Unique flavors are derived from cocoa beans that originate from different geographic regions. Continually monitoring these flavor differences using a trained sensory panel can be effective; however, this process is time consuming, costly, and subjective in nature. To simplify the screening process and, more objectively, gauge the flavor potential of cocoa beans, this study sought to develop a multivariate statistical model to enable predictions of cocoa bean flavor from analytical measurements of the volatiles emitted during nib roasting. Twelve cocoa bean samples were examined using traditional bean quality tests to assess fermentation, headspace/gas chromatography (GC) to provide analytical characterization, and subsequently, made into chocolate and evaluated by a trained sensory panel. Both the analytical and sensory data matrices allowed the cocoa beans and their corresponding chocolates to be distinguished and similarly grouped using principal component analysis (PCA). When the data matrices were subjected to partial least squares regression analysis (PLS) to test for correlation, a limited predictive model was generated.

Anhydrous milk fat (AMF) was fractionated by a two-stage dry fractionation process to produce three fractions: high melting (HMF), middle melting (MMF), and low melting (LMF). The HMF (m.p. 42°C) exhibited a broad melting range similar to a plastic fat. The MMF (m.p. 33°C) resembled the original AMF (m.p. 31°C), but with slightly higher solid fat content. The LMF (m.p. 16°C) was liquid at ambient temperature. Differences in the thermal properties of these fractions were attributed to the triacylglycerols (TAG) and their fatty acid composition. Saturated TAG with carbon numbers of 36–54 were concentrated in the HMF; whereas unsaturated TAG of carbon number 36–54 predominated in the LMF. Likewise, the long-chain saturated fatty acids were significantly higher and the long-chain unsaturated fatty acids were significantly lower in the HMF fraction. Binary blends of milk-fat fractions with a range of melting profiles were produced by mixing HMF with AMF, MMF, or LMF. Laboratory-prepared fractions were similar to commercially available fractions.

Milk chocolate (30% total fat) was formulated by replacing cocoa butter at various concentrations with milkfat fractions from 12.2 to 40% of total fat. Maximum concentration of milkfat addition that produced temperable milk chocolate were up to 40% AMF, MMF and LMF, and up to 35% HMF. Modified tempering procedures were used for milk chocolates containing over 20% milkfat. Degree of temper was evaluated using differential scanning calorimetry (DSC) and expressed as the ratio of enthalpies of melting for the higher stability polymorphs to those of lesser stability. Degree of temper was dependent on the crystallisation time and temperature and the type and quanity of milkfat fraction in the formulation. The solid fat content (SFC), as measured by DSC, of milk chocolate decreased with increasing milkfat addition. At 30 degrees C, the SFC for milk chocolate containing 12.2% AMF was 53.1% and at 40% AMF addition, the SFC was 13.1%. A significant decrease in hardness was observed as the cocentration of milkfat increased. No significant differences in viscosity were detected among all conched samples at 40 degrees C. However, a noted change in milk chocolate viscosity during tempering was observed. During accelerated fat bloom stability studies, milk chocolate samples with 25, 30, 35 or 40% AMF, MMF and HMF remained free of bloom after 100 days. Samples containing LMF at all concentrations bloomed within 37 days. No differences in sweet, milk powder, chocolate and butter flavor or thickness of melt were evident among the formulations. Significant differences in milk flavor and in the textural attributes of hardness, uniformity of mass and onset of melt were observed for increasing concentrations of milkfat. Sensory hardness and onset of melt decreased, and uniformity of mass increased with increasing concentrations of milkfat. No significant differences between the types of milkfat (AMF, HMF, MMF, LMF) were observed for any of the textural attributes tested.

