Avaliação de óleo e gordura vegetal de soja submetidos a ciclos de fritura através de espectroscopia molecular e quimiometria

Abstract

Frying is one of the most popular processes for food prepation. In addition to promoting speed and agility in cooking, a significant gain is linked to sensory properties conferred, such as flavor, appearance, texture, and odor. The reactions that occur in vegetable fats and oils are induced by the presence of oxygen and specially accelerated by heating, have as impact in the nutritional quality of oils with implications for human health, such as increased incidence of atherosclerosis and heart disease, the concern with the verification of the quality of the food has intensified. In this sense, the objectives of this work were to propose alternative methods for the evaluation of oxidative stability of soya oil and fat submitted to frying cycles. The first proposal evaluated the oxidative stability of soyabean oil and fat through ultraviolet-visible (UV-Vis) spectroscopy and chemometric method of multivariate curve resolution with alternating least squares (MCR-ALS). The results obtained suggest that the soyabean fat presents greater resistance when submitted to frying cycles than soyabean oil, but also an evaluation is important to check the quantity of trans fat acid. In a second proposal, the principal component analysis (PCA) was used to fusion data: physicochemical, UV-Vis and NIR spectroscopies, and gas chromatography. PCA showed correlation of specific absorptions in the UV-Vis and NIR spectral regions for soyabean fat with the results of smoke point, acidity index, peroxides and trans fats. For soyabean oil the spectral absorptions were correlated to polar compounds, polyunsaturated fats, omegas 3 and 6.