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ARS Home » Research » Publications at this Location » Publication #207112

Title: Effect of edible coatings on eating quality of ‘Valencia’ oranges

item Plotto, Anne
item Goodner, Kevin
item Baldwin, Elizabeth - Liz

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 1/10/2007
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Commercial coatings used for citrus fruit include carnauba- and shellac-based waxes or resins. Shellac provides a high gloss to fruit, but because it resists gas exchange, it is known to induce off-flavors in storage due to accumulation of anaerobic metabolites in the fruit. A new formulation containing only food grade ingredients was tested, along with an experimental polyethylene-candellila (PE) wax emulsion, and two commercial citrus coatings, one shellac-based, and the other carnauba wax-based. The food-grade formulation contained hydroxypropylmethylcellulose (HPMC), bee’s wax and shellac. Valencia oranges were obtained from a local grove in Florida in May 2006. Fruit were washed, hand-coated and dried, and stored at 5 C for 0, 3 and 6 weeks. After storage, fruit remained at room temperature (25 C) for an additional 2 weeks prior to evaluation. Carnauba, PE-can, and HPMC based coatings provided the best weight loss control over 6 weeks (5 C) + 2 weeks (25 C). Fruit coated with commercial carnauba and shellac had the highest gloss, followed by PE-based coated fruit. Even though gloss measurement was not different for carnauba and shellac coatings, a taste panel found the shellac coating to be the shiniest after 2 weeks at 25 C, but preference was given to fruit with intermediate shininess such as those coated with carnauba and the PE-based emulsion. Flavor of shellac-coated fruit was least preferred after 3 and 6 weeks at 5C + 2 weeks at 25C. Shellac coated fruit had significantly higher level of internal ethanol and CO2 compared to other treatments. However HPMC-coated fruit also had high ethanol levels, intermediate between shellac and other treatments. Volatiles analysis showed that ethanol, methanol and ethyl acetate were high in shellac-coated fruit, while uncoated oranges had the most of the volatiles compounds characterizing fresh citrus flavor. Carnauba and PE:candellila emulsion provided the best compromise for visual appearance and lack of ethanol production.