FTIR-based hierarchical modeling for prediction of average molecular weights of protein hydrolysates

Kenneth Aase Kristoffersen,Kristian Hovde Liland,Ulrike Böcker,Sileshi Gizachew Wubshet,Diana Lindberg,Svein Jarle Horn,Nils Kristian Afseth

doi:10.1016/j.talanta.2019.06.084

Kenneth Aase Kristoffersen, Kristian Hovde Liland + Show 5 more

Open Access

https://doi.org/10.1016/j.talanta.2019.06.084

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Journal: Talanta	Publication Date: Jun 22, 2019
Citations: 32	License type: cc-by

Affiliation: Nofima, Norwegian University of Life Sciences

Abstract

In the presented study, Fourier-transform infrared (FTIR) spectroscopy is used to predict the average molecular weight of protein hydrolysates produced from protein-rich by-products from food industry using commercial enzymes. Enzymatic protein hydrolysis is a well-established method for production of protein-rich formulations, recognized for its potential to valorize food-processing by-products. The monitoring of such processes is still a significant challenge as the existing classical analytical methods are not easily applicable to industrial setups. In this study, we are reporting a generic FTIR-based approach for monitoring the average molecular weights of proteins during enzymatic hydrolysis of by-products from the food industry. A total of 885 hydrolysate samples from enzymatic protein hydrolysis reactions of poultry and fish by-products using different enzymes were studied. FTIR spectra acquired from dry-films of the hydrolysates were used to build partial least squares regression (PLSR) models. The most accurate predictions were obtained using a hierarchical PLSR approach involving supervised classification of the FTIR spectra according to raw material quality and enzyme used in the hydrolysis process, and subsequent local regression models tuned to specific enzyme-raw material combinations. The results clearly underline the potential of using FTIR for monitoring protein sizes during enzymatic protein hydrolysis in industrial settings, while also paving the way for measurements of protein sizes in other applications.

Highlights

Fourier-transform infrared (FTIR) spectroscopy has become an established method for protein and peptide structural characterization over the last few decades
A total of 885 hydrolysate samples were prepared in the current study, collected at different time points during enzymatic protein hydrolysis of a variety of raw materials and enzymes
We have shown that molecular weight (Mw) of protein hydrolysates can be predicted with high accuracy using FTIR spectroscopy

Summary

Introduction

FTIR spectroscopy has become an established method for protein and peptide structural characterization over the last few decades. The inherent ability of FTIR spectroscopy to monitor the protein backbone can provide a range of possibilities to study parameters related to protein secondary structures. These parameters include hydration and solvent effects, pH and peptide size [3,4,5,6,7,8]. Protein size estimations can potentially have practical applications in a range of different fields, one of them being enzymatic protein hydrolysis This process represents an efficient and suitable method to extract protein from food processing residuals, involving the breakdown of proteins into peptides and free amino acids. There is a lack of fast and reliable analytical monitoring tools that can be used to achieve such process control

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