## 3 Results and Discussion
### Physicochemical Characteristics of Japanese Sauces
\begin{table}
\begin{tabular}{l l l l l} \hline  & **KS\_C** & **KS\_O** & **TS\_C** & **TS\_O** \\ \hline Density [g \(\times\) 100 cm\({}^{-3}\)] & 1.1746 \(\pm\) 0.0033 a & 1.1685 \(\pm\) 0.0013 a & 1.6430 \(\pm\) 0.0013 c & 1.5471 \(\pm\) 0.0005 b \\ Dry weight [\%] & 29.74 \(\pm\) 0.08 a & 31.22 \(\pm\) 0.05 b & 29.14 \(\pm\) 0.06 a & 29.76 \(\pm\) 0.11 a \\ pH & 4.78 \(\pm\) 0.04 b & 4.60 \(\pm\) 0.01 a & 4.45 \(\pm\) 0.02 a & 4.78 \(\pm\) 0.05 b \\ Nitrogen [g \(\times\) 100 cm\({}^{-3}\)] & 1.628 \(\pm\) 0.016 a & 1.661 \(\pm\) 0.066 a & 1.643 \(\pm\) 0.014 a & 2.112 \(\pm\) 0.059 b \\ \hline \end{tabular} Values with different uppercase letters in verses are significantly different using [PERSON]’s test (\(p<\) 0.05).  
\end{table} 
Table 1: Physicochemical characteristics of conventional and organic Japanese shoyu sauces available on the Polish market. Streptococcus [31]. However, some authors suggested a variable bacterial composition depends on minor changes in environmental conditions, such as differences in temperature in the koji production room, soybean lipid content, and the species of _Aspergillus_ used in the previous step. The growth and activity of lactic acid bacteria rapidly reduces pH. When pH drops below 6.0, the bacterial community begins to decline, and when pH drops below 5.0, lactic acid fermentation ends [30]. This state facilitates the growth of salt-tolerant yeasts, which produce alcohol from the remaining sugars [1]. Nitrogen content in soy sauce is one of the most important indicators of the quality of soy sauce, and the higher the content, the better the quality of the final product [32; 33; 34; 35]. While the differences between the three kinds of soy sauces were not significant, TS_O was recorded as the one that contains the highest content of total nitrogen (2.112 \(w/v\%\)) (Table 1). According to the requirements set out by Japanese Agricultural Standards for Soy Sauce with total nitrogen criteria, all tested samples of soy sauces can be qualified as Special grade. A study conducted in 2014 showed the protein content in organic soybeans was significantly higher than that of conventional soy [36]. This could suggest that organic soy sauce may contain higher total nitrogen, and hence better quality, in comparison to conventional soy sauce. It would be also in line with the results from another study that characterized and differentiated Chinese conventional and organic soy sauces and indicated an increased concentration of amino acids in the latter type compared to the former type [37]. However, for the tested samples in our studies, only organic tamari shoyu showed a higher content of total nitrogen. This result could be attributed to the reduced salt content in this sample, suggesting the method of low-salt organic tamari shoyu production is based on the elevation of total nitrogen content [24]. The total nitrogen content in soy sauce is composed of simple peptides (nearly 45%) and amino acids (50-75%) [34]. When analyzing and discussing the results in this study, we referred to the manufacturers' declarations specifying the type of sauce. Therefore, we know that differences in quality parameters may result from using different proportions of raw materials or production methods.