# Physicochemical and Structural Properties of Freeze-Dried Lacto-Fermented Peach Snacks
## 3 Results and Discussion
### Chemical Changes Induced by Lactic Acid Fermentation  
Fermentation using _Lactiplantibacillus plantarum_ (P_LP) and _Fruticlactobacillus fructurans_ (P_FF) caused observed changes in the chemical composition of freeze-dried peach samples (Table 3). These changes occurred due to the dynamic interactions of microbial activity, enzyme processes, and diffusion in the brine during fermentation [42; 43; 44]. Figure 2: Percent in volume range in tested samples. P—freeze-dried peach sample; P_LP—fermented with _Lactiplantibacillus plantarum_ and freeze-dried peach samples; P_FF—fermented with _Fruticlactobacillus fructurans_ and freeze-dried peach sample. The salt content in the fermented peach samples increased significantly compared with the control sample. Specifically, the salt levels measured approximately 0.50% for both fermented samples and only 0.16% for the control. This increase was likely due to the peaches absorbing salt from the brine, which enhanced flavor. The elevated salt content could influence the overall sensory experience of the fermented product, which was also shown in sensory analysis. The salt content in fermented samples showed the maximum intake level, while the salt addition was 0.5 m/v in brine. The diffusion of salt into the fruit tissue and the movement of soluble compounds into the brine suggested an osmotic balance shift, affecting the composition of the fruit [23]. The salt content measured in the control samples was due to its presence in the peach samples. Moreover, the addition of NaCl could create osmotic stress, to which LAB must adapt. For example, [PERSON] et al. [45] examined _Lactobacillus rhamnus_, which exhibited increased cell viability and biomass concentration when exposed to 0.5 M NaCl during exponential growth. This suggested that even a slight increase in salt concentration could improve the resilience of LAB. Additionally, the total acidity in the fermented samples increased after fermentation. It reached 22.5 mg/kg in P_LP and 21.7 mg/kg in P_FF, in contrast to just 3.8 mg/kg in the control sample. This substantial rise in acidity was linked to the metabolic processes of the bacteria, which generated organic acids, mainly lactic acid, as they broke down sugars [46; 47]. The resultant acidic environment symbolized lactic acid fermentation, promoting preservation, lowering pH levels, and imparting a distinctive sour taste to the final product. Fermentation significantly reduced the total sugar content, with a 43.5% decrease in P_LP and a 31.2% decrease in P_FF compared with the control peach sample. This reduction could be attributed to the consumption of sugars (mainly glucose, fructose, and sucrose) by lactic acid bacteria (LAB) as a carbon source for growth and acid production [47]. The amount of sugar reduction may depend on the specific needs of each type of bacteria, the composition of sugars in the fruit juice, the time of fermentation, and how sucrose is broken down into simpler sugars [48]. _Fructobacillus_ fermions glucose; however, fructose is fermented faster than glucose [49]. The ratios of total sugar to total acidity and salt content illustrated the impact of fermentation on the biochemical balance of the peach samples. In the control sample (P), the sugar-to-acidity ratio was approximately 11.13, while it decreased drastically in the fermented samples to 1.06 for P_LP and 1.34 for P_FF. Similarly, the sugar-to-salt ratio dropped from 264.38 in the control to 47.80 in P_LP and 60.63 in P_FF. These changes reflected the intense microbial metabolism of sugars into organic acids during fermentation and the associated increase in salt concentration due to processing. Analyzing both TA (total acidity) and TSC (total sugar content) as indicators of the lactic acid fermentation process can be based on the information that LAB used sugars to generate energy through glycolysis, leading to the production of lactic acid and other organic acids, which explained the increase in acidity and decrease in sugar content [50].