Abstract With rising global population and decreasing available land and fresh water resources, the oceans provide an attractive domain for sourcing nutrients. The marine macroalgae Ulva sp. and Gracilaria sp. are candidate raw biomass. Ulva sp. has high growth rate and Gracilaria sp. has high protein content and their seasonal growth is complementary, allowing almost year-round high yield protein production. In this study, we aimed at developing an effective process, to yield a high macroalgae protein content concentrate suitable for food application, and studying the digestibility, amino acid composition and antioxidant properties of the obtained algal protein concentrates (APCs). We developed a new protein extraction protocol, and compared it to several published protocols. The developed protocol is food-grade, and yielded APC from Ulva and form Gracilaria, containing 70 and 86% protein respectively. The amino acid compositions of the APCs suggest their possible use as sources of essential amino acids. Simulated gastro-intestinal digestion showed that APCs proteolysis of at least 89% can be reached. We found that the APCs exhibit antioxidant activity, which is similar to that of known protein isolates in the hydrogen atom transfer mechanism, but 10 to 20 times higher in the single electron transfer mechanism. These results suggest that polyphenolic compounds might be still present in the APCs and contribute to their antioxidant activity. Our results suggest that the protein concentrates extracted from Ulva sp. and Gracilaria sp. seem to be promising sustainable sources for human nutrition thanks to their essential amino acids content, digestibility and antioxidant properties.

中文翻译：

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从两种海洋大型藻类 Ulva sp. 中提取蛋白质。和江蓠 sp.，用于食品应用，并评估蛋白质浓缩物的消化率、氨基酸组成和抗氧化特性

摘要 随着全球人口的增加以及可用土地和淡水资源的减少，海洋为获取营养提供了一个有吸引力的领域。海洋大型藻类 Ulva sp。和江蓠 sp。是候选的原始生物质。石莼属 具有高增长率和江蓠 sp。蛋白质含量高，它们的季节性生长是互补的，几乎可以全年高产地生产蛋白质。在本研究中，我们旨在开发一种有效的方法，以生产适用于食品应用的高巨藻蛋白质浓缩物，并研究所获得的藻类蛋白质浓缩物 (APC) 的消化率、氨基酸组成和抗氧化特性。我们开发了一种新的蛋白质提取方案，并将其与几个已发布的方案进行了比较。开发的协议是食品级的，并从石莼中产生 APC 并形成江蓠，分别含有 70% 和 86% 的蛋白质。APC 的氨基酸组成表明它们可能用作必需氨基酸的来源。模拟胃肠消化表明，APCs 的蛋白水解至少可以达到 89%。我们发现 APCs 表现出抗氧化活性，在氢原子转移机制中与已知的蛋白质分离物相似，但在单电子转移机制中高 10 到 20 倍。这些结果表明多酚类化合物可能仍存在于 APC 中并有助于其抗氧化活性。我们的结果表明从 Ulva sp. 中提取的蛋白质浓缩物。和江蓠 sp。由于其必需氨基酸含量，似乎是人类营养的可持续来源，