Effects of Hot Air and Microwave Drying on the Phenolic Components and Physicochemical Properties of Unripe Grapes (Qoura)

Evaluation of nano-silica, microwave heating, and ultraviolet irradiation effects on zearalenone detoxification in sunflower oils

In the present study, we report three methods of silica nanoparticles (SNPs) as adsorbent, ultraviolet (UV) irradiation, and microwave heating and evaluate their capabilities in reducing and eliminating zearalenone (ZEN). The offered method not only was used for ZEN detoxification, but also greatly enhanced the sensitivity of ZEN measurement. The aim of this study was to evaluate ZEN concentration in sunflower oil samples by high-performance liquid chromatography (HPLC) method. This method was successfully validated for sunflower oil samples while the limit of detection (LOD) method (signal-to-noise ratio of 3:1) was 0.5 μg/l. The acquired removal data with the HPLC method through SNPs were fitted well with Freundlich isotherm, denoting that the multi-layer adsorption took place on the adsorbent. The equilibrium adsorption capacity of ZEN was 61.02 μg/g in an optimum time of 240 min on SNPs. The experimental results were evaluated by the adsorption kinetic model, which specified the adsorption kinetics of ZEN on SNPs, obeying the pseudo-second order model. This model demonstrated that the sorption rate depended on the sorption capacity but not the concentration of the sorbate. Moreover, the method presented to determine ZEN based on the use of SNPs in sunflower oil was accomplished by the adsorption process. Furthermore, the removal efficiencies of ZEN by SNPs, UV irradiation, and microwave heating were compared and obtained to be 92.1, 96.22, and 37.30%, respectively for determined times. These results confirm the removal efficiency of these methods is sensitive enough to ZEN analysis in sunflower oil samples.

Optimization of combined microwave and hot air drying technology for purple cabbage by Response Surface Methodology (RSM)

Purple cabbage is one of the world's most widely consumed vegetables with high nutritional values containing the antioxidants and anti-inflammatory activity of anthocyanins, vitamins, and minerals. But due to rapid postharvest quality decay, novel processing techniques including drying are required. In order to determine the conditions of combined microwave and hot air drying for purple cabbage, factors affecting the drying process including microwave density, hot air temperature, and the dry base water content at conversion point were investigated using the anthocyanin content, DPPH antioxidant capacity, chewiness, △E, rehydration ratio, and average drying rate as responses. The combined drying conditions were optimized considering three independent variables at three different levels by response surface methodology. The results showed that the processing parameters of purple cabbage with combined microwave and hot air drying technology were microwave density at 2.5 W/g, moisture content of conversion point at 4.0 g/g, and hot air temperature at 55°C. Under these conditions, the anthocyanin content, DPPH antioxidant capacity, chewiness, △E, rehydration ratio, average drying rate, and overall score of the dried purple cabbage were 175.87 mg/100 g, 87.59%, 4,521.468 g, 26.5, 4.3, 0.76 g/min, and 0.785, respectively. Therefore, combined microwave and hot air drying technology is an effective, suitable method for drying purple cabbage.