Use of mid-infrared spectroscopy to predict the content of bioactive compounds of a new non-dairy beverage fermented with water kefir

The present work aimed at development and characterization of a functional beverage and the construction of calibration models to predict the content of phenolic compounds, antioxidants, and anthocyanins in the fermented product. Mid-infrared spectra of the samples were obtained for different fermentation times, and PLS regression was applied to elaborate predictive models. The beverages were prepared and characterized by traditional methods, and, later, individual calibration models were built for each parameter analyzed. Through PCA it was possible to obtain a certain separation degree between the samples submitted to different fermentation times. The values of the coefficients of determination (R2) gathered in the validation stage of the models ranged from 0.74 to 0.89 and pointed to a good correlation between the data experimentally collected and the values predicted by the models. The results showed that the best prediction was obtained for estimating the content of total anthocyanins, which presented RMSEP, R2 and RPD values of 0.18, 0.89, and 3.11, respectively. This study demonstrated the applicability of MIR spectroscopy with chemometrics to predict some bioactive compounds of interest during kefir fermentation.