Pregelatinised amaranth flour as an ingredient for low-fat gluten-free cakes

This work explored the use of pregelatinised amaranth flour (PAF) as an oil substitute in the preparation of amaranth cakes. Amaranth flour was extruded to achieve approximately 50% gelatinisation, ground and sieved. The PAF was used to replace the oil in the cake preparation at levels 33, 66% and 100%. FTIR analysis of the cake formulations showed that PAF modified the molecular organisation of starch and proteins. The starch showed more hydrated structures, although less ordered. The proteins exhibited a significant reduction in the β structures and a marked increase of the side chains, probably caused by the interaction with amaranth starch. The in vitro digestibility of starch showed a slight increase with the addition of PAF. The slowly digesting starch fraction showed a visible decrease, reflecting the presence of starch chains more accessible to amylolysis. Instrumental texture revealed an increase (P < 0.05) in cake hardness with the addition of PAF, particularly for medium (66%) and high (100%) oil replacements. Sensory analysis showed that the perceived texture, flavour and colour were negatively affected by the addition of the pregelatinised flour. Overall, the sensory analysis indicated that cakes with low levels of PAF oil replacement may be acceptable to consumers.