Adaptation of the rapid near-infrared (NIR) spectroscopy technique to determine the mass fraction of protein and moisture in gluten-free bakery products

Abstract

Analysis of protein in food products is typically performed using a time-consuming and labor-intensive Kjeldahl method. The NIR method is allowed to determine the mass fraction of not only protein, but also moisture, fat, and sugar in one sample within 2 min. The NIR method is indirect; therefore, appropriate calibration models should be developed for each group of analyzed products. We performed a series of laboratory baking tests for gluten-free bakery products; the protein content in the products varied and depended on the ingredients included into the formula: rice, buckwheat and corn flour, starch and soy isolate. Continuous spectra were recorded using a NIR analyzer that operates in the wavelength range from 1400 to 2500 nm. It was shown that after validation for a specific device, the developed calibration models yield the root-mean-square deviation of 0.29 when determining the protein mass fraction and that of 0.46 when determining the moisture mass fraction.