Color kinetics and quality of fresh pineapple juice packed in polylactic acid-5% zinc oxide nanoparticles (PLA-5%ZnO NPs) composite films during chilling storage

Mohamad, Norsyahirah (2019) Color kinetics and quality of fresh pineapple juice packed in polylactic acid-5% zinc oxide nanoparticles (PLA-5%ZnO NPs) composite films during chilling storage. [Project Paper] (Submitted)

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Abstract

Polylactic-acid composite film containing 5% of ZnO nanoparticles (PLA-5%ZnO NPs) were prepare by solution polymerization of PLA resin and ZnO NPs in dichloromethane solvent. The performance of seal strength of PLA-5%ZnO NPs were analyzed in terms of tensile peel strength at three different levels of heat which is 3, 4, and 5. The sealed strength of films increased with the increasing of heat seals level. However, sealing of films at heat seal level 5 weakening the PLA films seal strength. At this level, PLA films at the molten state that reduced the thickness of the PLA films caused the films to torn apart without peeling. While the strength of PLA-5%ZnO NPs composite films were increased with the increasing of heat sealed temperature. At this levels of heat sealed, the sealed strength of PLA-5%ZnO NPs composite films were increased. The addition of 5% of ZnO into the PLA films increased the thermal properties of the films that caused increasing in sealed strength of the films. Then, the shelf life of the pineapple juice were evaluated on the physicochemical and microbiological properties of the pineapple juice stored in a dark place at 4°C for 14 days. The fresh pineapple juice were extracted and filled into sealed packaging of PLA films and PLA-5%ZnO NPs films under sterile condition. The color kinetics, pH, total soluble solid, browning index, total plate count, yeast and mold count shown increasing in trend during storage for both type of packaging. While for ascorbic acid analysis, the result showed a reduction in trend against storage period due to the oxidation of ascorbic acid. However, pineapple juice packaged in PLA-5%ZnO NPs composite films showed a better retention in quality for all analysis compared to PLA films alone. It is due the presence of ZnO as antimicrobial agent in the packaging films were able to the quality of juice during storage. The migration level of ionic zinc into pineapple juice packed in PLA-5%ZnO NPs were evaluated using atomic absortion spectrophotometry by wet digestion method. The ionic zinc migrated from the packaging films into the pineapple juice increasing with storage period. The factor that contribute in the migration of ionic zinc were the acidity of the pineapple juice and the surface area of the films with direct contact of juice. It caused higher tendency of ionic zinc migrated into pineapple juice.

Item Type:	Project Paper
Faculty:	Faculty of Engineering
Depositing User:	Ms. AZLINA ZAINAL ABIDIN
Date Deposited:	21 Nov 2024 06:11
Last Modified:	21 Nov 2024 06:11
URI:	http://psaspb.upm.edu.my/id/eprint/2226

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