## 3 Results and Discussion
### Odor Activity Value Analysis  
Figure 4 classifies the VFCs detected in bamboo shoots and bamboo shoots soaking solution according to [24], including citrus, fruity, floral, vanilla and others. To have better control of the quality of bamboo shoots and enhance the aroma appropriately, it is necessary to study the composition and dynamics of aroma active volatiles in bamboo shoots. The determination of food flavor is complicated, because not every ingredient has the same contribution to the overall feeling and some interactions may combine flavor compounds, so the introduction of the ROAV is particularly necessary. With (_E_)-2-nonenal having the maximum ROAV control (ROAVmax), other key VFCs in BS1 were (_E,E_)-2,4-nonadienal, (_E,E_)-2,6-nonadienal, nonanal, 1-hexanol, 1-octen-3-ol, hexanal, methyl salicate and 2-hydroxy-benzoic acid, pentyl ester (ROAV \(\geq\) 1). Among them, (_E_)-2-nonenal and 1-hexanol are common and important flavor components in vegetables and fruits, and are precursors of linear ester compounds, which are common in apricots and wheat [25; 26]. [PERSON] et al. [27] have shown that 1-hexanol is the most abundant alcohol compound in fresh bamboo shoots. (_E_)-2-nonenal was proved to be 13-(S)-hydroperoxide formed by \(\gamma\)-linolenic acid enzymatically during the division of plant tissues, and it has been detected in _Phylostalchys pubescens_ and speculated to have bamboo fragrance [28]. (_E,E_)-2,4-nonadienal, nonanal, methyl salicate has the smell of citrus fat, [PERSON] had reported that (_E,E_)-2,4-nonadienal and nonanal exhibited the bamboo-like odor and plays an important role in the aroma of fresh bamboo shoots [28]. Methyl salicate is the highest content of ester compounds in spring bamboo shoots, and when the odor is emitted, it can prevent insects during the growth of bamboo shoots [4]. 1-octen-3-ol, hexanal, 2-hydroxy-benzoic acid, pentyl ester have a grassy smell. Hexanal naturally exists in many fruits and vegetables, which process volatile substances that contribute the most to the aroma of the BS1 [29]. The presence of 1-dodecanol, decanal and (_E_)-2-octenal increases the citrus oil aroma alcohol and aldehyde compounds after boiling bamboo shoots, while the content of olefinic compounds in the fruit aroma decreases. Probably, it is during the heat treatment process that the aldehydes react with oxygen to form alcohols. Similarly, after steam sterilization heat treatment, six key VFCs in BS5 including dibenzofuran, nonanal, (_E_)-2-nonenal, octanal, 1-octen-3-ol and decanal (ROAV \(\geq\) 1) were found. Compared with BS4, methyl salicate, 2-hydroxy-benzoic acid, phenylmethyl ester, 3-methyl-1-butanol and 6-methyl-5-hepten-2-one with citrus oil aroma in BS5 were not detected, but 1-octen-3-ol with grassy fragrance and (_E_)-2-nonenal and octanal with fruity fragrance increased. Figure 3: Diagram of classification of volatile flavor substances. (**A**) was volatile flavor substance contents of bamboo shoots; (**B**) was volatile flavor substance contents of bamboo shoots soaking solution. Others contain hydrocarbons, ethers and phenol, etc. Among the three major types of flavor compounds produced by the Maillard reaction, furan compounds are oxygen-containing compounds, the other two are nitrogen-containing compounds such as pyrazine, pyrrole and oxazoline, and sulfur compounds such as thiazole and furan mercaptan. All of them impart caramel, meat, cocoa and other aromas in the Maillard reaction [30]. In the process of steam sterilization of bamboo shoots, heat treatment for a long time leads to the interaction of protein and carbohydrates, and Maillard reaction occurs to form characteristic flavor. During the heat treatment of bamboo shoots, a large number of ester compounds are reduced to alcohols and aldehydes, which is consistent with the boiling process. Dibenzofuran is the biggest contributor to the flavor of BS5, and the sweet aroma of caramel and honey are the representatives of furan compounds.