Chemical composition and nutritional properties of freshwater and marine microalgal biomass cultured in photobioreactors

• Published in: Journal of applied phycology Vol. 27; no. 3; pp. 1109 - 1119
• Main Authors: Tibbetts, Sean M, Milley, Joyce E, Lall, Santosh P
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer-Verlag 01.06.2015; Springer Netherlands; Springer Nature B.V
• Subjects: Amino acids; Aquaculture; arginine; biomass; Biomedical and Life Sciences; bioreactors; Botryococcus; calcium; Chemical composition; Composition; crude protein; digestible protein; Ecology; elemental composition; energy; essential amino acids; Ettlia oleoabundans; Feeds; freshwater; Freshwater & Marine Ecology; gallic acid; In vitro protein digestibility; iron; leucine; Life Sciences; lysine; Magnesium; Manganese; Microalgae; Nannochloropsis; nutrient content; Phaeodactylum tricornutum; Phenols; Plant Physiology; plant proteins; Plant Sciences; Porphyridium; potassium; Selenium; sodium; Sulfur; Tetraselmis chuii; Total phenolic content; Trace elements; tryptophan; zinc; Total phenolic content; Amino acids; Composition; Microalgae; In vitro protein digestibility
• ISSN: 0921-8971; 1573-5176
• DOI: 10.1007/s10811-014-0428-x

Proximate, amino acid and elemental composition, total phenolic content (TPC), and in vitro protein digestibility (IVPD) of microalgal biomass were determined. Microalgae contained low to moderate ash (5–17 %), moderate to high carbohydrate (18–46 %), crude protein (18–46 %), high crude lipid (12–48 %), and energy (19–27 MJ kg⁻¹). Characteristic of microalgae, non-essential amino acids (AAs), aspartic and glutamic acids, were predominant (20–30 % of protein; 8–12 % of dry weight). Microalgae had favorable essential AA profiles with high essential amino acid (EAA) indices (0.9–1.2). Expressed as g EAA 100 g protein⁻¹, Porphyridium aerugineum was rich in leucine (11.9), lysine (8.0), arginine (8.6), and tryptophan (3.3); Nannochloropsis granulata (A) in leucine (11.0), lysine (8.5), and tryptophan (2.8); Tetraselmis chuii and Botryococcus braunii in arginine (9.4 and 20.5, respectively); and Phaeodactylum tricornutum in lysine (6.4) and tryptophan (2.6). Mineral compositions (%) were calcium (0.1–3.0), magnesium (0.3–0.7), phosphorous (0.7–1.5), potassium (0.7–2.4), sodium (0.8–2.7), and sulfur (0.4–1.4), and trace element compositions (mg kg⁻¹) were copper (18–102), iron (1,395–11,101), manganese (45–454), selenium (0–0.5), and zinc (28–64). Microalgae contained low TPC (6–13 mg gallic acid equivalents (GAE) g⁻¹DW), except T. chuii (20 mg GAE g⁻¹DW). IVPD was high (>90 %) for B. braunii (A), P. aerugineum, and lipid-extracted N. granulata (B); mid-range (80–89 %) for P. tricornutum, N. granulata (A), B. braunii (B), Neochloris oleoabundans, T. chuii, and whole N. granulata (B); and lower (<80 %) for Acutodesmus dimorphus. Microalgal species P. tricornutum, B. braunii, N. granulata, and T. chuii had high protein (40–52 %), IVPD (82–97 %), and digestible protein (35–50 %), comparable to plant proteins used in animal feeds and aquaculture.