Effect of edible coatings to preserve physico-chemical and sensory quality for fresh and cooked zucchini products

María Teresa Blanco-Díaz, Anne Plotto, Jinhe Bai, Jan Narciso, Rafael Font, E. A. Baldwin

Abstract


This research studied different edible coatings for quality preservation of zucchini slices destined for fresh-cut consumption or for cooking. In the first experiment, antioxidants, including calcium ascorbate (CAA), cysteine (CYS) or ethanol (ET) in edible coatings made from chitosan (CHIT), chitosan + glucose (CHIT + GLUC), whey protein concentrate (WPC), soy protein isolate (SPI), carboxymethyl cellulose (CMC), hydroxypropyl methylcellulose (HPMC) and soy bean oil (SB) were tested for effects on appearance and weight loss of the zucchini slices stored at 6 °C and 20 °C. In a second experiment, the best coatings from the initial experiment (CHIT, HPMC, SPI, and SB including CAA + ET as antioxidants) were tested for effects on color of fresh-cut zucchini slices stored at two different temperatures (6 °C and 12 °C). The effectiveness of CHIT, SPI, with or without antioxidants, was observed best and HPMC and SB were eliminated from further testing. The use of antioxidants contributed to higher L* values (lightness) and h°ab (hue angle) while reducing b* values (yellowness–blueness) as an indication of less discoloration than for water-treated controls. Finally, selected coatings were tested in a third experiment monitoring firmness and sensory quality before and after boiling, steaming, griddling, frying and microwaving. The use of CAA+ET, SPI, and CHIT increased firmness of zucchini slices after boiling and steaming (CAA+ET and SPI only). SPI and antioxidants promoted an increase in overall color and visual liking 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.


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Proc. Fla. State Hort. Soc.     ISSN 0886-7283