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PLÎNGĂU, Ecaterina; RUDI, Ludmila; MISCU, Vera; DENCICOV-CRISTEA, Lidia. Application of microwave pretreatment technique of aplanospores of haematococcus pluvialis for astaxanthin recovering. In: Microbial Biotechnology. Ediția 4, 11-12 octombrie 2018, Chișinău. Chișinău, Republica Moldova: Institutul de Microbiologie şi Biotehnologie, 2018, p. 91. ISBN 978-9975-3178-8-7.
Ediția 4, 2018
Conferința "Microbial Biotechnology" |
Chișinău, Moldova, 11-12 octombrie 2018
In recent years, techniques of extracting carotenoids from algal biomass have been developed under intense research efforts, because carotenoids have many applications as agents for strengthening health and exhibit antioxidant properties. Although, synthetic carotenoids are relatively cheap and easy to prepare, natural ones are more stable and contain biologically active isomers. Application of microwaves in extracting biocompounds from vegetable raw material is considered to be less harmful to the environment and humans. Microwave-assisted extraction of carotenoids is little investigated. Main parameters in microwave-assisted extraction are microwave power, reaction medium, duration of action, temperature and type of microalgal cell wall. There were carried out researches for application of microwave drying technique as a method of cyst cell-wall pretreatment of Haematococcus pluvialis with later recovering of astaxanthin. In order to monitor the efficiency of microwave pretreatment technique, it was applied astaxanthin extractability, which is used in the analysis of the effectiveness of extraction methods. Extractability value consists of the ratio of “free astaxanthin”, which is amount of astaxanthin from native biomass of Haematococcus pluvialis by its shaking for 1 hour with acetone and “total astaxanthin”, which means its extraction in acetone under the same conditions, but treated in advance for destroying the cell wall. There were prepared samples of Haematococcus pluvialis biomass, aplanospores, with 10 mg in Petri dishes with a diameter of 60 mm. There were selected two variable parameters: microwave power and exposure to their action. Extraction of astaxanthin has been carried out with the use of ethanol as a solvent, in order to preserve the extracts or its later use in preparing oily product. By applying the microwave regime of 120 sec at 180W, astaxanthin extractability in acetone was 28% and 14% in alcohol. Under conditions of 20 sec at 180W microwave power, astaxanthin extraction has been possible only with using acetone and extractability was very low, only 11%. Application of 540W microwave power established a dependency between the time of the effects of electromagnetic waves and astaxanthin extractability. Thus, after 20 sec, astaxanthin extractability in ethyl alcohol was 32% and 38% in acetone. Doubling the time of exposure has not enhanced astaxanthin extractability, which was 38% for extracting in ethanol and 46% in acetone. Extraction of 50% astaxanthin from Haematococcus pluvialis biomass was set at wave action for 60 sec. Application of microwave regime of 540W for 120 sec favored astaxanthin extractability with 84% in ethanol and 82% in acetone. Therefore, the effect of microwave drying can be also applied for damaging the cell wall of red cysts of Haematococcus pluvialis. Microwave pretreatment technique (540W, 120 sec) of native biomass of Haematococcus pluvialis can be applied as pretreatment stage of robust cysts for astaxanthin recovering.