Effects of candelilla wax/canola oil oleogel on the rheology, texture, thermal properties and in vitro starch digestibility of wheat sponge cake bread

The use of oleogels for replacing solid fats is a hot topic in the food industry. The objective of this work was to partially or totally replace butter by candelilla wax/canola oil oleogel, and evaluate its effect on starch digestibility and texture of wheat sponge cake bread. Candelilla wax/canola oil oleogel/butter blends were made substituting butter in 0, 25, 50, 75 and 100% by the oleogel. Increased substitution levels of oleogel by butter produced batters with significantly reduced the viscoelastic properties (up to similar to 60-70%). Total butter substitution by oleogel decreased cakes hardness from 29.61 to 13.37 N, but increased cake specific volume from 1.91 to 1.98 cm(3)/g. FTIR analysis indicated the formation of hydrated and short-range crystallized starch structures at the expense of a reduction of amorphous domains, with the short-range ordering increasing by about 120%. Oleogel incorporation had a positive effect on the in vitro starch digestibility, as the digestible starch fraction increased from 70% to about 84%. Overall, the results showed that the use of oleogel for the preparation of sponge cake imposes a trade-off problem between improving the textural properties or increasing starch digestibility.