Publicação
Development of Chitosan Bionanocomposites Reinforced with Nanocellulose Extracted from Energy Crops - Characterization and Application as Active Packaging
| Resumo: | The renewable and biodegradable materials are crucial in combating the environmental impacts of fossil-based products. Lignocellulosic feedstocks, abundant in cellulose, hemicellu- lose, and lignin, can yield valuable products. Cellulose Nanocrystals (CNCs) exemplify bi- oproducts with diverse applications. Moreover, incorporating CNCs into chitosan (Ch) films presents a promising approach to enhance bioplastics. This doctoral thesis focuses on developing a high-value bionanocomposite for fully bio- degradable and active food packaging, contributing to the circular economy. Firstly, Cellulose was sustainably isolated from three lignocellulosic biomasses (Miscanthus × giganteus Greef et Deuter, Arundo donax L., and Hibiscus cannabinus L.) and converted into CNCs through acid hydrolysis. The CNCs exhibited a rod-like shape but formed strong aggregates, hindering in- dividual observation and aspect ratio quantification due to less effective dispersion. The sec- ond phase involved incorporating CNCs into chitosan bio-based films to determine the opti- mal formulation. The nanocellulose significantly improved the film's mechanical, thermal, and barrier properties, as well as U.V. light resistance, without altering color and opacity. Bionano- composites with 2.5% CNCs from any biomass showed the best overall properties. In the final stage, the optimized bionanocomposites were used for active food packaging, with novel for- mulations incorporating salvia essential oil (SEO) to enhance antimicrobial and antioxidant activities. The results demonstrated reduced microbiological degradation and lipid oxidation in meat packaged with bionanocomposites compared to unpackaged meat. However, the ad- dition of SEO did not significantly improve the bionanocomposites' active properties as ex- pected. The "in vitro" migration tests suggested that CNCs entrapped the phenolic compounds, resulting in decreased migration of SEO active compounds from the packaging. In conclusion, this thesis successfully demonstrated the potential of reusing lignocellulosic biomass to isolate and convert cellulose into nanocellulose. Incorporating CNCs into chitosan films yielded func- tional, renewable, and biodegradable bionanocomposites with active properties, offering a sustainable alternative to traditional fossil-based plastic food packaging. |
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| Autores principais: | Pires, João Ricardo Afonso |
| Assunto: | Energy Crops Nanocellulose Chitosan Bionanocomposite Salvia Essential Oil Food Packaging |
| Ano: | 2023 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade Nova de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório Institucional da UNL |
| Resumo: | The renewable and biodegradable materials are crucial in combating the environmental impacts of fossil-based products. Lignocellulosic feedstocks, abundant in cellulose, hemicellu- lose, and lignin, can yield valuable products. Cellulose Nanocrystals (CNCs) exemplify bi- oproducts with diverse applications. Moreover, incorporating CNCs into chitosan (Ch) films presents a promising approach to enhance bioplastics. This doctoral thesis focuses on developing a high-value bionanocomposite for fully bio- degradable and active food packaging, contributing to the circular economy. Firstly, Cellulose was sustainably isolated from three lignocellulosic biomasses (Miscanthus × giganteus Greef et Deuter, Arundo donax L., and Hibiscus cannabinus L.) and converted into CNCs through acid hydrolysis. The CNCs exhibited a rod-like shape but formed strong aggregates, hindering in- dividual observation and aspect ratio quantification due to less effective dispersion. The sec- ond phase involved incorporating CNCs into chitosan bio-based films to determine the opti- mal formulation. The nanocellulose significantly improved the film's mechanical, thermal, and barrier properties, as well as U.V. light resistance, without altering color and opacity. Bionano- composites with 2.5% CNCs from any biomass showed the best overall properties. In the final stage, the optimized bionanocomposites were used for active food packaging, with novel for- mulations incorporating salvia essential oil (SEO) to enhance antimicrobial and antioxidant activities. The results demonstrated reduced microbiological degradation and lipid oxidation in meat packaged with bionanocomposites compared to unpackaged meat. However, the ad- dition of SEO did not significantly improve the bionanocomposites' active properties as ex- pected. The "in vitro" migration tests suggested that CNCs entrapped the phenolic compounds, resulting in decreased migration of SEO active compounds from the packaging. In conclusion, this thesis successfully demonstrated the potential of reusing lignocellulosic biomass to isolate and convert cellulose into nanocellulose. Incorporating CNCs into chitosan films yielded func- tional, renewable, and biodegradable bionanocomposites with active properties, offering a sustainable alternative to traditional fossil-based plastic food packaging. |
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