Comparative study on caustic and enzymatic cleanings of stainless steel surface fouled with beta-lactoglobulin

Desorption behavior of beta-lactoglobulin (beta-Lg), one of the main constituents of fouling deposits in milk processing, from stainless steel surfaces during caustic and enzymatic cleanings was studied by using a glass column packed with stainless steel particles fouled with beta-Lg. Both in caustic and enzymatic cleanings, the amount of beta-Lg remaining on the stainless steel particles decreased according to first-order kinetics at the initial stage, and gradually reached a constant value, The desorption rate constant at the initial stage and the residual amount of beta-Lg after 2 h of cleaning were evaluated as the measures of cleaning efficiency under various conditions, In caustic cleaning, these two values were strongly affected by the concentration of NaOH. The initial desorption rate increased with increasing flow rate of the caustic solution, suggesting a mass transfer effect, In enzymatic cleaning, the maximum desorption rate constant was obtained at around the optimum pH for the enzyme reaction, The temperature dependence of the initial desorption rate constant was stronger in caustic cleaning than in enzymatic cleaning.