The effect of roasting on the nutritional and antioxidant properties of yellow and white maize varieties

Abstract

Maize varieties (yellow and white) were roasted for 17 min; and allowed to cool, and later milled into powder. The nutritional evaluation (proximate composition, mineral and antinutrient content determination) and antioxidant properties investigation (reducing power, free radicals scavenging ability and Fe 2+ chelating ability) of the product was subsequently carried out. The result of the study revealed that roasting caused a significant increase (P < 0.05) in the crude fat, carbohydrate, Ca, Na, Mg and Zn content. Conversely, a significant decrease (P < 0.05) was observed in crude protein, crude fibre, Fe and K content. A significant decrease in the phytate content was also observed. However, the reduced phytate content did not have sparing effect on Zn bioavailability. Roasting significantly (P < 0.05) reduced the extractible phenol and flavonoid content of the maize varieties. The antioxidant properties (1,1-diphenyl-2-picrylhydracyl free radical scavenging ability and Fe 2+ chelating ability) followed the phenolic content pattern. However, roasting caused a significant increase in the ferric reducing antioxidant power of the maize varieties. Thus, roasting reduced the protein content of maize but also increased the energy value and antioxidant capacity as exemplified by high reducing power.

Inter-varietal Variation in Biochemical, Phytochemical and Antioxidant Composition of Maize (Zea mays L.) Grains

“…7.77 − 8.16 and 8.90 − 10.29% respectively. The protein content was comparable with that reported (8.45 − 12.97%) in two maize varieties (Oboh et al, 2010).…”

“…Hwoever, no significant difference was observed in free radical scavenging capacities of ascorbic acids and Trolox. The free radical scavenging activity of these varieties was lower than those reported by Oboh et al (2010) in two different varieties. As IC 50 is the minimum concentration of an antioxidant compounds required to inhibit the 50% of free radical, a lower IC 50 value indicates a higher antioxidant activity.…”

“…The crude oil contents of the varieties under investigation were higher than those reported by Ali et al (2010) in two maize varieties (3.55 − 3.92%) and Guria (2006) in three maize varieties (2.92 − 5.53%). However, our results were found to be comparable to those reported by Oboh et al (2010) in two maize varieties (5.32 − 6.21%). The saponification value was found to be comparable while the iodine value was found to be higher than those reported by Ali et al (2010) in maize grains (193.07 − 194.82 mg KOH/g oil and 111.61 − 116.01 g I/100 g oil).…”

“…The varieties under investigation were 6 − 10 times higher in total flavonoids and 2 − 4 times higher in total phenolic acids contents than those reported by Chlopicka et al (2012). Similarly, the total phenolic contents were also 3 − 4 times higher than those reported by Oboh et al (2010) and 5 − 10 times higher than those reported by Lv et al (2012) in wheat flour. However, the flavonoid contents were comparable.…”

Minerals and antinutrients profile of rabadi after different traditional preparation methods

“…Arora et al 2009 also revealed increased in vitro minerals availability after autoclaving of fermented food mixtures. Reduction in antinutrients after heat treatment is in consonance with the findings of Vadivel and pugalenthi (2008) and Oboh et al (2010) who attributed it to the high temperatures. Lakra and Sehgal (2011) also found higher mineral availability and lower antinutrient after frying and fermentation of potato flour.…”