NUTRITIONAL QUALITIES, BLOOD SUGAR AND CHOLESTEROL REDUCING POTENTIAL OF DOUGH MEAL FROM PLANTAIN (Musa ABB ), SOYCAKE (Glycine max L) AND RICE BRAN (Oryza sativa L)FLOUR BLENDS

Abstract

Nutrition therapy is currently being embraced in the management of metabolic diseases such as diabetes mellitus instead of orthodox drugs that are controversial in extra-pancreatic degenerations, which often resulted from diabetic conditions. This research was aimed at determining the nutritional, functional, antioxidant, antidiabetic, cholesterol-lowering and angiotensin converting enzyme inhibition potential of flour blends and dough meal.Plantain, soycake and rice bran were processed into flour using standard methods. The flours were blended using response surface methodology (RSM). Theoptimized flour blends were obtained based on the recommended daily intake required for a diabetic patient (55-65% CHO, 18-20% protein and 10-15% fibre).Five runs were selected and sensory evaluations were carried out on the flour blends anddough prepared from the selected runs. Based on panelists’ preference, sample PSRF (60:25:15) of plantain, soycake and rice bran were used as optimized flour and made into the dough meal used in this study. Plantain and cerolina (100% flour and dough meal: CERF, CERD; PLTF, PLTD) respectively were used as control. The optimized sample was assessed for chemical compositions, functional properties, pasting properties, colour attributes, antioxidant activities, protein digestibility, biochemical properties and blood glucose lowering potentials in rats. Serum and organs of the rats fed with the diets and the control were analysed for haematological and endogenous enzyme antioxidant activities. Sensory qualities of the constituted dough meals were assessed by employing semi- trained panelist using 9-point Hedonic scale. Triplicate data were analysed using statistical package. Means were subjected to ANOVA and separated using Duncan New Multiple Range (DNMR) test at p<0.05. The protein content of the optimized flour blends and dough meals samples ranged from 3.50 in PLTF – 20.12% in CERF, and 2.79 in PLTD – 19.12% in CERD; while energy values (Kcal) ranged from 1501.97 in PSRF – 1650.36 in CERF. The most abundant amino acid is the glutamic acid while the limiting amino acid is methionine.The nutritionally important mineral composition shows that Ca ranged between 3.55 – 8.99 mg/100 g, Mg 14.20-16.00mg/100g, K 69.09 - 95.30 mg/100g, Fe 1.99 - 2.24mg/100g and Phosphorus 7.66 -28.22 mg/100g. It was also observed that Cd and Pb were not detected in theoptimized flour blends and dough meals samples.The lightness (L*)ranged between75.49 – 83.61 for optimized flour blends and 43.37- 47.40 for dough meal samples, red-green (a*) 3.44 - 4.92 for flour blends and 4.42-10.43 for dough meal samples.The result of weight-for age classification indicated that the growth pattern of rats placed on the optimized diet (PSRD and PSRF) were significantly (p<0.05) higher than those on control diets (CERD, CERF, PLTD and PLTF). The length-for-age classification depicted a similar growth pattern and significantly (p<0.05) higher than those on control diets. The glycemic index of the optimized flour and dough meal samples ranged between 38% in PSRD to 58% in CERD and theArginine/Lysine ratioranged from 1.37 to 2.62 respectively. The protein efficiency ratio of the optimized flour blends and dough meal samples fed on rat ranged between 0.73 in PLTF – 3.23 in PSRD. The flour blends were less digestible than the dough meal flour.The dough meal flours (PLTD, CERD and PSRD) have higher α – amylase inhibitory activity than the flour samples (PLTF, CERF and PSRF).The PSRD have the highest α–amylase inhibition (30%) and was significantly higher than others.Inhibition against α- glucosidase activity ranged from 25% (PLTD) to 32% (PSRD). The raw flours (PLTF, CERF, and PSRF) have less α–glucosidase inhibition than dough meal samples. The glycemic load range from 28% (PSRD) to 38% (CERD). The blood glucose reducing potential of the diets is PSRD > PLTD > PSRF > CERD > PLTF > CERF. Rats fed with the optimized diets enhanced the endogenous antioxidant status by elevating the levels of Glutathione (GSH), Catalase (CAT), Superoxide (SOD), Glutathione peroxidise (GPX ) and Glutathione transferase (GST) in the pancreas and the liver, while the diet depressed the levels of Malondialdehyde (MDA), Myeloperoxidase (MPO) and Xanthine oxidase (XO). The ACE-1 inhibitory activity of the optimized dough meal (PSRD) increased significantly (38.80%) and is comparable to CERD (39.04%). In conclusion, the study established that optimized flour blends and dough meal samples (plantain 60%, soycake 25% and rice bran 15%) have multifunctional properties such as high invitro and invivo antioxidant potential, it reduces hypercholesterolemic indices. It is also effective in the inhibition of ACE-1, alpha-amylase and alpha-glucosidase activities which are key enzymes implicated in hypertension and non-insulin dependent diabetes mellitus; hence, the sample has potential to be used as dietary intervention to modulate NIDDM and hypertension.