Evaluation of effect of edible coating base on carboxy methyl cellulose, Pectin and osmotic dehydration on drying of Pumpkin

Document Type : Research Paper


The pumpkin is an important kitchen garden crop with very high nutritional value and long lifetime for storage and lot of fiber that acts as one of the best preventive factors from morbid obesity, hypertension, and cardiac diseases. As pretreatment for dehydration, osmotic dehydration creates maximum possible quality in the product by transfer of water outside the tissue of the nutrient. In this study, pumpkin slices with dimensions of 1cm3 were immersed in edible coatings of carboxy methyl cellulose CMC (0.5, 1, 2%), and pectin (1, 2, 3%) for 30s and then they were put into sucrose osmotic solution (weight concentration 50 and 60%) by observance of weight ratio 10:1 (osmotic solution/ sample) for 3h and then in oven (80°C) in final drying for 3h. dried samples were analyzed in terms of lost water, absorption of solid materials, tissue hardness, and color. Sense assessment was done by 9 professional and expert raters via 5-point hedonic scale. To analyze data, 13 treatments were utilized with 3 iterations (12 treatments and one control sample) by means of factorial test within fully randomized design and Duncan’s multiple-range test. The amount of lost water was reduced in pumpkin slices by increase in concentration of carboxy methyl cellulose and pectin and sucrose osmotic solution. As concentration of carboxy methyl cellulose and pectin was added, the amount of absorbed substance was increased in pumpkin slices and by increase in concentration of sucrose osmotic solution, rate of absorbed substance was reduced in pumpkin slices. Tissue hardness was decreased by rising concentration of pectin. The mean difference in total color (ΔΕ) was increased following to increase in concentration of carboxy methyl cellulose, pectin, and sucrose osmotic solution. There was totally significant difference in concentration percent and type of edible coating and osmotic solution in terms of sense assessment of pumpkin slices (p<0.01). Treatment C1S2 with coating 0.5 w/w of edible and dehydrated carboxy methyl cellulose solutions including 60% of sucrose osmotic solution lost the maximum amount of water and it comprised of minimum amount of absorbent substance and it was introduced as premium treatment.