Antioxidant Activities, Nutritional Potential and Physico-chemical Analysis of Unripe plantain-Millet Composite flour blend

Abstract

The functional properties of plant foods had received much attention in recent times. However, several investigations have revealed the antioxidant, nutritional and medicinal potential of unripe plantain and millet when consumed separately. The present study therefore, sought to assess the antioxidant and nutritional potentials of phenolic containing unripe plantain (UP) and millet (M) composite blends (UP: M); 100:0, 80:20, 60:40, 40:60, 20:80 and 0:100) and also to evaluate the sensory properties and physico-chemical properties of the blends. HPLC/DAD analyses revealed the presence of some phenolic compounds mainly; flavonoids and phenolic acids. The result of the antioxidant indices of the composite blends increases progressively as the percentage inclusion of millet increases and a higher antioxidant indices were recorded for 100% millet (Total phenol: 0.0916mg/g, Total flavonoids: 4590mg/g, Ferric reducing antioxidant power: 1.6274mg AAE/g, ABTS radical scavenging activity: 0.0902μmol TEA/g, DPPH radical scavenging activity: 0.000676μmol TEA/g). Proximate composition revealed that 100M had the highest protein (7.05%), fibre (10.48%) and fat (0.69%) content compared with 100UP and that other blends have an increasing value of proximate composition with respect to inclusion of pearl millet in the blends. Mature unripe plantain (100UP) recorded the highest level of sodium, magnesium, potassium and calcium, while the 100M have the highest level of phosphorus. The result also showed a progressive increase in the level of most of the evaluated minerals with increase in the inclusion of unripe-plantain. The results of the evaluated anti-nutritional factors of unripe plantain and millet showed that 100UP have higher alkaloid content (13.17%), while higher phytate content (19.23mg/g) was recorded for 100M. However, no significant difference was observed for oxalate in 100UP and 100M. The results of the starch: sugar of the composite blend revealed a decreasing value with increase in inclusion of millet in the blends and 100UP recorded the highest starch: sugar (54.61), while 100M recorded the least (16.01). The result of the amylose: amylopectin showed an increasing value with increase in inclusion of millet in the blends and 100M recorded the highest amylose: amylopectin (4.87) while 100UP had the least amylose: amylopectin (2.45). Physico-chemical properties of the composite flour blends did not show any particular trend with increase in both unripe plantain and millet flours inclusion. However, 100UP recorded the highest pH (6.41) and bulk density (0.76g/ml), 40UP-60M ranked the highest in total soluble solid and water absorption capacity while 100M recorded the least total soluble solid (87.13%) and water absorption capacity (2.23ml). The result of the sensory properties of the porridge prepared from the blends showed a varied rating with respect to the evaluated sensory parameters; however, better overall acceptability was recorded for porridge prepared from 40UP:60M. Findings from the nutrient composition, antioxidant potential of the blends and sensory properties of the porridge revealed two blends (40UP:60M and 20UP:80M) could be harnessed as functional food in the management of free radical mediated diseases.