Abstract
There is growing consumer demand for food products derived from microalgae, driven largely by the perceived health benefits associated with them. The functional and bioactive potential of proteins isolated from two microalgae—Spirulina sp. and Isochrysis galbana T-Iso—were determined. The results obtained show the potential of microalgal protein extracts for use in the beverage industry, based on solubility values and other functional characteristics, including water and oil holding capacities, foaming, emulsifying activities and stabilities, water activities, solubility and pH. The solubility of algal proteins was pH-dependent, and they were largely insoluble at pH values between 2 and 11. However, the proteins were increasingly soluble at a pH of 12, and they have potential use in formulating foods with higher viscosities or gels, where they could act as fillers to strengthen networks. Compared with whey and flaxseed proteins, the Spirulina sp. protein extract had a superior oil-holding capacity (OHC). The OHC is important in developing texture in food products such as meats. Overall, better foam stability was observed for both Spirulina sp. and Isochrysis sp. soluble protein extracts, compared with flaxseed protein at pH values from 2 to 10 over a period of 120 min. The foam capacity and stability increase the physical properties of foods. However, the emulsion activity and stability values for soluble algal protein extracts were less than the values observed for flaxseed and whey proteins. Algal proteins would not be suitable for use in creaming and food processing involving flocculation. In addition, algal protein extracts inhibited Angiotensin-converting enzyme-I (ACE-I) and renin, and they have potential for use in functional food ingredient applications to maintain heart health and also to act as meat substitutes.
Highlights
There are over 30,000 microalgae species; fewer than ten species are commercially produced [1,2], and only two species are recognized for sale within the European Union with European Food Safety Authority (EFSA) approval
Better foam stability was observed for both Spirulina sp. and Isochrysis sp. soluble protein extracts, compared with flaxseed protein at pH values from 2 to 10 over a period of 120 min
This study suggested that protein extracted from this alga could be suitable for use in the formulation of a wide variety of food products, including sausages, breads, cakes, soups and salads [9]
Summary
There are over 30,000 microalgae species; fewer than ten species are commercially produced [1,2], and only two species are recognized for sale within the European Union with European Food Safety Authority (EFSA) approval. Select microalgae contain protein levels based on a dry matter basis, similar to some plant and animal sources of protein. Several research groups have looked at extracting proteins from microalgae, including Spirulina sp. Safi et al determined the proportion of proteins released from the microalgae Porphyridium cruentus, Arthrospira platensis, Chlorella vulgaris, Nannochloropsis oculata and Haematococcus pluvialis, following both mechanical and chemical treatments with a highpressure disruptor and 2N NaOH [8]. What protein extraction method is considered the best method depends on the alga treated and the structure of the algal cell wall. Protein extracts from microalgae, including Dunaliella sp., at an industrial scale can produce more protein compared with terrestrial plant harvests (about 100 times greater yield)
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