A comparative study of different drying methods on some proximate composition and pigments of marine microalgae Isochrysis galbana

Drying due to shelf-life extend, easy transportation, and increase in lipids extraction and other bioactive compounds yield is a vital step in harvesting of algae biomass. In the present study, the effect of four drying methods, including sun drying, oven drying, freeze drying and spray drying methods on some nutritional composition and pigments of a marine microalga Isochrysis galbana was investigated. Proximate compositions (moisture, crude protein, crude lipid, ash) and pigments (chlorophylls and carotenoid) of the dried algae were determined. The results indicated that dietary protein and lipid were the most abundant components of the microalgae. No significant differences was found in the content of Chl-a among all dried samples (P>0.05). Freeze-dried samples had the highest content of total protein (62.33±0.56%), Chl-b (0.167±0.02µg/ml) and carotenoid (0. 153±0.01µg/ml) compared to others (P<0.05). However, spray-dried and sun-dried algae had the highest values of crude lipid (15.41±0.25%) and ash (17.51±0.14%), respectively (P<0.05). It can be concluded that some of the nutritional composition of microalga I. galbana is significantly affected by different drying methods and freeze drying can be suggested as an efficient method to maintain the algae with relatively lower negative effect on the nutritional composition in the dried condition.