Metodologia de detecção de adulterações em óleo de macadâmia usando espectroscopia no infravermelho médio e ferramentas quimiométricas

Abstract

The extra virgin macadamia oil, obtained through the Macadamia intergrifolia tree, consists of a complex mixture of fatty acids and is characterized as a natural product of differentiated sensorial qualities. It has high economic value, being, therefore, subject to adulterations, mainly by the addition of lower value-added oils. Thus, it is necessary to develop new methods capable of quantifying these adulterants oils in extra virgin macadamia oil. In this work, mineral and sunflower oils contents were determined in binary mixtures with extra virgin macadamia oil, with concentration ranging from 1.0 to 31.5% (w/w). The instruments used were the Perkin Elmer Spectrum Two FT-MIR Spectrometer equipped with an Attenuated Total Reflectance accessory (ATR) of zinc selenide (ZnSe) with the follow configurations: wave number from 600 to 4000 cm-1 with resolution of 4 cm-1 and 16 scans per spectrum, as well as the multivariate calibration method Partial Least Squares (PLS). The obtained models were evaluated through the mean square error of calibration and prediction (RMSEC and RMSEP, respectively). They presented RMSECs of 0.3363 and 0.3592; RMSEPs of 0.4927 and 0.8034. The methodologies developed, besides being efficient, are also fast and detect adulterations in concentrations lower than those described in the literature. The results were satisfactory, with prospects that the methodologies developed in this work could be used as a viable alternative in the quality control of extra virgin macadamia oil.