Production of hydrophobic amino acids from biobased resources: wheat gluten and rubber seed proteins.

Widyarani Widyarani,Enny Ratnaningsih,Marieke E Bruins,Yessie W Sari,Johan P M Sanders

doi:10.1007/s00253-016-7441-8

Abstract

Protein hydrolysis enables production of peptides and free amino acids that are suitable for usage in food and feed or can be used as precursors for bulk chemicals. Several essential amino acids for food and feed have hydrophobic side chains; this property may also be exploited for subsequent separation. Here, we present methods for selective production of hydrophobic amino acids from proteins. Selectivity can be achieved by selection of starting material, selection of hydrolysis conditions, and separation of achieved hydrolysate. Several protease combinations were applied for hydrolysis of rubber seed protein concentrate, wheat gluten, and bovine serum albumin (BSA). High degree of hydrolysis (>50 %) could be achieved. Hydrophobic selectivity was influenced by the combination of proteases and by the extent of hydrolysis. Combination of Pronase and Peptidase R showed the highest selectivity towards hydrophobic amino acids, roughly doubling the content of hydrophobic amino acids in the products compared to the original substrates. Hydrophobic selectivity of 0.6 mol-hydrophobic/mol-total free amino acids was observed after 6 h hydrolysis of wheat gluten and 24 h hydrolysis of rubber seed proteins and BSA. The results of experiments with rubber seed proteins and wheat gluten suggest that this process can be applied to agro-industrial residues.Electronic supplementary materialThe online version of this article (doi:10.1007/s00253-016-7441-8) contains supplementary material, which is available to authorized users.

Highlights

As the building blocks of proteins, amino acids are important components in food and feed
Hydrophobic amino acids are predominantly present in the interior of the protein (Tanford 1962), as this conformation stabilises the protein in aqueous solution
The amounts of hydrophobic amino acids for the three substrates used in our experiments were 0.35, 0.37, and 0.35 mol/mol-total amino acid for rubber seed protein concentrate, wheat gluten, and bovine serum albumin (BSA), respectively

Summary

Introduction

As the building blocks of proteins, amino acids are important components in food and feed. From the 20 proteinogenic amino acids, isoleucine, leucine, valine, phenylalanine, tryptophan, methionine, threonine, histidine, and lysine are essential amino acids as they cannot be synthesised by humans and most farm animals. Producing mixtures rich in hydrophobic amino acids is an interesting process to investigate based on the ease in further processing and their potential application as a group in food and feed. This approach increases the feasibility of a biorefinery route from protein to food/feed and bulk chemicals (Sari et al 2015)

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Conclusion