## 4 Discussion  
Comparatively to our result, [PERSON] et al. [6] reported that aldehydes were the main class of VOC in the _A. mellifera_ beeswax ethanol extracts. [PERSON] et al. [20] had reported that aldehydes were an important source of honey flavor and provided the fragrant smell of flowers and fruits. In our study, terpen were the main VOCs present in AMC, followed by aldehydes. This is similar to the volatile characteristics of _A. mellifera_ beeswax, particularly linear aldehydes, such as octanal, nonanal, and decanal, because beeswax is recovered from the honeycomb [6]. terpen were also the main VOCs present in ACC, followed by esters. According to [PERSON] et al. [21], terpen are generally considered to be active constituents in natural products that exhibit antibacterial, antitumor, anti-wrinkle, antioxidative, anti-tussive, analgesia, and immune-regulatory effects. Figure 3: Discrimination of ACC and AMC. (**A**) PCA score plot of ACC and AMC; (**B**) OPLS-DA score plot of ACC and AMC; (**C**) VIP plot with VIP score > 1. The 12 potential markers in AMC are shown in Table 2. Linalool, \(\alpha\)-terpineol, limonene, decanal, benzaldehyde, octanal, and \(\alpha\)-cedrene isolated from propolisis [22; 23; 24; 25], another bee product closely related with honeycomb, showed antibacterial activity against a broad bacteria spectrum. Indeed, linalool and \(\alpha\)-terpineol showed remarkable antibacterial effects against periodontal and cariogenic bacteria [26]. Limonene showed strong antibacterial and antifungal effects on foodborne pathogens [27]. Benzaldehyde was found in higher concentrations in _A. mellifera_ honey [7]. It may be that some substances in the propolisis of a honeycomb would enter the honey. Linear aldehydes, such as octanal and decanal, also showed high contents in _A. mellifera_ beeswax, with octanal having the highest content [6]. Octanal isolated from other natural products showed antibacterial activity against _Escherichia coli_[28], _Staphylococcus aureus_[29], and Listeria monocytogenes [30]. Decanal isolated from other natural compounds showed better antibacterial activity to _E. coli, P. aeruginosa, and S. aureus_[22; 31]. Furfural was only detected in AMC samples, another difference between _A. cerana_ and _A. mellifera_ honey. However, heat treatment, which was essential in this experiment, will produce the Maillard reaction leading to the production of furfural, thus it was not considered a suitable marker of honeycombs from either _A. mellifera_ or _A. cerana_. Our results showed that _A. mellifera_ produces propolisis for the hive, which can enhance the antibacterial effect of the honeycomb. _A. cerana_ does not produce propolisis, the 8 potential markers in the ACC have been shown in Table 3, Figures 2 and 4. As reported, the content of 2-phenylethanol in ACC was significantly higher than that in AMC (\(p<0.05\)), over 15 times, in fact. 2-phenylethanol is a colorless liquid with a sweet rose-like floral fragrance. It occurs widely in nature and is found in a variety of essential oils, including rose, carnation, hyacinth, Aleppo pine. 2-phenylethanol is also one of the main VOCs in many kinds of monofloral honey [32; 33]. It is used as an additive in cigarettes and a preservative in soaps. As a mixed-type inhibitor, 2-phenylethanol had been shown to be inhibitory to Gram-negative [34] and Gram-positive [35] bacteria. [PERSON] et al. [36] reported that 2-phenylethanol could lead to reversible inhibition of the enzyme. [PERSON] and [PERSON] (1962a) reported that 2-phenylethanol blocked deoxyribonucle acid synthesis. Phenethyl acetate was only detected in ACC samples, and the content of phenethyl acetate in _A. cerana_ honey was significantly higher than that of _A. mellifera_ honey [7]. This compound was observed in most honey samples but at different concentrations, as the samples originated from different floral and geographical origins.