Antioxidant capacity of cocoa beans and chocolate assessed by FTIR

Abstract

The total antioxidant capacity (TAC) and total phenolic compounds (TPC) of cocoa beans and chocolate produced from spontaneous and inoculated fermentations of different cocoa varieties were evaluated. Fourier transform infrared spectroscopy (FTIR), as well as conventional methods: 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), was used to determine TAC and TPC. Chocolate showed higher (p < 0.05) TPC (47.17–57.16 mg GAE/g) and TAC (1.66–2.33 mM TE/g and 8.86–11.35 mM TE/g as measured by DPPH and ABTS, respectively) than cocoa beans (6.30–26.05 mg GAE/g, 0.24–1.17 mM TE/g and 1.29–4.83 mM TE/g for TPC, DPPH and ABTS, respectively). Partial least square (PLS) model for infrared data showed a good calibration coefficient (R2cal > 0.94), indicating that the FTIR technique represents a fast and reliable tool to evaluate TPC and TAC in cocoa beans and chocolate.