Evaluation of Efficacy of Four Commercial Enzyme-Based Cleaners of Ultrafiltration Systems

Abstract

Use of UF and RO in the dairy industry is rapidly expanding. Because the dairy industry demands high levels of cleanliness, this new technology requires close evaluation to assure adherence to these standards. Efficacy of four commercial enzyme-based cleaners (pH 7.0 to 8.4) in UF systems was determined by microbiological evaluation and permeate flux restoration. The UF system containing two polysulfone UF membranes in parallel, was soiled by recycling 380L of sweet whey (40°C) for 2.0h followed by concentrating whey for .5h. The cleaning cycle consisted of acid cleaner (.5h, 40°C), followed by enzyme cleaner (10.0h, 40°C), and rinsing (2.0h, 40°C). A chlorine sanitizer was circulated (5min, 40°C) and the unit containing sanitizing solution left idle overnight. Flux was determined and swabs and rinse water samples were taken immediately after soiling, after cleaning, and the next morning to check sanitizing. The four enzyme-based cleaners were unsatisfactory when microbiological criteria were considered. Loss of sanitizer strength and problems with yeast and especially mold growth over time also indicated lack of effective cleaning. Flux, however, was restored easily and did not correlate with efficacy of cleaning based on numbers of microorganisms remaining.