Enzymatic coagulation of raw and reconstituted skim dromedary and cows’ milk powders: Kinetics, rheological and morphological properties
Résumé
Gelation kinetics, rheological and morphological properties of enzymatic curds of raw skim dromedary and cows' milk and reconstituted milk prepared from powders produced by spray-drying these raw milk samples were investigated. Processing (spray-drying and reconstitution) significantly increased whey release by curds. Whey release was more pronounced for dromedary milk than for cows' milk. Milk type and processing had both significant effects on gelation kinetics and rheological properties of enzymatic curds. For raw milk, enzymatic coagulation began earlier and led to a more elastic curd for skim cows' milk than for skim dromedary milk. Reconstituted skim dromedary milk curd showed a longer duration before gel point and a higher maximal elastic modulus than raw dromedary milk curd. SEM showed a coarser structure with larger clusters and pores for curds obtained from processed milk. Processing-induced casein aggregation seemed to favour enzymatic coagulation of skim dromedary milk contrarily to skim cows’ milk.