A new study, due to be published in the journal Food Chemistry, has revealed interesting findings on the use of novel solvents for the extraction of astaxanthin from microalga.
An aspect of this study that will have a particular impact on the nutraceuticals industry is that the ingredients within these solvents were entirely GRAS (generally recognised as safe) and edible ingredients.
The three novel DESs used for this study were mixtures based on oleic acid and terpenes
Three novel hydrophobic deep eutectic solvents, known as DESs, were used in the experiment. Eutectic in this instance means a homogeneous mixture of substances that melts or solidifies at a single temperature that is lower than the melting point of any of the constituents.
The three novel DESs used for this study were mixtures based on oleic acid and terpenes (thymol, dl-menthol, and geraniol).
In the experiment, the DESs were prepared, characterised, and used to extract astaxanthin from the microalga Haematococcus pluvialiswithout any pre-treatment of the cells. This means that the extraction process bypasses dewatering.
Pitacco et al.wrote up the findings in the article titled: 'Extraction of astaxanthin from Haematococcus pluvialis with hydrophobic deep eutectic solvents based on oleic acid'.
Extraction findings
The team discovered that these novel solvents gave astaxanthin recovery values of about 60% and 30% in 6 hours if applied on freeze-dried biomass or directly on algae culture, respectively.
The team not only looked at the astaxanthin recovery values, but also the carotenoid profile. In this investigation, they found that the profile was qualitatively identical to what was obtained by using traditional organic solvents, regardless of the DES used. Looking further into the carotenoid profile, it was discovered that the monoesters of astaxanthin with C18-fatty acids were the main compounds in all the carotenoid extracts.
The team not only looked at the astaxanthin recovery values, but also the carotenoid profile
One of the solvents; the thymol:oleic acid DES, otherwise known as TAO, could preserve astaxanthin content after prolonged oxidative stress (40% of the astaxanthin initially extracted was still present after 13.5 h of light exposure), thanks to the superior antioxidant properties of thymol. This demonstrated the excellent light stability of thymol when applied to astaxanthin, a charachteristic that could be a great importance to the nutraceuticals industry.
"The capacity of improving astaxanthin stability combined with the intrinsic safety and edibility of the DES components makes the formulation astaxanthin-TAO appealing for the food ingredients/additives industry," the study concluded.
The study is already online, but will be out in an issue of Food Chemistry in June 2022.
