Chicken feather valorization by thermal alkaline pretreatment followed by enzymatic hydrolysis for protein-rich hydrolysate production

• Published in: Waste management (Elmsford) 2018-09, Vol.79, p.658-666
• Main Authors: Cheong, Chooi Wei, Lee, Yen Sze, Ahmad, Siti Aqlima, Ooi, Peck Toung, Phang, Lai Yee
• Format: Article
• Language: English
• Subjects: Animals; Autoclave alkaline pretreatment; Chicken feather; Chickens; Enzymatic hydrolysis; Feathers; Hydrolysis; Microwave alkaline pretreatment; Nitrogen; Protein Hydrolysates; Protein recovery; Thermal-alkaline pretreatment
• ISSN: 0956-053X; 1879-2456
• DOI: 10.1016/j.wasman.2018.08.029

•Thermal-alkaline pretreatment of feathers was optimized by RSM.•Feather was susceptible to degradation under optimized pretreatment conditions.•MAS and AAS treated feathers were hydrolyzed enzymatically to recover soluble protein.•FTIR and elemental analyses revealed change or disruption of feather after treatment. A huge amount of feathers is generated as a waste every year. Feathers can be a protein source if it is treated with an appropriate method. The present study investigates feasibility of autoclave alkaline and microwave alkaline pretreatments to be combined with enzymatic treatment for feather solubilization and protein production. Hydrolysis of chicken feather by autoclave alkaline pretreatment followed by an enzymatic method (AAS) or microwave alkaline pretreatment followed by an enzymatic method (MAS) was optimized by response surface methodology. Various NaOH concentrations for autoclave alkaline pretreatment (0.01–0.1 M) and microwave-alkaline pretreatment (0.01–0.05 M) were applied. The holding time for both pretreatments ranged from 1 to 10 min. The pretreated feathers were subjected to enzymatic hydrolysis using a commercial enzyme prior to analysis of protein content, feather solubilization, functional groups, and elemental composition (carbon, hydrogen, nitrogen and sulfur) of the treated feathers. The results revealed that both autoclave alkaline pretreatment and microwave alkaline pretreatment under optimized conditions of 0.068 M NaOH, 2 min holding time, 105 °C and 450 W, 0.05 M NaOH for 10 min, respectively, enhanced the subsequent Savinase hydrolysis of chicken feathers to achieve more than 80% degradation and more than 70% protein recovery. Fourier transform infrared spectroscopy results showed that both thermal-alkaline pretreatments weakened the structure of the feather. Reduction of carbon, nitrogen, and sulfur occurred in both thermal-alkaline pretreatments of feathers indicating degradation of the feather as well as protein release. Thermal-alkaline pretreatment may be a promising method for enhancing the enzymatic hydrolysis of chicken feathers and for producing a protein-rich hydrolysate.