Study on the structure and properties of wool keratin regenerated from formic acid

Aluigi, Annalisa; Zoccola, Marina; Vineis, Claudia; Tonin, Claudio; Ferrero, Franco; Canetti, Maurizio

doi:10.1016/j.ijbiomac.2007.03.002

Cited by 240 publications

(157 citation statements)

References 28 publications

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“…Millions tonnes of keratinous wastes are generated annually globally, especially in wool textile industry and in poultry slaughterhouses [1]. The bird feathers consist of approximately 90 % keratin.…”

Section: Introductionmentioning

confidence: 99%

Alternative Methods of Preparation of Soluble Keratin from Chicken Feathers

Sinkiewicz

Śliwińska

Staroszczyk

et al. 2016

Waste Biomass Valor

145

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Huge amount of keratinous waste, especially birds' feathers, demands more value-added application instead of dumping. The present work reports the results of experiments aimed at preparing soluble keratin useful for novel bioproduct formation. The effect of thermo-chemical treatments with various reducing agents, i.e. 2-mercaptoethanol, dithiothreitol, sodium m-bisulphite, and sodium bisulphite, as well as sodium hydroxide, on the yield of keratin extracted from chicken feathers was determined. It was shown that after 2-h reduction with 2-mercaptoethanol and sodium bisulphite, the yield of soluble keratin was about equal and amounted to 84 and 82 %, respectively. The cheaper and harmless sodium bisulphite additionally decreased the extraction time to 1 h with the same yield. Moreover, treatment of the feathers with 2.5 % NaOH further improved the extraction effectiveness by increasing the yield up to 94 %. The results of the study demonstrate the viability of hydrolytic processes to obtain soluble keratin useful for biodegradable film formation for food application, that are harmless and more effective than solubilization by reduction of the disulphide bonds. Graphical Abstract

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Section: Introductionmentioning

confidence: 99%

Alternative Methods of Preparation of Soluble Keratin from Chicken Feathers

Sinkiewicz

Śliwińska

Staroszczyk

et al. 2016

Waste Biomass Valor

145

View full text Add to dashboard Cite

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“…In the sample after the hydrolysis process this signal partially remained, which, in accordance with the lack of stretching vibration from S-H bonds at 2560 cm -1 , demonstrated no reduced thiols formation during hydrolysis, possibly resulting from sulfitolytic cleavage of most accessible disulfide bonds [50]. The signal between 1600 and 1700 cm -1 is usually referred to as Amide I region and it is known to be sensitive to secondary structure of proteins, it was therefore resolved into components [51]. In the initial bristle substrate exhibited nearly equal content of a-helix and b-sheet, 45 and 55 %, respectively (Fig.…”

Section: Resultsmentioning

confidence: 60%

Enzymatic Degradation of Pretreated Pig Bristles with Crude Keratinase of Bacillus cereus PCM 2849

Łaba

Chorążyk

Pudło

et al. 2016

Waste Biomass Valor

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Purpose The aim of the study was to apply and optimize the process of bioconversion of pig bristle waste using keratinolytic enzymes of Bacillus cereus PCM 2849, and to evaluate the amino acid composition of the resultant hydrolysate. Methods Hydrolysis with concentrated culture fluid of B. cereus was applied for bioconversion of pig bristles, after thermo-chemical pretreatment with sulfite. The effect of substrate concentration, sulfite concentration during pretreatment and reaction temperature on the release of amino acids was determined using Box-Behnken design. Amino acid composition of the obtained hydrolysate was determined by HPLC. Structural condition and substructural changes of the residual substrate were evaluated with SEM microscopy and FTIR spectroscopy. Results The applied enzymatic preparation for bristle biodegradation was verified to contain multiple proteases of a wide molecular weight range. A regression model was developed, in which influential parameters were: linear effect of substrate concentration, followed by quadratic effects of reaction temperature, substrate concentration and pretreatment. Optimum reaction conditions were also determined. The resultant hydrolysate was rich in branched-chain amino acids. Residual substrate was detriorated and sulfitolytic cleavage of disulfides and alteration of protein secondary structures was confirmed. Conclusions Application of B. cereus crude keratinase allowed for partial hydrolysis of pig bristles, preceded by sulfitolytic pretreatment. A regression model was built to describe the process of hydrolysis to release free amino acids, at constant enzyme load. Hydrolysis in given conditions allowed to obtain hydrolysate rich in branched chain amino acids. The presented process poses an alternate way of management over pig bristles, a hard-to-degrade keratinous waste.

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“…In particular, having a pK a about 4.5, free carboxyl groups of aspartyl and glutamyl residues are considered the most likely binding sites over a wide pH range (Maclaren & Milligan, 1981;Taddei et al, 2003). Recent studies showed that formic acid is a good media to dissolve keratin having strong solvation properties for keratin regenerated from wool (Alemdar et al, 2005;Aluigi et al, 2007a). Formic acid is also a solvent for polyamides so that it can be used to prepare keratin-polyamide 6 (PA6) blends in different proportions.…”

Section: Keratin/pa6 Blend Nanofibresmentioning

confidence: 99%