Department of Engineering for Innovation, University of Salento, Via Monteroni, 73100 Lecce, Italy.
Institute of Crystallography, National Research Council, 70125 Bari, Italy.
Int J Mol Sci. 2023 Jan 18;24(3):1938. doi: 10.3390/ijms24031938.
In the last two decades, fisheries and fish industries by-products have started to be recovered for the extraction of type I collagen because of issues related to the extraction of traditional mammalian tissues. In this work, special attention has been paid to by-products from fish bred in aquaponic plants. The valorization of aquaponic fish wastes as sources of biopolymers would make the derived materials eco-friendlier and attractive in terms of profitability and cost effectiveness. Among fish species, Nile Tilapia is the second-most farmed species in the world and its skin is commonly chosen as a collagen extraction source. However, to the best of our knowledge, no studies have been carried out to investigate, in depth, the age-related differences in fish skin with the final aim of selecting the most advantageous fish size for collagen extraction. In this work, the impact of age on the structural and compositional properties of Tilapia skin was evaluated with the aim of selecting the condition that best lends itself to the extraction of type I collagen for biomedical applications, based on the known fact that the properties of the original tissue have a significant impact on those of the final product. Performed analysis showed statistically significant age-related differences. In particular, an increase in skin thickness (+110 µm) and of wavy-like collagen fiber bundle diameter (+3 µm) besides their organization variation was observed with age. Additionally, a preferred collagen molecule orientation along two specific directions was revealed, with a higher fiber orientation degree according to age. Thermal analysis registered a shift of the endothermic peak (+1.7 °C) and an increase in the enthalpy (+3.3 J/g), while mechanical properties were found to be anisotropic, with an age-dependent brittle behavior. Water (+13%) and ash (+0.6%) contents were found to be directly proportional with age, as opposed to protein (-8%) and lipid (-10%) contents. The amino acid composition revealed a decrease in the valine, leucine, isoleucine, and threonine content and an increase in proline and hydroxyproline. Lastly, fatty acids C14:0, C15:0, C16:1, C18:2n6c, C18:3n6, C18:0, C20:3n3, and C23:0 were revealed to be upregulated, while C18:1n9c was downregulated with age.
在过去的二十年中，由于与传统哺乳动物组织提取相关的问题，渔业和鱼类工业副产品开始被回收用于提取 I 型胶原蛋白。在这项工作中，特别关注水产养殖鱼类在水培植物中的副产品。将水培鱼废物作为生物聚合物的来源进行增值，将使衍生材料在生态友好性和盈利性以及成本效益方面更具吸引力。在鱼类中，罗非鱼是世界上第二大养殖鱼类，其皮通常被选为胶原蛋白提取的来源。然而，据我们所知，尚无研究深入研究鱼类皮肤随年龄变化的差异，最终目的是选择最有利于胶原蛋白提取的鱼类尺寸。在这项工作中，评估了年龄对罗非鱼皮结构和组成特性的影响，目的是选择最适合用于生物医学应用的胶原蛋白提取条件，因为已知原始组织的特性对最终产品有重大影响。进行的分析显示出与年龄相关的统计学显着差异。特别是，随着年龄的增长，观察到皮肤厚度增加（+110 µm）和波浪状胶原纤维束直径增加（+3 µm），以及它们的组织变化。此外，还揭示了胶原分子沿两个特定方向的优选取向，并且根据年龄，纤维取向度更高。热分析记录到吸热峰的位移（+1.7°C）和焓的增加（+3.3 J/g），而机械性能表现出各向异性，具有随年龄变化的脆性行为。发现水（+13%）和灰分（+0.6%）含量与年龄直接成正比，而蛋白质（-8%）和脂质（-10%）含量则相反。氨基酸组成显示缬氨酸、亮氨酸、异亮氨酸和苏氨酸含量减少，脯氨酸和羟脯氨酸含量增加。最后，发现 C14:0、C15:0、C16:1、C18:2n6c、C18:3n6、C18:0、C20:3n3 和 C23:0 脂肪酸上调，而 C18:1n9c 随年龄下调。
