'Moist incubation' process for fruitier dark chocolate

New methods of making chocolate continue to be explored in order to develop the latest taste sensations. Now, researchers reporting in ACS’ Journal of Agricultural and Food Chemistry have found that an alternative processing step called 'moist incubation' results in a fruitier, more flowery-tasting dark chocolate than the conventional fermentation process.

Making chocolate is a multistep process that begins with freshly harvested cocoa beans. After harvest, the beans are traditionally covered in banana leaves and left for a few days to ferment. During this time, microbes in the environment degrade the pulp surrounding the beans, heating and acidifying them. This causes biochemical changes in the beans that reduce bitterness and astringency, while developing the pleasing flavours and aromas associated with chocolate.

Recently, scientists developed an alternative, non-microbial approach called moist incubation, in which dried, unfermented cocoa nibs are rehydrated in an acidic solution, heated for 72 hours and then re-dried. The method, which is said to be faster and more easily controlled than fermentation, produced similar aromas in beans as fermentation, with some differences. Irene Chetschik, Ansgar Schlüter and colleagues wanted to find out how the taste and aroma of the final product — chocolate — compared when using moist incubation versus traditional fermentation.

The researchers made chocolate bars using moist incubated or fermented dried cocoa beans, as well as unfermented beans as a control. Sensory panellists said the moist incubated sample had higher intensities of fruity, flowery, malty and caramel-like aromas, whereas the fermented one had higher roasty aroma notes, and the bar made from unfermented beans had a primarily green aroma. The panellists rated the moist incubated sample as the sweetest-tasting, while the unfermented chocolate was the most bitter and astringent.

Identification of aroma compounds by gas chromatography (GC)-olfactometry and their subsequent quantitation by GC-mass spectrometry revealed higher levels of malty compounds called Strecker aldehydes and lower amounts of roasty compounds called pyrazines in the moist incubated chocolate compared with the fermented one.

The researchers concluded that moist incubation produces a chocolate with a pleasant aroma and taste and could, therefore, serve as an alternative postharvest treatment.

Image credit: ©stock.adobe.com/au/Andrey Cherkasov