Effect of storage temperature and duration on glucosinolate, total vitamin C and nitrate contents in rocket salad (Eruca sativa Mill.)

Abstract

AbstractThe effect of storage temperature and duration on nitrate, total vitamin C and glucosinolate (GSL) contents was investigated in rocket salad (Eruca sativa Mill.) grown in soilless culture. Harvested plants were either maintained intact as leaves with roots (RL) or separated as leaves only (LO) before being placed in oriented polypropylene packages and immediately stored at 4 °C (RL and LO) or 15 °C (LO only) in darkness. Packages were sampled after 1, 3, 6 and 10 days of storage (DOS) and, along with fresh samples (0 DOS), submitted to chemical analysis. For RL (4 °C), leaf moisture content decreased gradually with increasing storage duration, from 98.7% at 1 DOS to 93.8% at 10 DOS. For LO (15 °C), leaf colour at 10 DOS had shifted from an initial greenish hue to a yellowish one. Nitrate contents were highest at 10 DOS in all treatments but did not show any significant differences between LO (15 °C) and RL (4 °C). Total vitamin C content ranged from 0.87 to 1.81 mg g−1 fresh weight and was higher in both LO (4 °C) and RL (4 °C) leaves than in those of LO (15 °C) regardless of storage duration. Total GSL content in the leaves of both LO (4 °C) and LO (15 °C) increased up to 3 DOS and decreased thereafter. The correlation between total vitamin C and GSL contents only existed at 0 DOS before storage and at 3 DOS of LO (15 °C) during storage in all treatments. Storage temperature generally had a significant effect on GSLs individually or collectively, except for 4‐methoxyglucobrassicin. Copyright © 2007 Society of Chemical Industry