UHT A2 milks marketed in Brazil: Physicochemical and electrical characterization, rheological behavior and fatty acid profile

Abstract

UHT A2 Milk offers a consumption alternative for consumers experiencing intestinal discomfort from consuming dairy products. A2 milk, derived from cows with the A2A2 genotype, does not promote the formation of betacasomorphin-7 (BCM-7). However, little is known about the comprehensive composition of this product, as well as its impact on physicochemical and electrical parameters. This study aimed to investigate potential physicochemical and chemical differences between UHT milk with the A2 β-casein genotype and conventional milk without A2 certification, sourced from brands available in the Brazilian market. Therefore, the physicochemical parameters, rheological behavior, electrical impedance, and fatty acid composition were evaluated. The results indicated that A2 milk had higher density, fat, protein, and total solids content compared to UHT milk without A2 certification. Furthermore, it obtained a higher electrical impedance modulus and lower admittance within the analyzed frequency range (1 kHz a 5 MHz). The UHT milk samples showed Newtonian fluid behavior at both temperatures analyzed (10 and 25 °C). Furthermore, the type of UHT milk (with and without A2 certification) did not significantly influence the absolute viscosity of the samples (p > 0.05) across both commercial brands and temperature. Overall, both types of milk had the same composition of fatty acids, with palmitic acid being the major compound. However, C12:0 and C18:1 cis-7 were more abundant in A2 milk. In this sense, the analytical methods used in this study were able to identify differences in macromolecules and compounds within the lipid fraction in the samples investigated. These analytes are suggested as potential identity markers to evaluate the authenticity of UHT bovine containing only beta-casein of the A2 genotype in its composition.