2.7. Sucrose, glucose and fructose
Frozen broccoli florets were ground in a refrigerated mill and 0.6 g of the obtained powder were homogenized with 5 mL of ethanol and vortexed for 1 min. The mixture was centrifuged at 5580 g for 10 min at 4 C; the supernatant was recovered and filtered through 0.2 mm RC membrane (ColeParmer, USA). Soluble sugars were determined by using a high-pressure liquid chromatography system equipped with a refractive index detector (Waters, IR 2414) and a Hypersil Gold Amino column (4.6 250, 5 mm, Thermo Sci. USA). An isocratic flow rate of 16.7 mL s1 of acetonitrile /water (70/30) was used for analysis. Results were expressed on a fresh weight basis as mg kg1. Three extracts per sample and storage time were obtained and measurements were done in triplicate.