Impact of Dried Garlic on the Kinetics of Bacterial Growth in Connection with Thiosulfinate and Total Phenolic Content

The health properties of garlic (Allium sativum L.) are attributed to thiosulfinates, flavonoids, phenols, and bioactive polysaccharides. These compounds, however, can degrade during processing methods. As hot air-drying is a commonly used preservation method due to its relatively simple operation, this study investigated the effects of garlic slices dried at various temperatures (50, 70, and 90 °C) on the growth kinetic parameters of model strain Escherichia coli ATCC 25922, the total thiosulfinate content (TTC), and the total phenolic content (TPC). Observations showed that the concentration of garlic extracts was a significant factor influencing the kinetics of bacterial growth, while the garlic drying temperature appeared to have no effect on E. coli activity. Analysis of TTS in fresh and dried garlic did not reveal statistically significant differences in their levels. However, hot air drying at 50 °C significantly reduced the TPC by nearly 25%, whereas drying garlic at higher temperatures (70 °C and 90 °C) did not lead to a significant loss in TPC compared to the raw samples. The determined growth kinetic parameters of the tested E. coli strain could serve as a basis for selecting optimal drying process conditions and extract concentrations when designing garlic products with enhanced antimicrobial properties.