Um novo método de determinação de caseína em leite de cabra por espectrofluorimetria e calibração multivariada

Abstract

Milk is an essential food for life due to its nutritional composition rich in proteins, lipids, carbohydrates, and vitamins. Casein is one of the main proteins present in milk and plays a significant role in clot formation and product stability. The determination of casein in milk is relevant to ensure its quality, comply with regulations, and control industrial processes. This study aimed to propose an innovative method for determining goat milk casein using spectrofluorimetry combined with chemometrics. Initially, standard solutions of casein were prepared to obtain a calibration curve through spectrofluorimetric measurements in the 280 nm excitation peak region and emission scanning from 324 to 360, using pure casein (P.A.) in the range of 8 to 80 ppm (w/v). Partial Least Squares Regression (PLS) was applied for analysis. The resulting curve provided values for the Root Mean Square Error of Calibration (RMSEC) and the calibration determination coefficient (R²cal), with values of 3.6442 ppm and 0.9779, respectively. For the synthetic samples comprising the prediction set, the Root Mean Square Error of Prediction (RMSEP) and the prediction determination coefficient (R²pred) were 3.9859 ppm and 0.7576, respectively. Subsequently, casein extraction was performed on raw milk samples. The RMSEP, R²pred, and bias values for real samples were 3.6442 ppm, 0.9779, and 1.447 x 10-7, respectively, indicating that the chemometric model achieved relevant results even in the presence of potential interferents. Despite these findings, the method is advantageous due to its ease of execution and the ability to quantify without sample treatment, presenting a viable alternative to conventional methods for determining casein in milk.