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Mohamed Azab, Ahmed Darwish, Refaat Mohamed, Marwa Sanad,
Volume 2, Issue 3 (9-2013)
Abstract
Effect of controlled atmospheres (CAs) at various concentrations of CO2, N2 and O2 on the lethal times of Tribolium castaneum and Trogoderma granarium was investigated at 20 and 30 ºC. Experiments were performed using a recirculatory multi-flask apparatus. The results revealed that, the shortest times (0.1, 0.3 and 0.9 day for adults, larvae and pupae, respectively) required to obtain 50% mortality of T. castaneum stages were at 100% CO2 followed by 75% CO2, 50% CO2, 99% N2 + 1% O2 and 25% CO2, at higher tested temperature (30 °C). Adults were more sensitive to the different treated CAs than larvae, while pupae were the most tolerant stages. Diapausing larvae of T. granarium were the most tolerant to all treated CAs at tested temperatures. The effectiveness of CAs to decrease its LT50 values were 100% CO2 followed by 99% N2 + 1% O2 and 98% N2 + 2% O2 at 30°C. It may be concluded that diapausing larvae are more difficult to control with CAs than normal larvae. A treatment with N2 relying on the absence of O2 will take a longer treatment time to control the diapausing larvae and in late winter, exposure times needed for control may be even longer. If CAs were to be applied under such circumstances, a high content of CO2 would be the best option to achieve control in a comparatively short time.
Volume 21, Issue 148 (June 2024)
Abstract
In this study, the effect of microwave pretreatment at the power of 500 and 900 W on the antioxidant properties (DPPH radical scavenging activity and total antioxidant capacity) of flaxseed protein hydrolysate was investigated in the period of 30-210 minutes. In the next step, the effect of different concentrations (20-100 mg/ml) of the optimum treatment on the antioxidant properties (total antioxidant capacity, Fe reducing power, DPPH radical scavenging activity and Fe chelating activity) was investigated and was compared with the antioxidant capacity of vitamin C as a synthetic antioxidant and unhydrolyzed flaxseed protein. The results showed that microwave pretreatment at a power of 500 W significantly increased the antioxidant properties (DPPH radical scavenging activity and total antioxidant capacity) of flaxseed protein hydrolysate, but higher microwave power (900 W) led to reduction of antioxidant activity in comparison to the sample without pretreatment or the sample with microwave pretreatment with a power of 500 W. The sample with microwave pretreatment with a power of 500 W and hydrolysis time of 180 minutes was selected as the optimum treatment with the highest total antioxidant capacity and DPPH radical scavenging activity. Investigating the effect of concentration on the antioxidant properties of hydrolyzed protein showed that the highest DPPH radical scavenging activity (52.7 %), total antioxidant capacity (1.35 absorbance at 695 nm), Fe reducing power (0.859 absorbance at 700 nm) were achieved at the concentration of 60 (mg/ml) and the highest Fe chelating activity (50.83%) was obtained at the concentration of 80 (mg/ml). As a result, the flaxseed protein hydrolysate with considerable antioxidant capacity, can be used in the production of functional food products, nutritional supplements for athletes and the elderly.