Production of low glycemic potential sponge cake by pomegranate peel extract (PPE) as natural enriched polyphenol extract: Textural, color and consumer acceptability

An effective strategy for controlling postprandial hyperglycemia and type 2 diabetes is by inhibiting the activity of alpha-amylase and alpha-glucosidase using natural inhibitors. In current study, the in vitro inhibitory potential of pomegranate peel extract (PPE) against alpha-amylase and alpha-glucosidase activity was investigated. The impact of PPE (0.5, 1, and 1.5 g/100 g) on starch digestibility, glycemic index (GI), the color, texture and sensory properties of sponge cakes was determined. The IC50 value for porcine alpha-amylase inhibition was 70.3 +/- 1.98 mu g/mL. The IC50 value for inhibition of a-glucosidase from rat intestines (6140 +/- 85.1 mu g/mL) was significantly higher than that from Saccharomyces cerevisiae (18.75 +/- 1.12 mu g/mL) (P < 0.05). In comparison to control cake, the addition of 1.5 g/100 g PPE to sponge cake decreased the digestible starch and GI by 43.5% and 44%, respectively. PPE affected color and texture of the cake significantly by decreasing the lightness (L*), redness (a*) and yellowness (b*) of the crust and increasing firmness (P < 0.05). The consumer acceptance study suggested that up to 1 g/100 g PPE supplementation gave an acceptable cake product. Taken together, PPE improves the quality of a functional low GI sponge cake.