Biodegradable food packaging using agricultural wastes (Banana Pseudostem)

Abstract

Biodegradable food packaging has been developed in this research from banana pseudostem. The research can be divided into three phases. The first phase was to explore the possible method to isolate nanocellulose from banana pseudostem as the main polymer for bioplastic formation. Alkaline treatment, bleaching, and TEMPO-mediated oxidation coupled with mild mechanical disintegration successfully removed non-cellulosic polysaccharides and isolated nano-sized fibre from banana pseudostem. The nanocellulose had diameters 7-35 nm, several micrometer lengths, highly negative zeta potential, and initial degradation temperature at 220 oC. Although the nanocellulose extracted was highly pure and separated from non-cellulosic polysaccharides, it contained significant amounts of ash, especially in the form of calcium oxalate crystals.

The second phase of this research was to study the properties of the film made from the nanocellulose. Modifications to the film were done to improve the quality of the film by incorporating plasticisers (glycerol and polyethylene glycol (PEG)) and nanofillers (nanoclay and graphene oxide) into the nanocellulose matrix. The addition of plasticisers did improve the film elasticity. Relative to the glycerol, PEG only slightly influenced the thermal stability of the film, making this plasticiser more preferable. The addition of nanofillers significantly (p<0.05) improved the tensile strength and contact angle of the film. Interestingly, the properties of the film were further improved when the nanofillers were combined with the plasticisers.

The third phase of this research was to study the stability of the film components from migration, recyclability, and biodegradability. Nanocellulose was stable from migration to the food simulants. However, plasticisers and some salts easily migrated and made the overall migration of the film exceed the safety value for food packaging. TEMPO containing solution and the nanocellulose was found to be recyclable for at least three times. The films also showed promising indication of biodegradation through appropriate soil tests.