Improving material properties of canola protein films using modified nanocrystalline cellulose for food packaging applications

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Dissanayake, Thilini
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The demand for biopolymer-based food packaging increases day by day with the increasing concerns over environmental and economic sustainability. Agricultural by-products such as canola meals are becoming more popular among researchers due to their high availability at a low cost. Canola protein isolate derived from the canola meal has already proven its film-forming abilities desirable for food packaging applications. However, compared to petroleum-based plastic food packaging, intact canola protein-based films possess poor mechanical properties and high hydrophilicity that limit their use in food packaging. Nanocrystalline cellulose (NCC) is an excellent reinforcing material that enhances the properties of biopolymers. However, their hydrophilicity and agglomeration in the polymer matrix limit their excellent properties. The objective of the first study of the thesis was to modify the NCC using the TEMPO (2,2,6,6- Tetramethylpiperidine-1-oxyl) method to obtain TEMPO modified NCC (TM-NCC) and fabricate the films using the solvent casting method at different levels of unmodified NCC (U-NCC) or TM-NCC (0, 1, 3, 5% w/w of protein). The second study aimed at a different modification where oleic acid (OA) was used to modify NCC and obtain OA modified NCC (OA-NCC). Then the films were fabricated using U-NCC or OA-NCC (0, 1, 3, 5, 7, 9% w/w of protein). In both studies, the effect of modified NCC and U-NCC on the films' mechanical, barrier, and thermal properties were evaluated. TM-NCC significantly increased the films' tensile strength, resulting in the highest value (8.36 ± 0.85 MPa) for TM-NCC 5% films. Moreover, both U-NCC and TM-NCC enhanced the films' water barrier and thermal properties compared to control. In the second study, OA-NCC significantly enhanced mechanical, barrier, and thermal properties compared to control and U-NCC resulting maximum of 3.44 ± 0.32 MPa for OA-NCC 3% films and a minimum of 0.054 ± 0.004 g mm/m2 KPa h water vapor permeability for OA-NCC 9% films. Overall, modification of NCC enhanced the properties of canola protein films due to the enhanced interactions and compatibility of the nanomaterials in the polymer network. This study provides a new platform of value addition to the canola industry’s main byproduct.
Canola protein, Food packaging, nanocrystalline cellulose modification, water barrier properties, tensile properties