Combined effects of selected food additives on adhesion of various foodborne pathogens onto microtiter plate and cabbage leaves

The study was conducted to examine the adhesion inhibition and antibacterial activities by combined use of some selected food additives such as Sucrose Fatty Acid Ester (SE) C18, Gardenia Yellow (GY), Monascus Pigment (MP), Protamine (PT), ε-polylysine (PL) and Milk Serum Protein (MSP), against Salmonella Enteritidis, Salmonella Typhimurium, Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus. The adhesion of those pathogenic bacteria was reduced by several combination of food additives compared to that of each of the single use. The combinations decreased the relative adhesion more than 10% compared to that of each of the single use were taken into consideration. The following combinations such as SE18 & GY, PT & MSP, and PL & MSP were effective in inhibiting the attachment of S. Enteritidis onto microtiter plate compared to that of each of the single use. In case of S. Typhimurium, the combination of MSP & MP, SE18 & GY, SE18 & PT, SE18 & PL, SE18 & MP, SE18 & MSP, MP & PT, MSP & PL, GY & PL, and MSP & PT were effective in adhesion inhibition. The combination of SE18 & GY, GY & MSP, and PL & MSP were effective in inhibiting the attachment of P. aeruginosa onto microtiter plate compared to that of each of the single use. The combination of GY & MSP, MSP & PT or PL and MP & PL were effective to inhibit the attachment of L. monocytogenes. The adhesion of S. aureus was reduced by combined use of SE18 & PT, GY & PT, GY & PL, MSP & GY, MSP & PL, SE18 & GY, SE18 & MP, and MSP & PT compared to that of each of the single use. On the other hand, there were no such significant changes in viable counts of all pathogenic bacteria tested by using combination of food additives compared to that of each of the single use. However, the viable counts of S. Enteritidis and P. aeruginosa decreased drastically in the presence of PL (0.01%) and PT (1%), respectively and reached to the lower detection limit. In addition, the viable counts of L. monocytogenes decreased around 4 Log in the presence of PL. These results clearly showed that the combination of MSP and PT or PL effectively reduced adhesion of all the Gram-positive and negative pathogens tested on the microtiter plate. The pretreatment of cabbage leaves with combination of PL & MSP was also effective to reduce the viable counts of secondary-contaminated S. Enteritidis on the cabbage leaves by washing with water compared to that of untreated cabbage leaves.