Effect of sucrose and mannitol on the accumulation of health-promoting compounds and the activity of metabolic enzymes in broccoli sprouts

The contents of ascorbic acid, glucosinolates, sulforaphane, anthocyanins, total phenolics, the activity of myrosinase and phenylalanine ammonialyase (PAL) and the antioxidant activity of broccoli sprouts grown under 88 mM and 176 mM of sucrose and mannitol were investigated. The results showed that the contents of sulforaphane, ascorbic acid and anthocyanins in broccoli sprouts were significantly increased after treatment with 88 mM of sucrose compared with the control. The contents of glucosinolates and total phenolics, the activity of PAL and the antioxidant activity in broccoli sprouts treated with 176 mM sucrose were also significantly increased, whereas the activity of myrosinase was significantly reduced. On the other hand, the contents of glucosinolate, sulforaphane and total phenolics in broccoli sprouts were also significantly increased after treatment with 176 mM of mannitol, although the contents of sulforaphane were markedly reduced compared to those treated with 176 mM of sucrose. Sucrose might induce the production of health-promoting compounds through its role of signaling, generating osmotic pressure or serving as a substrate. These results indicate that sucrose treatment could improve the nutritional value of broccoli, and the sprouts growing under adequate concentration of sucrose could benefit our diet by producing more health-promoting compounds. (C) 2011 Elsevier B.V. All rights reserved.