## 3 Results
### The Protein Content of Soybeans and Peas  
Proteins are substances with a high nitrogen content, on average 16%. A reproducible and accurate method for evaluating the amount of protein in samples is the Kjeldahl method, which involves the dosage of protein nitrogen in the form of an ammonium ion. The transformation of organic nitrogen into inorganic nitrogen is called digestion and consists of the mineralization of the samples at high temperature (440 \({}^{\circ}\)C) in a concentrated sulfuric acid environment and in the presence of a disaggregation mixture. Nitrogen results in the formation of an ammonium ion, which is transformed into ammonia in the basic environment created with the help of a sodium hydroxide solution. The obtained sample was distilled, and the ammonia was retained in a 4% boric acid solution. The resulting mixture was titrated with 0.1 N HCl solution in the presence of the methyl orange indicator. For protein contents, the post hoc Tukey test for multiple comparisons was performed at the level of each soybean sample (Ovidiu F early, Anduta F semi-early, Florina F semi-early, Fabiana F semi-late, Crina F semi-early) and pea type (Spectral F autumn, Aurora-type afila, Evelina F-type afila, Nicoleta-type afila) depending on the extraction method (Kjeldahl method and Bradford method by extraction with Tris-glycine buffer and by extraction with \begin{table}
\begin{tabular}{c c c c} \hline
**Soybean Variety** & **Sample Table Taken in Work (g)** & **Total Lipid Extract (g)** & **Total Lipid Extract (\% Dry Weight)** \\ \hline [PERSON] F early & 5.03 \(\pm\) 0.01 & 1.13 \(\pm\) 0.25 & 22.46 \(\pm\) 0.12 \\ \hline Anduta F semi-early & 5.03 \(\pm\) 0.01 & 1.17 \(\pm\) 0.33 & 23.28 \(\pm\) 0.25 \\ \hline Florina F semi-early & 5.01 \(\pm\) 0.02 & 1.03 \(\pm\) 0.55 & 20.67 \(\pm\) 0.18 \\ \hline Fabiana F semi-late & 5.01 \(\pm\) 0.02 & 1.10 \(\pm\) 0.66 & 22.00 \(\pm\) 0.33 \\ \hline Crina F semi-early & 5.00 \(\pm\) 0.01 & 1.11 \(\pm\) 0.42 & 22.29 \(\pm\) 0.15 \\ \hline \end{tabular}
\end{table} 
Table 5: The total lipid extract from the analyzed soybean samples. The Kjeldahl method is the most widely used method in research and quality control of protein determination, being more precise than other methods. The results obtained are different compared to those recorded using the Bradford method. The binding of Coomassieie Brilliant Blue G-250(r) reagent is specific to each protein. Although reproducible, the method has errors for different types of proteins. Amino acids are another complementary method of evaluating the amount of protein. By summing the amounts of amino acids, the amount of protein in the samples can be calculated. To dose them, protein hydrolysis was necessary, but amino acids are not volatile substances. A modern, precise, but difficult and expensive method is HPLC analysis. Due to the time-consuming nature of an HPLC analysis (more than 1 h for each injection, with the need for repeated washes due to precipitation of components in the elution mixture), an appropriate gas chromatography method was chosen. This method assumes that the amino acids resulting from protein hydrolysis are transformed into volatile derivatives, namely the grafting of trimethylsilyl groups. The amount of each amino acid can be calculated based on the standard curve. The results of the analysis of amino acids from the soybean and pea samples analyzed are presented in Table 6 and Figure 4.  
Figure 3: Protein percentage content in soybean and pea samples after extraction with Tris-glycine buffer solution and water extraction determined using the Bradford method and Kjeldahl methods. The results are presented as mean \(\pm\) SD (n = 3). Asterisks indicate the statistical significance examined by ANOVA with Tukey post hoc test (* \(p\)\(\leq\) 0.05, ** \(p\)\(<\) 0.01, *** \(p\)\(<\) 0.001, ns: \(p\)\(>\) 0.05).