Effect of ultrasound and magnetic field applications on microbiological shelf life of frozen meatballs

The search for alternative methods to pasteurization and sterilization processes is increasing day by day in order to reduce the negative effects of preservation techniques on nutritional value and quality parameters during food preservation. Ultrasound and magnetic field techniques are among the methods that emerged as a result of this search. In this study, high-power ultrasonic sound waves and magnetic field applications were applied alone or in combination with other preservation methods in order to inhibit microbial growth and inactivate enzymes in foods. In the study, meatball samples prepared from minced beef by traditional method were packaged with vacuum and stretch, and ultrasound-magnetic field processes were applied to the samples in both groups separately and in combination after the control groups were separated. All specimens were frozen at (-18) - (-20) oC for 90 days. Sample groups under frozen storage were analyzed microbiologically on 0, 7, 14, 21, 30, 45 and 90 days and combined with applications such as ultrasound, magnetic field, vacuum and stretch packaging to investigate the effects on microbiological quality parameters and shelf life of meatballs. On the fourteenth day of the study, it was determined that the total number of mesophilic aerobic bacteria in the vacuum-packed magnetic-fielded meatball sample (MAV) was 0.59 log cfu/g lower than the stretch-packed magnetic-fielded (MA) sample. It was observed that the number of generic Escherichia coli in the ninetieth day analysis of the vacuum-packed control sample (CV) was 1.38 log cfu/g less than the stretch-packed control sample (K). On the thirtieth day, the number of coagulase-positive staphylococci was found to be 0.9 log cfu/g less than in the stretch-packed 15-minute ultrasound sample (US15) compared to the vacuum-packed 15-minute ultrasound sample (US15V). It is thought that it may depend on the type of packaging preferred.