Moisture, solids-non-fat and fat analysis in butter by near infrared spectroscopy

Abstract

Abstract Moisture, solids-non-fat and fat were analysed in butter by near infrared (NIR) spectroscopy without any previous sample treatment. A set of 102 samples was used to calibrate the instrument by modified partial least-squares regression. The following statistical results were achieved: standard error of calibration (SEC)=0.192 and square correlation coefficient (R2)=0.90 for moisture, SEC=0.086 and R2=0.93 for solids-non-fat, and SEC=0.168 and R2=0.94 for fat. To validate the calibration performed, a set of 24 butter samples was used. Standard errors of validation were 0.255, 0.071 and 0.377 for moisture, solids-non-fat and fat, respectively, and R2 for the regression of measurements by reference method versus NIR analysis were 0.83, 0.94 and 0.72 for moisture, solids-non-fat and fat, respectively. To compare, for all three components of the validation set, the results obtained by NIR spectroscopy with those obtained by the reference methods, linear regression and paired “t”-test were applied and the methods did not give significantly different results for p=0.05. When mean square prediction error analysis was applied, it could be concluded that a strong calibration model was obtained and that for all three components the main error was unexplained.