Influence of pre-gelatinised maize starch on the rheology, microstructure and processing of imitation cheese

摘要

Imitation cheeses were manufactured with increasing levels (0-9%, w/w) of pre-gelatinised maize starch in partial replacement of rennet casein. At increased starch levels, longer processing times (10 min at 78℃ using 9%, w/w starch) were necessary compared to the control (5 min) because of the reduced protein present to emulsify/stabilise the fat droplets. Scanning electron and confocal microscopy revealed that increased starch addition resulted in a less homogeneous protein matrix, with a honeycomb appearance although the fat globules remained small and uniformly sized. With increased levels of starch up to 9% (w/w), the storage modulus, peak stress and stress relaxation times significantly increased while hardness values remained unchanged. Results indicated that the inclusion of pre-gelatinised maize starch impaired the hydration of the casein as well as the thermoplastic properties of the imitation cheese and has most application in food products where flow resistance is required, particularly at increased temperatures.