Drying behaviour of Jew’s mallow leaves using an oven dryer was studied.The influence of drying temperatures(50,60 and 70C)on moisture content of the leaves at stable air velocity was considered.Five drying models,i...Drying behaviour of Jew’s mallow leaves using an oven dryer was studied.The influence of drying temperatures(50,60 and 70C)on moisture content of the leaves at stable air velocity was considered.Five drying models,including,simple exponential,Page,Two-term exponential,Logarithmic,and Wang and Singh were fitted to drying data.Two-term exponential model adequately express the drying behaviour of Jew’s mallow leaves.Effective moisture diffusivity of Jew’s mallow leaves ranged from 8.18×10^-8 to 1.13×10^-7m^2/s.Dependence of the computed effective diffusivity on oven temperature was obvious.The energy required for oven drying of Jew’s mallow leaves was found to be 14.84 kJ/mol.The L^*,a^*,b^*,DE,a^*/b^*colour characteristics of the dried leaves range from 31.8 to 32.87,-3.73 to-4.37,13.6 to 16.47,69.00 to 69.73,and-0.26 to-0.34 respectively.Oven drying conditions of 50℃150 min and 70℃90min resulted to dried leaves with desirable colour characteristics.展开更多
Corchorus olitorius (Jew’s mallow), is one of the African indigenous leafy vegetables increasingly getting attention as a possible contributor of both micronutrients and bioactive compounds including proteins, lipids...Corchorus olitorius (Jew’s mallow), is one of the African indigenous leafy vegetables increasingly getting attention as a possible contributor of both micronutrients and bioactive compounds including proteins, lipids, fiber and vitamin C to human nutrition. Leaves of Corchorus olitorius have been found to have high level of phytochemicals: flavonoids, polyphenols, tannins, and saponins that possess strong radical scavenging activity and antioxidant power. In the arid and semi-arid areas of the world, drought is the main limiting factor affecting plant productivity and influences almost all aspects of plant biology. Water stress deficit is known to cause oxidative stress condition that has generally been reported to elevate phenolic antioxidants in various crops including Jew’s mallow. On the other hand, fertilization is crucial for crop management and high yield, it also affects nutritional value of the food plants. Nitrogen (N) fertilization affects health and nutritional value, including mineral content, fatty acid profile, anti-oxidative capacity and polyphenol levels and composition. The possible effects of fertilization should be considered when deciding on fertilization regime, to optimize both plant physiology, productivity and food-related effects. Nitrogen is an important element for Jew’s mallow production since it responds well to it. However, appropriate amounts of nutrients need to be provided to crops at the right time to favor both crop growth, yield and quality. Different reports confirmed that addition or increase of N, negatively affects the total phenolics and total flavonoids, and reduces accumulation of defense-related secondary metabolites resulting in lower oxidative capacity. Increased secondary metabolite production during water deficit and low nitrogen in the soil has been reported as a stress mechanism by most plants. However, further research is required to explore the biochemical response of Jew’s mallow to water deficit and nitrogen fertilization.展开更多
文摘Drying behaviour of Jew’s mallow leaves using an oven dryer was studied.The influence of drying temperatures(50,60 and 70C)on moisture content of the leaves at stable air velocity was considered.Five drying models,including,simple exponential,Page,Two-term exponential,Logarithmic,and Wang and Singh were fitted to drying data.Two-term exponential model adequately express the drying behaviour of Jew’s mallow leaves.Effective moisture diffusivity of Jew’s mallow leaves ranged from 8.18×10^-8 to 1.13×10^-7m^2/s.Dependence of the computed effective diffusivity on oven temperature was obvious.The energy required for oven drying of Jew’s mallow leaves was found to be 14.84 kJ/mol.The L^*,a^*,b^*,DE,a^*/b^*colour characteristics of the dried leaves range from 31.8 to 32.87,-3.73 to-4.37,13.6 to 16.47,69.00 to 69.73,and-0.26 to-0.34 respectively.Oven drying conditions of 50℃150 min and 70℃90min resulted to dried leaves with desirable colour characteristics.
文摘Corchorus olitorius (Jew’s mallow), is one of the African indigenous leafy vegetables increasingly getting attention as a possible contributor of both micronutrients and bioactive compounds including proteins, lipids, fiber and vitamin C to human nutrition. Leaves of Corchorus olitorius have been found to have high level of phytochemicals: flavonoids, polyphenols, tannins, and saponins that possess strong radical scavenging activity and antioxidant power. In the arid and semi-arid areas of the world, drought is the main limiting factor affecting plant productivity and influences almost all aspects of plant biology. Water stress deficit is known to cause oxidative stress condition that has generally been reported to elevate phenolic antioxidants in various crops including Jew’s mallow. On the other hand, fertilization is crucial for crop management and high yield, it also affects nutritional value of the food plants. Nitrogen (N) fertilization affects health and nutritional value, including mineral content, fatty acid profile, anti-oxidative capacity and polyphenol levels and composition. The possible effects of fertilization should be considered when deciding on fertilization regime, to optimize both plant physiology, productivity and food-related effects. Nitrogen is an important element for Jew’s mallow production since it responds well to it. However, appropriate amounts of nutrients need to be provided to crops at the right time to favor both crop growth, yield and quality. Different reports confirmed that addition or increase of N, negatively affects the total phenolics and total flavonoids, and reduces accumulation of defense-related secondary metabolites resulting in lower oxidative capacity. Increased secondary metabolite production during water deficit and low nitrogen in the soil has been reported as a stress mechanism by most plants. However, further research is required to explore the biochemical response of Jew’s mallow to water deficit and nitrogen fertilization.
