Matrix-dependent effects of ultrasound-assisted fermentation on physicochemical properties and mineral-related multivariate patterns in camel, goat, and cow milks

Abstract

Non-thermal processing technologies are increasingly explored to modulate the physicochemical properties and functionality of fermented dairy products while limiting thermal stress. In this work, ultrasound-assisted fermentation was examined in camel, goat, and cow milks. Four treatment conditions were studied for each species: untreated control, ultrasound treatment before fermentation, after fermentation, and a combined treatment. Fermentation and ultrasound-induced changes in pH, electrical conductivity, total soluble solids (°Brix), and color parameters were evaluated. Mineral composition (Ca, Mg, K, Na, Fe, Zn, Cu, Mn) was quantified by Atomic Absorption Spectroscopy. Multivariate analyses (HCA, PCA) were performed to identify treatment and species-dependent patterns. Ultrasound treatment significantly modified physicochemical behavior and mineral profiles in a matrix-dependent manner, inducing species-dependent changes in total soluble solids (from -7.2 % to +5.3 %) and electrical conductivity (up to -8.0 % compared to controls). Color attributes were moderately affected, with slight variations in Whiteness Index (±3.3 %), particularly in camel milk. Variations in Ca, Mg, and Na contributed strongly to the differentiation of camel milk samples from goat and cow milk, whereas Zn and Cu distinguished treated and untreated camel milk samples in the multivariate space. Principal Component Analysis revealed a clear separation of fermented milks primarily driven by milk type. Camel milk displayed a distinct mineral profile, while ultrasound treatments led to distinct multivariate shifts. These findings highlight ultrasound as a promising non-thermal approach that may improve physicochemical and processing-related properties of non-bovine fermented milks.