Alteration of imitation cheese structure and melting behaviour with wheat starch

Abstract

Imitation cheeses were manufactured with increasing levels (0–20%, w/w) of native wheat starch in partial or total replacement of rennet casein protein. With increased addition of native wheat starch up to 9% (w/w), irregular starch particles (sometimes horseshoe-shaped) became more numerous and disruptive of the protein structure. Differential scanning calorimetry showed the presence of a large endothermic peak at 42 °C, corresponding to the melting of the palm oil constituent, and a smaller second endotherm at 79–82 °C with the inclusion of starch at levels of up to 9% (w/w). This smaller endotherm was not present on heating imitation cheese containing 20% (w/w) starch, which had no meltability. Results indicated that the second smaller endotherm corresponded to a phase transition in the casein-continuous matrix facilitating flow behaviour in the imitation cheese network. At concentrations of 3–9% (w/w), wheat starch behaved like a filler material, with limited effects on the rheology of the casein matrix at temperatures below 50 °C, however its inclusion increased the processing time and reduced the meltability of the imitation cheese.