NUTRITIONAL QUALITY, GLYCEMIC INDEX AND BIOCHEMICAL EVALUATION OF DOUGH MEAL FROM ACHA-TIGERNUT ENRICHED WITH SORREL PROTEIN ISOLATE

Abstract

Diabetes mellitus (DM) is a chronic metabolic disease characterized by persistent hyperglycaemia that occurs either when the pancreas does not produce insulin (Type 1) or when the body cannot effectively utilize insulin (Type 2). Due to its high prevalence and potential harmful effect on a patients physical and psychological state, diabetes is a major medical concern. The disease remains incurable and usually managed with drugs. Recently, diets have been reported to possess potentials for managing diabetes in different patients. In Nigeria, several efforts have been made to control diabetes, one of which is conventional antidiabetic drugs. Over the years, there has been side effects that are associated with this conventional antidiabetic drugs such as flatulence, abdominal cramping, and diarrhoea Therefore, search for non-toxic antidiabetic agents from plant-based sources as substitute to synthetic drugs is of great interest among researchers. Diet and lifestyle adjustment approach have been identified as a corner stone in the management of diabetes mellitus. However, the use of bioactive-rich functional foods as antidiabetic agents has gained attention as a result of the safety, availability, low cost and consumer preference for natural products compared to synthetic drugs. Most commercially available functional foods are expensive and may not be within the reach of many. Hence, the need to explore locally available plant foods for development of low-cost functional foods with potentials for managing diabetes. In view of this, this study was carried out to evaluate the nutritional quality, glycemic index and biochemical evaluation of dough meal from acha-tigernut flour blends enriched with sorrel protein isolate. Flour samples were prepared from acha (ACF) and tigernut (TNF) while protein was isolated from sorrel seed (SPI). The flour blends were optimized using Response Surface Methodology (RSM) design expert 8.3.0.1(trial version) to generate eleven runs. The flour blends were developed into dough meal and evaluated for proximate and sensory attributes using a commercial flour sample (Cerolina) as control (CNL). Two flour blends were selected (based on their protein and fibre contents and sensory attributes) alongside the control (CNL) for further analysis of their nutritional quality, glycemic index and biochemical properties using in vivo studies. Results showed significant increase (p<0.05) in crude protein content of the blends with increase in the addition of sorrel seed protein isolate with ATS (SPI+TNF+ACF: 5.00+45.00+50.00) having highest value (22.24 g/100g). Panelist ranked ATS and TNS (SPI+TNF+ACF: 5.00+42.64+52.36) higher in term of appearance, aroma, taste, texture and overall acceptability compared to other samples. The total amino acid profile of the dough samples was not significantly different (p<0.05) from the control and ranged from 97.76 mg/100 g and 100 mg/100 g protein in ATS and TNA, respectively. The first and second limiting amino acid are lysine and methionine. Values obtained for total essential amino acids of ATS and TNA dough meal samples (31.47 and 34.73 mg/100 g) were significantly lower (p<0.05) than 36.06 mg/100g protein obtained for the control (CNL). However, a significantly higher (p<0.05) total monounsaturated fatty acid content of 45.13% was obtained for TNA as compared to the control (38.65%) (p<0.05). Furthermore, total polyunsaturated and saturated fatty acid contents of the formulated dough meal samples (ATS and TNA) were significantly lower than the control sample (CNL), while monounsaturated fatty acid values of ATS and TNA were significantly higher (p<0.05) than that of the control sample (CNL) (p<0.05). The nutritional status of experimental rats using Weight-for-Age and Length-for-Age nutritional indices showed that the rats fed with the ATS and TNA meal had significantly higher growth (p<0.05) as compared with those fed with the control (CNL) diet. The hematological parameters were significantly higher in ATS as compared with other samples (p<0.05). The packed cell volume (PCV), red blood cell (RBC), white blood cell (WBC) and hemoglobin ranged between 38.50% - 46.50%; 1362.00 X103rbc/mm3 – 1598.50 X103rbc/mm3; 478.55 X50 wbc/mm3 – 561.65 X50 wbc/mm3 and 12.60 g/100 ml – 14.80 g/100 ml in TNS and ATS, respectively. Glycemic index of ATS-formulated dough meal (30.40%) was significantly lower compared with other samples including the reference glucose (100%) (p<0.05). The results obtained from the present study revealed that induction of rats with a single low dose of streptozotocin and hyperlipidemia-induced type-2 diabetes mellitus (T2DM) significantly reduced the activity of antioxidant enzymes in the pancreas, kidney and liver compared to other treatment groups (p<0.05). However, a significant (p<0.05) increase was recorded in the pancreas, kidney and liver catalase (CAT), superoxide dismutase (SOD), glutathione peroxidase (GPx), Glutathione-S-transferase (GST), reduced glutathione (GSH), Non-Protein Thiol (NP-SH) and Na+/K+ ATPase activities of rats fed with ATS compared to other treatment groups. Likewise, all dough meal samples significantly (p<0.05) decreased the enzymes activities linked to kidney and liver function, while sample ATS significantly increased the liver function by inhibition of the enzymes linked to hepatotoxicity resulting from T2DM compared to CNL and TNA (p<0.05). Sample ATS showed better result in kidney and liver functionality with no side effects when administered on Wistar rats; hence, sample ATS may be a better remedy for management of protein energy malnutrition and hyperglycemia with no side effects on organs.