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There exists an increasing interest from consumers and scientific community in developing edible-natural-biodegradable coatings to replace commercial wax-based coatings for maintaining postharvest quality of vegetables. In this work, the effectiveness of guar gum coating on various quality characteristics of Roma tomato at 22 ± 2 ∘ C over a 20 d storage period was investigated. Tomatoes were covered with a 1.5% guar gum coating plasticized with glycerol at 30% and stored at 22 ± 2 ∘ C and 40% RH for 20-d. Tomatoes covered with edible coating significantly enhanced firmness and reduced weight loss, delayed changes on soluble-solids-content, retarded loss of total acidity, and decreased respiration rate compared with uncoated-control fruit. Sensory analysis by trained panelists revealed that the use of the edible coating influenced the acceptability of tomatoes. There were significant differences on the scores given by panelists when comparing the coated and uncoated tomatoes. It was concluded that guar gum affected favorably the physicochemical, microbial, and sensorial quality properties of Roma tomato and therefore could be beneficial in delaying the ripening process at 22 ± 2 ∘ C.

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The polymerization of vinyl acetate in one-phase o/w microemulsions stabilized with Aerosol OT (AOT) is examined as a function of concentration and type of initiator (V-50 and KPS) and temperature. Conversions and reaction rates increase with increasing concentration of V-50 and temperature. Faster polymerization rates and higher conversions are achieved with KPS because of the different electrostatic interactions between the charged microemulsion droplets and the free radicals of KPS and V-50. Average molar masses and polydispersity indexes (M̄ w/M̄ n) are much smaller than those observed in emulsion polymerization using the same surfactant, even at high conversions. Analysis of the molar mass distribution indicates that chain-transfer reactions to monomer are the controlling chain-growth mechanism in the polymerization of vinyl acetate in AOT microemulsions at all conversions.

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