Autenticidade do queijo de manteiga do Seridó por espectroscopia no infravermelho

Abstract

The present work has as main purpose the use of Fourier Transform Infrared Spectroscopy (FTIR) and Attenuated Total Reflectance (ATR) as a tool for rapid assessment of the authenticity of the butter cheese of Seridó, through the verification of the absence of vegetable oil, which is the most common fraud in this type of cheese. Samples of pure butter cheese (without fraud) were analyzed and chewed with vegetable oil in percentage of 10 to 100% of substitution of the bottle butter for soybean oil. The percentages of protein, fat, fat in the dry extract, moisture, pH, total solids, colorimetric analysis, texture profile and spectroscopic analyzes were determined for each sample produced. In each cheese three different points were taken and measurements were made through the MIR (Mid-Infrared) spectrometer in the range of 400 to 4000 cmˉ¹. The spectra obtained in triplicate were characterized by the presence of absorption bands in the region 3650 to 650 cmˉ¹. In order to evaluate the changes in cheese with the addition of vegetable oil, we have studied the characteristic peaks of lipids (2922, 2852, 1743, 1464, 1160 cmˉ¹) together with the peaks referring to long chain unsaturated fatty acids (3007 e 721 cmˉ¹). Peaks of the amide group (1640 e 1545 cmˉ¹) also showed differentiation when the samples underwent replacement of the bottle butter with vegetable oil, reducing the intensity of the former. Using chemometric techniques, PCA (Principal Component Analysis), it was possible to separate the samples in different groups according to the percentage of fraud and to differentiate cheeses with and without fraud. By the results obtained in the infrared spectroscopy with Fourier transform (FTIR) associated with the ATR technique, it can be concluded that the method and the technique used were able to identify the authenticity of butter cheese, as well as the presence of vegetable oil.