The effects of different inulin types on rheology and ultrastructure of rennet-induced gels and cast-type feta cheese
This thesis investigates the effects of different inulin types (short chain, native and long chain) on rennet-induced gelation of skim milk and their potential utilization as a functional ingredient in cast-type Feta cheese made with ultrafiltered (UF) skim milk. Gelation time, gel stiffness, strains at fracture, syneresis rates and microstructure depended on type and concentration of inulin added. All inulin-fortified gels had similar strength and brittleness as control and shorter gelation time. However, no significant differences were found between control and inulin-fortified cheeses. Protein networks in milk gels fortified with long versus short chain inulin molecules were more branched, and were associated with higher curd yields, slower syneresis rate, and better retention of inulin in curd and cheese. No differences could be observed in the microstructure of control and inulin-fortified cheeses. These findings stress the importance of inulin selection in cheese production for optimum functional and technological properties of inulin.