PACKAGING EVALUATION FOR HIGH‐PRESSURE HIGH‐TEMPERATURE STERILIZATION OF SHELF‐STABLE FOODS

Abstract

ABSTRACT The integrity of flexible packages during high‐pressure (HP) sterilization is of critical importance to the safety and shelf life of food products. For HP‐sterilization, packaged products need to be preheated to a target temperature before HP processing. Preheating efficiency can be affected by the packaging material utilized. The objectives were to quantify the impact of packaging materials on the rate of heat penetration into foods during preheating, and to evaluate the effects of preheating and HP processing (at 688 MPa and 121C) on package integrity, oxygen permeability and mechanicalproperties for commercially available packaging materials. Commercial scrambled egg patties were vacuum‐sealed in pouches. Four plastic‐laminated materials (nylon/coextruded ethylene‐vinyl alcohol, nylon/polypropylene [PP], polyethylene terephthalate [PET]/aluminum oxide/casted PP [CPP] and PET/polyethylene) and two aluminum foil‐laminated pouches (PET/aluminum [Al]/CPP and nylon/Al/PP) were tested. Selected packaging materials also were evaluated after thermal retort (TR) treatment and HP low temperature processing. The results demonstrated that foil‐laminated materials provided shorter preheating time than thinner polymeric materials. HP treatment at high temperatures (HP‐HT) increased seal strength of foil‐laminated pouches. However, the HP‐HT process did not significantly contribute to changes in seal strength of plastic‐laminated pouches. It was found that the HP‐HT process altered the oxygen barrier of the composite packaging materials. However, the increase in permeability observed during the HP‐HT process was attributed to thermal damage occurring during preheating. TR processing increased oxygen permeability to a higher extent than HP‐HT processing. It was concluded that the selected packaging materials could provide the required oxygen barrier for HP‐HT treated shelf‐stable foods. PRACTICAL APPLICATIONSResearch reporting the effects of high‐pressure/high‐temperature (HP‐HT) processing on packaging materials is limited. The results of this study demonstrated that foil‐laminated materials provided shorter preheating time prior to HP‐HT treatment than thinner polymeric materials. In addition, it was shown that foil‐laminated packages are a viable option for packaging materials for use in HP‐HT processing of shelf‐stable low‐acid food (LAF) products in terms of their overall appearance, seal strength and oxygen permeability rate. Among plastic pouches, HP‐HT treatment showed the lowest impact on EVOH packages. This study is useful for not only researchers who are working in the area of HP processing of shelf stable LAF, but also in research and development of HP treatment of extended shelf life foods. The results may be successfully used in the design and performance evaluation of new laminated packaging materials suitable for HP treatments at high and moderate temperatures.