Use of Edible Coatings to Improve Weight Loss, Microbial Stability, Appearance, Texture, and Sensory Qualities for Fresh and Cooked Zucchini

Various types of edible coatings were tested on sliced zucchini including chitosan (CHIT), whey protein concentrate (WPC), soy protein isolate (SPI), carboxymethyl cellulose (CMC), hydroxypropyl methylcellulose (HPMC) and soybean oil (SB), with or without various additives including calcium ascorbate (CAA), cysteine (CYS), glucose (GLUC) or ethanol (ETOH), and stored at 6 ºC and 20 ºC.  Weight loss, visual appearance and microbial stability were assessed and CHIT, HPMC, SPI and SB including CAA+ET as additives were selected for a second experiment where coated zucchini slices were stored at 6 ºC and 12 ºC.  The use of additives contributed to higher L* values (lightness) and hº (hue angle) while reducing b* values (yellowness-blueness) as an indication of less discoloration than for water-treated controls.  CHIT, and SPI with additives CAA+ETOH were selected for a third experiment, as they had decreased weight loss, and improved appearance for fresh-cut slices. Since fresh-cut vegetables are often processed for the ultimate purpose of cooking, after 4 days of storage at 10 ºC, coated slices were boiled, steamed, griddled, fried and microwaved. SPI and CAA+ETOH alone increased firmness of zucchini slices after boiling and along with CHIT, preserved firmness after steaming compared to water-treated controls.  SPI + CAA+ETOH promoted an increase in overall color quality and visual linking for fresh samples, while SPI increased zucchini flavor, general flavor and overall liking of boiled and steamed samples. Both SPI and CHIT increased color quality and visual liking for microwaved zucchini samples.