Phase Structures Impact The Theological Properties Of Rennet-casein-based Imitation Cheese Containing Starch

摘要

The dynamic rheological and microstructural properties of rennet-casein-based imitation cheeses containing various concentrations of potato starch were investigated using a stress-controlled rheometer and confocal laser scanning microscopy. The influence of added starch on the size of the oil droplets in the imitation cheeses was also examined. Imitation cheeses with 0-15% protein replaced by starch were processed in a Rapid Visco Analyser (RVA) at 90℃ for 10 min at a shear rate of 800 rev/min and were then evaluated using oscillatory shear measurement and a temperature sweep (20-90 ℃). The storage modulus (C) of the rennet casein imitation cheeses increased abruptly at added starch concentrations > 4%. In the temperature range 20-90℃, tan δ of the imitation cheeses decreased with increasing starch concentration and was < 1 at added starch concentrations > 4%. A binary continuous phase consisting of a protein phase and a starch phase was observed in systems containing > 4% starch, whereas the starch was dispersed in the protein matrix as small particles of irregular shapes at added starch concentrations ≤ 4%. As the dispersed phase, the size of the oil droplets increased with starch addition in the imitation cheeses. The marked increase in G' and the reduction in tan δ may be attributed to the formation of a binary continuous separated phase structure in imitation cheeses containing added starch that is driven by thermodynamic incompatibility between rennet casein and starch.