Submitted to: Annual Meeting Horticultural Society
Publication Type: Abstract Only
Publication Acceptance Date: 3/31/2008
Publication Date: 7/21/2008
Citation: Quist, E.E., Rubino, M.I., Bailey, B.B., Lu, R., Guyer, D.E., Auras, R., Ariana, D.P. 2008. The impact of wax application on gloss development of Michigan Red Delicious apples [abstract]. Annual Meeting Horticultural Society. HortScience. 43(4):1189. Interpretive Summary:
Technical Abstract: Human perception of quality is chiefly based on visual appeal. To enhance aesthetic value and extend shelf life, apples are coated with food grade waxes. Shellac formulations are used world wide as fruit coatings to enhance the quality and appeal of fruits. The objectives of this study were to develop a non-destructive method for measuring gloss on curved surfaces and to evaluate gloss development on apples from using a combination of different simulated packing line wax application processes. The effect of shellac formulation on the gloss development was also assessed. The customized noninvasive glossmeter was constructed of a Fire-iTM Digital Camera with two 60-Watt incandescent light bulbs as the light source. The apple fruit was automatically rotated at 360 degrees on a rotary jig while 130 images were taken. The average number of saturated blue pixels for all images was calculated and correlated to gloss. The glossmeter has been successfully correlated to the human perception of gloss through a consumer sensory panel. Michigan Red Delicious apples were waxed with three commercial shellac fruit coatings by spreading 0.5 and 1.0 ml on the fruits by gloved hands. The coatings had a volatile solvent base, of which 7% w/w was evaporated to produce a more viscose liquid. The waxes were either applied at room temperature or heated to 40 C prior to coating. Waxed fruits were then dried for either 90 or 300 sec at 50 C. Five samples per treatment were used, and three measurements were taken for each sample. Whilst the type of wax formulation, amount applied, viscosity and drying time significantly affected the resultant luster, the wax application temperature did not. Coatings with greater amounts of volatiles proved to produce a greater sheen. Increasing both the drying time and the quantity of applied coatings resulted in a greater sheen. Applying shellac wax formulation of higher viscosity also produced higher glossed fruits in comparison to the original formulation.