Interaction of alkaline and acid treatment on the removal of proteinaceous mineral-enriched dairy fouling from UHT treatment

Abstract

CIP processes in milk processing plants are frequently oversized to reliably meet hygienic and safety requirements. Cleaning follows a fixed protocol, but the exact mechanisms and intermediate products are often unknown. This study presents an experimental approach to elucidate the interaction between alkaline and acidic treatment with special regard to the impact of acid on proteinaceous deposits. The protein containing fouling layers become yellowish in colour by acidic treatment; this is attributed to the xantho-proteic reaction and no efficient removal is thereby achieved. In contrast, the removal is efficient if an efficient initial alkaline treatment step is performed. An efficient initial alkaline treatment step was identified as crucial for the further course of cleaning and a short alkaline treatment soaked the entire soil, which enabled an efficient subsequent acidic removal. Lower concentrations of HNO3 demonstrate more efficient cleaning than higher ones, suggesting an optimum acid concentration during CIP.