Adhesion and Removal Mechanisms of Composite Soils Formed on the Equipment Surface During Food Processing

点击翻译按钮获取中文摘要

In food manufacturing processes, proteinaceous soils derived from foods tend to strongly adhere to the サball surface of equipment/pipes and thus a lot of energy and detergents are usually consumed for cleaning of the equipment. Although it is strongly required to save energy and detergents by optimizing the cleaning conditions, few systematic approaches have been made. In this project, the intended to reveal scientifically the mechanism for adsorption of proteinaceous soils onto the metal surfaces and that for removal. As a model proteinaceous soil, we usually adopted β-lactoglobulin (β-Lg) and sometimes used a composite of the protein and tannic acid. Particles and plates of stainless steel were mostly used as a model surface. The findings obtained in this projects are summarized as follows.1. Interaction peptide regions of β-Lg that directly interact with a stainless steel surface was analyzed by the two methods : 1) peptide fragments of β-Lg digested with protease were first in cont … More act with the surface and peptides strongly interacting were identified and 2) β-Lg that had been adsorbed on the surface was subjected to digestion with protease and then the kinds and composition of the remaining peptides were analyzed. As a result, we found that peptide regions containing plural, acidic amino, acids are responsible for direct interaction with the surface at a pH region lower than neutral pH. With increasing the number of acidic amino acids of the peptide, affinity as well as the amount of adsorptiotn increased. Adsorption isotherms could be explained by taking into consideration the both reversible and irreversible adsorption modes.2. We developed a novel cleaning method, in which negative electropotential (around -0.2〜-0.8V vs. Ag/AgCl) is added to the metal surface being in contact with dilute H_2O_2 solution to generate hydroxyl radicals and generated radials could quickly decompose proteinaceous soils adsorbed on the surface. The proteinaceous soil strongly adsorbed on a stainless steel surface there found to be removed completely within 2 min at room temperature while the removal rate by caustic cleaning was much slower. The various factors including coexisting salt concentration, potential, and current on the removal kinetics there analyzed in details.3. Adsorption mechanism of the composite soil composed of β-Lg and tannic acid was analyzed under different conditions ~ using RAS-IR. The H_2O_2-electrolysis cleaning method was quite effective to remove the soil from the surface. Namely, tannic acid was removed effectively even by caustic cleaning while sufficient removal of β-Lg was possible only by the H_2O_2-electrolysis cleaning method at room temperature. Less