Abstract
Parallel application of an aroma extract dilution analysis (AEDA) to the volatiles isolated from a sample of fermented cocoa with an atypically pronounced coconut note and to the volatiles isolated from a reference cocoa sample revealed coconut-like smelling compounds δ-octalactone, δ-2-octenolactone, γ-nonalactone, γ-decalactone, δ-decalactone, and δ-2-decenolactone as potential causative odorants. Quantitation of these six compounds and calculation of odour activity values as ratios of the concentrations to the odour threshold values suggested δ-2-decenolactone as the crucial compound. Chiral analysis showed the presence of pure (R)-δ-2-decenolactone, commonly referred to as massoia lactone. Its key role for the coconut note was finally demonstrated in a spiking experiment: the addition of (R)-δ-2-decenolactone to the reference cocoa in an amount corresponding to the concentration difference between the two samples was able to provoke a coconut note in an intensity comparable to the one in the atypically smelling cocoa. To avoid an undesired coconut note caused by (R)-δ-2-decenolactone in the final products, the chocolate industry may consider its odour threshold value, that is 100 µg/kg, as a potential limit for the acceptance of fermented cocoa in the incoming goods inspection.
Highlights
Nomenclature 2-Acetyl-1-pyrroline 1-(3,4-Dihydro-2H-pyrrol-5-yl) ethan-1-one Ethyl cinnamate Ethyl (2E)-3-phenylprop-2-enoateCocoa is the key raw material in chocolate manufacturing and its quality is crucial for the pleasant aroma of chocolate products
Parallel application of an aroma extract dilution analysis (AEDA) to the volatiles isolated from a cocoa sample with an atypically pronounced coconut note (C1) and to the volatiles isolated from a reference cocoa (REF) revealed a total of 48 odorants with an flavour dilution (FD) factor of 4 or higher in at least one of the two samples, 46 of which were unequivocally identified (Table 1)
Given the fact that their coconut-like odour quality exactly matched the atypical note detected in cocoa sample C1, the six lactones were identified as potential causative compounds and a substantial contribution of other compounds was considered unlikely
Summary
Nomenclature 2-Acetyl-1-pyrroline 1-(3,4-Dihydro-2H-pyrrol-5-yl) ethan-1-one Ethyl cinnamate Ethyl (2E)-3-phenylprop-2-enoateCocoa is the key raw material in chocolate manufacturing and its quality is crucial for the pleasant aroma of chocolate products. Cocoa is derived from the seeds of the cocoa tree (Theobroma cacao L.) which is grown throughout the tropics, in Ivory Coast, Ghana, Nigeria, Cambodia, Indonesia, Ecuador, Peru, and Brazil. The cocoa fruits, known as the cocoa pods, are opened and the seeds, 30–50 per pod, are collected together with the surrounding white mucilaginous pulp. In a fermentation step of 2–10 days, the pulp is removed and the seeds, referred to as the cocoa beans [1], are dried. European Food Research and Technology (2022) 248:1513–1523 than 4 million metric tons of fermented and dried cocoa are produced [2]. Chocolate production starts with roasting of the cocoa. The roasted material is ground into cocoa liquor to which further ingredients such as sugar, cocoa butter, and milk powder are added before chocolate is obtained by conching, tempering, and moulding
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