Monitoring cereals sprouting by MicroNIR

Despite the enhancement of both nutritional and sensory profile of cereals, sprouting can lead to negatively affect the technological characteristics of the obtained cereal-based products (Morris & Rose, 1996). Thus, a controlled wheat sprouting process could be useful to assess the perfect balance between nutritional advantages and technological performance (Marti et al., 2018). Nowadays the analyses to assess the wheat quality performance require sample refinement and long-time of analysis. In this context, this study aims at developing a methodology for wheat sprouting evaluation directly on kernels by a NIR portable device. To the aim, two batches of wheat kernels were sprouted and sampled after 24, 36, 43, 48, 62, 67 and 72 hours. Wet and dried samples were analysed by a MicroNIR-OnSite (VIAVI) in the spectral range of 950-1650 nm. Then samples were milled for measuring the enzymatic activities, starch pasting properties, and gluten aggregation kinetics. All the data, after the suitable pre-treatments, were analysed by PCA to assess the behaviour of the wheat according to the sprouting progress. The PCA on technological features highlighted the relevance of Falling and Stirring Number, the main sprouting indicators, together with changes in gluten aggregation properties. PCAs on spectral data, both from wet and dried kernels, assessed a similar effect of sprouting time as observed by technological data analysis: the control and 24h-sprouted samples are well distinguished from the others, whereas the changes slow down for longer times and cease after 62 hours. Wavelengths responsible of sample distribution are linked to both starch and protein absorptions. The findings suggest that a NIR portable device can be applied for the determination of wheat sprouting degree directly on wet kernels, skipping both the drying and refinement steps, and giving similar information gained by complex analysis on refined flour.