Assessment of the adsorption capacity of food products with respect to copper(II) and zinc ions
N. A. NARONOVA, N. A. BELOKONOVA, I. L. TIKHONOVA, K. O. GOLITSYNA
Ural State Medical University, Ekaterinburg, Russia
Keywords: adsorption value, copper(II) ions, zinc ions, adsorption degree, adsorption isotherm, food adsorbents
Abstract
Promising adsorbents that normalize the content of copper(II) and zinc ions in the human body may be food products that contain pectin or a sufficient amount of fibres. Within the framework of this study, dependences of the value of copper(II) and zinc ion adsorption by the food products of plant origin (potatoes, carrots, radish, pumpkin, cauliflower, broccoli, vegetable marrow, bananas, plums, apples) were analysed (in the range of metal ion molar concentrations 1.25-5 mmol/L) depending on a number of parameters: temperature (20, 100 °C), acidity (pH 2.0, 6.5), adsorption time (20-60 min). It has been found that the value of adsorption of zinc and copper(II) ions by food products is on average 1.2 times larger after heat treatment than without it. However, with an increase in adsorption time (from 20 to 60 min), the amount of ions adsorbed by food products without their preliminary heat treatment increases by a factor of 1.9 on average, while after heat treatment - by a factor of 1.3. With an increase in the acidity of the medium (pH decrease from 6.5 to 2.0), the value of zinc ion adsorption decreases by a factor of 1.9, and copper(II) ions - by a factor of 1.2 on average. To determine the dependence of adsorption value on time and on concentration, several regression models were statistically constructed: linear, quadratic, cubic, power, logarithmic, hyperbolic, common exponential, and natural exponential. The results were compared with each other by correlation, average approximation error and selected graphical relationships that can be used to calculate the required amount of vegetables and fruits when adjusting nutrition in order to normalize zinc ions in the human body. Based on the comparison of regression models by correlation and average approximation error, the dependences providing the best proximate description of zinc ion adsorption at the studied parameters have been chosen. These dependences can be used to calculate the necessary amounts of legumes and fruits to correct nutrition for the purpose of bringing zinc ion content in human organism to the normal level.
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