Combined Effect of Ultrasound and Microwave Power in Tangerine Juice Processing: Bioactive Compounds, Amino Acids, Minerals, and Pathogens

The inhibition of Escherichia coli ATCC 25922 (E. coli), Staphylococcus aureus ATCC6538 (S. aureus), Salmonella Enteritidis ATCC 13076 (S. Enteritidis), and Listeria monocytogenes DSM12464 (L. monocytogenes) is one of the main aims of the food industry. This study was the first in which the use of ultrasound and microwave power were applied to optimize the values of the bioactive components, amino acids, and mineral compositions of tangerine juice and to inhibit Escherichia coli, Staphylococcus aureus, Salmonella Enteritidis, and Listeria monocytogenes. The response surface methodology (RSM) was used to describe the inactivation kinetics, and the effects of ultrasound treatment time (X-1: 12-20 min), ultrasound amplitude (X-2:60-100%), microwave treatment time (X-3: 30-40 s), and microwave power (X-4:200-700 W). The optimum parameters applied to a 5-log reduction in E. coli were determined as ultrasound (12 min, 60%) and microwave (34 s, 700 W). The optimum condition ultrasound-microwave treatment was highly effective in tangerine juice, achieving up to 5.27, 5.12, and 7.19 log reductions for S. aureus, S. Enteritidis, and L. monocytogenes, respectively. Ultrasound-microwave treatment increased the total phenolic compounds and total amino acids. While Cu, K, Mg, and Na contents were increased, Fe and Ca contents were lower in the UM-TJ (ultrasound-microwave-treated tangerine juice) sample. In this case, significant differences were detected in the color values of ultrasound-microwave-treated tangerine juice (UM-TJ) (p < 0.05). The results of this study showed that ultrasound-microwave treatment is a potential alternative processing and preservation technique for tangerine juice, resulting in no significant quality depreciation.