## 3 Results and Discussion  
### Kinetics of Bacterial Growth  
The antimicrobial activity of garlic, attributed to allicin, has been reported against a wide variety of microorganisms, including antibiotic-resistant Gram-positive and Gram-negative bacteria [24]. Some of these studies also included a quantitative evaluation of garlic antimicrobial properties by measuring the minimum inhibitory concentrations (MICs) and minimum microbicidal concentrations (MMCs) of various extracts against selected bacteria and fungi [25; 26]. In turn, other deliberations were focused on different solvents for extracting dried bulbs garlic to evaluate their insecticidal, antimicrobial, and antioxidant activities [12; 27]. Our study expands upon previous research by considering the effects of different concentrations of aqueous extracts obtained from raw garlic and garlic subjected to convective drying at various temperatures on the kinetic parameters describing the growth characteristics of _E. coli_. The selected bacterium is a model strain because it represents a widely distributed microorganism found in many environmental niches, including the human gastrointestinal tract, which, in some cases, may lead to foodborne illnesses. Moreover, considering findings of previous research indicated that allicin is thermally unstable and loses its antimicrobial activity within minutes when heated above 80 \({}^{\circ}\)C, while other thiosulfinates in garlic are more thermally stable, our experiments tested garlic subjected to drying at a range of temperatures 50-90 \({}^{\circ}\)C, including low, moderate, and high levels typically used in hot air drying [8; 28; 29]. The observations from our initial experiments carried out without garlic extracts demonstrated that growth curves of _E. coli_ based on changes in optical density over time exhibited the typical three stages of microbial growth: the lag phase, the exponential growth phase, and the stationary phase (Figure 1). The addition of garlic extracts--obtained from raw and dried (at different temperatures) garlic samples--to the medium altered the activity of the tested strain and modified the patterns of growth; however, most of the _E. coli_ curves still exhibited the three above-mentioned stages typical of microbial growth. The exception was the tests with the most concentrated extract (2%) obtained from both raw and dried garlic (regardless of the drying temperature), which exhibited complete growth inhibition for the examined bacterial strain during the analyzed period (18 h). The main compound responsible for the antimicrobial properties of garlic, allicin, is formed from allinin through the action of the enzyme alliinase, which is activated by the disruption of cell walls in garlic tissue. It is worth mentioning that the activation of allinase before garlic heat treatment is a critical factor in the development of the antimicrobial activity of the obtained products [25]. Heating whole garlic cloves without crushing them reduces the production of thiosulfinates from cysteine sulfoxides due to heat-induced inactivation of the enzyme before it converts allicin to allicin. In our study, the limitation of _E. coli_ growth in samples containing 2% garlic extract indicates that the initial preparation of garlic cloves before the drying process (cutting them into 2 mm pieces and allowing a 30 min waiting period before placing them in the drying chamber) activated alliinase and enhanced the antimicrobial properties of garlic. In further research, the modified Gompertz model was applied to the experimental data to assess the impact of garlic extracts on the growth kinetics of the tested bacterial strain. This model, widely used by researchers to describe microbial growth [3; 19; 30; 31; 32], was employed to predict biological parameters characterizing the dynamics of bacterial development in tested samples. The changes in the optical density (OD), describing the population level of the tested _E.