Abstract:
Glucomannan film is an edible polysaccharide-based film developed from konjac flour which has glucomannan as a main compound. The study showed that konjac flour concentration, plasticizer type, and plasticizer level affected Tensile Strength, Elongation, Water Vapor Permeability and Oxygen Permeability of glucomannan film significantly (p<_ 0.05). The edible film prepared from konjac flour 1 percent (w/v) and glycerol 30 percent (w/weight of konjac flour) was selected to further study. Tensile Strength, Elongation, Water Vapor Permeability and Oxygen Permeability of this film are 7.85 N/square m, 79.67 percent, 15.50 g mm./square m day kPa and 11.40 c cubic m um./square m day kPa, respectively. The study of sorbic acid diffusivity showed that sorbic acid concentration, film thickness and relative humidity affected the sorbic acid diffusivity significantly (p<_ 0.05). The lowest sorbic acid diffusivity of film incorporated with sorbic acid 10 percent (w/weight of konjac flour) was 0.060*10-12 and 0.3133*10-12 square m/s at 65 and 100 percent of relative humidity, respectively. Film's application was studied on durian paste which represented as a model of intermediate moisture food. It was found that shelf life of durian paste using glucomannan film incorporated with sorbic acid 10 percent (w/weight of konjac flour) and polypropylene was 10 weeks at the room temperature which was longer than that of durian paste using only polypropylene as packaging. Consumer test on using glucomannan film as wrapping package by sampling of 200 consumers between 16 to 35 years showed that 87.00 percent of consumer approved on its application for durian paste, banana paste, pineapple paste, and karamac (Thai dessert). 88.50 percent of consumer accepted durian paste, banana paste, pineapple paste, and karamac wrapped by glucomannan film incorporated with sorbic acid 10 percent (w/weight of konjac flour).