Production of edible coatings with twin-nozzle electrospraying equipment and the effects on shelf-life stability of fresh-cut apple slices

Abstract

In this study, apple slices were coated with electrospraying and dipping method for comparison of the coating efficiency, material uptake, color changes, and microstructure of coated surfaces. In electrospraying of 70% oil emulsion, a lower voltage was required for stable cone-jet geometry compared to the 80% oil emulsion which had the highest electrical conductivity and lowest viscosity. The material uptake of dip–coated samples was similar; however, the material uptake of electrospray coated samples was found between 0.051 and 0.122 mg emulsion/g apple. Electrospray coated apple slices had lower weight loss compared to the control and dip-coated samples, although the applied coating material was significantly lower. The total color change of electrospray coated samples was similar to the control; however the change in dip-coated samples was significant. The coating was uniform on the surface of electrospray coated sample, but a couple of pinholes and irregularities were visible in the microstructural image of dip-coated sample. Practical applications: Fruits and vegetables are good sources of vitamins, minerals, and dietary fiber, and their regular consumption is recommended for a healthy life. The fresh-cut fruits are easy to access and practical to meeting the daily need for the nutrients. However, the shelf-life of these foods is limited due to perishable characters of the fruits and short shelf-life. Edible coatings and films can be applied for extending the shelf-life and maintaining the sensory characteristics of the fruits. The electrospraying method is an emerging technology in the edible coating production with its less coating material use compared to the conventional alternatives and electrospraying helps to improve the shelf-life stability of fresh-cut fruits. © 2017 Wiley Periodicals, Inc.