en public specific orginal article <div style="text-align: justify;"><i><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">Spirulina platensis</span></span></span></i><span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times=""> is a microalgae type of <i>Cyanobacteria</i> in the form of filaments that resemble spirals (helix) ranging in size from 3-30 &micro;m. <i>Spirulina platensis</i> is rich in nutritional sources, one of which is protein. However, the utilization of protein is limited by the rigidity of the cell wall of spirulina. The study aimed to compare protein extraction using various methods. <b>Methods</b>: Extraction process was carried out to obtain <i>Spirulina platensis</i> protein concentrate. Three methods were evaluated: physical extraction using a conventional microwave, alkali-acid extraction, and a combination of the two, namely, microwave and alkali-acid extraction.</span></span></span> <span style="font-size:10.0pt"><span style="line-height:107%"><span new="" roman="" style="font-family:" times="">The protein extracts were dried and analyzed for its yield, protein content as well as its functional properties. <b>Results</b>: The spirulina powder contained 53.00&plusmn;1.13% protein (dry basis). The alkaline-acid extraction produced protein concentrate with the highest protein content (67.04&plusmn;3.85% dry basis), slightly higher than the combined methods (65.54&plusmn;1.92% dry basis) and significantly higher than the microwave extraction (55.44&plusmn;5.29% dry basis). However, the alkaline-acid extraction produced the lowest yield of protein concentrate powder (13.90&plusmn;0.28%) as compared to the other methods. The protein concentrate had a moisture content ranging from 7.68-10.81%, water holding capacity (WHC) ranging from 0.95-1.64 g H₂O/g protein and foaming capacity (FC) ranging from 102-168%. <b>Conclusions</b>: Alkaline-acid extraction produced dried protein concentrate of spirulina with the highest protein content, the highest WHC and the lowest FC. The extraction methods/techniques not only affect the protein yield and content, but also its functionality.</span></span></span></div> Proteins, Spirulina, Extraction and processing industry, Microwaves, Alkalies, Acids. 553 561 http://jnfs.ssu.ac.ir/browse.php?a_code=A-10-1326-1&slc_lang=en&sid=1 Siti Narsito Wulan wulan_thpub@ub.ac.id 0000-0002-9904-4972 Yes Department of Food Science and Biotechnology, Faculty of Agricultural Technology, Brawijaya University, 65145 Malang, East Java, Indonesia. Septian Dwi Nurrachman No Department of Food Science and Biotechnology, Faculty of Agricultural Technology, Brawijaya University, 65145 Malang, East Java, Indonesia Septian Dwi Raden Satrio Mukti Wibowo Jayadiningrat No Department of Food Science and Biotechnology, Faculty of Agricultural Technology, Brawijaya University, 65145 Malang, East Java, Indonesia Harijono Harijono 0000-0003-2013-7939 No Department of Food Science and Biotechnology, Faculty of Agricultural Technology, Brawijaya University, 65145 Malang, East Java, Indonesia