A Comparative study of the rare of heat penetration and quality preservation during thermal processing and short term storage in high barrier plastic trays and comparable metal cans was carried out using a model system of bentonite suspension and ascorbic acid. The rates of heat penetration (f(h) values) were 32 min for the trays and 52 min for the cans. The ascorbic acid retention, after thermal treatment to an F-o value of 11-12 min, was 83% for the trays and 75% for the cans. During storage, the rate of ascorbic acid degradation was similar in both packages. Therefore, after 107 days at 35 degrees C, the residual ascorbic acid in the trays remained still higher than that in the cans.