Engineering and functional properties of biodegradable pellets developed from various agro-industrial wastes using extrusion technology

Abstract

Different agro-industrial wastes were mixed with different plasticizers and extruded to form the pellets to be used further for development of biodegradable molded pots. Bulk density and macro-porosity are the important engineering properties used to determine the functional characteristics of the biodegradable pellets viz., expansion volume, water solubility, product colour, flowability and compactness. Significant differences in the functional properties of pellets with varying bulk densities (loose and tapped) and macro-porosities (loose, tapped) were observed. The observed mean bulk density of biodegradable pellets made from different formulations ranged between 0.213 and 0.560 g/ml for loose fill conditions and 0.248 to 0.604 g/ml for tapped fill conditions. Biodegradable pellets bear a good compaction for both loose and tapped fill methods. The mean macro-porosity of biodegradable pellets ranged between 1.19 and 54.48 % for loose fill condition and 0.29 to 53.35 % for tapped fill condition. Hausner ratio (HR) for biodegradable pellets varied from 1.026 to 1.328, indicating a good flowability of biodegradable pellets. Pearson's correlation between engineering properties and functional properties of biodegradable pellets revealed that from engineering properties functional properties can be predicted.

Physico-Chemical, Functional and Rheological Characterization of Biodegradable Pellets and Composite Sheets

“…According to Rosentrater [13], Maillard reactions and protein denaturing play main roles in colour alterations during the cooking process resulting from high temperatures. It was also observed that the color (∆E) value of samples containing CNSL as plasticizer were greater than samples containing glycerol as plasticizer which is due to the inherent dark color of the cashew nut shell liquid [7], resulting in maximum absorption of the light. In case of sheets, a significant increase in colour (∆E) was observed during pressing (hydraulic press) which may be due to higher temperature during processing as compared to that of pellets during extrusion.…”

“…The increased hardness may be attributed to the greater binding effect of CNSL as compared to glycerol. Moreover, the increased hardness measured by texture analyser is due to more resistance to compression [7]. Plasticizers are important to maintain dimensional stability, hardness and flexibility of protein-based polymer due to its high boiling temperature [9].…”

“…Moreover, it may be also due to the hydrophilic and hygroscopic nature of glycerol and its ability to form the large hydrodynamic plasticizerwater complex [7].…”

“…The thermal energy generated by viscous dissipation during extrusion, combined with shearing effect, quickly cooks the raw mixture so that the properties of materials are modified due to physico-chemical changes of the biopolymers [7]. The effect of extrusion on the properties of pellets, using rice husk as filler was analyzed by Simone [8].…”

Value Addition to Food Industry By-Products and Wastes (Deoiled Rice Bran and Banana Peel) by Optimizing Pellets' Formulation Using Response Surface Methodology: Characterisation and Classification by PCA Approach

“…It represents a sizeable and functional component to reinforce materials for biocomposites (Jan et al . ). Biopolymers generally present poor mechanical properties; hence, plasticizers are added to provide the necessary workability (Vieira et al .…”