RHEOLOGICAL PROPERTIES AND MICROSTRUCTURE OF MODEL PROCESSED CHEESE CONTAINING LOW-MOLECULAR-WEIGHT EMULSIFIERS

The influence of low molecular weight emulsifiers (SDS, CTAB, lecithin , mono-diglycerides) on rheological properties and the microstructure of model processed cheese, made using rennet casein, at three differen t pH values was investigated. Interactions between the low molecular w eight emulsifiers and rennet caseins in model processed cheese are con sistent With those found in model food emulsions of liquid continuous phase. Compared with the control, the addition of CTAB (cationic) resu lted in the hardest and most elastic processed cheese, while the incor poration of SDS (anionic) produced the softest and least elastic chees e. Processed cheese with added lecithin or mono-diglycerides behaved m uch like the controls, but with an increase in syneresis level. No syn eresis was observed with the SDS cheeses. In general, low pH cheeses ( pH 5.45) were harder than high pH cheeses (pH 6.05). Rheologically, al l the processed cheese samples can be described as 'weak gels'. The pr otein matrix of the high pH processed cheese containing CTAB consisted mainly of protein particles linked into a chain-like form, while thos e containing lecithin and SDS showed a mixture of individual as well a s short chained protein aggregates, and the control had protein aggreg ates of intermediate size. The added low molecular weight emulsifiers resulted in a finer dispersion of the fat in the protein matrix. Prote in-emulsifier charge interactions seem to be the prime determinant of the rheological properties of these model processed cheeses.