Pressurized liquid extraction yields microalgae extracts with significantly higher yields of nutrients and health-beneficial bioactive compounds than those obtained by other methods.
A recent study published in Food Chemistry (Zhou et al., 2022) tests this innovative technique on three microalgae and measures-in vitro-their functional anti-inflammatory, antioxidant, antibacterial and probiotic properties. (1)
The pressurized liquid extraction of three microalgae
The researchers selected the biomass of three microalgae:
– Spirulina cultivated in Spain (species Arthrospira platensis), Paracas strain, named after the Peruvian lake where it was originally isolated. This blue-green cyanobacterium, as noted, contains about 70 percent protein. Besides being rich in unsaturated fatty acids and pigments, such as linolenic acid and linoleic acid, carotenoids and chlorophylls,
– P. tricornutum
produced in four photobioreactors in Norway, with Novel Food authorization procedure in progress,
– Chlorella
grown in open ponds in Hainan Island (China), a champion of versatility.
The PLE-pressurized liquid extraction (PLE)-method adopted to extract nutrients and functional compounds has several advantages when compared with traditional methods (e.g., soaking, Soxhlet):
– Greatly reduces extraction time,
– does not require the use of expensive and/or toxic organic reagents (e.g., ether, chloroform, methanol, ethanol),
– improves biomass extraction efficiency, particularly for proteins, carbohydrates and phenols.
Higher concentrations of nutrients and functional compounds
The higher concentration of nutrients and functional compounds achieved by the innovative extraction method is marked. In comparison with the other methods, AWP increased the content of
- protein(P. tricornutum: 93.3 vs 68.6 mg/g; Chlorella: 30.8 vs 21.3 mg/g; Spirulina: 136.7 vs 120.8 mg/g),
- polyphenols(P. tricornutum: 4.6 vs 3.4 mg/g; Chlorella: 1.7 vs 1.3 mg/g) and
- carbohydrates(P. tricornutum: 39.0 vs 28.5 mg/g; Chlorella: 25.6 vs 20.4 mg/g).
The beneficial functions for health
In vitro tests on health-beneficial properties have shown that:
– antioxidant capacity is strongest with Spirulina extract, followed by P. tricornutum and Chlorella,
– The anti-inflammatory effect is greatest with P. tricornutum extract,
– antimicrobial action on the pathogenic bacterium Salmonella is significant with the PLE extracts of all three microalgae, as well as the non-PLE extracts of Chlorella and P. tricornutum. Less effective, unfortunately, on Listeria,
– probiotic activity, understood as growth of Lactobacillus casei BL23(L. casei) and Bifidobacterium lactis BB12(B. lactis) was increased by PLE on all three microalgae extracts.
In trials in vitro also showed that the intestinal microbiota is modulated by Spirulina and P. tricornutum extracts, with beneficial effects after gastrointestinal digestion.
Marta Strinati
Notes
(1) Jianjun Zhou, Min Wang, Christine Bäuerl, Erika Cortés-Macías, Joaquim Calvo-Lerma, Maria Carmen Collado, Francisco J. Barba. The impact of liquid-pressurized extracts of Spirulina, Chlorella and Phaedactylum tricornutum on in vitro antioxidant, antiinflammatory and bacterial growth effects and gut microbiota modulation. Food Chemistry, Volume 401, 2023, https://doi.org/10.1016/j.foodchem.2022.134083.
Professional journalist since January 1995, he has worked for newspapers (Il Messaggero, Paese Sera, La Stampa) and periodicals (NumeroUno, Il Salvagente). She is the author of journalistic surveys on food, she has published the book "Reading labels to know what we eat".
