8TH ASIAN PACIFIC PHYCOLOGICAL FORUM Drying and extraction effects on three edible brown seaweeds for metabolomics Shahlizah Sahul Hamid 1,2 & Masataka Wakayama 1,2 & Tomoyoshi Soga 1,2 & Masaru Tomita 1,2 Received: 30 January 2018 /Revised and accepted: 27 August 2018 # Springer Nature B.V. 2018 Abstract Metabolomics is often used to comprehensively elucidate the metabolites in organisms like seaweed. Amino acids hydrolysed from proteins and certain targeted metabolites in seaweed have been investigated. However, water-soluble metabolites like free amino acids, organic acids, and sugars have seldom been comprehensively analysed. Metabolomics are valuable tools for these studies, but they require optimisation of pre-treatment methodology. Here, we evaluated various pre-treatment drying and extraction methods for brown seaweed metabolomics. Three edible brown seaweeds (Cladosiphon okamuranus [Mozuku], Saccharina japonica [Kombu], and Undaria pinnatifida [Wakame]) were used. Freeze-drying and oven-drying at both 40 and 80 °C were investigated. Methanol-water extracts with and without chloroform were compared. Metabolites were evaluated and quantified using liquid chromatography-mass spectrometry and capillary electrophoresis-mass spectrometry. The results showed that metab- olite profiling was determined mainly by seaweed species identity rather than pre-treatment method. Freeze-drying yielded higher metabolite concentrations than oven-drying at either 40 or 80 °C. The effects of extraction with and without chloroform on metabolite concentration varied with seaweed species. Keywords Phaeophyceae . Metabolomics . Brown seaweed . Drying methods . Extraction methods Introduction Seaweeds are classified into three categories based on their pigmentation: red (Rhodophyta), green (Chlorophyta), and brown (Phaeophyceae). They have various bioactive compo- nents such as proteins, minerals, vitamins, soluble dietary fi- bres, antioxidants, phytochemicals, and polyunsaturated fatty acids (Mohamed et al. 2012). Brown seaweeds constitute the largest of the three groups. Many brown algal species are edible (Gupta and Abu-Ghannam 2011; Wijesekara et al. 2011). Brown seaweeds like Cladosiphon okamuranus (Mozuku), Saccharina japonica (Kombu), and Undaria pinnatifida (Wakame) are commonly consumed in Japan and Korea. These seaweeds have been studied for their nutritional and pharmaceutical benefits. They contain the carotenoid fu- coxanthin and fucoidan which form part of a complex of poly- saccharides with anticancer properties (Ale and Meyer 2013; Murphy et al. 2014; Malyarenko et al. 2017). Previous studies have focused on the variations in the specific properties of these compounds within and between species and among sea- sons and geographic regions. They have been extracted with different chemicals (Harnedy and FitzGerald 2011). There are comparatively few studies on the effects of drying on seaweed compounds (Chan et al. 1997; Sappati et al. 2018; Stévant et al. 2018). Therefore, it is important to comprehensively evaluate the effects of various drying and extraction methods on seaweed metabolites. Seaweed drying decreases water activity, delays micro- bial growth, preserves desirable qualities, and reduces stor- age volume (Gupta et al. 2011). Wet seaweeds must be dried after being harvested for processing or else their Electronic supplementary material The online version of this article (https://doi.org/10.1007/s10811-018-1614-z) contains supplementary material, which is available to authorized users. * Masataka Wakayama wakayama@ttck.keio.ac.jp 1 Keio University, Institute for Advanced Biosciences, Tsuruoka, Yamagata 997-0052, Japan 2 Systems Biology Program, Graduate School of Media and Governance, Keio University, Fujisawa 252-8520, Japan Journal of Applied Phycology https://doi.org/10.1007/s10811-018-1614-z