| MRE Choice Spread is a cheese spread variation containing large amounts of unsaturated lipids, which make lipid oxidation and development of rancidity the primary deterioration mode for this product. Lipid oxidation has traditionally been limited by adding antioxidants such as tocopherols directly to the food. However, the large amounts of antioxidant needed to provide the three year shelf life required by the military for MRE foods may cause phenol overloading, pro-oxidation, or browning. Controlled Release Packaging (CRP) addresses this problem by incorporating tocopherols in polymer films and releasing them into foods over time. Effectiveness of CRP in stabilizing model systems of pure unsaturated lipid has been demonstrated previously; this study was designed to extend testing of CRP technology to plant-scale applications that solve shelf life problems associated with a commercially processed real food system.;Control polymer films of PP-LDPE and CRP films of PP-LDPE impregnated with mixed tocopherols at 3000 ppm were produced by extrusion at Berry Plastics Corporation (Chippewa Falls, Wisconsin). They were laminated, filled with Choice Spread, and sealed at Thermo Pac, LLC (Stone Mountain, Georgia). For comparison, half the control samples were flushed with nitrogen gas before sealing to provide an inert atmosphere inside the package. Choice Spread in the three kinds of packages were stored at 40°C for 15 weeks and at 60°C for 10 weeks for shelf life studies. Color (browning and fading) was quantified as L*a*b* values using a colorimeter. Lipid peroxides, conjugated dienes, and aldehydes were measured to follow the progress of lipid oxidation.;Contrary to model system studies with oils and preliminary packaging studies with Choice Spread, control, nitrogen flushed and CRP packages showed similar browning and lipid oxidation during storage at both temperatures. This lack of apparent protection by CRP may be attributed to high levels of antioxidant (TBHQ) in Choice Spread that stabilize lipid oxidation during the storage period, overload the antioxidant system, and block both tocopherol access to active sites and protective effects of CRP. These results highlight the need to balance formulation and packaging and further customize Controlled Release Packaging to make it effective in stabilizing real food systems. |
