Hot-water Dips Extend the Shelf Life of Fresh Broccoli

Abstract

Freshly harvested heads of `Cruiser' or `Paragon' broccoli (Brassica oleracea L. Italica group) were heated by immersing in water at 42, 45, 48, 50, or 52C. Immersion times were decreased as treatment temperatures were increased and ranged from 20 to 40 minutes at 42C to 1 to 3 minutes at 52C. Control heads, dipped in 25C water for 0, 10, or 40 minutes, began to turn yellow after ≈3 days storage at 20C and 80% to 90% relative humidity. Immersion in 42C water delayed yellowing by 1 or 2 days; immersion in 45, 48, 50, or 52C prevented yellowing for ≤7 days. Water loss of broccoli during storage at 20C increased by ≤1% per day by some hot-water treatments. Immersion in hot water decreased the incidence of decay during storage at 20C. Immersion in 50 or 52C water for 2 minutes was most effective in controlling decay development. Broccoli immersed in 52C water for 3 minutes had a distinct off-odor. Control and treated broccoli held at 0C for 8 days following hot-water dips were similar in quality. Yellowing of heat-treated broccoli was inhibited when broccoli was warmed to 20C following storage at 0C. Hot-water treatments also delayed senescence at 20C when broccoli was treated following 3 weeks of storage at 0C. Immersion of broccoli in 50C water for 2 minutes was the most effective treatment for reducing yellowing and decay while not inducing off-odors or accelerating weight loss.