Green process to regenerate keratin from feathers with an aqueous deep eutectic solvent

Emmi Maria Nuutinen (Corresponding Author), Pia Willberg-Keyriläinen, Tommi Virtanen, Alice Mija, Lauri Kuutti, Raija Lantto, Anna Stiina Jääskeläinen

Research output: Contribution to journalArticleScientificpeer-review

Abstract

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.

Original languageEnglish
Pages (from-to)19720-19728
Number of pages9
JournalRSC Advances
Volume9
Issue number34
DOIs
Publication statusPublished - 1 Jan 2019
MoE publication typeA1 Journal article-refereed

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