# Influence of Malted Chickpea on the Composition of Volatiles in Humans
## 2 Results and Discussion
As observed with many other compounds lipoxygenase-derived compounds, its highest concentrations were detected in 4D and 5D, while the lowest levels were found in 1D, 2D, and 3D. 3-Ethyl-2,5-dimethyl-pyrazine is characterized by a pleasant, nutty odor and has previously been identified in thermally treated chickpea products [55]. This pyrazine is typically formed through thermal amino acid generation, with 4D and 5D exhibiting the highest concentrations [56]. The lowest concentration was found in 2D. This suggests that chickpeas germinated for 96 h or 120 h contain the highest levels of free amino acids. However, it remains unclear whether this results from increased proteolytic activity or simply from the accumulation of amino acids due to extended germination. Further research is needed to confirm these findings, but producing hummus from chickpea malts germinated for 96 h or 120 h could enhance the 'nutty' aroma of the product, as this compound is perceptible at very low concentrations [20]. Nonanal, an aldehyde primarily formed via linoleic acid oxidation, exhibited the highest concentration in 5D, nearly six times greater than in 0D [57; 58]. Interestingly, nonanal was one of the few volatiles with significantly higher levels in 5D compared to 4D. This suggests that 5D may have either higher LOX activity or increased lipase activity, leading to a greater release of linoleic acid. Alternatively, the accumulation of free fatty acids in 5D might have facilitated higher nonanal formation during the drying process. However, to confirm these hypotheses, further studies on LOX and lipase activity in chickpeas would be necessary. Unlike nonanal, trans-2-nonenal, a key off-flavor compound in barley malts, did not exhibit drastic differences in concentration among the samples [7; 59]. Multiple formation pathways have been proposed for trans-2-nonenal, including fatty acid oxidation, Maillard reaction, Strecker degradation of amino acids, oxidation of higher alcohols, and secondary oxidation of long-chain aldehydes [7]. In the analyzed hummus samples, trans-2-nonenal was present at relatively low levels, suggesting that its formation in hummus may differ from the typical lipoxygenase-driven pathway seen in the formation of other aldehydes. However, as with other volatiles, 4D and 5D contained the highest amounts of this compound, while 0D exhibited a concentration of this aldehyde compared to 2D and 3D. Trans-2-nonenal was not detected in 1D. Decanal, another aldehyde, showed considerable variation among the samples. Its concentration in 5D was nearly ten times higher than in 0D, while in 4D, it was slightly over three times higher. Interestingly, 1D and 3D also exhibited higher decanal levels than 0D, whereas 2D contained less than 0D. These results indicate that the decanal concentration is highly influenced by the germination period. Although the most probable source of decanal in legume seeds is fatty acid oxidation, the precise mechanism remains unclear, making it difficult to fully explain the observed changes in its concentration in hummus from malted chickpeas [37; 60]. Undecanal was the only volatile compound, which was not present in the 0D but present in small amounts in all hummus samples produced from the malted chickpeas. This suggests that undecanal formation may primarily result from thermally induced lipid oxidation occurring in the malt during the drying [61]. Similarly, dodecanal, an aldehyde typically found in legumes in trace amounts, can originate from the oxidative degradation of palmitic acid [62]. However, the results of this study indicate that the process of malting does not significantly increase dodecanal levels in hummus. These findings demonstrate that using malted chickpeas in hummus production can alter its volatile profile, potentially influencing its aroma. The duration of chickpea germination could be manipulated to enhance or reduce the concentrations of specific aroma-active components in the final product.