Profil aromatique de cacaos fins : mise en évidence des spécificités de la variété « Criollo » et du terroir haïtien

Details

Supervisors

Collin, Sonia

Faculty

Faculté des bioingénieurs

Degree label

Master [120] : bioingénieur en chimie et bioindustries

Abstract

enThe SAFE aroma-extraction method, previously applied in our laboratory on chocolates, turned also to be relevant for the analysis of fermented and dried cocoa beans. Numerous Haitian cocoa beans and derived chocolates were here analyzed through this method (hyphenated to GC-MS, GC-O-AEDA and GC-PFPD) and compared to other Criollo beans (Madagascar, Mexico and Comoros) and commercial chocolates (Marcolini). Besides linalool (coriander, flower aroma) detected above its odor threshold in all Criollo beans samples, but reaching 23-61 ppb (10 FU) only in beans from Jacmel, ethyl cinnamate (strawberry, 41 ppb / 3 FU), benzaldehyde (bitter almond, 4.9 ppm / 1230 FU), ⍺-terpineol (ripe orange, 60 ppb), and 4-methylphenol (burnt, 3 ppb) were found in concentrations significantly higher in Haitian beans sold by Ayitika (unsorted batches). Moreover, γ-nonalactone (coconut, 13 ppb), γ-decalactone (peach, 7 ppb), 3-methylbutanoic acid (cheese, 564 ppb / 26 FU) and ethyl heptanoate (brandy, 14 ppb / 7 FU) were quantitated in larger amounts in beans issued from SHA068 (an Haitian Criollo tree, genetically confirmed). Yet, the last ester from this list revealed also peculiar of the Comoran beans (164 ppb / 1 FU), exhaling an intense wine/brandy smell. Our results indicate the huge potential of the endemic Criollo cocoas from Jacmel, and furthermore, the possibility of differentiating batches for bean-to-bar chocolatiers looking for exclusivities. Our aroma analyzes also highlighted the quality of the post-harvest treatments operated by Ayitika. Indeed, many pleasant fermentation aromas were found, including 2-phenylethanol (rose, up to 5.5 ppm / 26 FU), ethyl hexanoate (apple, up to 112 ppb / 1 FU) and ethyl octanoate (pineapple, up to 165 ppb / 33 FU). In addition, the reducing sugars and free amines released during this stage made it possible to generate Strecker aldehydes during roasting (2- and 3-methylbutanal / chocolate / 690 ppb / 69 FU, methional / potato / 10 ppb / 50 FU and phenylacetaldehyde / honey / 1.2 ppm / 30 FU), and pyrazines (2,3-dimethyl / chocolate / 224 ppb / 1 FU, trimethyl / cocoa / 210 ppb / 1 FU, tetramethyl / walnut / 1.5 ppm / 1 FU and 2-ethyl-3-methyl / grilled hazelnut / 251 ppb / 2 FU), most of them detected above their odor threshold in our chocolate Essai 5. Traces of dimethyltrisulfide, known to synergistically amplify the chocolate aromas, were also evidenced. The recipe applied in our micro-chocolate factory consisted of 30 minutes roasting at 135-140°C, enabling to preserve the full potential of varietal aromas. This has been the case since we did recover ethyl cinnamate, benzaldehyde, ⍺-terpineol, γ- and δ-decalactone in chocolate Essai 5 at levels higher than in commercial chocolates (Marcolini) produced with Criollo beans from other origins. In addition to improving their batch to batch consistency, we recommend Ayitika managers to focus all their efforts on a better control of cadmium, whose content exceeds (up to 2.9 ppm) the standards recently adopted by the European Community for 50+% rich cocoa chocolates (0.8 ppm).