# Insights into Native Fermentation Process of Apples (_Malus domestica_) in Low Sodium Conditions
## 3 Results
### Physical and Chemical Analysis
#### 3.1.7 The Results of Phytochemical Analysis  
Apples are among the main sources of phenols in plants. However, only a few studies have so far reported the phytochemical characterization of naturally fermented apples, and not necessarily as apple pickles. Table 3 shows the average of three successive determinations of the main phytochemicals of fresh and fermented apples. Table 3 shows a gradual increase in TPC and TFC according to the three types of brine and the days of fermentation. According to [37], the effect of the fermentation of fruits and vegetables impacts the bioavailability of the TP and TF compounds, which will determine the increase in antioxidant activity. This affirmation could be sustained by the results of the present study on apple fermentation due to the notable increases: by 90% for the TPC \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Fermentation** & **KCl** & **NaCl** & **MgCl2** \\ \hline
7 days & 5.71 \(\pm\) 0.01 \({}^{\mathrm{a}}\) & 14.00 \(\pm\) 0.09 \({}^{\mathrm{a}}\) & 97.3 \(\pm\) 1.63 \({}^{\mathrm{a}}\) \\ \hline
14 days & 4.56 \(\pm\) 0.03 \({}^{\mathrm{a}}\) & 15.31 \(\pm\) 0.17 \({}^{\mathrm{a,d}}\) & 59.0 \(\pm\) 4.15 \({}^{\mathrm{b}}\) \\ \hline
21 days & 7.50 \(\pm\) 0.009 \({}^{\mathrm{a,b}}\) & 21.02 \(\pm\) 0.08 \({}^{\mathrm{b}}\) & 55.4 \(\pm\) 2.93 \({}^{\mathrm{c}}\) \\ \hline
28 days & 7.25 \(\pm\) 0.03 \({}^{\mathrm{a}}\) & 17.71 \(\pm\) 0.17 \({}^{\mathrm{c,d}}\) & 42.8 \(\pm\) 1.63 \({}^{\mathrm{d}}\) \\ \hline
35 days & 10.41 \(\pm\) 0.10 \({}^{\mathrm{b}}\) & 12.5 \(\pm\) 0.24 \({}^{\mathrm{a}}\) & 78.6 \(\pm\) 1.22 \({}^{\mathrm{e}}\) \\ \hline \hline \end{tabular} Values with different letters in a column indicate significant differences (\(p<0.05\)) among experimental variants.  
\end{table} 
Table 2: The dynamics of cation concentrations in the brine during the experimental trial (expressed as mg/L). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Fermentation** & \multicolumn{5}{c}{**Phyochemical Compounds**} \\ \cline{2-5}
**Time, Days** & **TPC mg GAE/g d.w.** & **TFC, mg EQ/g d.w.** & **TC, mg/g d.w.** & **mg/g d.w.** & **Lycopene, mg/g d.w.** & **Chl, \(\mu\)g d.w.** \\ \hline \multicolumn{5}{c}{**NaCl**} \\ \hline
0 & 5.95 \(\pm\) 0.63 \({}^{\mathrm{E}}\) & 7.23 \(\pm\) 0.30 \({}^{\mathrm{E}}\) & 1.59 \(\pm\) 0.01 \({}^{\mathrm{D}}\) & 1.03 \(\pm\) 0.00 \({}^{\mathrm{BC}}\) & 0.45 \(\pm\) 0.05 \({}^{\mathrm{E}}\  
registered for NaCl after 35 days of storage, by 33% for KCl fermentation, and by 23% for MgCl\({}_{2}\), respectively. The results of TPC are heavily dependent on the brine type. It is certain that lactic acid bacteria can increase the content of flavonoids (from \(9.57\pm 0.40\) to \(15.26\pm 0.42\) mg EQ/g d.w. for NaCl brine, from 8.03 \(\pm\) 0.35 to 16.30 \(\pm\) 0.33 mg EQ/g d.w. for KCl brine, and from 9.21 \(\pm\) 0.50 to 15.21 \(\pm\) 0.61 for MgCl\({}_{2}\) brine) and metabolize them into more bioavailable forms, which is confirmed by the TPC content evolution (Table 3) in dependence on the days of fermentation. These could be associated with the activity of the most common flavonoids (procyanidins, epicatechin, catechin and quercetin) found especially in apple peel and less in flesh, which have strong antioxidant activity and could also inhibit low-density lipoprotein (LDL) oxidation, as [PERSON] et al. [38] reported. It is to be remarked that comparable results were reported by [PERSON] et al. [39] for the biotransformation of flavonoids from alfalfa during fermentation with lactic bacteria. Interestingly, in accordance with the studies of [PERSON] et al. [40] and [PERSON] et al. [41], the \(\beta\)-carotene content, independent of the salt type but dependent on the fermentation time, could be associated with oxidative cleavage into apcarotenoids and other compounds because of some non-specific reactions such as lipoxygenase co-oxidation or photooxidation or by oxygenase influence. The \(\beta\)-carotene content is highly influenced by the fermentation phenomenon and the plant material, as [PERSON] et al.