Effect of phosphate salts and varying quantities of casein and whey protein on the syrup characteristics of a sweetened condensed skimmed milk and vegetable fat blend

A blend of sweetened condensed skimmed milk and vegetable fat is a product that can be prepared by mixing milk constituents and/or whey in powder form with the addition of sugar and/or vegetable fat. The aim of this study was to determine the influence of varied casein and whey protein compositions, as well as the use of phosphate salts, on the stability of milk mixture syrup. Syrup production was carried out using a mixture of skimmed milk powder, demineralized whey powder, glucose, vegetable fat, sugar, and phosphate. The casein: whey protein ratios used were 80:20, 70:30, and 56:44, and the phosphates were PQTS (phosphate salt composed of sodium phosphate, and sodium citrate) and OPSS (phosphate salt composed of orthophosphate, polyphosphate, and sodium citrate). The results indicated that the PQTS salt presented the best stability of the mixture, mainly in the 56:44 mixture. In addition, it modified the pH of the mixture to a greater extent than the standard and presented particles with larger sizes at both d₁₀ and d₉₀ (minimum and maximum particle size and represents 10 and 90% of the volume percentage distribution, respectively). However, the OPSS salt induced a higher phosphate content in the mixture, consequently lowering the free calcium and total calcium content. The mixture produced with the 56:44 ratio exhibited a reduction in the particle size of the mixtures with phosphates when evaluating the d₉₀. As a result, the industry will select one of these phosphates based on the qualities of the desired end product.