Submitted to: HortScience
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/19/2002
Publication Date: 6/1/2002
Citation: Bai, J., Baldwin, E.A., Hagenmaier, R.D. Alternatives to shellac coatings provide comparable gloss, internal gas modification, and quality for `Delicious' apple fruit. HortScience. 2002. v. 37(3). p. 559-563.
Interpretive Summary: Most red apples in the U.S. are coated with shellac or shellac-carnauba waxes to make them shine. Shellac is associated with non-food uses, which might be viewed negatively by consumers. Therefore, alternative coating materials including corn protein, starch and another used in chewing gum (polyvinylacetate) were tested for gloss and effect on apple quality. All coatings kept the apples shiny and firm, and compared well with shellac.
Technical Abstract: Zein, starch, polyvinyl acetate (PVA), carnauba, and carnauba-polysaccharide (CPS) coatings were applied post controlled atmosphere storage to `Red Delicious' apples for comparison to a commercial shellac coating. Coated apples were stored in air at 2 deg C for two weeks and then removed to 21 deg C for an additional two week simulated marketing period. Starch and carnauba coated apples showed high initial gloss, which were comparable to the shellac coating. Gloss decreased during storage to similar levels for all coatings after the 4 week experimental period, although all of the coated fruits remained significantly glossier than uncoated controls. Fruits coated with shellac and starch showed higher than 10% internal CO2, and lower than 10% O2 at 21 deg C. Zein-, PVA- and carnauba-coated apples showed moderate internal gases (6-7% CO2, 11-15% O2). Coated fruits exhibited less weight loss than uncoated, except for those treated with the CPS coating, but the carnauba coating was the most effective water barrier. Starch-, shellac-, and CPS-coated fruit were firmer than those from other coating treatments, and all coated fruits were firmer than uncoated controls. Titratable acidity was higher in the fruits coated with CPS, starch, and shellac than in uncoated controls.