Food College of Northeast Agricultural University
Key R & D projects in Heilongjiang(GA21B008);Special funds for the construction of modern agricultural industrial technology system(CARS-40-K25)
全蛋液富含蛋白质、脂肪及多种维生素和矿物质,是一种天然的营养补充来源,但高含量的磷限制了其在肾病患者饮食中的应用。选取活性炭、水滑石、硅藻土对全蛋液进行脱磷处理,以脱磷率、蛋白质损失率和色差变化为指标,优化吸附剂添加量、吸附时间和吸附温度,并对3 种吸附剂在全蛋液中磷吸附的吸附等温式、吸附动力学及吸附热力学进行拟合。结果显示:活性炭的优化添加量为8 g/ L,吸附时间为120 min,吸附温度为35 ℃;水滑石的优化添加量为8 g/ L,吸附时间为150 min,吸附温度为35 ℃;硅藻土的最佳添加量为8 g/ L,吸附时间为90 min,吸附温度为35 ℃。在吸附过程中,水滑石对蛋白质的损失最小,对磷酸基团的吸附专一性最高;活性炭对a*值的影响最大,硅藻土对b*值影响最大,3 种吸附剂均造成L*值的增加。对吸附机理的研究表明:水滑石多以单分子层形式吸附,3 种吸附剂的Freundlich 吸附等温式n 值均大于1。随着吸附温度的增加,活性炭、水滑石和硅藻土的KF均逐渐增大。3 种吸附剂的准一级动力学模型R2 均较低,并且随着温度的增加呈现波动变化;硅藻土的准二级动力学模型R2 较高,硅藻土化学吸附程度较高。活性炭、水滑石和硅藻土的ΔG 均为负值、ΔH 均大于0,即反应自发进行且为吸热反应。
Whole egg is rich in protein, fat, and many vitamins and minerals. It is a natural source of nutritional supplements, but high levels of phosphorus limit its use in the diet of patients with kidney disease. Activated carbon, hydrotalcite and diatomite were selected to dephosphorize the whole egg liquid, and the dephosphorization rate, protein loss rate and color difference were taken as the indexes, the optimum amount of adsorbent, adsorption time and adsorption temperature were optimized, and then, the adsorption isotherms, adsorption kinetics and adsorption thermodynamics of the three adsorbents in the whole egg liquid were fitted. The results showed that the optimum dosage of activated carbon was 8 g/L, adsorption time was 120 min and adsorption temperature was 35℃, while the optimum dosage of hydrotalcite was 8 g/L, adsorption time was 150 min and adsorption temperature was 35℃, and the optimum dosage of diatomite was 8 g/L, the adsorption time was 90 min and the adsorption temperature was 35℃. In the process of adsorption, hydrotalcite had the least loss of protein and the highest adsorption specificity for phosphoric acid groups. Activated carbon had the greatest effect on a*, diatomite had the greatest effect on b*, and all three adsorbents increased L*. The study of adsorption mechanism showed that hydrotalcite was adsorbed in the form of monolayer. Freundlich adsorption isotherm n of three adsorbents were all greater than 1. With the increase of adsorption temperature, the KF of activated carbon, hydrotalcite and diatomite increased gradually. The quasi-first-order kinetic model R2 of three adsorbents were lower, and fluctuated with the increase of temperature. The quasi-second-order kinetic model R2 of diatomite was higher, and the chemical adsorption degree of diatomite was higher. The ΔG of activated carbon, hydrotalcite and diatomite were all negative and the ΔH were greater than 0, which meant that the reaction was spontaneous and endothermic.