Modification of imitation cheese structure and rheology using pre-gelatinised starches

The rheological properties and microstructure of imitation cheeses containing 3%, w/w, pre-gelatinised maize, waxy-maize, wheat, potato or rice starches were compared to a control (0%, w/w, starch). Dispersions of pre-gelatinised rice or waxy-maize starches with casein had the highest viscosities following heating at 80 °C compared to casein heated alone or in mixtures with the other starches. Imitation cheese products containing pre-gelatinised starches had larger fat globule size distributions (especially rice or waxy-maize starch) and less homogeneous background protein matrices than the control as evidenced by scanning electron microscopy, which indicated poorer fat emulsification. The resultant imitation cheeses were softer, less cohesive and had reduced melting properties compared to the control. During processing, the pre-gelatinised starch competed with the rennet casein for water and impaired the caseins hydration as evidenced visually by delayed emulsification of free oil. Differences in levels of amylose retrogradation may have been responsible for variances in functionality between starches of different origins.