphenols were discussed. Finally, flavor, sensory, microbiological, and toxicological aspects of cocoa consumption were presented.     

Antioxidant Properties of Cocoa Beans (Theobroma cacao L.): Influence of Cultivar and Roasting Conditions

Effects of various roasting conditions on antioxidant properties of five Theobroma cacao L. varieties were investigated. The cocoa beans were roasted at four different temperatures (110–150°C) and three different air humidities (0.3–5.0%). The raw cocoa beans were characterized by high antioxidant activities. The antioxidant properties of the roasted cocoa beans varied markedly among the analyzed cultivars and geographical regions and were affected by roasting conditions. Generally, cocoa beans of the cv. Forastero from Brazil exhibited higher total phenolic content, free radical scavenging activity, and metal chelating ability than samples of the other analyzed cocoa varieties. Roasting at 110°C caused negligible changes in total phenolics content and antioxidant activity of cocoa beans, while almost all samples tended to have lower antioxidant potential when roasting temperature increased. The air humidity used in roasting did not affect the total phenolics content and antioxidant activity for lowest roasting temperature (110°C). Moreover, the obtained results revealed that thermal processing at the higher temperatures and elevated air humidity resulted in the higher antioxidant capacities. It was also found that the ferrous ion chelating activity of cocoa beans increased with the roasting temperature (in the range from 110 to 150°C), with the exception of cv. Trinitario from Papua New Guinea. The data showed that roasting at lower temperatures with humid air are more favorable in terms of preserving the bioactivity of roasted cocoa beans.     

The Precursors of Chocolate Aroma: Production of Reducing Sugars during Fermentation of Cocoa Beans

SUMMARY— The sucrose in fresh cocoa beans is hydrolyzed to glucose and fructose during fermentation and the rate of the reaction confirms the possible inclusion of reducing sugars among the precursors of chocolate aroma. The optimal concentration of reducing sugars in the bean is reached at about the same time as maximal flavor development, and coincides approximately with the peak in amino acid concentration. An objective method for assessing the "Degree of Fermentation" of cocoa beans has been proposed and tested.     

Improved Fermentation of Cocoa Beans with Enhanced Aroma Profiles

The cocoa (Theobroma cacao) fermentation was carried out using starter consortia of Saccharomyces cerevisiae, Lactobacillus plantarum, and Acetobacter aceti with 10% inoculum. The fermented beans were soaked with sterile water (1:3 wt/v) for the duration of 1, 3, and 5 h. The treated beans were dried to the moisture content of 7 ± 1%. The samples were then roasted, ground and subjected to steam distillation. The volatiles were extracted and identified using GC-MS. The samples soaked for 1 h scored 100% cut score along with 0.85% fermentation index. The volatile and non-volatiles were associated with beans treated in water after fermentation. Volatile compounds were classified as esters, alcohols, acids, aldehydes, ketones, pyrazines, hydroperoxides, and hydrocarbons. Most of the oxygenated aliphatic compounds and aromatics were potentially derived via an acetic acid and shikimic acid pathways, respectively. Untreated cocoa beans contained 12 sesquiterpene hydrocarbons potentially derived through the mevalonic acid pathway and contributed to harsh notes. Also, these metabolites were completely absent in the treated samples indicating depletion while soaking. Thus, the treated samples (1 h) had enhanced quality with high flavor notes with 8.5 rating on sensory evaluation. Thus, these soaking treatments with fermentation lead to improvement of flavor profiles which confers improved cocoa quality.     

发酵和焙烤对可可豆多酚、黄酮和风味品质的影响

本实验采用高效液相色谱仪（high performance liquid chromatography,HPLC）、色差仪、电子鼻分别检测未发酵、发酵和焙烤海南可可豆的总酚含量、总黄酮含量、色度和可可豆风味差异。结果表明：未经焙烤的未发酵豆总酚（464.03 mg/10 g）和总黄酮（126.86 mg/10 g）含量明显高于发酵豆总酚（211.86 mg/10 g）和总黄酮（61.98 mg/10 g）含量。105～145 ℃焙烤30 min,未发酵豆总酚和总黄酮含量分别为419.5～129.8 mg/10 g和77.8～16.8 mg/10 g;发酵豆总酚和总黄酮含量分别为182.53～86.25 mg/10 g和34.7～7.0 mg/10 g。其中,125 ℃焙烤20～40 min,未发酵豆总酚和黄酮含量分别为353.74～289.45 mg/10 g和42.86～32.20 mg/10 g;发酵豆总酚和黄酮含量分别为152.08～123.55 mg/10 g和25.12～21.14 mg/10 g。在105～145 ℃的温度焙烤下没食子酸含量变化显著。可可豆色度值的范围：L*值集中在40.0～47.0之间,a*值集中在5.0～6.8之间,b*值集中在4.0～8.5之间。未发酵和发酵可可豆之间,以及不同温度焙烤可可豆之间的电子感官风味分析结果差异较大。     

烘焙温度对可可豆苦涩味的影响

对不同烘焙温度下的可可豆进行致苦涩味物质分离分析,基于感官评价和相对香味活力值的概念筛选出参与可可豆苦涩味形成的主要组分,并结合热裂解-气质联用技术研究烘焙温度上升时可可豆挥发性物质的变化规律。结果表明:(1)可可豆提取物苦涩味流分共检测出55种挥发性成分,其中醇类7种,酸类5种,酯类9种,醛类8种,酮类6种,烯烃类2种;(2)致苦涩味的关键组分为2-甲基丙醛、2-甲氧基苯酚、2-庚醇、戊醛、2-戊酮、苯甲醛、2,5-二甲基-4-羟基-3(2H)-呋喃酮,修饰组分为3-甲基丁醇、2,3-二甲基-5-乙基吡嗪、2,5-二甲基吡嗪、2,3-二甲基吡嗪、2-甲基丙醇;(3) 130~135℃为降低可可豆苦涩味的最佳烘焙温度。     

Synthesis and Aroma Properties of New Alkyloxazoles and Alkylthiazoles Identified in Cocoa Butter from Roasted Cocoa Beans

Previous work provided evidence for the occurrence of new alkyloxazoles and alkylthiazoles in the volatiles of cocoa butter from roasted cocoa beans. The synthesis, mass spectral data and sensory properties of these compounds are reported.     

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.     

Evaluation of the effect of processing on cocoa polyphenols: antiradical activity,anthocyanins and procyanidins profiling from raw beans to chocolate

The content and composition of anthocyanins and procyanidins in fermented cocoa beans (from different geographic origins: Ecuador, Cameroon, Ivory Coast, Ghana and Nigeria), roasted nibs, cocoa mass and chocolate were determined, beside the determination of the total antiradical capacity. Concerning geographic origin, cocoa beans and processed products from Ecuador showed the highest levels of anthocyanins, followed by Nigeria and Cameroon. Generally, as cocoa beans were further processed, the levels of anthocyanins and flavan‐3‐ols decreased. The largest observed losses of phenolics occurred during roasting. A progressive decreasing trend in polyphenol concentration was observed in the other processed samples as well. Despite the original content of polyphenols in raw cocoa beans, technological processes imply a significant impact on cocoa quality, confirming the need of specific optimisation to obtain high value chocolate.