The effect of fermentation and roasting on free amino acids profile in Criollo cocoa (Theobroma cacao L.) grown in Venezuela

Abstract

The development of cocoa flavor and aroma is a complex phenomenon that depends on how the fermentation and roasting processes are carried out. During fermentation, the formation of some compounds so-called “aroma and flavor precursors” takes place, which are finally expressed during the roasting stage. Therefore, the evaluation of aroma precursors such as the amino acids formed during fermentation is crucial in order to determine the quality of the cocoa. In this context, we developed and validated a method for the study of these compounds in cocoa samples. The amino acids were quantitatively converted into their trimethylsilyl derivatives before their determination by gas chromatography with mass spectrometry detection. The results were verified performing precision and accuracy studies. The inter and intra assay coefficients of variation (C.V, n = 5) were lower than 4.7% and 4%, respectively. The analytical recoveries (95% to 108% with C.V < 4.2, n = 5) demonstrated the high performance of the extraction procedure. The method was successfully applied to the analysis of the amino acids in 110 samples of Venezuelan Criollo cocoa during the three days of fermentation and roasting (110 °C for 25 min). All samples had an appreciable content of free amino acids ranging between 3.87 and 5.97 g/kg in the absence of fermentation. We observed degradation of the acidic amino acids during the first day of fermentation, while the rest of amino acids increased progressively during the fermentation process with a predominance of the hydrophobic ones, mainly leucine, phenylalanine, valine, alanine and isoleucine. Additionally, during the roasting stage a fraction of the amino acids, especially the hydrophobic ones, was partially degraded through Maillard reaction to form the compounds associated with the cocoa aroma and flavor.

Dissecting industrial fermentations of fine flavour cocoa through metagenomic analysis

“…Like LAB, AAB species have been previously reported to play an important role in flavour development 5 , 34 and by affecting the microbial community structure 33 , 35 . Moreover, their ability to convert ethanol into acetic acid is very important to allow the release of enzymes from the dead seeds, which are crucial to producing flavour precursors such as hydrophilic peptides, hydrophobic amino acids, polyphenols, and reducing sugars 2 , 5 , 8 , 9 . At both farms, the relative abundance of AAB was observed to increase over fermentation (Fig.…”

“…Moreover, it contributes together with AAB to the production of weak acids involved in embryo death, thus allowing the release of enzymes (e.g. proteases, lipases) present in the seeds and several flavour precursors 2 , 5 , 8 , 9 . In this work, we also identified the lactic acid bacterium Weissella ghanensis recently reported on Ghanaian cocoa fermentations 41 and colombian coffee fermentations 42 .…”

“…Up to now, several studies have focused on the identification of microorganisms during bulk cocoa fermentations 17 – 22 . Comprehensive studies regarding the fermentation of fine-flavour cocoa beans are rare 9 , 23 and this field is still in its infancy. Very recently, the effect of different on-farm traditional fermentation protocols and environmental conditions in the composition of microbial communities have been studied in two different agro-ecological zones in Colombia 23 .The authors evaluated the effect of dissimilar fermentation protocols, climate, and other parameters on the microbial composition over time.…”

Influence of S. cerevisiae and P. kluyveri as starters on chocolate flavour

“…Some studies confirmed the presence of endoprotease and carboxypeptidase. 47,48 Both these proteases are composed mainly of albumin and vicilin-class (7S) globulin, which can degrade the majority of protein content inside beans during fermentation. 49,50 Free amino acids and hydrophilic peptides derived from the vicilin-class (7S) globular storage protein are necessary for the formation of the cocoa-specific flavours during the roasting process.…”

Avaliação da composição nutricional, caracterização e correlação dos parâmetros de qualidade da polpa do cacau

“…O cacaueiro é uma planta pertencente à Família Malvaceae, gênero Theobroma, nativo da América do Sul e Central (Brunetto et al, 2020;Souza et al, 2018).…”