## 3 Results and Discussion
### Effects of Domestic Cooking on Faba Leaf Flavonoid Metabolites Variations  
The only flavonoids detected in faba leaves were flavonol glycosides (Table 1), which is consistent with results reported by [PERSON] et al. [8] and [PERSON] et al. [24] Ten types of kaempferol glycoside and three types of quercetin glycoside were identified among the flavonol glycosides.  
The effect of domestic cooking on changes in the content of each flavonoid metabolite in faba leaves is shown in Table 2. For the content of each kaempferol glycoside in the faba leaves, there were no significant differences between the freeze-dried (control), microwaving, and steaming treatments. The roasting treatment specifically increased the contents of K-3-ara-7-rha (6.13 mg/g d.w.) and K-3-rha-gal (glu)-7-rha (1.21 mg/g d.w.), but had no effect on the other metabolites. The boiling treatment significantly reduced the content of the faba leaf kaempferol glycosides, particularly of K-3-ara-7-rha (2.83 mg/g d.w.), K-3-rha-7-rha + un (1.56 mg/g d.w.), and K-3-acetyl-rha-gal-7-rha (0.29 mg/g d.w.). Otherwise, the effects of the four domestic cooking methods on the contents of quercetin glycosides were significantly different from those of the kaempferol derivatives. Compared with fresh leaves, leaves cooked by microwaving and steaming both exhibited higher contents of  
\begin{table}
\begin{tabular}{c c c c c c} \hline
**Peak No.** & **Rt (min)** & **MW** & **MS** & **MS/MS** & **Identification** \\ \hline
1 & 10.87 & 432.5 & 431.5 & & K-3-O-rha \\
2 & 11.37 & 886.7 & 885.7 & 739, 449.7 & K-3-O-rha-g-7-O-rha-4\({}^{\prime}\)-rha \\
3 & 12.71 & 610.6 & 609.6 & 447.2, 301 & Q-3-O-rha-gcl \\
4 & 13.43 & 756.6 & 755.6 & 609, 447.3 & Q-3-O-rha-gal (gcl)-7-O-rha \\
5 & 13.87 & 726.5 & 725.5 & 579.3, 446.2 & Q-3-O-rha-area-7-O-rha \\
6 & 15.49 & 594.8 & 593.8 & 447.2, 285 & K-3-O-rha-gal-7-O-rha \\
7 & 15.83 & 740.8 & 739.8 & 593.3 & K-3-O-rha-gal (gcl)-7-O-rha \\
8 & 18.03 & 710.9 & 709.9 & 563.3 & K-3-O-rha-area-7-O-rha \\
9 & 19.25 & 564.6 & 563.6 & 417.2, 285.1 & K-3-O-ara-7-O-rha \\
10 & 20.15 & 782.8 & 781.8 & 635.4 & K-3-O-a-acy-rha-gal-7-O-rha \\
11 & 27.34 & 578.8 & 577.8 & 431.2, 285.1 & K-3-O-rha-7-O-rha \\
12 & 27.79 & 625.1 & 624.1 & 579.2 & K-G (Unknown) \\
13 & 30.06 & 636.8 & 635.8 & 431.1, 285.1 & K-3-O-acetyl-gal-7-O-rha \\ \hline \end{tabular}
\end{table}
Table 1: Flavonoids identified in faba leaves by LC-MS/MS.  
Q-3-rho-gal (glu)-7-rho and Q-3-rho-ara-7-rho; however, there were no significant variations in Q-3-rho-glu content, whichever treatment was used.  
Kaempfer glycosides are the main type of flavonoid compound in faba leaves [24,25]; however, the variations in the content of individual compounds with each cooking method were significantly different. Similar results have also been observed by [PERSON] et al. [26] who investigated the changes in the flavonoid contents of broccoli caused by three domestic cooking methods. Quercetin derivatives only formed a small proportion of flavonoids in faba leaves (Table 2); however, all of the cooked faba leaves exhibited a higher content of quercetin derivatives than the fresh leaves. These differences in the pattern of variation between kaempfer and quercetin glycosides might be explained by the variation in the thermal stability of the compounds caused either by the type of aglycone or the variation in the glycosides attached to the aglycone [27]. It has often been suggested that the changes in the content of individual polyphenols during domestic cooking are mainly affected by an increase in the efficiency of extracting the compounds, and by a reduction in the content of compounds caused by thermal degradation or water leaching [13,15].