The efficiency of the commercial proteolytic preparation 'Alcalase' in removing model proteins (casein, BSA and haemoglobin) experimentally burned onto a model solid surface (glass) was investigated. The cleaning efficiency was monitored qualitatively by direct observation and quantitatively by monitoring polypeptide/peptide/amino acid accumulation in the wash and by three-dimensional atomic force microscopy. The results indicate that treatment with enzyme at industrially realistic inclusion levels removes a very significant proportion of protein foulant and that post-cleaning residual enzyme activity on the glass surface can be easily removed or inactivated. Results are discussed in the context of their potential application in the bioprocess sector. (c) 2005 Elsevier Ltd. All rights reserved.