Preserving the inherent flavour of chocolate

Proponents of ‘natural’ foods claim that reduced processing can help to preserve the food’s inherent flavour. Now research published in ACS’s Journal of Agricultural and Food Chemistry has found that in certain artisanal chocolates, some of the fruity flavours and sour tastes could be lost when the cacao beans are processed at high temperatures.

Chocolate is made from cacao beans which are fermented, roasted and processed into cacao nibs, which can be eaten on their own or melted down and sweetened to form chocolate products. Similar to wines, the environmental conditions, or ‘terroir’, where the cacao is grown provide a unique flavour profile to the bean. When the beans are roasted during processing, these subtle flavours can be hidden or destroyed.

To preserve the terroir and potential health benefits of cacao beans, some chocolatiers have shown interest in creating minimally processed products by skipping the roasting step. Though these are often called ‘raw’, this could be misleading because chemical changes have already occurred during fermentation. However, exactly which flavour compounds are potentially lost during this process is not well understood. Researchers Marlon Ac-Pangan, Nicki Engeseth and Keith Cadwallader wanted to investigate how the aroma and sensory characteristics of chocolate change during high-temperature roasting.

Unroasted cacao beans, as shown here, feature unique fruity flavours that can be lost when they’re processed at high temperature. Credit Marlon Ac-Pangan.

The researchers made two groups of nibs from the same set of cacao beans, one roasted and one not. Both groups were moulded into chocolates. The researchers used solvent-assisted flavour evaporation and aroma extract dilution analysis to find that volatile flavour compounds, including the ‘hazelnut-like’ 2- or 3-methylbutanoic acid and the ‘caramel-like’ HDMF were more pronounced in the roasted samples. However, the roasting process masked other volatiles, including the ‘bell pepper-like’ 2-isobutyl-3-methoxypyrazine — which were more noticeable in the unroasted chocolate, along with others that have fruity or flowery aromas.

A trained sensory panel found that unroasted samples tasted sourer and sweeter. The researchers say that this is probably because the vinegary flavours produced during fermentation were allowed to shine, instead of being masked by the more ‘roasty’ flavours. While roasting does change the flavour profile and may make it more ‘chocolatey’, it may hide some of the more subtle flavours from the raw cacao.

Image credit: iStock.com/Alexander Labut