Novel soybean-based high protein bar rich in isoflavones improves insulin sensitivity in diabetic Wistar rats

Abstract

This study assessed the effect of whey protein substitution with isolated soy protein in protein bar (PB) formulations at 25% (PB2), 50% (PB3), or 75% (PB1) weight/weight on the proximate and mineral composition, sensory, and antidiabetic properties. Sensory evaluation was conducted within diabetic (DB) and non-diabetic (NDB) consumers by preference ranking and acceptance test. The formulations were analysed in terms of moisture, ash, protein, lipid, carbohydrates, fibers and mineral content. The consumers did not distinguish the formulations by preference ranking test. However, the acceptability test showed a rating of 9 most frequent for PB1 (36.30%), followed by PB2 and PB3 (both 34.09%), among DB consumers. The PB1 and PB3 showed higher content of total, soluble and insoluble fibers and, PB 2 presented higher carbohydrate content. Potassium, sodium and calcium showed the highest mineral content in the formulations. PB3 was assessed for glycaemic and lipidemic control in diabetics and non-diabetics female Wistar rats, for this 20% of PB was added in the ration consumed ad libitum, besides, the rats received 100 mg/kg b. w. by gavage daily. The treatment did not reduce significantly fasting glucose, lipid profile, or peripheral glucose disposal in DB or NDB rats. However, it significantly improved insulin tolerance test values in diabetic rats. The results suggest that the formulations showed good acceptance and potentially ameliorate insulin resistance both in control group and in animal model of type II diabetes.

Keywords: Animal models of diabetes; Insulin sensitivity; Isolated soy protein; Sensory evaluation; Type-2 diabetes.

Fig. 1

Oral glucose tolerance test and area under the curve of serum glucose 30 days after treatment in rats in the diabetic and control groups. Diabetic control (DC, n = 8), diabetic ration + isoflavone (DTRI, n = 8), and diabetic group with a modified ration group (DTR, n = 8), control group (C, n = 8), control group with a modified ration (CR, n = 8), and control group with a modified ration + isoflavones (CRI, n = 8). The differences between the means were determined using ANOVA and Tukey’s test with significance set at p ≤ 0.05. There were no significant differences among the diabetic groups

Fig. 2

Insulin tolerance test 32 days after treatment in rats in the diabetic control group (DC, n = 8), diabetic group with a modified ration + isoflavones (DTRI, n = 8), diabetic group with a modified ration group (DTR, n = 8), control group (C, n = 8), control group with a modified ration (CR, n = 8), and control group with a modified ration + isoflavones (CRI, n = 8). The difference among the means was determined using ANOVA and Tukey’s test, with significance set at p ≤ 0.05. Different letters indicate a significant difference among groups