Stepwise extraction of high-value chemicals from Arthrospira (Spirulina) and an economic feasibility study.

Arthrospira (Spirulina) consists of diverse high-value chemicals, such as phycocyanin, lipids/total fatty acids (TFA), and polysaccharides, which have been used for food, cosmetic and pharmacological applications. This study compared various stepwise extraction processes for these high-value chemicals. Considering the yield and properties of extracts, the most suitable extraction order was phycocyanin, lipid/TFA and polysaccharides. The yield of the main product (food-grade phycocyanin) was 8.66% of the biomass dry weight, whereas the yields of the subsequent lipid/TFA and polysaccharide coproducts were 3.55% and 0.72%, respectively. The economic analysis showed that producing phycocyanin alone was economically feasible, but producing coproducts (lipid/TFA and polysaccharides) was not. The production cost of phycocyanin was US$ 249.70 kg-1, which is an encouraging figure for large-scale production. Moreover, the phycocyanin content of Arthrospira materials utilized for extraction should not be lower than 15% of dry weight to ensure positive the net present value (NPV) of investment.

Polysaccharide extraction from Spirulina sp. and its antioxidant capacity.

To optimize polysaccharide extraction from Spirulina sp., the effect of solid-to-liquid ratio, extraction temperature and time were investigated using Box-Behnken experimental design and response surface methodology. The results showed that extraction temperature and solid-to-liquid ratio had a significant impact on the yield of polysaccharides. A polysaccharides yield of around 8.3% dry weight was obtained under the following optimized conditions: solid-to-liquid ratio of 1:45, temperature of 90°C, and time of 120 min. The polysaccharide extracts contained rhamnose, which accounted for 53% of the total sugars, with a phenolic content of 45 mg GAE/g sample.

Separation and purification of phycocyanin from Spirulina sp. using a membrane process.

The highest purity ratio of phycocyanin extract was obtained when fresh biomass was used as raw material. The crude extract was purified by membrane process using microfiltration and ultrafiltration. Membrane of pore sizes 5 µm, at feed flow rate of 150 mL min(-1), permeate flux of 58.5 L h(-1)m(-2) was selected for coarse filtration and membrane with pore size 0.8/0.2 µm at the flow rate of 100 mL min(-1), permeate flux of 336 L h(-1)m(-2) was selected for fine filtration, giving phycocyanin recovery of 88.6% and 82.9%, respectively. For ultrafiltration, membrane with MWCO at 50 kDa, 69 kPa and 75 mL min(-1) of flow rate with a mean permeate flux 26.8 L h(-1)m(-2) and a retention rate of 99% was found to be optimal. Under these filtration conditions, food grade phycocyanin with the purity around 1.0 containing c-phycocyanin as the major component was obtained.

The effect of pH on the foam fractionation of beta-glucosidase and cellulase.

The surface tension-pH profile of beta-glucosidase was established to determine its relationship to the corresponding profile of cellulase and to the foam fractionation of that cellulase. The goal of this work was to determine the optimal foaming points for both cellulase and cellobiase. This data may prove useful in the separation of certain components of cellulase, since the non-foaming hydrophilic beta-glucosidase does not foam as well as the hydrophobic components of cellulase at low concentrations. A key finding from these experiments was that there are two local minima in the surface tension-pH trajectory for Trichoderma reesei cellulase, as contrasted to the usual single minimum. The lower of these minimum points corresponds to the cellulase isoelectric point. The double minimum surface tension-pH profile was also observed for cellobiase alone. The optimal foaming pH for cellobiase alone was determined to be around 10.5, while for cellulase it was between 6 and 9.

Air-water interfacial protein model for egg albumin and cellulase

Egg albumin and cellulase solutions were used to study the surface protein concentration at an air-water interfaces. It was found that the surface tensions of egg albumin and cellulase solutions were a function of the bulk solution pH and concentration. Both surface tensions of egg albumin and cellulase decrease significantly and linearly when the bulk protein concentration increases. Two lines were employed to fit the surface tensions vs. protein concentrations. The intersection of these two lines could be interpreted as the protein monolayer formed entire the interface. Below the monolayer regime, the interfacial protein concentrantion can be estimated by using the Gibbs' isotherm...