Avaliação espectral do efeito do aquecimento em proteína de arroz e proteína tipo whey por quimiometria

Abstract

Proteins play an important role in the human body through biological functions, and in food, proteins can be of vegetable or animal origin. Proteins of animal origin are widely used, while those of plant origin have been gaining attention thanks to appeals that range from philosophies about animal life to deforestation, related to the need to expand agricultural production. Considering these protein alternatives, the consumers need to know about the limits of using these foods, mainly regarding their stability, since different treatments are necessary for the preparation of protein-enriched food formulations, such as heat treatments, which can drive protein denaturation, resulting in the loss of their biological functions. Therefore, this study aimed to spectrally evaluate the influence of heating in samples of rice and whey proteins in the nearinfrared region (NIR). In the experiment, the proteins were heated at temperatures of 35, 50, 100, 150, 160, 170, and 180 °C. The samples were heated for 20, 40, and 60 minutes, and the spectra were obtained using the MicroNIR® equipment (VIAVI-JDSU) for measurements between 900 and 1700 nm. The spectra obtained were smoothed and subjected to second-derivative with second-order polynomial and 7-point window using the Savistky-Golay algorithm and subsequently evaluated by multivariate curve resolution with alternating least squares (MCR-ALS ). The spectra recovered by MCRALS indicated that the temperature of 50 °C promotes spectral variations that are more pronounced in proteins of animal origin, and these variations were more noticeable above 100 °C. It was also observed that heating promotes more changes in the spectra of whey proteins than rice ones. Thus, the study suggests that rice proteins are more stable than whey proteins because they have suffered less spectral variation. However, it is important to note that the suggested limit temperature considering the application of the MCR-ALS is 100 °C for both proteins.