Active Packaging of Green Mature Tomatoes with Pectin Coating to Extend the Shelf Life

A study -was conducted to investigate the effect of pectin as an active packaging on the storage quality and the shelf life of mature green tomatoes (cv. KC-1). The tomatoes were dipped into the concentrations of 1, 3 and 5% (w/v) pectin solutions for 5 minutes and stored at 30°C. Fruits were tested for physiological weight loss, ascorbic acid, titratable acidity and total sugars at different ripening stages such as breaker, turning, pink, light red and red. Fruits were also evaluated to determine the number of days taken for ripening and shelf life. Based on the quality parameters the best treatments were assessed for sensory characteristics using nine-point hedonic test. Fruits coated with 5% pectin solution showed most effective result in minimizing weight loss at red stage and tomatoes coated with 3% of pectin showed greater retention of ascorbic acid, titratable acidity and total sugars during storage. The ripening of tomato fruits was delayed by the pectin coating and the tomatoes coated with 3% pectin solution were kept for 28 days without decay. In the sensory analysis, highest overall acceptability was observed in the tomatoes coated with 3% pectin solution. Based on these results, tomatoes coated with 3% of pectin solution stored at 30°C was found to be the best treatment to extend the shelf life of the tomatoes. Key wards: Active packaging, pectin, quality, shelf life, tomatoes INTRODUCTION Fruit perishability is a main problem faced by the fanners during their marketing of the commodity. Tomato is a delicate fruit which contributes 40 60% of postharvest losses in Sri Lanka. Reduction in postharvest losses could reduce unit cost of production. Many techniques such as low temperature, high relative humidity control, controlled and modified atmosphere packaging have been studied in order to overcome these problems and to JScEUSL(2009) Vol.6 No.l, p 1-9 extend the shelf life of tomatoes. However, the maintenance of the quality of fresh produce is still a major challenge for the food industry. At present, active packaging such as edible skin coatings have many advantages over other techniques, but only when the coated products are stored at proper temperatures. Such coatings are made of edible materials which provide a semi permeable barrier to gases and water vapor. Edible coatings are thin layers of edible material applied to the product surface in addition to or as a replacement for natural protective waxy coatings and provide a barrier to moisture, oxygen and solute movement for the food [1 ]. Skin coatings are applied directly on the food surface by dipping, spraying or brushing to create a modified atmosphere. Previously, edible coatings have been used to reduce water loss, but recent developments of formulated edible coatings with a wider range of permeability characteristics extended the potential for fresh produce application [2]. The effect of coatings on fruits and vegetables depends greatly on temperature, pH, thickness, type of coating, variety and ripening stages of the fruit [3]. Edible coatings may be composed of polysaccharides, proteins, lipids or a blend of these compounds. Their presence and abundance determine the barrier properties of material with regard to water vapor, oxygen, carbon dioxide and lipid transfer in food systems [4]. Generally, the potential benefits of edible coatings and films for lightly processed produce are to stabilize the product and thereby extend product shelf life. More specifically, coatings have the potential to reduce moisture loss, firmness loss, provide moisture and oxygen barrier properties, retard respiration rates, retard ethylene production, seal in flavour volatiles and improve the appearance. The major benefit of edible coatings is that they can be consumed along with food, provide additional nutrients, enhance sensory characteristics and include quality enhancing antimicrobials [4]. In this research study, green mature tomatoes were dipped in different concentrations of pectin solution and stored at room temperature in order to extend shelf life and maintain the quality by using polysaccharide edible coating. Therefore, this study was conducted to select the suitable concentration of pectin solution to extend the shelf life and to evaluate the effect of coating on nutritional and sensory qualities during storage and ripening of tomatoes.