A systematic review of fermented Saccharina japonica: Fermentation conditions, metabolites, potential health benefits and mechanisms

Background: Saccharina japonica (SJ) is a brown seaweed widely consumed as food in Asian countries, and its use has been rapidly increasing in European and American countries as a food and for biocompound extraction purposes. Considering the difficulty of biocompound release under the current processing techniques of drying and salting, the fermentation process of SJ has been studied in recent years.Scope and approach: This review presents current research describing fermented SJ (FSJ) processes, including the manufacturing process, chemical compound changes and flavor properties of FSJ. The health benefits and mechanisms of FSJ are evaluated, and the limitations and potential applications of FSJ are explored.Key findings and conclusions: Fermentation of SJ can be achieved by bacteria (Lactobacillus spp. and Bacillus subtilis) and fungi (Aspergillus oryzae, Monascus spp., and Saccharomyces cerevisiae), and the core metabolites are degraded polysaccharides, phenolic compounds, flavonoids, gamma-aminobutyric acid and other amino acids. It is noteworthy that the I, Cd and Hg contents were reduced by fermentation while the flavor properties were enhanced. Recent studies of FSJ suggested that the fermentation process of SJ could loosen algal tissues and result in the release of fermentable compounds, which consequently promote antioxidant activity, improve cognitive impairment, as well as support hepatoprotective, anti-obesity and anti-inflammatory activities. Although the industrial applications of FSJ remain underdeveloped, the improvements in nutrition, flavor, safety and bioactive properties identified in this review demonstrate the bright future for FSJ applications in the food industry.