Bazi doğal antimikrobiyal bileşiklerin S. enteritidis, E. coli O157:H7 ve L. monocytogenes üzerine etkinliğinin taze tavuk eti sisteminde incelenmesi.

In the first part of this study, the effectiveness of natural antimicrobial substances [nisin (0-500 ppm) and/or EDTA (20 mM); grapefruit seed extract; GFSE (0-300 ppm)] on the growth of each pathogenic bacteria (S. enteritidis, E. coli O157:H7, L. monocytogenes 4b) on the level 5 log10/ml were investigated in Tryptic Soy Broth (TSB) media. In the second part of the study, the effects of addition of grapefruit seed extract, nisin, garlic powder and NaCl on the bacteria were investigated in minced chicken meat samples or formulations under different temperature storage (4 and 10ºC) and packaging (aerobic and modified atmosphere) conditions. In microbial culture media, nisin-20 mM EDTA combination did not exhibit an inhibition effect on S. enteritidis and E. coli O157:H7 (p>0.05), whereas 73-500 ppm nisin alone in the pH range of 3.44-5.22 showed strong bactericidal effect (p<0.05) on L. monocytogenes It was also observed that 20 mM EDTA itself at pH 5,22 had a bacteriostatic effect on S. enteritidis and E. coli O157:H7. Grapefruit seed extract (60-300 ppm) was found to have a bactericidal effect at pH 6.0 against all pathogenic microorganisms in the first hour and at the end of the 24- hour incubation period (p>0.05) in TSB. The number (log10 CFU/g) of S. enteritidis and L. monocytogenes in minced chicken meat samples treated with 2000 ppm GFSE was found to be 0.5 log10 and 1 log10 CFU/g less respectively than in control at 4°C over the 6-day storage period. It was found that all factors (GFSE, period and packaging type) had a significant effect on the growth of S. enteritidis and E. coli O157:H7 over the 6-day storage period in minced chicken meat samples which were treated with 3000 and 6000 ppm of GFSE and packaged under aerobic (%21 O2+%79 N2) and modified atmosphere packaging (MAP) (%70 CO2+% 30N2) conditions at 10°C (p<0.05). High concentration level of GFSE (6000 ppm) was more effective in inhibitions of S. enteritidis and E. coli O157:H7. The growth of these pathogenic bacteria was also inhibited using modified atmosphere packaging (p<0.05). A statistically significant difference was found between packaging methods for L. monocytogenes, whereas no statistically significant difference was found between the inhibition effects of 3000 and 6000 ppm GFSE. In the formulation study, the effects of eight different combinations of GFSE (6000 ppm) with garlic powder (% 2 w/w) and NaCl (% 2 w/w) on pathogenic microorganisms were investigated under aerobic and modified atmosphere packaging conditions at 10°C during 6-day storage period. The results showed that growths of S. enteritidis and E. coli O157:H7 were significantly influenced by GFSE, NaCl, time and packaging method at 10° C. In addition to these factors, garlic powder had a significant (inhibitory) effect on L. monocytogenes growth (p=0.018). It was observed that treated samples with GFSE resulted in a reduction of 2 log10 mean for S. enteritidis and E. coli O157:H7 counts compared to controls over the first 3-day storage period. However, no further reduction activity was observed at the end of the 6-day storage period. MAP packaging resulted in 1 log10 mean reduction for S. enteritidis and 2 log10 mean reduction for E. coli O157:H7 compared to aerobic packaging over the 6-day storage period. During the first 3 days of storage the growth of L. monocytogenes was controlled with GFSE. At the end of 6 days storage, the number of L. monocytogenes was lowered by 2.5 log10 mean compared to controls with the addition of GFSE. MAP packaging led to a reduction of 1 log10 mean for L. monocytogenes compared to aerobic packaging. The addition of GFSE (6000 ppm) resulted in approximately 2 log10 reduction of S. enteritidis after 24 h at 4° C in aerobic packages. MAP packaging did not provide any advantage in the reduction of S. enteritidis. It was found that packaging method did not have a significant effect on E. coli O157:H7 (p=0.279). GFSE and MAP packaging was found to be effective in controlling Listerial growth at 4°C. It was found that nisin had a significant inhibition (p<0.05) effect on L. monocytogenes growth in minced chicken meat at 4°C. At the end of 6 days, the use of 250 ppm nisin with modified atmosphere packaging lowered Listeria counts by 2.5 log10 mean compared to aerobic-controls. [ABSTRACT FROM AUTHOR]