NUTRITIONAL, ANTIOXIDANT, BLOOD GLUCOSE AND PRESSURE LOWERING POTENTIALS OF FLOUR BLENDS FORMULATED FROM PLANTAIN (Musa AAB), SOYCAKE (Glycine max (L.) Merrill), RICE-BRAN (Oryza sativa Linnaeus) AND OAT- BRAN (Avena sativa Linnaeus)

Abstract

The use of dietary intervention to prevent degenerative diseases continue to attract research attention. The bioactive components when incorporated into food aid in the treatment and management of several chronic diseases like diabetes and hypertension. The present study was aimed at determining nutritional, antioxidant and blood glucose lowering potentials of plantain, soycake, rice-bran and oat-bran flour blends and dough meal samples as alternative to synthetic anti-diabetic drug which has been implicated with side effects. Unripe mature plantain (Musa ABB); soy-cake (Glycine max); rice-bran (Oryza sativa) and oat-bran (Avena sativa) were processed into flour. The flour samples were blended using mixture response surface methodology, Design-Expert version 10.0.0 (Stat-Ease, Inc., USA) with reference to protein (14 g) and fibre (5 g). After blending, 16 runs were generated from which 4 blends were selected on the basis of sensory quality, crude protein and crude fibre composition. The selected runs were as follows: plantain 70% and soycake 30% (PSC); plantain 65%, soycake 30% and rice bran 5% (PSR); plantain 65%, soycake 30% and oat bran 5% (PSO); and plantain 60%, soycake 30%, rice bran 5% and oat bran 5% (PSRO). Cerolina (CNL) (wheat and soybean flour blends, a commercial dough meal flour sample produced by More Foods Lagos, Nigeria) and 100% plantain (PLT) were used as control samples. The flour blends were evaluated for chemical composition (proximate, minerals, amino acid, phytochemical); functional properties, in vitro and in vivo antioxidant activities, nutritional qualities, biochemical and haematological parameters using Albino Wistar rats, in vitro angiotensin-1-converting enzyme inhibition, in vivo glycaemic index/ load, and blood glucose lowering potentials of the flour blends and prepared dough meals in Streptozotocin induced diabetic rats. Sensory qualities of the constituted dough meals were evaluated by employing semi-trained panelist using 9-point Hedonic scale. Triplicate data were analysed using statistical package. Means were separated using New Duncan Multiple Range Test (NDMRT) test at p<0.05. The moisture and crude protein content of the flour blend samples varied from 5.10 g/100 g in PLT to 5.50 g/100 g in PSRO and 5.69 g/100 g in PLT and 19.59 g/100g in PSRO, respectively. The moisture and crude protein content of the dough meal samples varied from 4.20 g/100 g in PLT to 5.43 g/100 g in PSRO and 4.97 g/100 g in PLT and 19.43 g/100g in PSRO, respectively. Phosphorous (24.37 - 33.36 mg/100g) was the most abundant, while copper (0.12 - 0.16 mg/100g) had the least concentration in the formulated flour blends respectively. The glycaemic index of the flour samples varied from 28.96% in PSO to 39.31% in PSC, while that of CNL was 38.96% and PLT was 40.09% respectively. The blood glucose concentration reduction potential of PSRO sample was the highest (54.74%) and PSC (52.50%) had the lowest blood glucose reduction activity. The blood glucose reduction activities of the developed food samples decreased in this order PSRO > PSO > PSR> PSC. The total cholesterol, triglyceride, high-density lipoprotein concentration, low-density lipoprotein concentration and very low-density lipoprotein concentration of the formulated diets in rats fed varied as follows: 20.11 - 34.61 mg/dL, 17.45 - 25.93 mg/dL, 12.89 - 23.72, mg/dL 3.73 - 5.87 mg/dL and 7.93 - 11.79 mg/dL, respectively and were similar to those of rats fed on PLT (100% plantain) and CNL (Cerolina). PSRO exhibited higher antihyperlipidemic and angiotensin-1-converting enzyme inhibitory activities compared to other food samples. Furthermore, PSRO was also ranked best next to 100% plantain and Cerolina in terms of sensory qualities. Hence, the flour blends and dough meal, that is, PSRO (Plantain 60% + Soycake 30% + Rice bran 5% and Oat bran 5%), may be suitable as functional food for promotion of good health and prevention of diseases such as type-2 diabetes and hypertension.