Effect of surface properties of different food contact materials on the efficiency of quaternary ammonium compounds residue recovery and persistence

Residues of quaternary ammonium compounds (QACs) remaining after sanitising were evaluated for a number of materials used in food plants. The residues were collected by swabs and measured using a spectrophotometric method. Surface topography and energy affected the QACs recovery. Highest percentage of QACs recovery was achieved for the tile material (102.2%) which had the most hydrophilic properties and least irregularities in surface topology, followed by stainless steel (82.1%). Meanwhile, the lowest recovery occurred in PVC (42.1%) and resin (44.3%) that exhibited hydrophobic characteristics and abrupt changes in height profile in a given surface area. Monitoring of QACs residues deposited on the surfaces after 7 days showed that the recovery of QACs in PVC and resin reduced significantly (P < 0.05), supposing that QACs might be degraded or interacted with the materials. However, no significant changes in residue recovery were observed for tiles and stainless steel surfaces after 7 days.