Effect of processing and storage of fresh-cut onion on quercetin

Abstract

Total quercetin concentration in unprocessed ‘Grano de Oro’ onions was 557 mg/kg f.w. (fresh weight). No significant statistical differences in total quercetin concentration were shown between products packed under vacuum and modified atmosphere packaging (MAP), at the end of 30 days at 4°C. No significant statistical differences in total quercetin concentration were shown between water-washing and hypochlorite solution-washing products at the end of 30 days at 4°C, packed under vacuum or MAP. Only slight significant differences in total quercetin concentration were shown between whole onion and cut onion product, in all the treatments after long-term refrigerated storage at 4°C (11-30 days). Chopped samples packed in MAP after washing in either water (462 mg/kg f.w.) or hypochlorite (471 mg/kg f.w.) had increases in quercetin concentration of 19.5% and 22%, respectively, when compared to whole onions stored in MAP after washing in water (386 mg/kg f.w.) or hypochlorite (387 mg/kg f.w.). Minimal processing did not seem to significantly affect the quercetin concentration in onion products, and consequently the health-promoting characteristics described for raw onion are preserved.