ARS | Publication request: The effect of washing treatments on the surface cleanliness of Michigan Red Delicious apples

Submitted to: Annual Meeting of the Institute of Food Technologists
Publication Type: Abstract Only
Publication Acceptance Date: May 7, 2008
Publication Date: June 29, 2008
Citation: Quist, E.E., Rubino, M.I., Guyer, D.E., Auras, R., Lu, R. 2008. The effect of washing treatments on the surface cleanliness of Michigan Red Delicious apples [abstract]. Annual Meeting of the Institute of Food Technologists Abstracts. No. 133-02.

Technical Abstract: Most Red Delicious apples on the U.S. market are coated with food grade wax. The surface of the fruit needs to be prepared adequately by thorough cleaning prior to waxing and subsequent packaging for the consumer. The objective of the research was to evaluate the packing line washing conditions for efficient cleaning of Michigan Red Delicious apples, as a preparative step for subsequent processing and improvement of consumer appeal. Several factors including cleanliness have been considered for preparing the apple surface for waxing; the absence or presence of different types of commercially available surfactants (alkaline or neutral) in both the dump tank (DT) and on the washing brushes (WB) were assessed on fruit cleanliness. The apples’ dwell time in DT (30 sec and 60 sec), DT temperature (19 C and 40 C), and rinse time (60 sec and 120 sec) on WB at a constant temperature of 40 C and pressures (60 psi and 120 psi) were also evaluated. Each factor with their interactions was analyzed to determine the best conditions for surface cleanliness and preparation of Michigan Red Delicious apples. In this study a novel method using a solvent extraction system was developed to determine the amount of residue left on the apple surface after each treatment, and correlated to surface cleanliness. Alkaline surfactants cleaned better than neutral surfactants. No improvement in cleanliness was observed with dwell time increment in both DT and on WB. Increasing temperature of DT was effective in acquiring a cleaner surface. The results suggest that using a DT of 40 C for 60 sec and a 40 C rinse at 60 psi were significantly effective. These washing treatments can be used in the Michigan apple industry for efficient surface preparation of Michigan Red Delicious apples prior to drying and waxing; extrapolation to other apple varieties and the best waxing conditions are being considered.