## 1 Introduction  
Flavor is one of the key elements influencing the preferences of consumers [1]. Currently, many different types of traditional fermented foods are consumed all over the world, especially in Asia and Europe. Examples include _Chouguiyu_[2, 3] and stinky tofu [4] in China, _Surstronming_ in Sweden [5], and _Kiviak_ in Canada. However, these fermented foods have a shared feature; they give off an unpleasant odor that is unbearable to some people. This limits some people from the delicious pursuit of fermented food. Understanding the fermentation-stinky compounds better is necessary in order to discern how to lessen the stink without altering the characteristics of the whole flavor. The production of these fermentation-stinky compounds is primarily determined by the following two factors. (1) Under the metabolic reactions of microorganisms, foods undergo a complex set of related reactions during fermentation, involving lipid oxidation, hydrolysis of carbohydrates, proteolysis, etc., which produce low molecular weight stinky compounds [2, 6]. These fermentation-stinky compounds include nitrogen and sulfur compounds produced by amino acid hydrolysis and short-chain fatty acids (SCFAs) produced by lipid oxidation [2, 7]. For example, indole, isovaleric acid, dimethyl disulfide, and dibutyl phthalate are typical stinky compounds found in fermented mandarin fish [2, 3, 8]. Obviously, the majority of previous studies have focused on the formation of the fermentation flavor. (2) The release of these key compounds could affect the flavor of fermented foods. Complex matrixes (proteins, lipids, carbohydrates, etc.) interact with flavor compounds in fermented foods, particularly myofibrillar proteins (MPs). Generally, MPs account for more than 50% of the total protein content in meats, especially over 60% in fish muscle [9]. MPs play an important role in forming meat flavors, since they can bind with the flavor molecules by interaction, such as aldehydes or ketones [10; 11; 12], and affect the sensory and consumption quality of foods. Flavor molecules can bind to MPs by hydrophobic bonds, ionic bonds, van der Waals forces, covalent bonds, etc. due to differences in their functional groups and binding sites [13]. Moreover, the interaction between flavor molecules and MPs has the potential to alter the secondary structure of MPs. [PERSON] et al. [14] found that the \(\alpha\)-helix content gradually decreased with increasing concentrations of ketones. Furthermore, MPs can be utilized as flavor carriers to deliver and preserve the flavors of food components. This property is especially valuable in the creation and formulation of unique food flavors [15]. During food processing, many environmental conditions could affect the binding capacity, such as microwaves, pH, high pressure, oxidation environment, etc. [16]. The reversible binding effect can help minimize flavor loss during food processing and release the flavor components upon consumption, whereas the nonreversible interaction plays a crucial role in removing undesirable off-flavors from foods [17]. Understanding the release mechanism of the fermentation-stinky compounds is significant for improving the flavor of fermented foods. Multi-spectroscopy methods are powerful tools to clarify the changes in the structures of MPs. However, the interactions between fermentation-stinky compounds and MPs have not been fully explored. The main aims of the current study were to use a typical example of fermented fish to explore the release mechanism of fermentation-stinky compounds through the interactions between them and MPs, including (i) clarifying the binding performance and forces between the typical fermentation-stinky compounds and mandarin fish MPs using GC-MS and various bond-disrupting agents, (ii) depicting the effects of the interactions on the structure of MPs using circular dichroism spectroscopy, fluorescence quenching, and synchronous fluorescence, and (iii) revealing their binding sites by molecular docking.