Mahmoud N S, Ghaly A E
Biological Engineering Department, Dalhousie University, PO Box 1000, Halifax, Nova Scotia, Canada B3J 2X4.
Appl Biochem Biotechnol. 2005 Sep;126(3):157-75. doi: 10.1385/abab:126:3:157.
This article reports on lamp fouling during on-line ultraviolet (UV) sterilization of cheese whey. The extent of fouling as well as the composition of fouling materials was studied after the operation of three tubular UV reactors of different flow thicknesses (18, 13, and 6 mm) for 48 h at a 2-h residence time. Lamp fouling, which significantly affected the sterilization efficiency, was realized after an extended period of operation. The extent of lamp fouling increased with a decrease in the thickness of the flowing cheese whey (14.42, 15.31, and 25.25 g for 18-, 13-, and 6-mm thickness, respectively). A strong relationship between the extent of fouling and the steady-state outlet temperature was observed. The fouling material contained 63.51 to 77.19% protein, 12.57 to 16.49% fat, and 6.51 to 9.47% minerals on dry weight bases compared with 1% protein, 0.5% fat, and 0.4% minerals in raw cheese whey. The organic and inorganic material concentrations in the fouling material increased with a decrease in the flow thickness. The fouling mechanism was owing to adsorption and direct ion exchange, which were enhanced by the high temperature and low pH attained in the study. Improved designs of UV reactors in which the contact between the flowing material and the quartz surface should be developed.
本文报道了奶酪乳清在线紫外线（UV）杀菌过程中的灯管结垢情况。在三种不同流道厚度（18毫米、13毫米和6毫米）的管式紫外线反应器中，以2小时的停留时间运行48小时后，研究了结垢程度以及结垢物质的组成。经过较长时间的运行后，发现灯管结垢显著影响了杀菌效率。灯管结垢程度随着流动的奶酪乳清厚度的减小而增加（18毫米、13毫米和6毫米厚度的结垢量分别为14.42克、15.31克和25.25克）。观察到结垢程度与稳态出口温度之间存在密切关系。与生奶酪乳清中1%的蛋白质、0.5%的脂肪和0.4%的矿物质相比，以干重计，结垢物质中含有63.51%至77.19%的蛋白质、12.57%至16.49%的脂肪和6.51%至9.47%的矿物质。结垢物质中的有机和无机物质浓度随着流道厚度的减小而增加。结垢机制是由于吸附和直接离子交换，在本研究中高温和低pH值增强了这种作用。应改进紫外线反应器的设计，以改善流动物质与石英表面之间的接触。
