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Browsing Theses (Ph.D.) by Author "ADARSH M. KALLA"

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    DEVELOPMENT OF COCONUT SHELL POWDERBASED BIOCOMPOSITES FOR PACKAGING OF SELECT DAIRY PRODUCTS
    (ICAR-SRS-NDRI, KARNAL, 2021) ADARSH M. KALLA; F. MAGDALINE ELJEEVA EMERALD
    Biodegradable packaging materials developed using agricultural wastes can be a promising alternative to non-degradable synthetic polymers. In this context, the present study was envisaged to utilise the coconut shell powder (CSP) as a biodegradable packaging material for select dairy products. CSP was used to make containers and to extract cellulose, which was utilised as reinforcing material in polyvinyl alcohol (PVA) and casein matrix films. The development of CSP based container with different binders such as acacia gum, guar gum, starch, gluten and sodium alginate were unsuccessful due to breakage and sticking to die. The setup used to make containers was later modified by providing guide rods and hydraulic press but no satisfactory shaping of containers were obtained. Cellulose was extracted from CSP by alkalisation and delignification methods. The average yield and moisture content of the extracted cellulose were 27.5% of the initial weight of CSP and 2.5% d.b., respectively. Flow properties such as bulk density, tapped density, angle of repose and porosity of extracted cellulose, CSP and commercial cellulose were found to be 368.80, 500.90 and 303.90 kg/m3, 493.80, 682.50 and 452.30 kg/m3, 44.18, 43.17 and 55.75° and 0.71, 0.69 and 0.79, respectively. The size of extracted cellulose fibres was observed from scanning electron micrographs (SEM) as 5-20 μm. Energy dispersive X-ray spectroscopic analysis confirmed the absence of chemicals used for cellulose extraction. Atomic force microscopy revealed that the extracted cellulose had mean roughness of 1.37 nm. X-ray diffractograms (XRD) revealed the crystalline nature of extracted cellulose, with crystallinity index of 65.9%. Fourier transform infrared (FTIR) spectra confirmed the absence of lignin and hemicelluloses in the cellulose extracted from CSP. D-optimal mixture design was used to optimise the ingredients such as CSP, PVA and casein in the cast films. The viscosity of film forming solutions (FFS) ranged from 3.88 to 87.41 mPa.s, which also displayed non-Newtonion behaviour. The rheological data of all FFS were best fitted to Casson’s model with R2 ranging from 0.995 to 0.999. The viscoelasticity of FFS showed linear and higher value of loss modulus over the entire shear rate range, indicating dominant viscous behaviour. The FFS were formed into films using film casting method. The thickness of films ranged from 0.256 to 0.312 μm. The mechanical properties such as tensile strength, tensile strain and modulus of elasticity were measured, and were found range from 3.20 to 7.20 MPa, 8.66 to 104.16% and 5.67 to 83.42 MPa, respectively. Moisture content and solubility were analysed and found to be varied from 25.56 to 16.55% d.b and 17.47 to 27.44%, respectively. Transparency of films ranged from 1.50 to 4.61 AU nm/mm. Lightness and whiteness index value of films ranged from 38.23 to 72.03 and 38.22 to 71.12, respectively. The water vapour permeability of biocomposite films ranged from 8.09×10-10 to 11.60×10-10 g/msPa. The composite films containing higher percentage of PVA were more resistant to biodegradation. The SEM micrographs confirmed the dispersion of cellulose in casein-PVA polymer matrix. The oxygen permeability values were also within the range. The FTIR and XRD results of films indicated good interaction between cellulose and polymer matrix. PVA, casein and cellulose in the ratio of 4:3:2 was found to be optimum with respect to film properties. Moisture sorption isotherms of PVA, casein and optimised biocomposite films at 25, 30 and 40°C followed Type-II BDDT classification. The GAB model best fitted the moisture sorption data of all samples as evident from R2 and RMSE values of nearly 1 and less than 10, respectively. The optimised biocomposite film was used to package paneer and storage study was done at 7±1°C for 9 days. The physico-chemical and microbiological analysis revealed that the biocomposite film was comparable with LDPE pouches. Organoleptic studies revealed that the paneer packaged in composite film had statistically acceptable sensory scores except for its body and texture, and had slightly less shelf-life than those packaged in LDPE pouches.