# Headspace Volatile Evaluation of Carrot Samples--Comparison of GC/MS and AuNPs-hpDNA-Based E-Nose
## 3 Results and Discussion  
### Flavor Profile of Carrot Samples Using GC-MS/SPME  
In the first step, the GC-MS/SPME method was used to monitor the volatile compound (VOC) changes in carrot samples stored at different conditions. In Table 1, the volatile compounds varying significantly in relative amount (%) during the experimental phase are listed as a function of time and temperature of storage. In total, 18 volatile compounds were found and identified by means of the NIST library (over 80% of probability of identity); the majority of carrot volatiles are terpenoids. Considering the literature data on fresh carrots [19], the number of volatile compounds determined in this study on the samples is significantly lower; this can be attributed to the initial blanching step (this pretreatment is commonly used in industrial production to reduce the enzymatic degradation). [PERSON] et al. [20] observed a significant change of many volatiles of blanched carrot slices, in particular terpenoids (sabinene, \(\beta\)-pinene, \(\beta\)-myrcene, D-limonene, trans-caryophyllene, \(\alpha\)-humulene, \(\beta\)-bisabolene, and \(\alpha\)-farnesene), and a decrease by at least 50% within 60 s of blanching. The mostly represented volatile compounds were \(\alpha\)-pinene and \(\gamma\)-terpinolene, which were detected in all samples stored at the different temperatures, except for samples stored at 40 \({}^{\circ}\)C on the first day of analysis; butane-2,3-diol, followed by acetoin and lactamide, were formed only for storage at 25 \({}^{\circ}\)C from the 8 th day and during storage at 40 \({}^{\circ}\)C. The presence of acetoin and butane-2,3-diol was attributed to fermentation during the storage, producing degradation of samples. Octanal, determined in refrigerated samples, is a fatty acid-derived volatile and its presence in refrigerated carrot has already been reported by other authors [19]. Compounds, such as terpenoids and alcohols, were identified by other authors [21] as potential markers of carrot quality. A simple multivariate data treatment was performed using PCA to extract the most important information from the obtained data set. Figure 1 shows a samples (scores) and variables (loadings) plot corresponding to the first two components, which concentrate 57.01% of the total variance (PC1: 31.19% and PC2: 25.82%) of the dataset. \begin{table}
\begin{tabular}{c c c c c c c c c c c c c c c c c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Volatile Compounds**} & \multicolumn{11}{c}{**GC Area (\%)**} \\ \cline{2-13}  & \multicolumn{11}{c}{**Storage Time (days)**} & \multicolumn{11}{c}{**} \\ \cline{2-13}  & \multicolumn{11}{c}{**–18 \({}^{\circ}\)C**} & \multicolumn{11}{c}{**–4 \({}^{\circ}\)C**} & \multicolumn{11}{c}{**–4 \({}^{\circ}\)C**} & \multicolumn{11}{c}{**–25 \({}^{\circ}\)C**} & \multicolumn{11}{c}{**–4 \({}^{\circ}\)C**} & \multicolumn{11}{c}{**–4 \({}^{\circ}\)C**} \\ \cline{2-13}  & **1** & **4** & **8** & **12** & **19** & **1** & **4** & **8** & **12** & **19** & **26** & **1** & **4** & **8** & **12** & **19** & **26** & **1** & **4** & **8** & **12** & **19** & **26** & **1** & **4** & **8** & **12** \\ \hline \(\alpha\)-phellandrene & n.d & n.d & n.d & n.d & n.d & n.d & 1 & 1 & 1 & 1 & n.d & n.d ** **1** & n.d & n.d & 1 & n.d & 7 & 1 & n.d & n.d \\ \(\beta\)-phellandrene & 2 & 1 & 2 & 1 & 1 & 3 & 3 & 2 & 1 & 4 & 1 & n.d & 3 & 1 & 1 & 2 & n.d & n.d & n.d & n.d \\ terpinolone & n.d & n.d & 1 & 1 & 0 & 1 & 1 & 1 & n.d & n.d & n.d & n.d & 1 & n.d & n.d & n.d & n.d & n.d \\ \(\alpha\)-pinene & 14 & 9 & 12 & 12 & 10 & 14 & 12 & 14 & 14 & 18 & 8 & 12 & 7 & 12 & 11 & 15 & 2 & n.d & 10 & 15 & 5 \\ (\(\epsilon\))-\(\beta\)-pinene & 3 & 2 & 3 & 3 & 3 & 3 & 3 & 3 & 3 & 3 & 3 & 2 & 2 & 3 & 2 & 3 & 1 & n.dA bi-plot graph is an interesting tool to represent the changes in the headspace pattern during storage. The analytical data of the headspace composition of carrot samples stored at different temperatures is spatially distinct, and the effect of storage conditions can be clearly observed.