Investigations into the total antioxidant capacities of cultivars of gluten-free grains using near-infrared spectroscopy

Millet, buckwheat and oat are considered to be minor crops, hence chemical profiles for different cultivars are rare. The examination of a sum parameter, like the total antioxidant capacity (TAC) can thus be a first step to systematically assess the quality of different cultivars of mentioned gluten-free grains and thereby serve as an indicator for the selection of cultivars for food processing. TAC of 20 common buckwheat, 14 proso millet and six common oat cultivars was analysed using Folin-Ciocalteu assay and an optimized NIBS methodology. PLS regressions for milled and intact samples were established and yielded a R-2 (CV) of 0.892 and 0.929. The SEPs for milled and intact samples were approximately 1.7 and 1.6 mgGAE/g. Multivariate LOD and LOQ were also calculated. LODmax for intact and milled samples was 1.72 and 2.80 mgGAE/g. TAC varies considerably among cultivars of one species, emphasising the need for full chemical profiles. Values for LOD and LOQ show that established PLS-R models can be used to quantify TAC of buckwheat and oat cultivars. TAC of millet cultivars can be detected, however not quantified.