Yüksek Hidrostatik Basıncın Bazı Patojenlere ve Etin Kalite Özelliklerine Etkisi

In this study,high hydrostatic pressure (HHP)parameters, which can the protect the fresh characteristics of beef meat,were investigated and optimum process conditions were tried to be determined at 300-450 MPa pressure, -10 to 20ºC temperature and 5-15 minutes interval. Within the scope of the study, the effect of the pressure treatment on TVC counting was investigated and the effect of HPP on important pathogens that could be etched was investigated with studies done with inoculated samples of Escherichia coli 25922, Salmonella typhimurium 14028, Listeria innocua 33090 strains. Changes in color and texture of minced meat as quality parameters, were investigated during HPP treatment and shelf life. Comparisons of frozen samples before HPP and frozen samples were investigated and the pressure treatment parameters which caused the least changes in fresh characteristics of the meat were investigated. In addition, microbial growth levels, color, textural change and oxidation formation were evaluated in inoculated and non-inoculated samples during storage of the meat in the freezer. Microbial safety was achieved with HHP and color and sensory values and consumer acceptability of pressure-treated meat with preserved color and texture were evaluated. The highest inactivation L. innocua and S. typhimurium 14028 with HHP was 450 MPa (10 ºC, 10 min) (5.89 log cfu/g) at, 450 MPa (10 ºC, 5 min) (5.52 log cfu/g) at S. typhimurium. The highest inactivation in E. coli 25922 was achieved with 300 MPa (-5 ºC, 5 min.) (4,10 log cfu/g) and 450 MPa (20 ºC, 5 min) (4,30 log cfu/g). The highest inactivation in TMAB was obtained at 300 MPa (-5ºC, 15 min.) in uninoculated samples. In the unfrozen samples at 350-450 MPa (10-20ºC) HPP range, significant color change was observed in fresh meat, characterized by 300 MPa HPP and was obtained close to the control sample in fresh meat at temperatures below zero. However, no significant color difference was observed in frozen samples before pressure treatment with 350 and 450 MPa HHP (P>0.05). Tissue profiles of the meat with 300 MPa (-5ºC, 5 min) HHP at subzero temperatures were not changed, but at 350 and 450 MPa (10ºC) hardness, chewiness, gumminess, recillence were found different from control samples. When pressure treated samples were reshaped, values close to control samples were obtained.Any oxidation did not occur immediately after HPP (350 MPa, 10 ºC, 10 min) (P>0.05).The maximum level on the 15 day of storage was 2.01 for unfrozen controlsamples and 0.8-1.0 for pressure treated groups and the oxidation levels did not exceed the consumption limits. In pressure treated samples at the 3day of storage, total color difference (ΔE) was determined at the limit values. When the synthetic parameters increase after HHP, this increase can be regarded as a low increase in numerical value and remain stable during storage. 4-4.5 log cfu/g inactivation was detected in uninoculated samples after HHP and TMAB level in pressure treated samples remained below legal limits during 45 days. Listeria spp., Salmonella spp. and E. coli were detected in fresh meat and no pathogene was detected after 350 MPa HHP. Only E. coli was found on HHP treated samples on the 3rd day of storage. During storage, levels of three bacteria species were also different in control and HHP treated samples (P<0.05). In the following days of storage microorganisms developed in the pressured meat. Sensory values were found to be similar at pressure treated and control meatballs.in this study it has been determined that low temperature and pressure prior to freezing and HHP combined with lower pressures can be used to obtain microbial safe and fresh products with similar taste, color and texture.