A CRITICAL COMPARISON OF 4 TEST METHODS FOR DETERMINING OVERALL AND SPECIFIC MIGRATION FROM MICROWAVE SUSCEPTOR PACKAGING

Four approaches for testing for overall migration and specific chemica l migration from microwave susceptors were evaluated. The methods used olive oil as a conventional liquid food simulant, a semisolid simulan t of olive oil and water absorbed onto diatomaceous earth, Tenax(TM) a s a dry simulant, and compositional analysis of the susceptor by ASTM methods. The different methods were tested on five susceptor types use d for the packaging of pizza, potato chips (French fries), pasty, popc orn, and a curry. For the comparison, the susceptor materials were imp regnated with model substances as migration markers covering a range o f molecular weight, volatility and polarity. Levels of specific migrat ion (SM) and overall migration (OM) were determined using the four tes t methods, which were then evaluated on the basis of their ease and re producibility of use along with the agreement between specific migrati on levels into simulants compared with migration into foods. There wer e severe problems with olive oil as a conventional liquid simulant as it was absorbed by the susceptor and made SM and OM measurements diffi cult. Humidity conditioning the susceptor for OM was a further difficu lty with olive oil. Oil absorption was also a problem using the semiso lid simulant, with OM being untried using this approach. The ASTM meth ods were found to be time-consuming, although the results for SM were similar to those obtained for foods. Overall, however, using Tenax was the preferred method for migration testing of susceptors. It allowed easy measurement of both OM and SM. SM values were generally much high er than for foods, however, and a reduction factor would be required f or control of regulated ingredients. For other substances, such as the rmal degradation products, a threshold of regulation approach applied to the Tenax extract would be a simple and effective control measure.