Effect of anti-browning solutions on quality of fresh-cut fennel during storage

Fresh-cut fennel (Foeniculum vulgare Mill. subsp. vulgare var. azoricum cv. Orion) is a very perishable crop due to the browning that affects the cut-surface, especially on the stem portion of the slices. The occurrence of browning is the main cause of quality loss and decrease of visual acceptance of this product. In the present work the effectiveness of different anti-browning solutions (0.5% ethanol, 1% L-ascorbic acid, 0.5% L-cysteine at pH 7, 1% citric acid and 0.5% 4-hexylresorcinol) on maintaining quality characteristics of fresh-cut fennel during 6 days at 5 °C in air conditions were investigated. Results showed that dipping in solutions of citric acid, ascorbic acid, cysteine and 4-hexylresorcinol, did not result in substantial improvement of the appearance of fresh-cut fennels cut-surfaces compared to water control. Among all applied anti-browning solutions, dipping in 1% citric acid and 0.5% 4-hexylresorcinol produced a more severe browning than control, in both stem and sheath cut-surfaces. Dipping for 2 min in 0.5% ethanol was effective in preserving visual quality of fresh-cut fennel stored in air for six days at 5 °C, significantly reducing the browning in both stem and sheath cut-surface. In addition ethanol is a 'generally recognized as a safe' (GRAS) product and did not negatively influence the aroma of fresh-cut fennel. Based on these considerations, dipping in 0.5% ethanol for 2 min could be a useful pretreatment for extending the shelf-life of fresh-cut fennel.