# The Volatile Compounds Change during Fermentation of _Saccharina japonica_ Seedling
## 1 Introduction  
_Saccharina japonica_ ([PERSON]) [PERSON], [PERSON], [PERSON], also known as kelp and kombu, is a type of brown algae. _S. japonica_ is a marine product that is rich in nutrients and contains a variety of functional substances, including protein, amino acids, polysaccharides, minerals, and vitamins [1, 2]. _S. japonica_ is particularly rich in iodine, and consuming this marine product could help prevent thyroid diseases [3, 4]. In addition, _S. japonica_ exhibits a variety of functional properties, including antioxidant, anti-inflammatory, hypoglycemic, and antihypertensive effects [5, 6, 7, 8, 9]. Therefore, _S. japonica_ represents an important marine alga with the potential to provide health benefits to humans.  
The aroma quality of food has a noticeable effect on the consumption preference of consumers. However, _S. japonica_ products always have a strong fishy odor, which becomes the main barrier to human consumption [10, 11]. In order to increase the consumption of _S. japonica_, it is essential to eliminate its fishy odor [12]. The methods of deodorization mainly include physical, chemical, and biological methods [13]. Compared with physical and chemical methods, biological methods are attracting more and more attention from researchers and manufacturers, due to their safety, environmental friendliness, and ease of implementation. [PERSON] et al. [14] proposed fermenting _S. japonica_ extract with _Aspergillus oryzae_ to reduce its off-flavor. Although researchers have developed effective deodorization processes to remove the off-flavor from extracts and blends of _S. japonica_, few studies have been conducted to eliminate the fishy malodor from the foods made from _S. japonica_[14].  
Recently, fermentation has been proposed to eliminate the off-flavors of _S. japonica_ and improve the quality of _S. japonica_ food products [15]. [PERSON] et al. [16] demonstrated that theferentation of _S. japonica_ resulted in the reduction of fishy odorants, including hexanal and nonanal. [PERSON] et al. [17] demonstrated that fermentation with _Saccharomyces cerevisiae_ could reduce 91% of unsaturated aldehydes from _S. japonica_. In addition, _Lactobacillus plantarum_ and _Acetobacter pasteurianus_ have also been used to ferment foods with desirable aromas [18; 19]. In comparison, fermentation with _Saccharomyces cerevisiae_ not only reduces fishy odors but also enhances fruit and floral aromas [17]. Therefore, researchers prefer to use _S. cerevisiae_ to enhance the flavor of plant, seaweed, and fish products [20; 21], which could be a practical method to enhance the flavor quality of food products made from _S. japonica_.  
The _S. japonica_ seedling is the _S. japonica_ harvested at the early growth stage. It has higher nutritional and bioactivity values [22], making it increasingly important in food processing in recent years. However, _S. japonica_ seedlings have a fishy odor, which limits consumer acceptance. Therefore, this study aimed to investigate the effectiveness of fermentation with _Saccharomyces cerevisiae_ in removing the fishy odor from _S. japonica_ seedlings. This study contributes to the understanding of the fishy odor of the novel food material _S. japonica_ seedlings and provides a reference for enhancing the fruity, sweet, green, and floral notes of food products derived from _S. japonica_ seedlings.