In the scope of efficient keratin extraction from the feather and wool waste

D. Trojanowska^1*, R. Simonutti², A. Athanassiou¹, G. Perotto¹

¹ Istituto Italiano di Tecnologia, (IIT) Central Research Labs Genova, Via Morego, 30, 16163 Genova (Italy). Email: Giovanni.Perotto@iit.it, ² Department of Materials Science, University of Milano-Bicocca, via R. Cozzi 55, 20125 Milan (Italy). Email: Roberto.Simonutti@unimib.it

*dagmara.trojanowska@iit.it

The waste streams of chicken feather from the poultry industry and low-grade wool from the fabric preparation are keratin-rich materials currently underutilized. Therefore, development of appropriate waste employment with value added final product is required. Wool and chicken feather waste consist of 95 and 91 % keratin protein, respectively. Keratin can be composed of 18-20 types of amino acids bonded via peptides bonds. The amino acids of different proteins are interacted by intra- and intermolecular disulfide bonds, ionic bonds, hydrogen bonds or hydrophobic bonds that make the structure of keratin strong but conversely difficult to extract and reprocess. Consequently, the key to successful keratin extraction is selection of appropriate chemicals to break these bonds [1, 2]. In the present study, we would like to investigate the efficiency of keratin extraction with the high yield target. Furthermore, we would like to explore the possibilities of using keratin in preparation of biodegradable packaging. Suitable application of keratin encourages continual use of resources and waste reduction.

Keratins were extracted from the feather and wool using thermo-chemical treatment, such as sulfitolysis [3, 4], hydrolysis [3] and reduction [3, 5, 6]. These methods were selected due to their high efficiency reported in the literature. The keratin yields were determined gravimetrically. Molecular weights, surface charges, isoelectric point, morphological structures and chemical composition of extracted keratins were investigated.

The 24-h treatment of chicken feather was the most efficient with the application of reduction method (yield up to ~88 %). On the other hand, the 24-h treatment of wool was the most effective using sulfitolysis process (~63 %). Dissimilarity in the yields of keratin extracted from the chicken feather and wool can be explained by different compositions of the raw materials. Characterization techniques indicate that the chemical structure of proteins is retained after the extraction processes.

References

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[3] I. Sinkiewicz, et al. Waste and biomass valorization, 2017, 8(4): p. 1043-1048.

[4] S.I.N. Ayutthaya, et al. Journal of Polymers and the Environment, 2015, 23(4): p. 506-516.

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[6] F. Pourjavaheri, et al. Process Biochemistry, 2019, 82: p. 205-214.