Alginate coating was prepared as de

Alginate coating was prepared as described by Rojas-Graü et al. (2008). Alginate powder (1%, w/v) was dissolved in distilled water under controlled heating (80 ◦C) and stirred until the mixtures became clear. Glycerol was added as plasticizer (1.5%, w/v). The solution was emulsified with 0.025% (w/v) sunflower oil, using an Ultra Turrax T25 (IKA® WERKE, Germany) with a S25N-G25G device for 5 min at 24,500 rpm and degassed under vacuum. Freshcut pineapple pieces were submerged for 2 min in the coating solution, drained for 2 min and submerged for another 2 min in a 2% (w/v) calcium chloride bath for carbohydrate polymer crosslinking. Ascorbic acid (1%) and 1% citric acid were also added to the latter solution.