Effect of nanocellulose extracted from rice husk on the film properties of native starch based edible films

Abstract

Edible films are thin films intended to contain, store, and protect the food and beverages. As they are made from edible polymers, the consumption of edible films does not harm human or living things. They are easily biodegradable, producible from renewable sources, and safe for consumption. Hence, they have high potential in food packaging sector to overcome the problems associated with synthetic and biodegradable plastics. Hydrocolloids and lipids are widely investigated and found suitable for making the edible films. Among many sources of hydrocolloids, starch based films have advantages, such as highly transparent, highly flexible, having high degree of polymerization, easy processability, requiring less chemicals for production etc. However, literature showed that the edible films produced from native starch exhibit poor water resistance and low mechanical strength as compared to those of other hydrocolloids. Incorporation of nanomaterials with edible films is considered to be an effective method to improve the functional properties. In the present investigation, the influence of nanocellulose on the film properties of edible films is investigated. Nanocellulose was produced from rice husk through a three step chemical process: alkaline treatment, bleaching and acid hydrolysis. The edible films were prepared from native potato starch through solution casting method by varying nanocellulose content (0%, 5%, 10% & 15%). Water vapor transmission rate (WVTR), mechanical strength (tensile strength, Young's modulus and percentage of elongation) and film color were tested for the produced films. From the results, it was observed that the addition of nanocellulose had shown lower WVTR, increased mechanical strength and higher transparency, as compared to the control films.