Electrospray coating of minimally processed strawberries and evaluation of the shelf-life quality properties

Abstract

In this study, strawberries were coated with electrospraying and dipping method. Water-in-oil (w/o) emulsions were used as coating material, and quality parameters, namely water loss, pH, titratable acidity, color, firmness, total antioxidant activity and phenolic content, microbial load, sensory properties, and microstructure of strawberries were evaluated. Moisture loss of strawberries significantly reduced with coating compared to the control sample; however, the reduction in moisture was similar for dip-coating and electrospraying methods. The brightness of strawberries decreased with storage, while redness, yellowness, and Chroma values were increased significantly (p < .05). The firmness of control and dip-coated strawberries decreased significantly, but the firmness of electrospray-coated samples was comparably higher than control and dip-coated samples. Sensory properties were not affected from the coating formulation, and samples were found as acceptable at the end of storage. Homogeneous coating of the surface was provided with electrospray coating method. Moreover, the electrospray coating has a potential in edible coating applications for fresh fruits and help to extend their shelf life. Practical Applications Electrospray coating is a novel coating method of producing fine droplets down to submicron sizes from a conductive or semiconductive feeding solution. This method allows obtaining homogeneous surface coatings with small amount of coating material applications. Thus, excessive coating material consumption and drip loss from the coated target is prevented. Besides regarding electrical potential application during electrospraying, the sprayed material adheres well on the surface to be coated, even if the nonconductive or uneven surface structure is present. Hydrophobic coating material application such as oil-in-water based emulsions via electrospraying helps to reduce moisture transfer, and fresh-cut or minimally processed fruit and vegetable quality is improved during storage. Therefore, w/o emulsion-based coatings were applied with electrospraying method in order to evaluate coating efficiency by means of quality properties of minimally processed strawberries.