14B-33

U. R. ABBOTT¹, C. Adhikari¹, R. E. McDonald², and V. M. Balasubramaniam¹. (1) Processing, National Center for Food Safety and Technology, 6502 S. Archer Road, Summit-Argo, IL 60501, (2) Processing, Food and Drug Administration, 6502 S. Archer Road, Summit-Argo, IL 60501

JUSTIFICATION: Lipid oxidation is a main factor in determining the deterioration of the shelf-life of microbiologically safe processed foods. A rapid FTIR spectroscopic method has been developed for the determination of methyl sulfide and hexanal as lipid degradation indicators. This study validates the application of this method in the shelf-life study of modified atmosphere packaged and thermally processed ready-to-eat meals.

OBJECTIVES: Applying static headspace analysis in a shelf-life study with rapid FTIR scan to assess the oxidative status of chicken, fish, and egg ready-to-eat meals in a shelf-life study after packaging and processing under modified atmosphere conditions.

METHODS: Frozen food samples were placed in a glass bottle and crimp-sealed. Samples equilibrated at 4° C were heated to 90° C for 25 min. Five ml samples from the headspace were injected into the FTIR gas cell and then scanned. The sample bottle was purged with nitrogen, refrozen and 5 ml headspace samples were extracted two more times and scanned under similar conditions. Linear regression analysis of data was performed to determine partition constants. Shelf-life studies were conducted at 80, 100, and 120° F.

RESULTS: Partition Coefficients varied significantly with the sample matrix, which included chicken breast patties, tuna with noodles, omelet with ham, and chicken stew. The values were -0.0043, -0.0084, -0.0065, -0.0086, respectively and the R² values were 0.963, 0.973, 0.999, 0.997, respectively. Up to 15 samples of several different products could be analyzed for hexanal and methyl sulfide in one day. For example, in the case of chicken breast patties hexanal content increased from 12.6 ± 0.9 mg/g to 17.2 ±1.4 mg/g in 6 weeks storage at 120° F.

SIGNIFICANCE: This new FTIR technique was demonstrated to be an effective rapid method to determine lipid oxidation volatiles in retorted food products.