Microwave Roasting as an Alternative to Convection Roasting: Sensory Analysis and Physical Characterization of Dark Chocolate.

Roasting cocoa beans by means of microwave radiations seems to be a potential alternative to convection roasting, but little is known about the impact of this method on the perceived flavor profile of the chocolate. Therefore, this research focused on revealing the flavor perception of chocolate produced with microwave roasted cocoa beans assessed by both a trained panel and chocolate consumers. Samples of 70% dark chocolate produced from cocoa beans microwave roasted at 600 W for 35 min were compared with samples of 70% dark chocolate produced from cocoa beans convectively roasted at 130 °C for 30 min. Non-significant differences (p > 0.05) in the measured physical properties, such as color, hardness, melting, and flow behavior, showed that chocolate produced from microwave roasted cocoa beans can exhibit the same physical qualities as convection roasted chocolate. Moreover, combined discriminative triangle tests, with 27 judgements in total, performed by a trained panel, showed that each type of chocolate exhibited distinctive characteristics (d'-value = 1.62). Regarding the perceived flavor, "cocoa aroma" was cited as significantly higher for the chocolate produced from microwave roasted cocoa beans (n = 112) compared to chocolate produced from convection roasted cocoa beans (n = 100) by consumers. Both preference and willingness to buy were higher, though insignificant at a 5% level, for the microwave roasted chocolate. A final potential benefit (studied in this research) of microwave roasting cocoa beans is the reduced energy consumption, which was estimated at 75%. Taking all these results together, the microwave roasting of cocoa is shown to be a promising alternative to convection roasting.

An in-depth multiphasic analysis of the chocolate production chain, from bean to bar, demonstrates the superiority of Saccharomyces cerevisiae over Hanseniaspora opuntiae as functional starter culture during cocoa fermentation.

Hanseniaspora opuntiae is a commonly found yeast species in naturally fermenting cocoa pulp-bean mass, which needed in-depth investigation. The present study aimed at examining effects of the cocoa isolate H. opuntiae IMDO 040108 as part of three different starter culture mixtures compared with spontaneous fermentation, regarding microbial community, substrate consumption, and metabolite production dynamics, including volatile organic compound (VOC) and phytochemical compositions, as well as compositions of the cocoa beans after fermentation, cocoa liquors, and chocolates. The inoculated H. opuntiae strain was unable to prevail over background yeasts present in the fermenting cocoa pulp-bean mass. It led to under-fermented cocoa beans after four days of fermentation, which was however reflected in higher levels of polyphenols. Cocoa fermentation processes inoculated with a Saccharomyces cerevisiae strain enhanced flavour production during the fermentation and drying steps, which was reflected in richer and more reproducible aroma profiles of the cocoa liquors and chocolates. Sensory analysis of the cocoa liquors and chocolates further demonstrated that S. cerevisiae led to more acidic notes compared to spontaneous fermentation, as a result of an advanced fermentation degree. Finally, different VOC profiles were found in the cocoa beans throughout the whole chocolate production chain, depending on the fermentation process.

The effect of cocoa alkalization on the non-volatile and volatile mood-enhancing compounds.

Alkalization is a process to improve color, dispersibility and flavor of cocoa powder but is likely to have a negative effect on the phytochemicals. Hereto, the impact of alkalization degree (none, medium and high) on the potential mood-enhancing compounds corresponding to the four levels of the mood pyramid model (flavanols, methylxanthines, biogenic amines and orosensory properties) was investigated. The phytochemical content, analyzed via UPLC-HRMS, showed reduction of specific potential mood-enhancing compounds upon alkalization, implying a decrease in bitterness and astringency. Moreover, volatile compounds analysis via HS-SPME-GC-MS indicated that alkalization reduced the levels of volatile compounds, responsible for acidity, fruity, floral and cocoa aromas. With respect to the orosensory properties, the cocoa powder palatability was suggested to be increased due to reduced acidity, bitterness, and astringency, while the desired volatile compounds were reduced. However, sensorial analysis is required to link the volatile results with the overall effect on the flavor perception.

Assessing the flavor of cocoa liquor and chocolate through instrumental and sensory analysis: a critical review.

The performance of appropriate instrumental and/or sensory analyses is essential to gain insights into the flavor profile of cocoa products. This three-part review is compiled of an overview of the most commonly used instrumental techniques to study cocoa liquor and chocolate flavor, their perception by a trained panel and the potential relationship between them. Each part is the result of a thorough literature study, principally focusing on the assumptions, features and limitations of these techniques. Reviewing of the literature revealed that cocoa matrix effects and methodology restraints were not always considered when instrumentally analyzing cocoa flavor. With respect to sensory analyses, various studies lacked reporting of accomplished trainings and performance of panelists. Moreover, a discrepancy was noticed in the descriptive flavor lexicon employed. Finally, when linking instrumental and sensory data, linear modeling is regularly applied, which might not always be appropriate. This review paper addresses the challenges associated with flavor assessment, intending to incite researchers to critically study cocoa flavor and apply standardized protocols and procedures.

Roasting-induced changes in cocoa beans with respect to the mood pyramid.

The mood pyramid of cocoa, which was previously proposed as a new concept, consists of four levels (flavan-3-ols, methylxanthines, minor compounds and orosensory properties). Roasting is a crucial process for flavor development in cocoa but is likely to have a negative impact on the phytochemicals. We investigated the effect of roasting time (10-50 min) and temperature (110-160 °C) on the potential mood-enhancing compounds corresponding to the distinct mood pyramid levels. Phytochemicals were analyzed using UPLC-HRMS, while the flavor was mapped via aroma (HS-SPME-GC-MS) and generic descriptive analysis (trained panel). Results revealed that roasting at 130 °C for 30 min did not significantly affect the levels of epicatechin, procyanidin B2 and theobromine, while salsolinol significantly increased. Moreover, bitterness and astringency were reduced and the desired cocoa flavor was developed. Thus, through selection of appropriate roasting time and temperature conditions phytochemicals of interest could be retained without comprising the flavor.

Antioxidant activity and quality attributes of white chocolate incorporated with Cinnamomum burmannii Blume essential oil.

White chocolate is often considered as an unhealthy product with low phenolic content and antioxidant activity since it does not contain cocoa liquor. In this study, investigation on the phytochemical composition of cinnamon essential oil as well as its potential use to improve the antioxidant activity of white chocolate were carried out. The effect of the essential oil incorporation on the quality attributes of white chocolate was also examined. The results show that cinnamon essential oil was rich in cinnamaldehyde and exhibited antioxidant activity. The incorporation of cinnamon essential oil at a level of 0.1% (w/w) increased the antioxidant activity of the white chocolate more than twofold without significant effect on its hardness, melting properties and colour. However, a slight alteration on the flow behaviour of the white chocolate was observed. This study clearly shows that natural cinnamon essential oil could be an alternative to synthetic additives in foods to improve their antioxidant activity.