Nuutinen Emmi-Maria, Willberg-Keyriläinen Pia, Virtanen Tommi, Mija Alice, Kuutti Lauri, Lantto Raija, Jääskeläinen Anna-Stiina
Solutions for Natural Resources and Environment, VTT, Technical Research Centre of Finland Tietotie 2 FI-02044 Espoo Finland
Université Côte d'Azur, Université Nice-Sophia Antipolis, Institut de Chimie de Nice UMR CNRS 7272 06108 Nice Cedex 02 France.
RSC Adv. 2019 Jun 25;9(34):19720-19728. doi: 10.1039/c9ra03305j. eCollection 2019 Jun 19.
Poultry feathers, a source of keratin, are a significant side stream from the food industry, for which valorization is essential considering the circular economy aspects. For this, ecofriendly processes are the tools that allow the easy and feasible transformation of the feathers. Deep eutectic solvents (DESs) are generally considered as inexpensive, relatively simple, mild and environmentally friendly solvents which can dissolve proteins from protein-rich biomasses. In this work, feathers were processed with an aqueous DES to produce a uniform keratin feedstock. The proposed DES is composed of non-toxic sodium acetate and urea, with a small amount of water. After the DES treatment, water was used to dilute the DES components and regenerate the dissolved keratin. The processing conditions were optimized in terms of keratin yield and properties by varying the dissolution time from 2 h to 24 h and temperature from 80 °C to 100 °C. The yield of regenerated keratin was followed at different sodium acetate-urea molar ratios, and compared to the treatment performed with choline chloride-urea or 8 M urea as reference solvents. Sodium acetate-urea in the molar ratio of 1 : 2 at 100 °C and with 6 h dissolution time dissolved 86% of the feathers with a regenerated keratin yield of 45%. In the characterization of regenerated keratin, it was found that when the dissolution temperature was higher and the dissolution time longer, the disulfide and total sulfur content of feather keratin decreased, the range of molecular weights became wider, and some of the ordered secondary structure and crystallinity were lost.
家禽羽毛是角蛋白的来源，是食品工业的重要副产品，从循环经济的角度来看，对其进行增值利用至关重要。为此，生态友好型工艺是实现羽毛轻松且可行转化的工具。深共熔溶剂（DESs）通常被认为是廉价、相对简单、温和且环境友好的溶剂，能够从富含蛋白质的生物质中溶解蛋白质。在这项工作中，采用含水DES处理羽毛以制备均匀的角蛋白原料。所提出的DES由无毒的醋酸钠和尿素以及少量水组成。DES处理后，用水稀释DES成分并再生溶解的角蛋白。通过将溶解时间从2小时变化到24小时以及温度从80℃变化到100℃，对角蛋白产量和性质方面的加工条件进行了优化。在不同的醋酸钠 - 尿素摩尔比下跟踪再生角蛋白的产量，并与以氯化胆碱 - 尿素或8M尿素作为参考溶剂进行的处理进行比较。在100℃下，醋酸钠 - 尿素摩尔比为1∶2且溶解时间为6小时时，86%的羽毛被溶解，再生角蛋白产量为45%。在再生角蛋白的表征中发现，当溶解温度较高且溶解时间较长时，羽毛角蛋白的二硫键和总硫含量降低，分子量范围变宽，并且一些有序的二级结构和结晶度丧失。
