# Physicochemical and Structural Properties of Freeze-Dried Lacto-Fermented Peach Snacks
## 3 Results and Discussion  
### Basic and Color Attributes of Freeze-Dried Peach Samples  
The freeze-dried peach sample (P) had the highest dry matter content at 96.9%. The fermented samples showed lower dry matter, about 6% (freeze-dried peach sample fermented with _L. plantarum_--P_LP) or 7% (freeze-dried peach sample fermented with I. _fructivorans_--P_FF) compared with the control (Table 1). This decrease suggested that the fermentation process in brine made the fruit tissue retain more water, which remained even after freeze-drying. During fermentation, water may be absorbed into the fruit tissue, while at the same time, water-soluble compounds can diffuse into the brine. The higher the salt content in brine, the faster this process was. In the presented study, the amount of salt was relatively small compared with those presented in the literature, usually from 2 to 10%. Additionally, the reduction in sugar content was likely due to its consumption by lactic acid bacteria (LAB) during growth and lactic acid production. It was demonstrated that a minimal addition of sodium chloride (0.5%) to the brine could exert a favorable influence on the proliferation and viability of lactic acid bacteria. This was achieved by instigating the osmotic stress, to which the bacteria could adapt through a range of physiological and metabolic alterations [25; 26]. Moreover, the loss of soluble substances, such as sugars and polyphenols, into the brine may further contribute to decreased dry matter content [23; 27]. In a study comparing methods regardless of pretreatment, freeze-drying carrot slices resulted in higher dry matter content (93.6-95.8%) than other methods, such as convection, microwave convection, and microwave vacuum drying [28]. The water activity (aw) was low and did not change much among the samples, ranging from 0.13 to 0.15 (Table 1). This meant that even though the fermented samples had more moisture, their resistance to microbial spoilage was similar to that of the control sample [29]. However, a low aw, below 0.3, meant that dried samples were considered microbiologically and chemically safe [30]. When analyzing the samples as potential snack products, it was essential to consider their sensory attributes, such as texture, color, and taste, as these elements must be appealing to consumers to ensure product acceptance and market success. Among them, color is one of the most significant parameters that define food quality as it significantly influences consumer preferences and purchasing decisions [31]. In the present study, color was used as one of the quality indicators to evaluate the quality of peach-based fermented snack products. The color parameters of the CIE L*a*b* system were analyzed to observe the impact of the fermentation process and the strain used on the product's color. The results showed that the color parameters were dependent on the fermentation process. The control sample was also characterized by a lighter color as evidenced by the highest values of the L* parameter, the lowest intensity of the red color (the lowest value of a* parameter), and a higher yellow color (the highest value of b* parameter) (Table 1). Chroma (C*), representing color intensity, was the highest in the control and lower in the fermented samples, confirming that fermentation resulted in less vivid coloration. The parameter that could give us the final information that could influence the consumer choice was the total color difference (\(\Delta\)E), calculated compared with the control. Its value was high in both fermented samples (18.2 for P_LP and 15.6 for P_FF), indicating a substantial visual change in color due to fermentation.