Comparison the impacts of thermal sonication and pasteurization process on qualitative and microbial features of canned pickled olive

Thermal methods are among the common methods of food processing that increase the shelf life of food products by reducing the microbial population and inactivating enzymes. Despite the favorable effects of the traditional thermal process, this method reduces the nutritional and sensory quality of food products. Increasing consumer demand for food products with minimal changes in characteristics has provided the basis for examining new methods of food processing. Therefore, in the current work, the impact of conventional pasteurization and thermosonication (TS) on the microbial populations, antioxidant activity and quality parameters of fermented green table olives was studied. Olives were subjected to ultrasound treatment (30 kHz, 100 W) at different temperatures (45, 55, and 65 ºC) and times (5, 10, and 15 min) and compared with the conventional heat treatment (85 ºC, 15 min). After treatment, TS at 45 and 55 ºC markedly (p < 0.05) improved firmness, color parameters, and sensory attributes relative to the thermally processed olives. Furthermore, TS enhanced total phenolic content (8.45-25.37%) and antioxidant activity (8.43-31.21%) compared to the untreated samples. TS at 55 ºC-15 min, 65 ºC-10 min, and 65 ºC-15 min successfully reduced the microbial counts to nil. However, TS at 65 °C notably diminished the quality parameters. Thus, TS can improve the safety and quality of table olives and can be used as a suitable alternative to the thermal processing.