36E-25 |
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M. L. Navarro and M. B. PÉREZ-GAGO. Postharvest Department, Instituto Valenciano de Investigaciones Agrarias, Ctra. Moncada-Naquera Km 5, Moncada, 46113, Spain Edible coatings can extend the shelf-life and improve the quality of fruits and vegetables by providing a barrier to gas and water vapor exchange between the fruit and its environment, reducing respiration rate and weight loss. However, coatings with high gas barrier can induce off-flavor. The internal gas modification of coated fruit has been directly related to coating thickness through the solid content (SC) and viscosity of the coating solution. The objective of this work was to study the effect of solid content and viscosity of hydroxypropyl methylcellulose (HPMC)-besswax (BW) composite coatings on the quality of ‘Clemenules' mandarins. Coatings consisted on HPMC, BW, stearic acid and glycerol. HPMC of three different molecular weights were used to prepare emulsion coatings with 2%, 4% and 8% solid content and similar viscosity (20cp). An emulsion coating having 8% solid content and a viscosity of 100cp was also prepared. After coating, mandarins were stored up to four weeks at 5º C followed by one week at 20º C. Quality analysis of the mandarins were done periodically after storage. Coatings reduced weigh loss and deterioration index, and improved texture of mandarins compared to uncoated samples. However, these parameters were not affected by SC and viscosity. Internal CO2 and ethanol levels increased as SC increased from 2% to 4%, but did not further increase above 4% SC in the formulations with similar viscosity. Increasing emulsion viscosity from 20cp to 100cp also increased internal CO2 and ethanol levels of mandarins. The increase in ethanol levels as SC and viscosity of the coating formulations increased was only detected by the sensory panel when mandarins were coated with the high viscosity coating. The results indicate the need to control SC and viscosity of edible coatings to avoid the overproduction of volatiles associated with anaerobic conditions.
Session 36E, Fruit & Vegetable Products: General
2005 IFT Annual Meeting, July 15-20 - New Orleans, Louisiana |