Direct Measurement of Chocolate Components Using Dispersive Raman Spectroscopy at 1000nm Excitation.

Abstract

Chocolate is a popular food around the world. Making chocolate-based confectionaries involve multiple processing steps including cocoa bean fermentation, cocoa bean roasting, grinding, and then a controlled crystallization, where the processing conditions yields the desirable polymorph V to give chocolate its characteristic snap and texture. Raman spectroscopy is well known as a technique that can provide a non-contact, non-destructive analysis of chemical composition and molecular structure. Yet, excitation in the visible and near-infrared (532-785nm) has not been possible for dark or milk chocolate because of the samples' overwhelming fluorescence. New technologies enabling Raman spectroscopy closer to shortwave infrared wavelengths, closer to 1000 nm, are likely to reduce fluorescence of chocolate and other highly fluorescent samples. Based on the successes of 1064nm excitation to understand chocolate blooming, we hypothesized that 1000nm excitation would also reduce fluorescence and enable Raman spectroscopy in dark and milk chocolates. We used dispersive Raman spectroscopy at 1000nm to measure white, milk, and dark chocolate and cocoa nibs. The use of 1000nm excitation effectively reduced fluorescence, enabling qualitative and quantitative Raman spectroscopy directly on chocolate samples. These feasibility studies indicate that 1000nm Raman spectroscopy can be used to measure chocolate in a laboratory or process environment.