Inhibitory activity of phenolic-rich pistachio green hull extract-enriched pasta on key type 2 diabetes relevant enzymes and glycemic index.

Phenolic compounds as agro-industrial by-products have been associated with health benefits since they exhibit high antioxidant activity and anti-diabetic properties. In this study, polyphenol-rich extract from pistachio green hull (PGH) was evaluated for antioxidant activity and its ability to inhibit α-amylase and α-glucosidase activity in vitro. The effect of PGH extract powder on in vitro starch digestibility was also evaluated. The results showed that PGH had stronger antioxidant activity than Trolox. The inhibitory effect of PGH extract against α-amylase from porcine pancreas was dose dependent and the IC50 value was ~174µgGAE/mL. The crude PGH extract was eight times more potent on baker yeast α-glucosidase activity (IC50~6µgGAE/mL) when compared to acarbose, whereas the IC50 value of PGH extract against rat intestinal maltase activity obtained ~2.6mgGAE/mL. The non-tannin fraction of PGH extract was more effective against α-glucosidase than tannin fraction whereas the α-amylase inhibitor was concentrated in the tannin fraction. In vitro starch digestibility and glycemic index (GI) of pasta sample supplemented with PGH extract powder (1.5%) was significantly lower than the control pasta. The IC50 value of PGH extract obtained from cooked pasta against α-amylase and α-glucosidase was increased. These results have important implications for the processing of PGH for food industry application and therefore could comply with glucose control diets.

Sensory, digestion, and texture quality of commercial gluten-free bread: Impact of broken rice flour type.

This research investigated the effects of two varieties of broken rice (Khouzestan and Lenjan) from warm and dry regions, and two (Hashemi and Tarom) from mild and humid regions on different parameters including dough rheology, digestibility, and quality (color, specific volume, textural properties, and sensorial properties) of a commercial gluten-free bread (GFB). Furthermore, the rice varieties' hydration properties, gelatinization temperatures, and starch-granule morphology were assessed. Significant differences were observed in the varieties' proximate composition and hydration properties from both climate zones. The granules' average size was 3.17-4.9 µm. The specific volume of the breads showed no correlation with either the damaged starch content or the amylose content, but had a significant negative correlation with hardness (r = -.923, p < .05). The crumb hardness of bread was positively correlated with water-binding capacity and was affected by elastic modulus of dough. Results of predicted glycemic index were in accordance with total carbohydrates. Khouzestan received the highest score in sensory evaluation test. Based on the outcomes for bread-quality attributes, Khouzestan from the warm and dry region, which is a cheaper rice variety in Iran, was the most appropriate variety for GFB production. Moreover, it was determined that the rice varieties currently used in commercial manufacture of gluten-free bread do not necessarily yield the highest-quality bread. PRACTICAL APPLICATIONS: Gluten-free breads (GFBs) are generally used by Coeliac patients. In comparison to wheat bread, the quality of GFBs is lower. Rice is one of the main ingredients of GFBs' formulation, thence by determining the quality-related features of the rice, improvement in the final product could be achieved. In addition, by implementing the cheap and the broken rice variety, the price of the final product could be decreased and be more affordable for the patients.