In vitro pepsin digestibility and amino acid composition in soluble and residual fractions of hydrolyzed chicken feathers

• Published in: Poultry Science
• Main Authors: Adler, S. A., Slizyte, R., Honkapää, K., Løes, A. K.
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2018
• Subjects: Beta-keratin; Keratinolytic protease; Sodium hydrooxide; Sodium sulfite; Atlantic salmon; amino acid; avian protein; pepsin A; animal food; Salmo salar; solubility; protein degration; chicken; /fi/minedu/virta/publicationtypes/a1; A1 Refereed journal article; /fi/minedu/virta/openaccess/3; 3 Hybrid publication; /fi/minedu/virta/scienceareas/1181; 1181 Biology; /fi/minedu/virta/scienceareas/412; 412 Animal and dairy science; /dk/atira/pure/subjectarea/asjc/1100/1103; Animal Science and Zoology; Processing and Products; sodium hydroxide; Feeding and growth; Recycling; balancing and resource management; Processing; packaging and transportation; ta1181; ta412; General Medicine; VDP::Landbruks- og Fiskerifag: 900; envir; stat
• Online Access: http://academic.oup.com/ps/article-pdf/97/9/3343/25497910/pey175.pdf; http://hdl.handle.net/11250/2580634; https://cris.vtt.fi/en/publications/c74b9568-6f0d-4a98-9610-9d9aac5e7dcb; https://doi.org/10.3382/ps/pey175; http://europepmc.org/articles/PMC6093747; http://orgprints.org/33408/; http://juuli.fi/Record/0333044818; https://api.elsevier.com/content/article/PII:S0032579119308818?httpAccept=text/xml; https://api.elsevier.com/content/article/PII:S0032579119308818?httpAccept=text/plain; https://www.sciencedirect.com/science/article/pii/S0032579119308818; https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6093747; https://cris.vtt.fi/en/publications/in-vitro-pepsin-digestibility-and-amino-acid-composition-in-solub; https://brage.bibsys.no/xmlui/handle/11250/2577836; https://academic.oup.com/ps/article/97/9/3343/5001673; https://www.cabdirect.org/cabdirect/abstract/20193085320; https://search.bvsalud.org/portal/resource/en/mdl-29796647; https://academic.microsoft.com/#/detail/2804148377

Beta-keratin in poultry feathers is a structural protein that is resistant to degradation due to disulfide and hydrogen bonds. Feather meal can be a valuable feed compound if the digestibility can be increased. The objective of the present study was to analyze the effects of chemical, enzymatic, and pressure-thermic treatments for chicken feathers on solubility, in vitro protein digestibility (IVPD), and amino acid composition of solubilized and residual fractions. Two experiments were conducted. In experiment 1, models for solubility and IVPD were developed including the above factors applying a central composite face-centered design. Addition of sodium hydroxide (NaOH) and sodium sulfite (Na2SO3) and autoclaving time affected solubility and IVPD of the feather hydrolysates, but not addition of keratinolytic enzyme. In experiment 2, 7 combinations of the hydrolysis factors NaOH, Na2SO3, and autoclaving time with a predicted IVPD of 900 g/kg of DM, calculated for the sum of solubilized and residual feather fractions, were included to measure effects on IVPD and amino acid composition in each fraction. The IVPD values were higher for solubilized than residual fractions when treated with NaOH and autoclaving, but no differences were found when treated with Na2SO3 and autoclaving. Losses of cystine were substantial for all treatments, but lower for Na2SO3 than for NaOH. Furthermore, use of lower Na2SO3 concentration and longer autoclaving time reduced losses of cystine. Compared with NaOH treatments, Na2SO3 gave lower losses of threonine, arginine, serine, and tyrosine. With reference to the ideal protein profile for Atlantic salmon (Salmo salar L.), the treatments with 60 or 90 min autoclaving and 0.36 or 0.21% Na2SO3 had the highest chemical scores. The scores were generally higher for amino acids in residual than solubilized fractions, but with 90 min autoclaving and 0.21% Na2SO3 differences were small. In conclusion, hydrolysis of chicken feathers with low concentrations of Na2SO3 combined with autoclaving ...