Dissertation
DEVELOPMENT OF AN OXYGEN SENSOR TO EVALUATE THE PERFORMANCE OF METAL OXIDE COATED FLEXIBLE FILMS FOR THERMALLY STERILIZED SHELF STABLE FOOD PACKAGING
Washington State University
Doctor of Philosophy (PhD), Washington State University
01/2021
DOI:
https://doi.org/10.7273/000002457
Handle:
https://hdl.handle.net/2376/119853
Abstract
High oxygen and moisture barrier metal oxide (MO)-coated multilayer polymer packaging can retain the shelf life of in-package sterilized food products. However, presence of cracks and pinholes in the coating layer of these films can increase their oxygen and moisture permeabilities. The defects have microscopic dimensions and can be present at random locations in the films’ coatings, making it difficult to find and characterize them using traditional microscopes. To solve these challenges, this research focused on three objectives: (i) to develop an oxygen indicator that can locate the defects in the metal-oxide coated films and validate its functionality; (ii) to assess the performance of newly developed MO-coated films with multiple coated-PET layers; (iii) to accelerate the detection process of the indicator to make it more industry oriented. In the first study, a methylene blue and agar gel-based color changing oxygen indicator was developed that could visually identify the defects in MO-coated films. Microscopic characterization confirmed the presence of defects at the locations indicated by the indicator, hence validating its effectivity. The indicator worked efficiently at 23 ℃ to detect the defects but was not successful when tested under accelerated conditions at 40℃.
The second study assessed the efficacy of two newly developed MO-coated films with multiple coated-PET layers by exposing them to retort and microwave assisted thermal sterilization (MATS) processes. Films with three coated PET layers showed no oxygen permeation after retort and MATS processing. The three-layer coated-PET films had limited moisture absorption and least number of defects, as demonstrated by the oxygen indicator, SEM and CLSM.
The third study explored the possibility of accelerating the detection process by formulating the indicator using three different gelling agents: Agar, Gellan_ NaCl, Gellan_ CaCl2 and testing them at 23 ℃ and 40 ℃ with two MO-coated films. Gellan_ NaCl was faster than the other two gel-based indicators. Additionally, Gellan_ NaCl could detect the defects in 20 days at 40 ℃. This reduced the detection period from 180 days at 23 ℃, as seen in the first study. Overall, the method could expeditiously detect the defects and thus, could reduce the cycle time needed for developing newer MO-coated films.
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- Title
- DEVELOPMENT OF AN OXYGEN SENSOR TO EVALUATE THE PERFORMANCE OF METAL OXIDE COATED FLEXIBLE FILMS FOR THERMALLY STERILIZED SHELF STABLE FOOD PACKAGING
- Creators
- Ashutos Parhi
- Contributors
- Shyam S. Sablani (Advisor)Juming Tang (Committee Member)Barbara Rasco (Committee Member)
- Awarding Institution
- Washington State University
- Academic Unit
- Biological Systems Engineering, Department of
- Theses and Dissertations
- Doctor of Philosophy (PhD), Washington State University
- Publisher
- Washington State University
- Number of pages
- 213
- Identifiers
- 99900606856101842
- Language
- English
- Resource Type
- Dissertation