Effects of whey protein concentrate on shelf life of cookies using corn and sunflower oils

Abstract

The objective of this work was to study the effect of whey protein concentrate (WPC) on shelf life of cookies using corn and sunflower oils as fat source. Wheat flour was partially replaced by WPC with levels of 5, 7.5, 10 and 15 %. A User Defined Design was used and the three following responses were measured: peroxide index (meqO2/kg), flavour (score from 1-10) and rancidity (detectable and non-detectable) at 0, 7, 14, 21 and 70 days of storage. Results show that during storage peroxide index (PI) increases in all cookies samples. However a significant decrease was found when corn oil was used instead of sunflower oil and when the level of WPC goes from 0% to 15%. Regarding sensory evaluation, all cookies were evaluated as acceptable (scored flavour ≥ 6) and no rancid flavour was perceived, except for two samples which were assigned with 5 and rancid flavour was considered as detectable; these samples correspond to cookies evaluated at day 70, elaborated with sunflower oil and the lowest dose of WPC. No significant differences were found in cookies flavour prepared with different oils. On the other hand and relative to the level of WPC replacement, differences were found by the panel at days 0 and 7, a reduction in assigned score when WPC dose was increased, however this difference was not significant in the subsequent assessment days. According to research results, an increase in stability was clearly obtained in cookies elaborated with corn oil and the highest concentration of WPC.