EFFECT OF GLYCEROL CONCENTRATION, AND DRYING TEMPERATURE ON PHYSICOCHEMICAL AND MECHANICAL PROPERTIES OF PLASTIC BIOFILM DEVELOPED FROM MANGO PEEL PECTIN

Major Advisor: Dr. Ebisa Olika (Assistant Prof.)

Synthetic plastics made from petroleum have recently caused severe environmental contamination due to their inability to be biodegradable, which is a global problem around the world. The most effective way to address this major problem is to produce biodegradable plastic biofilm. Thus, the effect of glycerol concentration (20%, 30%, and 40% v/w) (2, 3, and 4 mL) and drying temperature (45oC, 55oC, and 65oC) on the physicochemical and mechanical properties of plastic biofilm developed from mango peel pectin was investigated following the standard analytical methods. Thirteen experimental runs were generated by Design Expert® software version 13.0.5.0 using the Response Surface Methodology. Statistical model evaluation and optimization were done using the same software. The result on a dry weight basis showed that the proximate composition of mango peel was found to be 5.06%, 3.5%, 7.45%, 3.93%, 2.725%, 77.335%, and 17.14% for moisture, ash, crude protein, crude fat, crude fiber, carbohydrate, and pectin content, respectively. Mango peel pectin contained 7.21% and 2.89% for moisture and ash content, respectively. It is also characterized by a 550.6% equivalent weight, 8.68% methoxyl content, 71.62% anhydrouroni c acid, and 68.80% degree of esterification. The ANOVA analysis showed that the quadratic model had highly significant (P < 0.0001) effects on tensile strength, elongation at break, water absorption, and biodegradability. The produced plastic biofilm samples' tensile strength, elongation at break, water absorption, and biodegradability ranged from 4.15MPa 7.19MPa, 18.00%-25.9%, 63.92%-71.24%, and 80.15%-85.5%, respectively. The optimum values of the influencing factors were found to be glycerol at 20% v/w and a drying temperature of 54°C. Under optimal conditions, a biofilm with a tensile strength of 7.132MPa, elongation at break of 20.43%, water absorption of 67.96%, and biodegradability of 81.87% was achieved from the predicted results. Statistical model validation showed an insignificant difference between predicted and experimental results. Besides the above findings, using calcium carbonate (CaCO3) as a filler, the water absorption of the biofilm decreased by 37.4% compared to the filler-free biofilm, while all other parameters remained at their optimum values. The findings suggested that the addition of CaCO3 as a filler has better water absorption during the development of biodegradable plastic biofilm from mango peel pectin. Key words: Biodegradable, Biofilm, Filler, Mango peel, Pectin, Plastics, Synthetic