Viability of IR spectroscopy for the accurate measurement of yeast assimilable nitrogen content of grape juice

Abstract

[EN] Up to date, there have been only a few reports on'the measurement of YAN and/or its components using IR spectroscopy, suffering from various limitations (number of samples, validation strategies, etc.). In this work, three IR spectral instruments measuring in different modes and ranges of the IR spectrum (FT-IR, FT-NIR, and ATR-MIR), were compared and evaluated for their accuracy to measure both total YAN as well as the components, FAN and ammonia separately, using over 900 grape juice samples from 28 cultivars over three seasons. The global and vintage-based models were evaluated using R-CAL/VAL(2) RMSEC/P, and RPDCAL/VAL. Randomization tests were used for pair-wise comparison of models. FT-IR and FT-NIR instruments gave the best results, while ATR-MIR can be used for screening purposes. Considering the accuracy, robustness, high throughput, and costeffective nature, the models produced by both FT-IR and FT-NIR spectroscopy can provide winemakers with the opportunity to make timelier and more informed nutrient supplementation decisions, facilitating the achievement of their desired wine style and quality.