Study of volatile profile in cocoa nibs, cocoa liquor and chocolate on production process using GC x GC-QMS

摘要

Chocolate quality depends on the type of cocoa and how its manufacture was conducted. In this work, the analysis of the volatile fraction of the principal steps - from cocoa to chocolate - was performed. For this purpose, unroasted nibs, liquor and chocolate samples from five different places were used, and the isolation was conducted by HS-SPME (headspace solid phase microextraction) using a DVB/CAR/PDMS (divinylbenzene/carboxen/polydimethylsiloxane) fiber, lately desorbed in a homemade GC x GC chromatograph and detected by mass spectrometry. All the compounds with appropriate chromatographic resolution in the contour plots were identified by mass spectrum and retention index. After that, the compounds areas with match greater than 90% were used on two principal component analyzes to determine the volatile compounds differences in some steps of chocolate production. In the unroasted nibs-liquor step, pyrazines were found as the main difference between the composition of the sample, while in the liquor-chocolate step several chemical classes compounds were found. It was also possible identify the main compounds responsible for the different steps in chocolate production using HS-SPME and GC x GC-QMS.