## 3 Results
### Physical Properties
#### 3.2.2 Water Activity (AW)  
Water activity and dry weight are parameters that characterize the persistence of a dried vegetable. Plant materials can be considered effectively dried when the water content is less than or equal to 12%. However, only water activity below 0.6 can protect the product from biochemical changes, physical changes, and, most importantly, the proliferation of microorganisms [41]. In all samples tested, AW was \(<\)0.6, indicating microbiological safety. The regression equation explains 95% of the dependence on the drying method used, the vacuum impregnation process, and the type of vegetable (Table 5). The study concludes that AW was significantly influenced by the drying method (\(p\)-value \(<\) 0.0001). Lower values of the studied parameter were observed for FD than for VD, which is consistent with previous studies by the authors of this publication [8; 21; 28]. This may be related to the influence of the drying method on moisture sorption isotherms. [PERSON] et al. (2022) examined sorption isotherms depending on the drying method and parameters. The authors noticed that the equilibrium moisture of 10% corresponds to a water activity of approximately 0.35 for freeze drying at 27 \({}^{\circ}\)C and a water activity of 0.51 for vacuum drying at 37 \({}^{\circ}\)C [42]. This proves that with different drying techniques and the same equilibrium moisture, water activity may be different. Moreover, the authors noticed that the level of equilibrium moisture tends to decrease in relation to the increase in temperature at a given water activity. Furthermore, [PERSON] et al. (2011) comparing spray and freeze drying, they noticed that the equilibrium moisture tends to decrease with increasing temperature in a given water activity [43]. This decrease may be due to a reduction in the number of active sites due to chemical and physical changes during drying. [PERSON] et al. (2023) reported similar results for various varieties of blueberry fruits when vacuum dried at different temperatures; droughts with lower moisture were characterized by higher water activity [44]. The composition of vegetables and fruits can be presented as an aqueous solution of low-molecular-weight substances consisting of organic acids, sugars, and salts. Additionally, aqueous solutions of substances contain large particles that are contained in the water-insoluble cellular matrix of macromolecules, mainly carbohydrates, pectin substances, proteins, hemicelluloses, and sometimes also lignin. The pulp tissue of fruits and vegetables contains intracellular air spaces that play a huge role in the perception of structure. The ingredients listed above can interact with water to varying degrees, which is why they have the ability to reduce water vapor pressure. Moreover, the water contained in fruits and vegetables may be related to chemical and enzymatic reactions, oxidative changes, and the content of volatile compounds. The quality and stability of processed vegetables and fruits are influenced by physical and structural changes, i.e., collapse during drying, crystallization, loss of crunchiness, loss of volatile compounds, and other forms of texture degradation [45]. The use of the vacuum impregnation process resulted in lower