Resistance of pathogenic and spoilage microorganisms to disinfectants in the presence of organic matter and their residual effect on stainless steel and polypropylene.

OBJECTIVES

The effectiveness of disinfectants can vary according to the microorganism, type of residues and surface. The aim of this study was to determine the effectiveness of four disinfectants in the presence of organic matter and their residual effect on stainless steel grade 304 (SS) and polypropylene B (PP-B).

METHODS

The effectiveness of the disinfectants in the presence of meat extract, egg yolk and whole milk was determined according to AOAC and UNE-EN 1040:2015, and the residual effect was determined according to UNE-EN 13697:2015 using approved strains.

RESULTS

The effectiveness of the disinfectants was affected to different degrees depending on the organic matter present. SANICIP Q5 [400μg/mL; fifth-generation quaternary ammonium compound (QAC)] was most effective in the presence of 10% meat extract, whilst SANICIP PAA (200μg/mL; peracetic acid) showed better activity in the presence of 10% egg yolk and whole milk. In the evaluation of residual effect on SS and PP-B, the QAC had a better effect, reducing Listeria monocytogenes ATCC 19111 by 6 Log CFU/mL at 24h after its application. Conversely, the disinfectants had no residual effect against Pseudomonas aeruginosa ATCC 15442.

CONCLUSIONS

The antimicrobial activity of the disinfectants tested against pathogenic and spoilage microorganisms was affected according to the type of organic matter present. SANICIP Q5 had a greater residual effect than the other disinfectants evaluated. Moreover, the residual effect of a disinfectant is greater on SS than on PP-B and is dependent on the microorganism tested.