Fourier Transform Infrared Spectroscopy for Assessing Structural and Enzymatic Reactivity Changes Induced during Feather Hydrolysis.

Chicken feathers are major byproducts of the livestock processing industry with high potential in the feed sector. In this study, we present a new approach using Fourier transform infrared (FTIR) spectroscopy to detect the structural changes of feather keratin and its availability for enzymatic hydrolysis (AEH) induced by the thermal pressure hydrolysis (TPH) process. Compared to time-consuming in vitro measurement techniques, the proposed method provides rapid information about the structural changes during TPH which enables quick adaptation of TPH conditions as the quality of the incoming feather changes. By analyzing the FTIR spectra of raw and processed feathers, it was found that AEH negatively relates to the β-sheet content (represented by two IR peaks centered at 1635 and 1689 cm-1), while it positively relates to a new series of peaks centered around 1700 cm-1 appearing after the TPH process. The proposed FTIR technique provides a reliable and rapid approach to determine the digestibility indicated by AEH of the processed feather and may be used in process control and optimization.