Abstract
The aim of this study was to prepare enzymatic hydrolysates from whey protein concentrate with a nutritionally adequate peptide profile and the ability to inhibit angiotensin-converting enzyme (ACE) activity. The effects of the type of enzyme used (pancreatin or papain), the enzyme:substrate ratio (E:S ratio=0.5:100, 1:100, 2:100 and 3:100) and the use of ultrafiltration (UF) were investigated. The fractionation of peptides was performed by size-exclusion-HPLC, and the quantification of the components of the chromatographic fractions was carried out by a rapid Corrected Fraction Area method. The ACE inhibitory activity (ACE-IA) was determined by Reverse Phase-HPLC. All parameters tested affected both the peptide profile and the ACE-IA. The best peptide profile was achieved for the hydrolysates obtained with papain, whereas pancreatin was more advantageous in terms of ACE-IA. The beneficial effect of using a lower E:S ratio on the peptide profile and ACE-IA was observed for both enzymes depending on the conditions used to prepare the hydrolysates. The beneficial effect of not using UF on the peptide profile was observed in some cases for pancreatin and papain. However, the absence of UF yielded greater ACE-IA only when using papain.
Highlights
Whey is currently a major by-product of the modern cheese and casein production industries and representsM
Sixteen hydrolysates were prepared by varying the Analysis of whey protein hydrolysates: peptide profile and ace inhibitory activity following parameters: type of enzyme, enzyme:substrate ratio (E:S) and the use of UF
The fractionation of whey protein concentrate (WPC) hydrolysates was conducted by size exclusion (SE) HPLC on a PHEA column, according to the method previously developed by Silvestre, Hamon and Yvon (1994a), using 0.05 M formic acid as the mobile phase, with isocratic conditions at a flow rate of 0.5 mL min-1 for 35 min
Summary
An efficient method was previously developed by Silvestre, Hamon and Yvon (1994a,b) using this principle, which enabled the separation of peptides with molecular masses lower than 1,000 Da, and this is the method used in the current study. This method was used for the characterisation of the peptide profiles of hydrolysates obtained from different protein sources (Carreira et al, 2004; Lopes et al, 2005, 2008; Morais et al, 2005; Silva et al, 2007). The effects of several parameters, such as enzyme type, E:S ratio and the use of UF, were evaluated
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