Sodium Alginate and Lemon (Citrus Limon) Waste-Based Biodegradable Film

Abstract

The aim of the study was to develop a biodegradable packaging film using sodium alginate and waste lemon peel. For this purpose, different concentration of both sodium alginate and lemon peel powder was taken in ratios Sodium alginate: lemon peel powder:: 0.5:1, 0.5:2, 0.5:3, 0.5:4, 1:1, 1:2, 1:3, 1:4, and 1.5:1, 1.5:2, 1.5:3, 1.5:4 to obtain 12 film specimens. The films were plasticized using glycerol (5% v/v) and crosslinked with a 2% CaCl2 solution. The films were developed using the solution-casting method. Dried films obtained were visually homogenous, flexible, and without any cracks. The films were analyzed for various physical, mechanical, optical, and light barrier properties. The physicochemical properties of the film were thickness (0.07 ± 0.01 to 0.27 ± 0.01 mm), grammage (246.72 ± 0.35 to 445.78 ± 0.23 g/m2), moisture content (10.38 ± 0.31% to 14.14 ± 0.37%), ash content (3.23 ± 0.05% to 5.13 ± 0.04%), water solubility (64.14 ± 0.07% to 81.91 ± 0.23%), and water absorption (19.20 ± 1.18% to 38.54 ± 1.45%). The developed films displayed good mechanical properties with a maximum tensile strength of 6.42 ± 0.02 MPa for sample SA1:LPP1 having sodium alginate: lemon peel ratio of 1:1. Elongation at break and burst strength ranged from 4.67 ± 0.12 to 15.27 ± 0.12% and 0.23 ± 0.01 to 0.66 ± 0.02 MPa, respectively. The highest retraction ratio of 98.33 ± 0.29% was observed in sample SA1:LPP1. Lemon peel had a significant effect on the color values. An increase in its concentration resulted in an increase in the a* and b* values and decreased the L* value. Lemon peel also improved the light barrier properties of the film with transparency ranging from 3.56 ± 0.47 to 7.03 ± 0.09. The light transmittance decreased with an increase in lemon peel powder which was in accordance with obtained opacity. The films also showed 83.80 to 90.76% biodegradability in a soil burial test. Based on the results, the film sample SA1:LPP1, sodium alginate: lemon peel ratio of 1:1 had better properties as compared to other films. Therefore, the use of lemon peel can serve as a promising source for the development of biodegradable packaging.