جستجوی مقالات مرتبط با کلیدواژه « سونیکاسیون حرارتی » در نشریات گروه « صنایع غذایی »

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.

The purpose of this study is to investigate the effect of thermosonication in comparison with usual pasteurization methods on bioactive compounds and some of the properties of pomegranate juice (Brix, pH, acidity, vitamin C content, phenolic compounds, antioxidant properties and anthocyanin content). The treatments were: controlled sample (without treatment), pasteurized sample (90, 30 °C), heated sample at 60 ° C for 4,8,12 min, ultrasound sample without heating for 4,8, 12-minute with amplitudes of 24.4, 42.7, 61 μm, ultrasound sample with heating (60 ° C for 4,8,12 minutes) with 24.4, 42.7 and 61 μm amplitudes. The results showed that the treatments did not have a significant effect on the Brix, pH and acidity of pomegranate juice. Pasteurization treatment was one of the treatments that had the highest reduction in quality parameters of samples.The highest percentage of vitamin C degradation in 34.1% pomegranate juice was due to pasteurization and long periods of high level of temperature about 60 ° C resulted in 28.7% decrease in vitamin C.The highest phenolic content was in the treatment at 25 ° C, 61 μm in 12 minutes which increased this trait by 22%, and pasteurization treatment reduced 27.9% of phenolic content.Antioxidant activity decreased by 8.8% due to pasteurization.Sonication treatments with high intensity at 25 °C and long period increased this trait by 10.5 %. Pasteurization and ultrasound treatments at 60 ° C, 61 μm in 12 min, have a significant effect on the anthocyanin content of pomegranate juice and decreased this trait by 10 and 8.8%. In general, the results of the study indicate that the increase in the amplitude of ultrasound, temperature and duration of treatment, reduces the positive effect of these treatments on quality parameters and even reduces these traits significantly and due to the combined results, ultrasound amplitude of 42.7 μm at 60 ° C can be the most effective treatment to maintain the quality parameters of pomegranate juice compared with the pasteurization method.