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Recently, moist incubation has been proposed as an alternative postharvest processing method for cocoa beans. During this treatment, unfermented and dried cocoa nibs are rehydrated with a lactic acid solution containing ethanol and subsequently incubated for 72 h at 45 °C before drying. Previous studies focused on the aroma formation during this treatment and the further processing of chocolate. The current study focused on the influence of aerobic and anaerobic moist incubation on selected nonvolatile components in comparison with the unfermented raw material and traditionally fermented cocoa. Total phenolic content and total flavan-3-ol content, contents of (+)-catechin, (-)-epicatechin, procyanidins B2 and C1, cinnamtannin A2, methylxanthines (theobromine and caffeine), contents of sugars (sucrose, d-glucose, and d-fructose) and free amino acids (17 proteinogenic amino acids) were determined. The fermentation index was also evaluated. The aerobically incubated and fermented cocoa showed low levels of phenolic compounds in comparison to the unfermented cocoa and the anaerobically incubated cocoa. The level of methylxanthines was unaffected by all treatments. The contents of reducing sugars were more than 2-fold higher after both incubation treatments compared to fermentation. The level of free amino acids liberated was highest after anaerobic incubation followed by fermentation and aerobic incubation. The aerobically incubated cocoa showed the highest FI, while the anaerobically incubated cocoa may be considered under-fermented (FI <1.0). Statistical analysis (ANOVA) showed significant differences between all treatments, which was verified by principal component analysis.

Fine flavor properties of chocolates such as fruity, floral, and cocoa-like were decoded on a molecular level for the first time. The molecular compositions of six chocolates made out of liquors that were referenced with specific sensory attributes were analyzed. After the screening for odor-active molecules by aroma extract dilution analysis, selected compounds were quantitated with the overall aim to decode the distinct fine flavor attributes on a molecular level. Acidic and fruity flavor notes were associated with high dose over threshold factors (DoT factors) of acetic acid and fruity smelling esters such as ethyl 2-methylbutanaote, ethyl 3-methylbutanoate, and 3-methylbutyl acetate, respectively. Cocoa-like and roasty flavor notes were associated with high DoT factors for 2-methylbutanal, 3-methylbutanal, 4-hydroxy-2,5-dimethylfuran-3(2 H )-one, and dimethyltrisulfane. The floral and astringent flavors were linked to high DoT factors of (-)-epicatechin, procyanidin B2, procyanidin C1, and 2-phenylethan-1-ol.

In a previous investigation, "moist incubation" was described as a novel postharvest treatment for cocoa and the aroma composition of the resulting cocoa nibs was compared to unfermented and fermented cocoa nibs. For this treatment, unfermented and dried nibs are rehydrated with an aqueous solution containing lactic acid and ethanol to adjust the pH value and are subsequently incubated at 45 °C under aerobic conditions for 72 h before drying. The aim of the present study was to investigate the sensory properties and aroma composition of dark chocolates made of these materials after roasting. Therefore, gas chromatography-olfactometry (GC-O) in combination with aroma extract dilution analysis (AEDA), quantitation with isotopically labeled standards, odor activity value (OAV) determination, and sensory analysis were performed. The three different chocolates had distinct sensory and OAV profiles. The sensory profiles showed a higher intensity of fruity aroma notes and a lower intensity of bitterness and astringency in the chocolate made with the moist incubated cocoa, while the chocolate made of fermented cocoa reached higher scores in the roasty aroma notes. Furthermore, higher OAVs were determined for the Strecker aldehydes in the chocolate made of the moist incubated cocoa, whereas higher OAVs for the pyrazines and the acids were detected in the chocolate made of fermented cocoa. In contrast, the chocolate produced with the unfermented cocoa showed low cocoa specific aroma notes and high levels of astringency and bitterness. The detected differences reveal interesting insights into the influence of different postharvest treatments on the resulting aroma composition in the final chocolate. Furthermore, the alternative postharvest treatment was demonstrated to result in chocolates with a pleasant sensory profile.

