Factors Affecting the Formation of Alkylpyrazines during Roasting Treatment in Natural and Alkalinized Cocoa Powder

Abstract

The cocoa roasting process at different temperatures (at 125 and 135 degrees C for 3 min, plus 44 and 52 min, respectively, heating-up times) was evaluated by measuring the initial and final free amino acids distribution, flavor index, formol number, browning measurement, and alkylpyrazines content in 15 cocoa bean samples of different origins. These samples were also analyzed in manufactured cocoa powder. The effect of alkalinization of cocoa was studied. Results indicated that the final concentration and ratio of tetramethylpyrazine/trimethylpyrazine (TMP/TrMP) increased rapidly at higher roasting temperatures. The samples roasted with alkalies (pH between 7.20 and 7.92), such as sodium carbonate, or potassium plus air injected in the roaster during thermal treatment, exhibited a greater degree of brown color formation, but the amount of alkylpyrazines generated was adversely affected. The analysis of alpha-free amino acids at the end of the roasting process demonstrated the importance of the thermal treatment conditions and the pH values on nibs (cocoa bean cotyledons), liquor, or cocoa. Higher pH values led to a lower concentration of aroma and a higher presence of brown compounds.

Radical scavenging activity, anti‐bacterial and mutagenic effects of Cocoa bean Maillard Reaction products with degree of roasting

“…However, in the lower MW polymers, many compounds seem to be incorporated, which are able to form highly active products during the prolonged heating conditions used for roasting [4,7]. Roasting products such as pyrazines, pyrroles, furans, pyridins or thiazoles, which are well known to be formed in coffee [31,32] but also in cocoa [33] might also contribute to the antioxidative potential of the roasted samples. This fact is confirmed by the profile found in 10 -5-kDa fractions: the roasted samples showed the highest antioxidative potential, which correlated with the concentration of reducing substances (p a 0.05; r 2 = 0.990; see Table 1) in comparison to raw and pre-roasted fractions (p a 0.05).…”

A Headspace Solid Phase Microextraction (HS-SPME) method for the chromatographic determination of alkylpyrazines in cocoa samples

“…For cocoa, in terms of contribution to their sensorial characteristics (and, in consequence, to their commercial value), the most important Maillard reaction products are the alkylpyrazines. 3 Considering their impact on the aroma, the ratios between the amounts of some alkylpyrazines on the volatile fraction of of cocoa and chocolate (the pyrazinic ratios) can be adopted as parameter for quality assessment of these products. 4 The determination of alkylpyrazines on cocoa products has been performed using techniques such as vacuum distillation, 5 extraction 6 or supercritical fluid extraction 7 for analyte isolation and pre-concentration, always followed by separation and detection of extracted materials by Gas Chromatography (GC).…”

Studies on the aroma of cupuassu liquor by headspace solid-phase microextraction and gas chromatography

“…1 shows typical GC-IT-MS chromatograms of cupuassu liquor headspace. The most intense peak corresponds to tetramethylpyrazine (a product of the Maillard process), which was already recognized as one of the key odorants in cocoa products [11,27]. Other detected alkylpyrazines include 2,3,5-trimethylpyrazine; 3-ethyl-2,5-dimethylpyrazine; 2,3,5-trimethyl-6-ethylpyrazine; 2,5-dimethylpyrazine and 2,3-dimethylpyrazine.…”

“…For example, Bonvehí and Coll [11] found, for natural and alkalinized cocoa powder, 0.5-2.0 g g −1 tetramethylpyrazine. Counet et al [27] found up to 6.6 g g −1 of this analyte in chocolate; finally, for roasted cocoa beans, Sanagi et al [36] detected up to 0.9 g g −1 .…”

“…Among the Maillard reaction products, alkylpyrazines are the most significant in terms of aroma-impact on cocoa products [11]. In light of its resemblance to cocoa, any methodology for aroma screening of cupuassu chocolate or liquor should be able to isolate and detect alkylpyrazines.…”