Physicochemical and Rheological Properties of Acid-Induced Milk Proteins Gel

The spontaneous syneresis of acid gels was studied. We investigated the effect of temperature and acid concentration on the degree of syneresis, rheological properties and microstructure of curds. Milk was coagulated with citric acid solution, syneresis extent and curd yield were determination afterward the whey was drained and weighed. Rheometer was used to analyze the viscoelasticity of the curd and SEM (Scanning Electron Microscopy) was used for the curd microstructure. The syneresis extent was influenced by the heat treatment of the milk before its coagulation and by the acid concentration. In addition, the interaction effect of the two factors showed that the combination 2.5 %, 80 had higher syneresis degree and the combinations 5 %, 90 ; 7.5 %, 90 and 10 %, 90 recorded the highest curd yield. The density and the porosity of the casein matrix decreased with the increase of the temperature. The viscoelasticity of the curds was also affected by the temperature and the acid concentration. These results can be used to manufacture heat combined acid type cheeses.