## 3 Results and Discussion
### Microbiological Changes in Apple Pickle Fermentation  
This study aimed to determine how the pickling process influences the microbiota, including LAB, yeast, and aerobic mesophilic bacteria, over the storage period. The Granny Smith apples' microbiological quality obtained by pickling is shown in Figure 9. Four stages of microbial development can be distinguished during the natural fermentation of primed vegetables: initiation, primary fermentation, secondary fermentation, and post-fermentation deterioration [51]. Depending on environmental variables (salt type and concentration, temperature, vegetable matrix, etc. ), aerobic spore-formers, LAB, and other types of bacteria and yeasts can remain active for days. Figure 8: Antioxidant activity of pickled Granny Smith apples. Regarding the meaning of the grouping information rendered by the Tukey method, with 95% confidence, the letters from A–C indicate significant differences in the antioxidant activity results between the days of fermentation. Figure 9: Microbiota of pickled apple samples during the fermentation period: lactic acid bacteria (**a**), aerobic bacteria, (**b**) and yeast (**c**) counts. The LAB eventually take control by reducing the pH as primary lactic acid fermentation occurs. As seen in Figure 9a, the total LAB count increased rapidly until the seventh day for all the samples. Figure 9a also shows a significant difference in the number of LAB in the pickle samples analyzed. The total LAB count had a constant value from the 7 th day to the 15 th day and then increased for KCl- and NaCl-treated samples, whereas for the MgCl\({}_{2}\)-treated samples, a decrease was observed. At the end of the storage period, a decrease in LAB count was observed for all tested samples. The reduction in the total LAB count sample following the 15 th day of the fermentation is considered to be associated with the fact that LAB may have a brief metabolic cycle, poor salt tolerance, and acid resistance [52]. The pH of canned pickles drops below a value of 4.6 or below, a level that does not allow the survival of most spoilage and pathogenic organisms, as Figure 2 shows. Lactic acid and maybe other metabolites that are commonly produced by lactic acid bacteria during pickle fermentation are the cause of the low pH. Our findings, which are consistent with prior research, indicate that KCl inhibits the growth of the majority of LAB strains, although the extent of this reduction is not as significant as that induced by NaCl [53]. Additionally, our findings suggest that their acidification capacity may not be significantly affected (Figure 3) [54]. This may be partially attributed to the fact that NaCl has a more substantial influence on water activity than KCl [55]. Since every food product has unique compositional and microbiological specificities that need to be considered, replacing NaCl with KCl or MgCl\({}_{2}\) should not be a general rule in this respect [56]. The MAB (Figure 9b) of the pickled apple with various salt types fluctuated during storage, with pickles made with NaCl containing the highest levels (3.69-5.44 log CFU/mL). The cans of pickles made with MgCl\({}_{2}\) had the lowest counts (4.78 log CFU/mL) after 35 days of storage. The MAB count may be considered safe if the aerobic plate counts of bacteria are as high as 5 log CFU/mL [57; 51]. The lowest counts of YM were observed in pickles made with MgCl\({}_{2}\) (2.69 log CFU/g) after seven days of storage (Figure 9c). For the apple pickles made with CaCl\({}_{2}\) and KCl, the yeast concentration was relatively high compared with MgCl\({}_{2}\) during the same storage interval. According to [58], yeasts can grow at a relatively low pH and in weak lactic acid concentrations. After 35 days, the yeast counts for all samples tested were below the detection limit (<1 log CFU/g). It is generally accepted that the critical yeast population that can cause spoilage is higher than log 6 CFU/g.