Influence of Packaging Material and Storage Conditions on the Quality Attributes of Pressure-Assisted Thermally Processed Carrots

The influences of barrier properties of packaging materials and storage conditions on selected quality attributes of carrot samples processed by pressure-assisted thermal processing (PATP) were investigated. Baby carrots were packaged in three different pouches made of multilayer films (Nylon/EVOH/EVA, Nylon/EVA and MetPET/PE) and processed at 600 MPa and 110 °C for 10 minutes. Processed pouches were stored at 25 and 37 °C and withdrawn over 12 weeks of storage on a periodical basis and analyzed for color, β-carotene, and total mesophilic aerobic count. Oxygen transmission rates (OTR), water vapor transmission rates (WVTR), melting point and enthalpy of fusion of the packages were also evaluated. Scanning electron microscope images were utilized to document the impact of processing on the packages. Results showed that the chosen processing parameters resulted in shelf stability of processed carrots during 12 weeks storage at 25 and 37 °C. Packaging type, storage temperature and time significantly influenced (p < 0.05) product color and β-carotene content. Nylon/EVOH/EVA laminate pouch best preserved color and β-carotene. PATP increased OTR of the MetPET/PE, which might have caused considerable change in color and β-carotene content of carrot samples after 12 weeks storage. After 12 weeks of storage at 37 °C, Nylon/EVOH/EVA, Nylon/EVA and MetPET/PE lost 36, 100 and 100 % of β-carotene content, respectively. The red color of carrot samples was reduced by 20, 87 and 72 % for Nylon/EVOH/EVA, Nylon/EVA and MetPET/PE, respectively. Thermal analyses indicated a structural change in the packaging polymers following PATP treatment. In summary, our study demonstrated the importance of utilizing high barrier packaging material for preserving quality attributes of PATP-treated carrots.