Investigation of coating pineapple slices with different emulsions by electro-spraying method

In this study, water-in-oil emulsions (w/o) were produced as edible coating material. The quality characteristics of pineapple samples coated with the prepared emulsions were evaluated by examining the weight loss (%) , pH, titratable acidity, color, texture, total antioxidant activity (TAA) and total phenolic content (TPC), microbiological and sensory analysis results of the sliced pineapple coated by immersion and electrospraying method. Maltodextrin (MD), whey protein isolate (WPI) and (MD + WPI) solutions containing 50-50% of these were used in the internal phases of w/o. Grape seed oil (GSO) or pomegranate seed oil (PSO) from the essential oils used as antimicrobial agents in coating materials were added to the oil phase of the emulsions at 2%. Oil separation %, viscosity, electrical conductivity and surface tension analysis of emulsions prepared by high speed homogenizer were conducted. The use of MD/WPI/MD+WPI in the internal phases of emulsions containing GSO or PSO showed a decrease in the oil separation, viscosity and electrical conductivity values of the emulsions, no significant difference was found in surface tension values. Coated and uncoated pineapple slices were stored in transparent polystyrene cups and in a cooling cabinet set at 5 °C and 80% RH for 7 days. At the end of storage, weight loss value (2.98%) of the control sample was observed as below the determined limits (4-6%) for weight loss value, even though it was more than the coated samples. Through the storage both coating methods gave positive results in terms of the quality criteria examined on the products. During storage, decrease in pH values, increase in % titration acidity values of products were observed. When the color values were examined, there was a significant decrease in b* values whereas the L* values varied slightly. ΔE values were found to be higher in samples coated with immersion than samples coated with electrospraying. Hardness values varied throughout storage, but decreased at the end of storage. It has been determined that the samples coated with the electrospraying using emulsion containing PSO gave better results in TTA and TPC values at the end of storage.