The impact of water on odor-active compounds in fermented and dried cocoa beans as well as in chocolate either produced by a novel processing (NPC) or a traditional processing (TPC) technology from the same batch of cocoa beans was investigated in this study. Quantitation of selected key odorants revealed significantly higher concentrations of Strecker aldehydes such as 3-(methylsulfanyl)propanal (66-fold) and phenylacetaldehyde (50-fold) after water treatment of the cocoa beans. The comparison of the two chocolates showed that higher amounts of the Strecker aldehydes 2-methylbutanal, 3-methylbutanal, and phenylacetaldehyde are released with water in the NPC (24-fold to 39-fold), compared to the TPC (7.3-fold-11-fold). In addition to Strecker aldehydes, the concentrations of many further characteristic key odorants of cocoa and chocolate increased after water treatment. Based on the results, a more intense retronasal odor perception of the analyzed compounds is expected due to their release during consumption in contact with saliva.

The aroma properties of cocoa nibs obtained by applying a novel postharvest treatment were investigated using methods of the molecular sensory science approach, i.e., solvent extraction and solvent-assisted flavor evaporation, aroma extract dilution analysis (AEDA), stable isotope dilution analysis, calculation of odor activity values (OAVs), and orthonasal sensory evaluation; those properties were then compared to the unfermented and dried raw material and a traditionally fermented sample of the same harvest. For the treatment, unfermented and dried cocoa nibs were, first, rehydrated with lactic acid and ethanol solution to adjust the pH value to 5.1 and, second, incubated under aerobic conditions for 72 h at 45 °C and subsequently dried. This treatment was used to induce enzymatic reactions within the cotyledon matrix, which also occur inside the bean during microbial fermentation of the surrounding fruit pulp. The results of the AEDA showed that many of the key aroma compounds found in fermented and dried cocoa increased during the incubation treatment. Especially some "fruity" esters were found with an equal or even higher flavor dilution (FD) factor in the incubated sample compared to the fermented sample, whereas the fermented sample showed high FD factors for "pungent, sour" and "sweaty" acids, such as acetic acid and 2- and 3-methylbutanoic acids. The quantitative data and calculated OAVs for the samples supported the findings of the AEDA, underlining the potential of this approach as a controllable and reproducible alternative postharvest treatment.

Dark chocolates produced by a novel technological approach (NCs) were characterized in comparison with those traditionally produced (TCs) by sensory evaluation, gas chromatography-olfactometry in combination with aroma extract dilution analysis, quantitation of the aroma-relevant chocolate odorants by stable isotope dilution assays, and calculation of the odor activity values (OAVs). The results of the sensory investigation by cluster analysis clearly showed a differentiation between the NC and the TC samples. The findings of the aroma measurements revealed that NCs were characterized by low OAVs of volatile acids such as acetic and 3-methylbutanoic acid and high OAVs especially for the esters ethyl 2-methylbutanoate and ethyl 3-methylbutanoate in comparison to TC samples. In contrast to that, no relevant differences could be observed for thermally generated compounds such as Strecker aldehydes and pyrazines.

The odor-active constituents of cocoa pulp have been analyzed by aroma extract dilution analysis (AEDA) for the first time. Pulps of three different cocoa varieties have been investigated. The variety CCN51 showed low flavor intensities, in terms of flavor dilution (FD) factors, in comparison to varieties FSV41 and UF564, for which floral and fruity notes were detected in higher intensities. To gain first insights on a molecular level of how the cocoa pulp odorants affected the odor quality of cocoa beans during fermentation, quantitative measurements of selected aroma compounds were conducted in pulp and bean at different time points of the fermentation. The results showed significantly higher concentrations of 2-phenylethanol and 3-methylbutyl acetate in pulp than in the bean during the different time steps of the fermentation, whereas the reverse could be observed for the odorants linalool and 2-methoxyphenol. The findings of this study constitute a basis for further investigations on the aroma formation of cocoa during fermentation.