Fruit sensory, nutritional and microbiological quality are the main factors that determine fruit postharvest life.  Coating application over fruit surface preserves fruit quality and helps extending fruit postharvet selflife.  During the last years, consumers and producers preferences have changed focusing on healthier foods.  This demanding has led to the development of postharvest technologies.  Edible coatings formed by natural components have being taking protagonism.  However, its use has not been totally explored and there are not many edible coatings available on the market.  More research is needed to develop edible coating applications.  The first step would imply research on the effect of edible coating composition on fruit quality.
      The objective of this thesis was to study the effect of edible coating composition made with hydroxypropilmethyl cellulose (HPMC), beeswax (BW), fatty acid (FA) and plasticizer in the postharvest quality of plums, tangerines and oranges, in order to develop edible fruit coatings that preserve fruit quality.
      The coatings improved postharvest quality of coated ‘Angeleno’ plums compared to control plums, reducing weight loss, softening and internal physiological disorders.  The coatings also reduced weight loss, fruit softening and physiological disorders of ‘Clemenules’ and ‘Ortanique’ tangerines.  However, the coatings did not significantly improve postharvest quality of coated ‘Valencia’ oranges compared to the control.  Coating composition affected coating barrier properties and appearance.  However, changes in coatings composition did not affect fruit postharvest quality in the same way (i.e some fruit quality parameters were improved, while others were worsened).
      Among the factors studied, the ratio of HPMC and BW was the main factor affecting coating performance.  In ‘Angeleno’ plums, an increase of BW content and a decrease in HPMC content reduced weight loss and shrinkage, improving plum external appearance; while a reduction in BW content and an increase in HPMC content increased shininess and reduced internal physiological disorders.  In ‘Clemenules’ tangerines, an increase in BW content and a reduction in HPMC content reduced fruit weight loss and ethanol levels, improving fruit flavor.  However, an excess of BW in the coating formulations and/or a defect of HPMC content worsened fruit external appearance and decreased shininess.  These results, both in ‘Angeleno’ plums and ‘Clemenules’ tangerines, were explained by the mechanical and barrier properties of HPMC and BW.  It was hypotized that HPMC was the main component providing the coating mechanical cohesion and coating gas barrier, while the BW was the main component providing the moisture barrier.
      The type and content of FA and plasticizer also affected coating performance.  Among the FA studied, oleic acid was the FA that provided the best coating performance in both fruits studied (‘Angeleno’ plums and ‘Ortanique’ tangerines).  It was hipotized that an increase in coating flexibility by adding oleic acid to coating formulations improved coating ability to adapt to fruit surface, and the coating ability to reduce fruit respiration and transpiration.
      Glicerol addition as plasticizer increased coating flexibility, which improved coating performance and postharvest quality of coated ‘Angeleno’ plums and ‘Valencia’ oranges.
      Solid content (SC) of the coatings affected postharvest quality of coated ‘Clemenules’ tangerines.  A decrease in SC decreased coating CO2 and O2 barrier, ethanol and acetaldehyde levels in juice and fruit off-flavor.  In addition, a decrease in formulation SC improved appearance and shininess of coated tangerines.
      The results of this thesis provided information of the effect of the different ingredients of HPMC-based coatings applied to ‘Angeleno’ plums, ‘Clemenules and ‘Ortanique’ tangerines, and ‘Valencia’ oranges.  However, more research is needed in order to optimize coating composition of this type of coatings.  Future work may also be performed in order to study the ability of this coatings acting as carriers of microbiological and nutritional ingredients.