Development of an Oxygen Sensitive Model Gel System to Detect Defects in Metal Oxide Coated Multilayer Polymeric Films

Abstract

Metal oxide coated multilayered polymeric pouches provide a suitable alternative to foil‐based packaging for shelf‐stable products with extended shelf‐life. The barrier performance of these films depends upon the integrity of the metal oxide coating which can develop defects as a result of thermal processing and improper handling. In this work, we developed a methodology to visually identify these defects using an oxygen‐sensitive model gel system. Four pouches with different metal oxide coatings: MOA (Coated PET), MOB (SiOx‐coated PET), MOC (Overlayer‐AlOx‐Organic‐coated PET), MOD (Overlayer‐SiOx‐coated PET) were filled with water and retort‐processed for 30 and 40 min at 121 °C. After processing, the pouches were cut open, dried and subsequently filled with a gel containing methylene blue that changes color in the presence of oxygen. The pouches were then stored at 23 and 40 °C for 180 and 90 days, respectively. Defects were identified by observing the localized color change from yellow to blue in the packaged gel. These observations were confirmed through measurement of oxygen and water vapor transmission rates, as well as SEM and CLSM analyses. The MOC pouches showed the least change in barrier properties after thermal processing. This was due to crosslinking in the organic coating and protection provided by the overlayer. The melting enthalpy of all films increased significantly (P < 0.05) after sterilization. This may increase the brittleness of the substrates after processing. Findings may be used to improve the barrier performance of metal oxide coated polymeric films intended for food packaging applications. Practical Application In this study, we developed a methylene blue‐based, oxygen‐sensitive model gel system to identify defects in metal oxide coated polymeric structures induced by thermal processing and mechanical stresses. We also performed a comprehensive analysis of these defects through CLSM and SEM. The gel system and methodology developed may be useful in the design and development of high barrier metal oxide coated films.

Stability of vitamin C, color, and garlic aroma of garlic mashed potatoes in polymer packages processed with microwave‐assisted thermal sterilization technology

“…The change in OTR may be due to a higher permeation of oxygen through these defects, leading to an overall increase in OTR of these films. Similar results have been reported by others (Byun, Bae, Cooksey, & Whiteside, 2010; Parhi, Bhunia, Rasco, Tang, & Sablani, 2019; Struller, Kelly, & Copeland, 2014; Zhang et al., 2017).…”

Preserving Ready-to-Eat Meals Using Microwave Technologies for Future Space Programs

“…Moisture loss in packaged products during storage can reduce sensory food quality. Lengthy exposure to oxygen results in color changes such as browning; oxidation in foods with lipid content will cause rancidity, and nutritional losses [ 3 , 40 , 41 , 42 , 43 , 44 ]. In addition, packaging intended for thermostabilized foods must be able to withstand sterilization conditions.…”

“…Commercial polymer materials for food packages include polypropylene (PP), ethylene vinyl alcohol (EVOH), nylon 6, and polyethylene terephthalate (PET) [ 40 , 42 , 44 ]. As no single polymer intrinsically possesses the desired gas barrier and thermal and mechanical properties, these polymers are combined during the manufacturing stage to form multilayered structures [ 45 ].…”

Multilayer packaging: Advances in preparation techniques and emerging food applications

“…The study examined the barrier performance and integrity of metal‐oxide‐coated multilayer films for thermal processing applications. Among the four coatings of metal oxide (MO) [MO A (coated PET), MO B (SiOx‐coated PET), MO C (overlayer‐AlOx‐coated PET), and MO D (overlayer‐SiOx‐coated PET) pouches], MO C pouches showed least changes in barrier properties after retort processing (Parhi, Bhunia, Rasco, Tang, & Sablani, 2019). These observations provide us with a better understanding on the effect of different food processing techniques on the quality and integrity of multilayer packaging films.…”