Selective Conversion of Hemicellulose in Macroalgae Enteromorpha prolifera to Rhamnose

Abstract

Direct hydrothermal conversion (HC) of macroalgae Enteromorpha prolifera was conducted over the temperature range of 140–240 °C. At 160 °C, monosaccharides and small molecular acids began to generate. A high yield (18.8%) of monosaccharides was obtained at 180 °C, whereas 29.6% of small molecular organic acids was attained at 200 °C. Formic acid (FA) was then employed as a catalyst, which could selectively catalyze the conversion of hemicellulose at low temperature (94.1%, 140 °C). Rhamnose (45.2%) based on the mass of carbohydrates in E. prolifera was produced by the catalysis of 0.7 mL of FA (160 °C, 60 min, 1 g of biomass loading). A low ratio of biomass amount to water was beneficial to the solution of water-soluble components of hemicellulose in E. prolifera to get high yields to monosaccharides. HC showed promise to be an applicable and efficient method in the treatment of E. prolifera with high conversion of carbohydrates.

Extraction Techniques, Biological Activities and Health Benefits of Marine Algae Enteromorpha prolifera Polysaccharide

“…A study by Chi et al (25) showed that the acid extraction method produced a better yield and higher molecular weight E. prolifera polysaccharide with intense iron chelating capacity compared with their respective water and alkali methods. Apart from extraction techniques, extraction conditions, such as time, temperature, pH, the ratio of biomass amount to solvent, and the type of elution solvent could affect the chemical composition and function of polysaccharides (19,29). For example, Yuan and his colleagues evaluated the effects of extraction temperature on the monosaccharide composition of E. prolifera polysaccharides (30).…”

“…Although E. prolifera tide put a threat to the marine ecosystem, it has been used as traditional medicine and functional food (13)(14)(15)(16)(17). Recently, the nutritional composition and safety of E. prolifera have been investigated, and has been found that E. prolifera contains essential nutrients such as carbohydrate (43-51%), protein (26-33%), fat (0.2-0.8%), total amino acid (20.26-23.32%), ash (13-14%) and iron (1.1-3.4mg/g) (18), of which carbohydrate is the most abundant component (19). Furthermore, health risk assessment studies showed that the level of major micropollutants such as heavy metals, pesticides, and polycyclic aromatic hydrocarbon in E. prolifera is below the limit to cause health hazards and thus can be regarded as safe for human consumption (18).…”

Regulatory Effects Mediated by Enteromorpha prolifera Polysaccharide and Its Zn(II) Complex on Hypoglycemic Activity in High-Sugar High-Fat Diet-Fed Mice

“…E. prolifera is one kind of green algae and the dominant species of green tides in the Yellow Sea of China [4]; its main component is polysaccharide [5]. Previous studies have shown that the polysaccharide has many biological activities, such as hypoglycemia [6][7][8], hypolipidemic [9,10] and immunomodulatory activity [11,12], antioxidant [13,14], gut microbiota modulation [15], and so on.…”

Catalytic Thermochemical Conversion of Algae and Upgrading of Algal Oil for the Production of High-Grade Liquid Fuel: A Review

“…Hydrolysis of algal polysaccharides is usually carried out in the presence of acidic catalyst, such as Brønsted acid, metal chlorides, and heterogeneous catalysts such as HZSM-5 and Sn-Beta. Over these catalysts, highly selective chemicals such as rhamnose, 5-HMF, levulinic acid or lactic acid are formed [150][151][152][153][154]. 5The research of algal biorefinery should also focus on improvement of the process, in order to realize the commercialization and industrialization.…”