## 3 Results and Discussion
### Microbiology and Enzymatic Activity  
The presence of microorganisms (bacteria, yeasts, molds) is a critical factor that influences the shelf-life of juices, leading to undesirable changes, such as fermentation processes, including alcoholic and lactic fermentation [42]. MFP and traditional pasteurization were effective in the inactivation of microorganisms at 90 \({}^{\circ}\)C from 1.83 \(\times\) 10\({}^{2}\), 4 \(\times\) 10\({}^{2}\) and 1.1 \(\times\) 10\({}^{3}\) log CFU/mL, respectively, for bacteria, molds and yeasts to below the limit of quantification. All juices were microbiologically stable during the whole 12-month storage time, which confirmed that MFP can be a useful technology for the industry. The study conducted by [PERSON] et al. (1998) [43] demonstrated that microwave pasteurization effectively inactivates _Saccharomyces cerevisiae_ and _Lactobacillus plantarum_ in apple juice. The study showed that these microorganisms were inactivated at 60 \({}^{\circ}\)C and 65 \({}^{\circ}\)C, respectively. Moreover, [PERSON] et al. (1992) [44] illustrated nearly 100% inactivation of _L. plantarum_ using microwave flow pasteurization on orange juice with beneficial effects observed after 20 s at 70 \({}^{\circ}\)C. In another study by [PERSON] et al. (2017) [45], microwave pasteurization of strawberry pure resulted in complete inactivation of yeasts and molds, with a total microbial count < 1 log CFU/mL when two different temperatures 90 and 120 \({}^{\circ}\)C were used. [PERSON] et al. (2018) [46] observed almost complete inactivation of aerobic bacteria, molds, yeasts and coliforms in tamarind beverages. The result was attributed to the phenomenon associated with a wider distribution of energy in microwave pasteurization compared to traditional pasteurization. According to [PERSON] et al. (2017) [47], microwaves affect microorganisms through different mechanisms: selective heating, electroporation and magnetic field coupling. The selective heating effect can lead to faster heating of microorganisms that absorb microwave energy compared to the surrounding liquid, thereby reaching pasteurization temperatures [48]. Electroporation induces the formation of pores in the cell walls of microorganisms, resulting in the leakage of cell contents and, consequently, cell lysis [49]. Microbial inactivation can also occur due to the coupling of electromagnetic energy with critical particles inside the cell, such as proteins or DNA. Microwaves impact the cell's internal components, leading to their demise [50]. Another factor contributing to changes in juices is the influence of enzymes, which can lead to phenomena such as browning [21]. Our study revealed that both microwave pasteurization and traditional pasteurization resulted in the inactivation of PPO and a significant reduction in POD activity (almost 99.8%). Throughout almost the entire storage time, no PPO activity was detected. However, the study demonstrated the ability of POD to regenerate during the storage time. After 12 months of storage, a minimal level of POD activity (5%) was observed. In the early 1950s, [PERSON] and [PERSON] [51] demonstrated the regenerative activity of POD with 99.9% inactivation of the enzyme. In a study conducted by [PERSON] et al. (2016) [8], it was shown that higher temperature and microwave pasteurization power (3600 W/93 s) resulted in the complete inactivation of peroxididases in vegetable smoothies. Similar results were obtained by [PERSON] et al. (2007) [52] in a study on coconut water where the authors found that microwave pasteurization was more efficient compared to traditional pasteurization. [PERSON] et al. (2015) [16], in their study on strawberry pure, noted an approximately 80% reduction in PPO activity within 10 s regardless of the temperature applied (90 \({}^{\circ}\)C and 120 \({}^{\circ}\)C). Reducing the microwave processing time to 7 s at 90 \({}^{\circ}\)C resulted in a reduction in PPO activity to approximately 62%.