ABSTRACTMaximum additions of milk fat that produced temperable milk chocolates were anhydrous milk fat (AMF), middle‐melting fraction (MMF) or low‐melting fraction (LMF) up to 40 wt % total fat, and high‐melting fraction (HMF) up to 35%. The solid fat content (SFC), melting point, melting enthalpy, instrumental and sensory hardness of milk chocolates decreased with increasing milk fat addition. No differences in sensory attributes sweetness, milk powder, chocolate, butter flavor or thickness of melt were observed. Chocolate with 40% MMF or LMF had greater milk flavor than that with 12.2% HMF. Onset of melt correlated (r = 0.96) with melting enthalpy. No differences between types of milk fat (AMF, HMF, MMF, LMF) were observed for any textural attribute assessed.

Anhydrous milk fat (AMF) was fractionated by a two-stage dry fractionation process to produce three fractions—high-(HMF), middle-(MMF), and low-melting (LMF). The effect of replacing 12.2–40% by weight of cocoa butter with these fractions on the tempering profile of milk chocolate was studied. Degree of temper was evaluated by differential scanning calorimetry, and expressed as the ratio of enthalpies of melting for higher-stability polymorphs to those of lesser stability. The degree of temper was dependent on the crystallization time and temperature, and the type and quantity of milk-fat fraction in the formulation. Chocolates containing AMF or its fractions in concentrations of up to 20 wt% (total fat basis) were tempered after a conventional thermocycling tempering process (50°C/30 min, 27.7°C/4 min, 31°C/2 min) to obtain products with good contraction and mold release properties. For those milk chocolate formulations that did not temper by the conventional method and resulted in poor contraction and mold release, a new tempering protocol was developed. Lower crystallization temperatures and/or longer holding times were required at concentrations of AMF, MMF, or LMF above 20%. Chocolate containing HMF required slightly higher crystallization temperatures because of high viscosity. Chocolates containing up to 35% HMF and up to 40% of the total weight of fat in the chocolate of AMF, MMF, and LMF were successfully tempered by adjusting crystallization time and temperature.

ABSTRACTHeadspace volatiles from ground roasted Florunner medium peanuts, stored at 65°C for 1–68 days, were separated and identifled by GC/MS. Selected pyrazines, resulting from Maillard browning and selected aldehydes from autoxidation were evaluated to determine their mechanistic contributions to peanut ‘flavor‐fade.’ The 2,6‐dimethylpyrazine, 2‐methylpyrazine, 2‐ethyl‐5‐methyl or 6‐methylpyrazine, 2,3,5‐trimethylpyrazine, and pentanal remained constant during storage (p < 0.05). Flavor scores for ‘roasted peanut’ decreased slightly, then leveled off and hex‐anal, heptanal, octanal and nonanal increased during storage (p < 0.05). Oxidative ‘rancid’ flavor scores and thiobarbituric acid values also increased during storage (p < 0.05). Based on results, the ‘flavor‐fade’ of stored roasted peanuts is due to masking of pyrazines and other ‘roasted peanut’ flavor compounds by large quantities of low‐molecular weight aldehydes from lipid autoxidation, and not due to polymerization and/or degradation of the pyrazines.

Flavour characteristics of the chocolate made from 14 dried, fermented cocoa bean samples from eight different countries of origin and the relationship with pH, titratable acidity and acetic and lactic acid were studied. The fermented dried cocoa beans were processed into semi-sweet dark chocolate and were evaluated for their flavour difference by the multiple comparison test using the Ghanaian sample as a reference. The descriptors and the intensities of the chocolate flavour perceived by the taste panel members were also obtained. There was no correlation between the flavour score and the pH, tritratable acidity, acetic and lactic acid concentrations. The study found that chocolate samples made from the low pH (4.75–5.19) and high pH (5.50–5.80) cocoa beans have low response in strong chocolate flavour. On the other hand, chocolate samples made from the Ghanaian and Nigerian beans which have medium pH values of 5.20–5.49 received a high response in strong chocolate flavour. More off-flavour descriptors were perceived from chocolate samples made from low-pH cocoa beans.

