Abstract
Chocolate made from small-batch production is known for distinct sensory properties that differentiate its products from large-scale production. Specifically, small-batch processing includes a melanging step, a chocolate refining (a process involving time and temperature to refine texture and flavor) process that occurs in a stone wet-grinder. Chocolatiers understand that melanging is essential to flavor and overall quality, however the influence of melanging on the aroma chemistry of the finished chocolate is anecdotal and largely uncharacterized. Here, we evaluated the effects of time and temperature of melanging on the volatile chemistry of the finished chocolate. Specifically, chocolate aroma was profiled using HS/SPME–GC–MS for three different time and temperature combinations. A total of 88 compounds were annotated by mass spectrometry and included a diverse set of chemical classes such as pyrazines, aldehydes, terpenes, alcohols, esters, and ketones. Analysis of variance (ANOVA), principal component analysis (PCA), and partial least squares analysis (PLS) revealed that the overall aroma profile was influenced by the type of melanging, and time had a greater effect than temperature. Example compounds affected by time include 2-methylpropanal, dimethyl sulfide, and benzaldehyde. Particle size was also measured for each sample. Majority particle size was found to be below 25 microns generally at all time points beyond 8 h. Analysis showed significant p-values for the temperature variable for several compounds, but significant p-values for the time variable were apparent for a greater number of compounds. For compounds which showed dependency on both time and temperature, the p-value for the time variable was much smaller in most cases. Both PCA and OPLS analyses suggested the same trends. These data support that time is a critical factor in determining the aroma chemistry of chocolate and affects a diverse set of known flavor active compounds.
Highlights
Chocolate made from small-batch production is known for distinct sensory properties that differentiate its products from large-scale production
All samples tested other than those at the zero time points showed most particle sizes were below 30 microns
To explore if the samples varied in their volatile profiles, and if this variation was time- or temperature-dependent, an untargeted metabolomics experiment was performed on the 36 samples (4 time points, 3 temperatures, 3 technical replicates) using HS/SPME GC–MS as described in the previous section
Summary
Chocolate made from small-batch production is known for distinct sensory properties that differentiate its products from large-scale production. Both PCA and OPLS analyses suggested the same trends These data support that time is a critical factor in determining the aroma chemistry of chocolate and affects a diverse set of known flavor active compounds. Below 4 microns, excessive surface area becomes available for the fats to coat, and the chocolate may be perceived as slimy and too viscous[6] with a high Casson yield value due to increased particle interactions[5]. For this reason, most producers aim for a particle size between 15–25 microns[7]. When the chocolate is smooth, it undergoes a series of controlled heating and cooling steps to crystalize the fats into the most desirable structure in a process known as “tempering”[8]
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