Characterization of Nutritional and Biological Properties of Microalgae Species from the <i>Tetradesmus</i> Genus for Their Use as Novel Dietary Ingredients

This study aimed to assess the nutritional and nutraceutical potential of three strains from the Tetradesmus genus (formerly known as Scenedesmus sp.): T. acutus, T. obliquus, and T. abundans. The protein content ranged from 33.62 to 42.5 g 100 g–1, primarily comprising alkali-soluble glutelin-like proteins. Tryptophan and sulfur amino acids were the limiting essential amino acids (EAA). The EAA scoring indicated that Tetradesmus proteins were inferior to conventional sources, like eggs and dairy, but superior to cereals, such as wheat. Lipid composition showed a higher ratio of unsaturated fatty acids, suggesting potential health benefits. Essential micronutrients, such as iron and zinc, were found in abundance compared to common food products. Lutein was the predominant carotenoid, making for 0.1–0.25% of the total biomass. In vitro simulated gastrointestinal digestion increased the bioaccessibility of phenolics in these microalgae. Their strong antioxidant activity and α-amylase inhibitory properties suggest their potential nutraceutical applications. Among the three strains, Tetradesmus acutus possessed optimal growth and nutritional composition, indicating its potential as a novel source of dietary ingredients alongside established microalgae species like Spirulina, Chlorella, and Nannochloropsis.