# The Influence of Proteolytic Salt Modification on the Aging Potential of Final Wort
## 3 Results and Discussion
### Dicarbonyl Formation during Word Boiling  
Aside from the amino acids, another important group of precursors is the dicarbonyl compounds. They play a key role in aging aldehyde formation during the Strecker degradation and the Maillard reaction. Thus, they directly contribute to aging potential because of their precursor activity. Therefore, the main dicarbonyls, 3-DG and 3-DGal, were monitored during word boiling due to different malt modification levels (P1 < P2 < P3). Figure 2 shows the concentrations of 3-DG and 3-DGal during word boiling at all proteolytic variations. Comparing both compounds, it could be confirmed that 3-DG was the major dicarbonyl [10] because it occurred in higher concentrations during word boiling. The 3-DGal was formed from 3-DG by interconversion [47] and, therefore, resulted in lower concentrations during word boiling. The 3-DG concentration showed a linear increase during word boiling at all variations. The linearity combined its formation in the Maillard reaction or caramelization and the occurring evaporation effect. The formation of 3-DG indicated that the Maillard reaction was already at its advanced phase during word boiling [8]. The higher proteolytic malt modification level showed a strong accelerating effect on the initial and final concentrations of the dicarbonyl. Presumably, the enhanced content of amino acids promoted its formation through the Maillard reaction. Additionally, 3-DG precursors, such as Amadori products, are increased by a higher malt modification level in malt [14] and can lead to higher 3-DG concentrations during word boiling. The 3-DG formation rate was also increased by higher malt modification levels (B1P1: 0.09 mg/(min*L), B1P2: 0.10 mg/(min*L), B1P3: 0.17 mg/(min*L), B2P1: 0.10 mg/(min*L), B2P2: 0.12 mg/(min*L), and B2P3: 0.17 mg/(min*L)). This effect indicates that a higher proteolytic malt modification level forms an increased aging potential for the final beer due to 3-DG during word boiling. Regarding the calculatable influence (correlation coefficient) of the malt modification level, the initial 3-DG concentration (R\({}^{2}\) = 0.95), final 3-DG concentration (R\({}^{2}\) = 0.97), and 3-DG formation rate (R\({}^{2}\) = 0.81) showed good correlations with the soluble nitrogen content of the malts used (Table 1). Therefore, it could be concluded that the \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Amino Acid** & **Correlation Coefficient** & **Amino Acid** & **Correlation Coefficient** \\ \hline Valine & 0.97 & Asparagine & 0.64 \\ Isoleucine & 0.90 & Methionine & 0.52 \\ Phenylalanine & 0.87 & Glutamic acid & 0.46 \\ Leucine & 0.82 & Proline & 0.42 \\ Threonine & 0.78 & Tyrosine & 0.40 \\ Lysine & 0.74 & Glycine & 0.29 \\ Typtophan & 0.69 & Aspartic acid & 0.25 \\ Alanine & 0.65 & Glutamine & 0.05 \\ Arginine & 0.64 & Serine & 0.01 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Correlation coefficients of amino acid concentration in the final word and soluble nitrogen content. proteolytic malt modification level strongly influenced the Maillard and caramelization reactivity toward 3-DG formation during word boiling in this study. The second observed dicarbonyl 3-DGal was linearly formed during word boiling, much like 3-DG. The occurring formation was a combined effect of the 3-DG interconversion and evaporation during boiling. The 3-DGal formation indicated that 3-DG formation and degradation took place simultaneously during word boiling. The proteolytic P3 level showed the highest initial and final concentrations of 3-DGal. P1 and P2 showed no significant difference in their 3-DGal contents. It could be assumed that a certain level of 3-DG reactivity was needed to promote its interconversion to 3-DGal. The formation rates showed no differences and were calculated to an average of 0.04 mg/(min*L). The 3-DG formation was stronger than the 3-DGal formation, and the effect confirmed the importance of 3-DG as the major dicarbonyl during word boiling.