Differential scanning calorimetry measurements of crystallization and melting characteristics of commercial samples of anhydrous milk fat (AMF), cocoa butter (CB) and hydrogenated palm kernel stearin (PKS) in ternary blends were studied. Results showed that stabilization at 26°C (either for 40 h or 7 d) did not greatly affect the melting thermogram trace of PKS. However, the effect of stabilization became prominent as CB was added into the system. Deviation of measured enthalpy from the corresponding values, calculated for thermodynamically ideal blends, showed clear interaction between all three fats. At 20°C, the strongest deviation occurred at about the AMF/CB/PKS (1∶1∶1) blend, whereas at 30°C the deviation moved toward the CB/MF (1∶1) blend. The presence of 25% AMF in PKS had little effect on its solidification capability, but solidification was adversely affected with inclusion of CB.

Commercial samples of anhydrous milk fat (AMF), Ivory Coast cocoa butter (CB) and palm mid-fraction (PMF) were blended in a ternary system. The melting characteristics of the blends were studied by differential scanning calorimetry (DSC). Results suggest that in the studies of interaction involving more than two fats, partial area (Ai) under the melting peak should be converted to partial enthalpy (ΔHi) rather than to solid fat index. The ΔH values of the blends decreased as the amount of AMF was increased and increased as the amount of CB was increased. In general, the effect of PMF was less pronounced compared to the effect of the other two fats. Eutectic effects within the ternary system could be detected by measuring the deviation of melting enthalpy by DSC, and from the corresponding values that were calculated for the thermodynamically ideal blends. The deviation reached a maximum when the amount of AMF was about 33%. On the binary line of CB/PMF, the eutectic effect was maximum at about 50–75% PMF. The interaction effect in the system was more noticeable at 30 and 20°C than at lower temperatures. Evaluation at 30°C was preferred because both the effect of AMF in the ternary system and the effect of PMF on the binary line were more readily observed.

Thirty-three cured cocoa bean samples were roasted at 150-degrees-C for 20 min (short roast) or 30 min (long roast) and evaluated for pH, titratable acidity, volatile acid concentration (acetic, propionic, isobutyric, butyric and isovaleric acid) and non-volatile acid concentration (oxalic, citric, tartaric, malic, succinic and lactic acids). Titratable acidity decreased following roasting, whereas pH increased during the long roast only. Long roasting increased butyric acid and reduced the concentration of the other volatile acids and malic acid but not that of oxalic, citric, succinic and lactic acids. Butyric acid concentration was also increased by short roasting, but propionic, isovaleric and malic acids were reduced under these conditions.

ABSTRACTPolyphenol oxidase (PPO) was extracted from cocoa beans and subsequently purified using ammonium sulfate precipitation followed by high performance liquid chromatography (HPLC) for enrichment. HPLC analysis was performed using hydrophobic interaction chromatography which resulted in a 6.5‐fold enrichment and a 24.6% recovery of the enzyme. Enrichment was confirmed using polyacrylamide gel electrophoresis under nondenaturing conditions. Comparison of enzyme‐ and protein‐stained electrophoretic gels revealed the presence of possible multiple molecular forms of PPO and the absence of non‐enzymic contaminating protein, indicating a rapid procedure of enzyme extraction and enrichment.

ABSTRACTThirty‐nine fermented and dried cocoa bean samples from 13 countries were evaluated for pH, titratable acidity and concentrations of volatile and nonvolatile acids. The correlation coefficient between pH and log10 titratable acidity was ‐0.94. Cocoa beans from Brazil and Far Eastern countries were highly acidic while those from Central American and South American countries were low in acidity. Samples from West African countries were intermediate with titratable acidity values from 0.12 to 0.15 meq NaOH/g sample and pH values from 5.20 to 5.49. Highly acidic beans were characterized by high concentrations of acetic and lactic acids. The high correlation between acetic acid and both pH (r=0.86) and titratable acidity (r = 0.91) indicated that this acid could be primarily responsible for high acidity in cocoa beans.