Comparison between official methods and ultrasound spectroscopy used to determine the physicochemical features of raw milk

Abstract

The aim of the current study is to compare official methodologies (OM) and ultrasound spectroscopy (US) used to determine the physicochemical features of raw milk. Twenty-five (25) milk samples deriving from a rural property in Bacabeira County, Maranhão State, were assessed. Fat and protein contents, density at 15°C, cryoscopic index, total dry extract (TDE) and defatted dry extract (DDE) were determined based on official analytical techniques and ultrasound spectroscopy, in laboratory environment. Mean protein densities and contents determined through US and OM did not differ from each other (P > 0.05). Mean fat contents and mean values recorded for cryoscopic index, TDE and DDE - determined through US and OM - differed from each other (P = 0.026, P = 0.040, P < 0.001 and P = 0.014, respectively); positive correlations were observed in the analysis of these parameters (R = 0.470, R = 0.118, R = 0.087 and R = 0.315, respectively); methods’ accuracy reached 0.180, 0.058, 0.155 and 0.075, respectively. Ultrasound spectroscopy is a fast technique whose results correlate to those of official analyses. However, it is necessary adopting a specific profile by calibrating the equipment based on information deriving from official analyses. Results in the present study have suggested the need of conducting more comprehensive studies to validate its conclusions.