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Keywords:

  • antioxidant activity;
  • chitosan;
  • isoflavone;
  • sprouts;
  • sunflower

ABSTRACT:  The effects of chitosan molecular weights, solvent types, and concentrations of chitosan solution, and seed soaking times on growth and selected quality of sunflower sprouts were investigated. Among 5 chitosans tested (746, 444, 223, 67, and 28 kDa), 28 kDa chitosan exhibited the highest DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity both at 0.1% and 1.0% concentrations. Optimal conditions selected for cultivation of sunflower sprouts involved soaking seeds in 0.5% chitosan with 28 kDa (dissolved in 0.5% lactic acid) for 18 h. After cultivation for 6 d at 20 °C, sunflower seeds soaked in chitosan solution for 18 h under the optimal conditions yielded sprouts with 12.9% higher total weight and 16.0% higher germination rate, compared with those of seeds soaked in water for 18 h (control). Furthermore, the total amino acid content of the former sprouts (12098 mg/100 g) was slightly higher than that of the latter (12057 mg/100 g). Sprouting of sunflower seeds improved DPPH radical scavenging activity, probably due to the increased total phenolic, melatonin, and total isoflavone contents. Similarly, chitosan-treated sprouts exhibited slightly improved DPPH radical scavenging activity, probably due to slightly increased total phenolic and melatonin contents, and moderately increased total isoflavone content compared with those of the control. Chitosan treatment increased the total isoflavone content of sprouts by 11.8%, due mainly to the increased daidzein content, compared with that of the control.