Impact of solar pre-drying and yeast starter inoculation treatments on volatile compounds in cocoa (Theobroma cacao L.) beans from Southwestern Colombia

Abstract

In the region of Tumaco (Nariño, Colombia), in Southwestern Colombia, the CCN-51 cocoa clone has been commonly cultivated in recent decades. Determining the influence of cocoa processing conditions (pre-drying and yeast starter inoculation) on the profile of volatile compounds is essential to ensure maximum cocoa quality. To this aim, cocoa beans were fermented following four different treatments: (1) spontaneously (at room temperature for 120 h) in traditional conditions (control; CO); (2) traditional processing with a pre-drying (sun-dried for 24 h) treatment (PD); (3) with fermentation (for 120 h) after inoculation of a yeast starter culture (YS); and (4) including both treatments, pre-drying and yeast inoculation (PD+YS). A total of 45 volatile compounds were identified by SPME-HS/GC–MS and classified as: alcohols (9), aldehydes and ketones (17), acids (6), esters (3), pyrazines (2), aliphatic hydrocarbons (4) and others (4). Pre-drying and yeast starter inoculation reduced the concentration of acids, which are associated with off-flavour notes. Fermentation with a selected yeast culture generated desirable flavour notes (sweet, fruity, floral, buttery and malty). The PCA score plot showed a clear separation of the samples obtained from the different treatment studied. In conclusion, pre-drying and inoculating with selected yeasts during processing help enhance the sensory quality of the cocoa.

Keywords

• Theobroma cacao
• Fermentation-drying process
• Starter culture
• Volatile profile
• Principal component analysis