Pasteurization of pickled asparagus using 915 MHz microwaves

Asparagus spears are sensitive to thermal treatments. Lengthy pasteurization at elevated temperatures may cause severe thermal degradation. In this research we explored the application of short-time microwave pasteurization for pickled asparagus in glass bottles and studied the effect of this process on the textural quality of the products in comparison with the conventional hot-water pasteurization method. A pilot-scale 915 MHz microwave system was used in this study for heating pickled asparagus in 1.8 kg (64 oz) glass bottles to 88 C. Heating uniformity was determined using fiber optical temperature sensors. The textural quality of asparagus was evaluated in shear tests and the C-value was used to assess the impact of different processes. Pasteurization of pickled asparagus using 915 MHz microwaves resulted in a uniform heating and it reduced process time by at least one-half compared to water-bath heating. Microwave pasteurization markedly reduced thermal degradation of asparagus. 2002 Elsevier Science Ltd. All rights reserved.