Influence of some physico-chemical characteristics of commercial rennet caseins on the performance of the casein in Mozzarella cheese analogue manufacture

Abstract

Abstract The compositional and chromatographic characteristics of ten rennet caseins and their relationships to rennet casein performance in Mozzarella cheese analogue manufacture were determined. Some compositional parameters (moisture, ash and calcium) were weakly related to performance, while cation-exchange fast protein liquid chromatography did not indicate differences between the caseins which could be related to performance in Mozzarella cheese analogue manufacture. When the rennet caseins were hydrated at 8.0% (w/w) protein for 120 min in 0–1.0% (w/w) disodium orthophosphate (DSP), the level of protein and calcium solubilised varied depending on the DSP concentration and on the particular rennet casein. Differences were also observed in the rates of protein and calcium solubilisation when each rennet casein was hydrated at 4.0% (w/w) protein in 0.5% (w/w) DSP for up to 120 min. Levels of protein and calcium solubilised and rates of solubilisation were in some instances found to relate to rennet casein performance in Mozzarella cheese analogue manufacture. These results suggest that calcium mediated protein–protein interactions in the different caseins are disrupted at different rates and to different extents during hydration at similar concentrations of calcium sequestering salt. These differences may arise due to protein and/or mineral (ash, calcium) modifications during heat treatment of skim milk prior to rennet casein manufacture or on heat treatment during manufacture; the extent of modification appears to subsequently influence the hydration and solubilisation of a rennet casein in DSP and its performance in Mozzarella cheese analogue manufacture.