Optimization of Cutin Recovery from Tomato Industry Wastes and Evaluation in Bioplastic Film Production
Project no. 23383 · Status: Kapanmış · 2022
Summary
<p> The objectives of this project were to carry out the optimization of tomato peel extraction under alkali conditions; to perform the characterization of tomato peel extracts (TPE) treated with alkali solution under atmospheric (AC) and oxygen free conditions (OFC); to produce biocomposites used as food packaging material by the incorporation of TPE into Poly (lactic acid) (PLA) and to perform the characterization of PLA/TPE biocomposites. The optimization of the extraction for AC was performed using Response Surface Methodology. The conditions in which the highest yield (31,31%) were obtained were determined as 100 °C and 6 h. The results of this project indicated that there is no significant difference between AC and OFC extracts in terms of chemical, thermal, antioxidant and antimicrobial properties (p > 0,05). </p><p> In the following stage, TPE was introduced to the biodegradable PLA material at the weight ratios of 1% (TPE1), 2% (TPE2) and 3% (TPE3) in a single screw extruder at temperatures of 170-175-180-170 °C to form biocomposite films. It was determined that the composite films were visually more transparent and brighter than PLA. On the other hand, as the ratio of TPE in the composite increased, the morphological structure was adversely affected, and the number of cracks, voids and folds on the surface of the composites increased. The high fiber content of TPE caused a decrease in the thermal strength of PLA. With the increasing TPE ratio in the composite, the glass transition temperature of PLA decreased and the thermal stability of the crystal structure and the crystal size increased. As the TPE ratio increased in the composite, the tensile strength and elasticity modulus decreased but the elongation at break of the films increased. Compared to PLA, the water vapor permeability increased in TPE1, TPE2 and TPE3 composites by 1.15; 1.23 and 2.02 times respectively. As the ratio of TPE in the composite increased, the surface contact angle decreased and the hydrophilic property of the composite surface increased. The increase in the volume of the spaces between the crystal spherulites with the increase of the TPE ratio in the composite also negatively affected the oxygen transmission rate (OTR) of the composites and the OTR values increased significantly compared to PLA. It was determined that the PLA/TPE biocomposites exhibited antioxidative and antimicrobial effect at minor levels since the concentrations of TPE introduced into PLA were low. In model food applications, adding 2% TPE to PLA revealed the best results in terms of total color change, browning and antioxidant capacity, but did not bring a significant difference in terms of total mesophilic bacteria and mold-yeast growth. Based on these results, it is thought that TPE added to PLA can improve the properties of the samples, but new studies should be conducted to further increase this concentration.</p>