Influence of sprouting on phenolic acids, carotenoids, and antioxidant activity of millet varieties
Trang H.D. Nguyen, Lien Le Phuong Nguyen, László Baranyai
Abstract
The kernels of two millet varieties (foxtail and red proso) were germinated for 24, 48, and 72 h at 30 °C. Changes in free and bound forms of phenolic acids, lutein/zeaxanthin, and antioxidant activity were evaluated in wholegrain flours from the germinated seeds. Lutein/zeaxanthin increased from 4.08 to 6.65 μg/g in foxtail and 1.62–4.85 μg/g in red proso millets. The two millets significantly scavenged ABTS free radicals, increasing from 351.47 (0 h) to 521.58 μg AAE/g (72 h) and from 288.12 (0 h) to 692.46 (72 h) μg AAE/g, respectively. A similar trend was observed in the millets regarding the DPPH assay, in which DPPH free radicals were scavenged from 140.69 (0 h) to 314.25 μg AAE/g (72 h) and from 290.59 to 432.05 μg AAE/g, respectively. Free ferulic acid content was higher in germinated flour for 24 h (1.57 mg/kg dry weight basis) than in ungerminated grains (0.05 mg/kg). The concentrations of bound caffeic acid increased with germination time, from 12.78 mg/kg (0 h) to 31.2 mg/kg in germinated flour for 24 h. The foxtail millet had significant changes in phenolic acid content during germination. This study may provide insights into utilizing different millet varieties and their sprouted flours in food industry.