Impact of ohmic heating conditions on the behavior of metallized f lexible packaging

Abstract

The integrity of packaging material is crucial for understanding the interactions among food, packaging, and processing, as it directly influences packaging performance, the efficacy of processing methods, and the stability of food. This study aimed to evaluate the effects of various ohmic heating (OH) processing conditions on the integrity of PETmet/PE films (PET: polyethylene terephthalate, met: metallization, and PE: polyethylene). OH processing was conducted on sealed packages containing a food simulant (0.1% (w/v) sodium chloride solution) with a voltage gradient of 3.7 V/cm and electrical frequencies of 20 kHz and 50 Hz. The target temperature was set at 80 °C, with holding times of 5, 10, and 15 min. The packages were assessed before and after OH processing concerning their structure and properties. The PETmet/PE films demonstrated no changes in chemical groups, thermal properties, or barrier properties related to water vapor and oxygen. However, the results show that OH processing caused measurable changes, such as a decrease in crystallinity from 21.4 to 14.8%. Mechanical properties like tensile and seal strength were also affected but remained within the typical range for such films, and the packaging integrity was preserved with no leaks. These minor variations do not compromise the material’s performance, supporting its suitability for practical applications. Therefore, it can be concluded that PETmet/PE packaging is suitable for food products that will undergo OH processing under the conditions utilized in this research.