BACTERICIDAL ACTIVITY OF ORGANIC-ACIDS IN COMBINATION WITH TRANSDERMAL COMPOUNDS AGAINST SALMONELLA-TYPHIMURIUM ATTACHED TO BROILER SKIN

The aim of this research was to determine the bactericidal activity of low levels of organic acids (0.5% and 1%) when combined with various chemical agents (potential transdermal synergists). The skin attachmen t model (SAM) was used to determine bactericidal activity of treatment s against Salmonella typhimurium attached to chicken breast skin. Trea tments consisted of the following synergists: no synergist (control), 125 ppm sodium lauryl sulfate (SLS), 2% ethanol (ETOH), 100 ppm sorbit an monolaurate (Span 20), or 15% dimethyl sulfoxide (DMSO), in combina tion with acetic, citric, lactic, malic, and tartaric acids at 0.5% (E xperiment 1) or 1% (Experiment 2). Treatments were applied during a si mulated chill, post-process dip, or scald. The synergists alone were t ested and had no bactericidal activity. Addition of ETOH to all organi c acids (0.5%) did not increase their activity, and in some cases redu ced activity. Addition of SLS to lactic acid in the chiller increased activity (log(10) cfu skin(-1)) of the acid against firmly attached ce lls from 0.16 (control) to 1.29. Addition of DMSO to lactic acid cause d a 0.83 log(10) cfu skin(-1) vs. a 0.36 reduction in the lactic acid control. Adding SLS and DMSO to other acids had little or no effect, a nd in some cases, decreased activity. Span 20 caused the greatest incr ease in activity. Addition of Span 20 in the scalder increased activit y of all acids against loosely attached cells. Reductions in counts in creased by 0.81 (acetic acid) to 2.35 (tartaric acid) log(10) cfu skin (-1). Span 20 also increased activity of citric acid against firmly at tached cells by 1.63 log(10) cfu skin(-1) in the scalder. When added t o 1% concentration of the acids, SLS caused the greatest increase in a ctivity. Against firmly attached cells, addition of SLS increased acti vity of the acids in the dip by 0.61 and 0.40 when combined with citri c and tartaric acids, respectively. Against loosely attached cells, SL S increased activity of tartaric acid in the scalder application by 1. 16 log(10) cfu skin(-1). Activity varied among different potential syn ergists and was dependent on method of application and acid concentrat ion. In some cases, synergists showed greater activity when combined w ith 0.5% acid than with 1%. In other cases, the addition of a synergis t decreased activity of the acid. In cases where the activity of the a cid was increased, the resultant activity was greater than the added a ctivity of the synergist and acid alone, indicating a synergistic effe ct. (C) 1997 Academic Press Limited.