Group of Recycling and Valorization of Waste Materials (REVAL), Marine Research Institute (IIM-CSIC), Eduardo Cabello 6, 36208 Vigo, Spain.
Centro de Investigaciones Biomédicas (CINBIO), Departamento de Física Aplicada, Facultad de Ciencias, Universidade de Vigo, 36310 Vigo, Spain.
Mar Drugs. 2021 Aug 28;19(9):491. doi: 10.3390/md19090491.
Rising trends in fish filleting are increasing the amount of processing by-products, such as skins of turbot, a flatfish of high commercial value. In line with circular economy principles, we propose the valorization of turbot skins through a two-step process: initial gelatin extraction described for the first time in turbot, followed by hydrolysis of the remaining solids to produce collagen hydrolysates. We assayed several methods for gelatin extraction, finding differences in gelatin properties depending on chemical treatment and temperature. Of all methods, the application of NaOH, sulfuric, and citric acids at 22 °C results in the highest gel strength (177 g), storage and loss moduli, and gel stability. We found no relation between mechanical properties and content of pyrrolidine amino acids, but the best performing gelatin displays higher structural integrity, with less than 30% of the material below 100 kDa. Collagen hydrolysis was more efficient with papain than alcalase, leading to a greater reduction in Mw of the hydrolysates, which contain a higher proportion of essential amino acids than gelatin and show high in vitro anti-hypertensive activity. These results highlight the suitability of turbot skin by-products as a source of gelatin and the potential of collagen hydrolysates as a functional food and feed ingredient.
随着鱼片加工量的增加，鲆鱼等商业价值高的比目鱼的加工副产物（如皮）也在增加。为了遵循循环经济原则，我们提出通过两步法来提高鲆鱼皮的附加值：首先描述首次在鲆鱼中提取明胶，然后对剩余固体进行水解以生产胶原蛋白水解产物。我们对几种明胶提取方法进行了评估，发现化学处理和温度的不同会导致明胶性质的差异。在所有方法中，NaOH、硫酸和柠檬酸在 22°C 下的应用可得到最高的凝胶强度（177 g）、储能模量和损耗模量以及凝胶稳定性。我们发现机械性能与吡咯烷氨基酸含量之间没有关系，但性能最好的明胶显示出更高的结构完整性，低于 100 kDa 的物质含量不到 30%。木瓜蛋白酶水解比碱性蛋白酶更有效，导致水解产物的 Mw 降低更多，其中必需氨基酸的比例高于明胶，并且具有很高的体外抗高血压活性。这些结果突出了鲆鱼皮副产物作为明胶来源的适用性以及胶原蛋白水解产物作为功能性食品和饲料成分的潜力。
