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There is a great demand for developing efficient extraction methods in order to reduce extraction time and increase the yield and activity of functional antioxidants. The yields, activities, and extraction kinetics of antioxidants from dry peel of pomegranate marc were studied using ultrasound-assisted extraction in continuous and pulsed modes and the results were compared with conventional extraction (CE) at a temperature of 25±2°C and water/peel ratio of 50/1, w/w. The studied factors were intensity level and treatment time for continuous ultrasound-assisted extraction (CUAE), and intensity level, number of pulse repetition, and pulse duration and interval for pulsed ultrasound-assisted extraction (PUAE). The results showed that all factors significantly affected the antioxidant yield, but only treatment time had a significant effect on the antioxidant activity. Compared to CE, PUAE at intensity level of 59.2 W/cm(2), and the 5 and 5s of pulse duration and interval increased the antioxidant yield by 22% and reduced the extraction time by 87%. Similarly, CUAE at the same intensity level increased the antioxidant yield by 24% and reduced the extraction time by 90%. Since PUAE had 50% energy saving compared to CUAE, we recommend using PUAE for the extraction with antioxidant yield of 14.5% and DPPH scavenging activity of 5.8 g/g. A second-order kinetic model was successfully developed for describing the mechanism of ultrasound-assisted extractions under PUAE and CUAE. This research clearly demonstrated the superiority of PUAE for producing antioxidants from peel of pomegranate marc.

The aim of this study was to investigate the effect of multi-frequency power ultrasound (sweeping frequency and pulsed ultrasound (SFPU) and sequential dual frequency ultrasound (SDFU)) on the enzymolysis of corn gluten meal (CGM) and on the structures of the major protein fractions (zein, glutelin) of CGM. The results showed that multi-frequency power ultrasound pretreatments improved significantly (P<0.05) the degree of hydrolysis and conversion rate of CGM. The changes in UV-Vis spectra, fluorescence emission spectra, surface hydrophobicity (H0), and the content of SH and SS groups indicated unfolding of zein and glutelin by ultrasound. The circular dichroism analysis showed that both pretreatments decreased α-helix and increased β-sheet of glutelin. The SFPU pretreatment had little impact on the secondary structure of zein, while the SDFU increased the α-helix and decreased the β-sheet remarkably. Scanning electron microscope indicated that both pretreatments destroyed the microstructures of glutelin and CGM, reduced the particle size of zein despite that the SDFU induced aggregation was observed. In conclusion, multi-frequency power ultrasound pretreatment is an efficient method in protein proteolysis due to its sonochemistry effect on the molecular conformation as well as on the microstructure of protein.

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The response surface method was used to investigate the results of experiment designed with the Box‐Behken approach to make known the effects of air temperature, air velocity and sample thickness, on drying time, lycopene content, ascorbic acid content, non‐enzymatic browning and color of dried tomato slices. Three levels of temperature (40 to 60C), air velocity (1.0 to 2.0 m/s) and sample thickness (7 to 11 mm) were used for the experiment. The desirability index technique was used to predict the ideal drying condition. At the best conditions of 44C air temperature, 2.0 m/s air velocity and 7.72 mm sample thickness, drying time was 527 ± 76 min, lycopene content was 62.7 ± 4.3 mg/100 g dry matter, ascorbic acid content was 3.07 ± 0.14 mg/g dry matter, brightness value was 62.92 ± 2.18, ratio of redness to yellowness was, 0.78 ± 0.05 and the non‐enzymatic browning index was 0.55 ± 0.06 absorbance unit. Practical Applications The research took practical desires of minimum drying time and non‐enzymatic browning and maximum values of lycopene content, ascorbic acid, color brightness and redness to yellowness ratio into consideration. These quality indicators are of topmost importance to the food industries involved in tomato drying. The quality of dried products obtained using response surface methodology provides industries with optimized conditions for improving the quality of dried tomatoes. The dried product is a valuable ingredient in the preparation ready to enjoy soups, sauces and pizzas.

The study investigated the influence of four microwave powers on the drying kinetics and quality of tomato slices in a microwave-vacuum dryer at vacuum pressures of 0.04, 0.05 and 0.06 MPa. The results showed that increase in microwave-vacuum drying conditions increased drying rates and resulted in decreased drying time from 84 to 14 min. The nonenzymatic browning index increased with microwave power whereas the overall flavor degradation was between 18.99 and 20.80%. The brightness and the yellowness of the dried tomatoes generally increased but there was a slight reduction in redness when compared with the fresh. The effective moisture diffusivity increased with microwave power and was 7.22 ¥ 10 -9 , 9.10 ¥ 10 -9 , 14.99 ¥ 10 -9 and 25.19 ¥ 10 -9 m 2 /s at respective microwave powers of 200, 300, 500 and 700 W. PRACTICAL APPLICATIONSMicrowave-vacuum drying is one of the advanced methods with numerous advantages including high thermal efficiency, shorter drying time and improved product quality. Tomato is the second most important vegetable with enormous health benefits, which include reduction of cholesterol, improvement of vision, maintenance of gut, lowering of hypertension, alleviation of diabetes, and prevention of urinary tract infections and gallstones. The quality of dried products obtained using the microwave-vacuum dryer provides industries with method that can be used to enhance the quality of dried tomatoes.Thedriedproductisavaluableingredientinthepreparationof soupsandsauces,as well as in cosmetics and pharmaceutical formulations. bs_bs_banner Journal of Food Quality