Effects of Ascorbic Acid Applied by Two Hydrocooling Methods on Physical and Chemical Properties of Green Leaf Lettuce Stored at 5°C

Abstract

ABSTRACT: The effect of ascorbic acid applied by 2 hydrocooling methods on chemical and physical properties of‘Waldmann's’dark green leaf lettuce (Lactuca sativa L.) during cold storage was evaluated. Lettuce was immersed (in 1% ascorbic acid or tap water) or sprayed (with 1% ascorbic acid or tap water) or left untreated (control). Treatment solutions for immersion or spraying were applied at 5°C for 2 min. Afterward, lettuce was packaged in moisture impermeable plastic bags and stored at 5°C for up to 21 d. Analytical assays included total ascorbate content, 2,2′-azinobis (3-ethylbenz-thiazoline-6-sulphonic acid) (ABTS˙+) Trolox equivalent antioxidant capacity, total phenolic content, relative water content and instrumental color. Lettuce was analyzed at 5 time intervals: before treatment application and at days 1, 7, 14, and 21 of storage time. Hydrocooling of leaf lettuce by immersion or spraying using 1% ascorbic acid solution increased total ascorbate content for up to 7 d, with an increase of more than 300% in total ascorbate content on day 1 compared with its initial value before treatments. However, the ABTS antioxidant capacity of leaf lettuce did not increase in ascorbic acid treated lettuce even though total ascorbate content increased. Ascorbic acid immersion was the only treatment that maintained the relative water content of leaf lettuce for 21 d. Further experimentation with the application of ascorbic acid during hydrocooling is needed to assess its usefulness as a processing treatment.