## 2 Results and Discussion
### Volatile Organic Compounds
Previous studies showed that the analysis of fresh vegetables resulted in a high abundance of sulphur compounds, including isothiances derived from glucosionolates, which are responsible for a cabbage-like aroma [38; 39]. On the contrary, in this study, no isothiances were detected. Isothiocyanates are products of the enzymatic hydrolysis of glucosionolates; therefore, a lack of these compounds can be explained by the inactivation of myrosinase  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Volatile** & **RI\({}_{\text{Exp}}\)***** & **RI\({}_{\text{Lit}}\)****** & **BLP** & **C** & **B2.5** & **B5** & **Odour** \\  & & & &  
during the blanching step in BLP preparation. Moreover, isothi cyanates are high volatility and could possibly be evaporated during freeze drying. It should also be noted that analysis of isothi cyanates by SPME is challenging and possible only in high abundances. Various odour descriptors could be associated with compounds detected in BLP, with fruity and green being the most frequent. An important compound responsible for sulphur aroma is dimethyl sulphide. Although its abundance was low in BLP and did not differ between pastas B2.5 and 5, this compound was previously reported to be one of the key odorants in Brassica vegetables [41]. Importantly, the odour threshold of dimethyl sulphide is very low and was estimated as 0.0008-0.03 and 0.0003-0.16 mg kg\({}^{-1}\) in water and air, respectively [42]. Low odour thresholds indicate odours are detectable at extremely low concentrations--very often below the limit of detection [41]. Therefore, despite its low abundance, it can be assumed that this compound was responsible for the cabbage-like aroma detected by the sensory panel. On contrast, the odour thresholds in water for the most abundant compounds in BLP were estimated as 0.15, 0.40, 0.05-8.2 and 0.72 for (_E,E_)-3,5-ocatdeni-2-one, 1-penten-3-ol, 6-methyl-5-hepten-2-one and (_Z_)-2-penten-1-ol, respectively. Semolina and pasta are usually not considered for their aromatic properties. Nevertheless, a total of 29 VOCs were identified in cooked C pasta, and the most frequently associated odours were citrus and fatty. Aldehydes and alcohols were the major chemical groups present, which is in agreement with results reported by [PERSON] et al. [35], who investigated the VOCs of cooked pasta. In that research, 29 VOCs were identified, but only 12 were common to those identified in the present study, which highlights the existing differences between semolina and olive oil used to produce pasta. However, in both studies, hexanal was the most abundant aldehyde in cooked pasta samples. The presence of hexanal, which has been associated with oxidation of unsaturated fatty acids [35], can result from the olive oil added to pasta formulations. Oxidation of fatty acids is also the source of other aldehydes, ketones and alcohols detected in this study, which suggests that these compounds were formed during thermal processing of olive oil and pasta [43]. An interesting phenomenon was observed with respect to hexanal when all the pasta formulations were compared. Although BLP was found to be a rich source of hexanal itself, the level of this compound decreased with increased BLP percentage. This can be explained by the presence of other compounds in B2.5 and B5 formulations, which contributed to a richer headspace. It should be noted that SPME is a competitive method with an observed problem of the replacement of polar compounds with non-polar VOCs, which are highly abundant in food matrices with saturation effects [44]. Therefore, the observed difference in the level of hexanal in this study does not necessarily mean that its concentration decreased but that it could be extracted with lower efficiency due to the presence of other compounds. 2-pentylfuran exhibits a medium-strength fruity, green, earthly, beany, vegetable-like odours [45], and it has been reported to be frequently present in samples of cooked pasta [35].