3.2. Extraction of protein from lipid extracted algae (LEA)
…………………………………. The algal biomass after extraction of lipids was further utilized to recover protein and reduced sugars. Protein contents (% w/w) of lipid extracted algal biomass should theoretically increase in comparison to whole cell algae with their increased fraction to account for the removed mass of extracted lipids. However, the cell disruption and solvent application during lipid extraction also results in loss of some protein from the biomass reducing the total amount available for extraction. Hence it is important to investigate and compare the protein yields from such lipid extracted algae (LEA) to establish their applicability as a protein source. Fig. 2 presents the protein yields from such lipid extracted algae with different treatments. Similar yields from whole cell algae without lipid extraction were also determined, and are presented in Fig. 2. Sun dried samples of S. obliquus without any lipid extraction resulted in the protein yield of 41.13 ± 1.64%, while significantly higher (P < 0.05) yields of 51.42 ± 1.01% for oven dried and 51.19 ± 0.81% for freeze dried intact samples were achieved. Becker (2007) reported protein contents for S. obliquus to be around 50–56% which are similar to those obtained in the present study. LEA demonstrated sufficient protein recovery yields when compared to whole cell algae. Protein yields in LEA depended on the drying and cell disruption procedures for lipid extraction. The highest yield of 58.03 ± 1.29% was observed for oven dried samples assisted with ultrasonication while sun dried samples with autoclaving resulted in the lowest protein yield of 37.51 ± 1.57%.