PDF(Pubmed)
Abstract：
The obtained seeds from fruit processing are considered by-products containing proteins that could be utilized as ingredients in food manufacturing. However, in the specific case of soursop seeds, their usage for the preparation of protein isolates is limited. In this investigation a protein isolate from soursop seeds (SSPI) was obtained by alkaline extraction and isoelectric precipitation methods. The SSPI was sonicated at 200, 400 and 600 W during 15 and 30 min and its effect on the physicochemical, functional, biochemical, and structural properties was evaluated. Ultrasound increased (p < 0.05) up to 5 % protein content, 261 % protein solubility, 60.7 % foaming capacity, 30.2 % foaming stability, 86 % emulsifying activity index, 4.1 % emulsifying stability index, 85.4 % in vitro protein digestibility, 423.4 % albumin content, 83 % total sulfhydryl content, 316 % free sulfhydryl content, 236 % α-helix, 46 % β-sheet, and 43 % β-turn of SSPI, in comparison with the control treatment without ultrasound. Furthermore, ultrasound decreased (p < 0.05) up to 50 % particle size, 37 % molecular flexibility, 68 % surface hydrophobicity, 41 % intrinsic florescence spectrum, and 60 % random coil content. Scanning electron microscopy analysis revealed smooth structures of the SSPI with molecular weights ranging from 12 kDa to 65 kDa. The increase of albumins content in the SSPI by ultrasound was highly correlated (r = 0.962; p < 0.01) with the protein solubility. Improving the physicochemical, functional, biochemical and structural properties of SSPI by ultrasound could contribute to its utilization as ingredient in food industry.
摘要：
从水果加工获得的种子被认为是含有蛋白质的副产品，可以用作食品制造中的成分。然而,在特殊的情况下，它们用于制备蛋白质分离物的用途是有限的。在这项研究中，通过碱性提取和等电沉淀法获得了来自酸草种子（SSPI）的蛋白质分离物。SSPI在200、400和600W下超声处理15和30分钟，功能，生物化学，并对结构性能进行了评价。超声增加(p<0.05)至5%蛋白质含量,261%的蛋白质溶解度，60.7%发泡能力，30.2%发泡稳定性,86%乳化活性指数，乳化稳定性指数4.1%,85.4%的体外蛋白质消化率，423.4%白蛋白含量,总巯基含量83%,316%游离巯基含量,236%α-螺旋,46%β-折叠，和43%的SSPIβ转角，与没有超声的对照治疗相比。此外，超声降低(p<0.05)至50%粒径，37%的分子柔性，68%的表面疏水性，41%的固有荧光光谱，和60%的无规卷曲含量。扫描电子显微镜分析显示SSPI的光滑结构，分子量为12kDa至65kDa。超声使SSPI中白蛋白含量的增加与蛋白质溶解度高度相关（r=0.962；p<0.01）。改善物理化学，功能，超声检测SSPI的生化和结构特性可能有助于其在食品工业中用作成分。
