Akademik Veri Yönetim Sistemi
Tezin Türü: Yüksek Lisans
Tezin Yürütüldüğü Kurum: Wageningen Universiteit, VLAG Graduate School, Food Process Engineering, Hollanda
Tezin Onay Tarihi: 2022
Tezin Dili: İngilizce
Öğrenci: Madhumitha Muthurajan
Danışman: Murat Yanat
Özet:
Polylactic acid (PLA), despite being the most promising biodegradable plastic has not been able to
completely replace the traditional plastics in food packaging. Advancements in nano packaging have
led to the reinforcement of PLA by the addition of nanoparticles as fillers. Chitin nanocrystals (ChNC)
is a non-toxic nanofiller that has enhanced the mechanical and barrier properties of PLA. However,
growing consumer awareness on food safety accompanied by a shift of consumer preferences towards
sustainability emphasises the need to evaluate the safety of ChNC/PLA nanocomposites in food
packaging. The aim of the study is to investigate the migration and biodegradability of chitin
nanocrystals in the PLA nanocomposite and verify its suitability in food packaging applications.
ChNC/PLA nanocomposite films of different concentrations (0, 1, 5 and 10 %) were produced by
solvent casting method. The standard overall migration tests (EU regulation No 10/2011) were
conducted with 10% ethanol and pure iso-octane as food simulants. The overall migration values
(OMVs) of all the films were below the safety limit of 60 mg/kg except 10 % ChNC/PLA nanocomposite
in 10% ethanol. The OMV increased with the increase in ChNC concentration indicating a potential
migration of ChNC. Further, the addition of the plasticiser glycerol triacetate (GTA) improved the
dispersion of ChNC in the PLA nanocomposites and simultaneously also notably increased the OMV of
the nanocomposites. Numerous analyses including visual, microstructure, gel permeation
chromatography, mechanical and thermal analysis were conducted for the ChNC/PLA film samples
before and after the migration test. Despite the analyses, the mechanism of migration in isooctane
could not be strongly concluded. However, all the analyses directed towards hydrolytic degradation
of PLA in the nanocomposite film samples exposed to 10 % ethanol which could have caused the
migration. Also, the presence of ChNC filler seemed to delay the hydrolytic degradation of PLA.
Furthermore, the biodegradability of chitin macromolecule and nanocrystals studied through a
manometric respiratory method (ISO 14851 -2019) showed that the degree of biodegradability of
chitin powder remained similar at the nanoscale.
The findings of the study suggest that the ChNC/PLA nanocomposite films with nanoparticle
concentrations below 5 % were safe to be utilised as food packaging for foods with high-water or oil
content. Also, the transformation of chitin to ChNC did not alter its biodegradability.