Viabilidade tecnológica do uso de proteína do soro do leite microparticulada em leite condensado

Abstract

The growing demand for dairy ingredients with differentiated technological properties has driven research into whey proteins and their applications in a wide range of dairy products. In this context, the objective of this study was to develop sweetened condensed milk formulations containing microparticulated whey protein (MWP) and to evaluate its effects on the physicochemical, microstructural, and rheological properties of the product during storage. Seven sweetened condensed milk formulations were produced: one control formulation (containing only milk and sugar as ingredients) and six formulations with partial replacement of milk by skim milk powder (SMP), whey protein concentrate (WPC), and microparticulated whey protein (MWP), at concentrations of 2.0% and 4.0% (w.w⁻¹). MWP was obtained through the simultaneous application of thermal and mechanical treatments to WPC, promoting protein denaturation and particle size reduction. The microparticulation process was evaluated through particle size distribution and additional protein denaturation analyses, while the mixes (formulations before the vacuum evaporation process) were evaluated for composition. The sweetened condensed milk samples were analyzed in terms of composition and physicochemical properties, including water activity, particle size, and texture, as well as Maillard reaction indicators, browning index, optical microscopy, and rheological behavior, with the latter four analyses being performed throughout 28 days of shelf life. The results demonstrated that the microparticulation process was effective, significantly reducing the average particle size and promoting extensive whey protein denaturation, especially of β-lactoglobulin. The formulations produced presented compositions compatible with the standards established by Brazilian legislation for sweetened condensed milk, with no significant changes in moisture, protein, and mineral contents. However, the addition of the replacers influenced important technological characteristics. Formulations containing WPC and MWP showed reduced water activity and modifications in texture parameters, particularly increased hardness and gumminess, especially in the formulation containing 4.0% WPC. In addition, the added ingredients influenced the particle size distribution of the products, suggesting structural changes in the sweetened condensed milk matrix. Microscopic analyses indicated that formulations containing WPC and MWP exhibited a homogeneous distribution of lactose crystals throughout storage, with MWP showing the most pronounced effect. Rheological analyses demonstrated pseudoplastic behavior for all formulations, and once again MWP stood out, especially at the 2.0% concentration, providing greater stability of viscosity and consistency index throughout shelf life, whereas formulations containing WPC exhibited greater variations during storage. Regarding the Maillard reaction, only 5-hydroxymethylfurfural (HMF) was detected, with higher concentrations observed in formulations containing whey proteins, particularly MWP. Overall, the results indicate that microparticulated whey protein presents high technological potential for application in sweetened condensed milk, especially at the 2.0% concentration, contributing to the structural stability and rheological modulation of the product without compromising its compositional characteristics.