Effect of Processing Treatments on the Nutritional, Anti-Nutritional, and Bioactive Composition of Blue Maize (Zea Mays L.)

Abstract

Maize is considered as an important annual cereal crop cultivated widely throughout the world. Blue Maize (Zea mays L.) is a blue-colored variety of maize containing high content of anthocyanin and belongs to the family Poaceae. The current study aimed to evaluate the effect of soaking, germination, natural fermentation, and roasting on nutritional, anti-nutritional, and bioactive components of blue maize. The changes in chemical composition were studied after 12 and 24 h of soaking and 24, 48, and 72 h of germination treatment. The blue maize grains were subjected to natural fermentation for time intervals of 12, 24, and 36 h, and roasting treatment by heating at 180 °C on a hot plate for 10 s. The results revealed that the phenolic content increased significantly (p≤0.05) from 44.88 to 51.56 mg GAE/100g after 36 h fermentation and from 44.88 to 61.05 mg GAE/100g after 72 h of germination whereas it decreased from 44.88 to 35.73 mg GAE/100g during the roasting process. Further, there was a 44.02 and 20.22% increase in protein content during germination and fermentation processes, respectively, and a slight decrease of 2.16% after roasting treatment. The antioxidant activity increased significantly (p≤0.05) from 10.41 to 18.85% during germination and 10.41 to 14.50% during fermentation, respectively. But it was found to get decreased by 6.53% after the roasting process. The anti-nutrients such as phytic acid and tannins declined significantly (p≤0.05) during the processing treatments. Phytic acid decreased to the extent of 63.57, 55.99, and 27%, and tannin contents as 62.5, 50, and 41.66%, after germination, fermentation, and roasting processes, respectively. There was a significant (p≤0.05) increase in mineral contents after all processing treatments of blue maize.