Insecticidal property of Ocimum essential oil embedded polylactic acid packaging films for control of Sitophilus oryzae and Callosobruchus chinensis.

Naturally derived essential oils (EOs) from Ocimum basilicum (OB) and Ocimum gratissimum (OG) were incorporated in polylactic acid (PLA) matrix with concentration of 2.5 % and 5 % respectively by solvent casting method, with an aim to develop insecticidal polymer pouches (insect proof polymer pouches). The major components following GC-MS analysis revealed the presence of EOs as estragole (69.998 %) in OB and thymol (29.843 %) in OG. The developed films with EOs showed remarkable insecticidal activity with 100 % and 80 % mortality rate for OB and OG respectively at 2.5 % concentration against rice weevil (Sitophilus oryzae). While, both OB and OG EOs observed 100 % mortality against pulse beetle (Callosobruchus chinensis) after 96 h exposure in presence of grain conditions and the insecticidal efficacy was equivalent to the commercial hermetic bags (CSB). The physical property of film showed increase in the film thickness in EO-PLA films whereas the mechanical properties of EO-PLA films matrix have increased the polymer flexibility with decreasing tensile strength (TS) and Youngs modulus (EM) as TS OB 5 %, OG 5 % - 15.64 MPa, 17.66 MPa respectively. While, water vapour transmission rate (WVTR) was reduced to 0.015 g/m2.hr, optical characteristics showed slight significant change in colour and FTIR spectra exhibited a change in -OH stretching compared to blank PLA matrix. The surface morphology of the blank and EO embedded PLA films visualized by SEM depicted a complete homogenization of essential oils in the PLA matrix.

Effect of lignin on water vapor barrier, mechanical, and structural properties of agar/lignin composite films.

Biodegradable composite films were prepared using two renewable resources based biopolymers, agar and lignin alkali. The lignin was used as a reinforcing material and agar as a biopolymer matrix. The effect of lignin concentration (1, 3, 5, and 10wt%) on the performance of the composite films was studied. In addition, the mechanical, water vapor barrier, UV light barrier properties, FE-SEM, and TGA of the films were analyzed. The agar/lignin films exhibited higher mechanical and UV barrier properties along with lower water vapor permeability compared to the neat agar film. The FTIR and SEM results showed the compatibility of lignin with agar polymer. The swelling ratio and moisture content of agar/lignin composite films were decreased with increase in lignin content. The thermostability and char content of agar/lignin composite films increased with increased lignin content. The results suggested that agar/lignin films have a potential to be used as a UV barrier food packaging material for maintaining food safety and extending the shelf-life of the packaged food.

Preparation, characterization, and antimicrobial activity of chitin nanofibrils reinforced carrageenan nanocomposite films.

Present study illustrates the preparation of chitin nanofibrils (CNF) reinforced carrageenan nanocomposite films by the solution-casting technique. CNF was prepared by acid hydrolysis of chitin, followed by high speed homogenization and sonication. FTIR result demonstrated that the chemical structure of chitin had not changed after acid hydrolysis. However, the crystalinity of CNF was found to be higher than chitin. The crystallite size of chitin and CNF was 4.73 and 6.27 nm, respectively. The char content at 600 °C of chitin (19.2%) was lower than the CNF (25%). The carrageenan/CNF composite films were smooth and flexible and the CNF was dispersed uniformly in the carrageenan polymer matrix. The tensile strength and modulus of carrageenan film were increased significantly (p<0.05) after CNF reinforcement with up to 5 wt%, however, elongation at break, water vapor permeability, and transparency decreased slightly. Carrageenan/CNF nanocomposite films showed strong antibacterial activity against a Gram-positive food-borne pathogen, Listeria monocytogenes.

Characterization of bionanocomposite films prepared with agar and paper-mulberry pulp nanocellulose.

Crystallized nanocellulose (CNC) was separated from paper-mulberry (Broussonetia kazinoki Siebold) bast pulp by sulfuric acid hydrolysis method and they were blended with agar to prepare bionanocomposite films. The effect of CNC content (1, 3, 5 and 10 wt% based on agar) on the mechanical, water vapor permeability (WVP), and thermal properties of the nanocomposites were studied. Changes of the cellulose fibers in structure, morphology, crystallinity, and thermal properties of the films were evaluated using FT-IR, TEM, SEM, XRD, and TGA analysis methods. The CNC was composed of fibrous and spherical or elliptic granules of nano-cellulose with sizes of 50-60 nm. Properties of agar film such as mechanical and water vapor barrier properties were improved significantly (p<0.05) by blending with the CNC. The tensile modulus and tensile strength of agar film increased by 40% and 25%, respectively, in the composite film with 5 wt% of CNC, and the WVP of agar film decreased by 25% after formation of nanocomposite with 3 wt% of CNC. The CNC obtained from the paper-mulberry bast pulp can be used as a reinforcing agent for the preparation of bio-nanocomposites, and they have a high potential for the development of completely biodegradable food packaging materials.