Dual function peptides from pepsin hydrolysates of whey protein isolate Caroline Mellinger-Silva a, * , Luisa O.L. Rosa b , Marilia P. Stephan a , Ana Iraidy S. Brígida a , Lourdes M.C. Cabral a , Gabriel O. da Silva c , Karla L. Guarido c , Danillo Mac ^ edo Gomes c , J. Eduardo da Silva-Santos c a EMBRAPA Food Technology, Rio de Janeiro, Brazil b Instituto de Química, Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil c Laboratory of Cardiovascular Pharmacology, Departamento de Farmacologia, Universidade Federal de Santa Catarina, Florian opolis, Brazil article info Article history: Received 10 October 2014 Received in revised form 27 January 2015 Accepted 28 January 2015 Available online 12 February 2015 abstract The aim of this study was to investigate the effect of pepsin hydrolysates of whey protein isolate (WPI) on vascular relaxation and emulsifying capacity. WPI was subjected to pepsin hydrolysis for 5 h. The chromatographic profiles of the samples showed the formation of a wide variety of peptides. Addition of WPI hydrolysates in phenylephrine-contracted rat aortic rings induced a similar concentration- dependent relaxation in both endothelium-intact and endothelium-denuded preparations. In endothelium-denuded vessels the maximum relaxation induced by WPI fractions increased along the time, reaching over 70% after 3 h-hydrolysis on. In addition, the vascular relaxation was not associated with an inhibition of the angiotensin-converting enzyme or activation of K þ channels. Hydrolysed fractions were further evaluated for the emulsifying capacity (EC) and all tested fractions were able to keep an EC over 60%. These results reinforce the potential of WPI pepsin-hydrolysates as an option in the search for dual function peptides from whey proteins. © 2015 Elsevier Ltd. All rights reserved. 1. Introduction Whey proteins are being extensively studied for the last de- cades, especially after the consolidation of technologies for pro- cessing whey into concentrated or isolated protein-enriched ingredients, giving rise to valorized products for food, nutraceutical and pharmaceutical industries (Tavares et al., 2012; Tavares & Malcata, 2013). Recent studies on whey proteins generally concern issues related to their structures and functionalities, and how processes, in varied conditions, could interfere on such a relation (Hern andez- Ledesma, Contreras, & Recio, 2011; Lam & Nickerson, 2013; O'Loughlin, Murray, FitzGerald, Brodkorb, & Kelly, 2014a). In this respect, enzymatic hydrolysis of whey proteins has also been extensively explored, and is considered the most promising process for producing bioactive peptides, which, in many instances enhance biological functionalities when compared to intact proteins (Madureira, Tavares, Gomes, Pintado, & Malcata, 2010; O'Loughlin, Murray, FitzGerald, Brodkorb, & Kelly, 2014b). Among the biological functionalities described for peptides from whey proteins, emphasis has been given to actions on the cardiovascular, nervous, gastrointestinal, and immune systems (Madureira et al., 2010). Cardiovascular diseases, mainly involving hypertension, are the major cause of morbidity and mortality around the world (Celermajer, Chow, Marijon, Anstey, & Woo, 2012). In spite of the drug therapy currently available, the development of alternative strategies to prevent or reduce high blood pressure, including the intake of functional food, is highly desired (Norris & FitzGerald, 2013). Several reports have suggested the ability of whey proteins and their peptides in modulating the cardiovascular function. However, the majority of the developed studies, including those involving hydrolysates obtained from the well-known gastrointestinal en- zymes, such as pepsin and trypsin, associate the putative vascular effects of whey protein hydolysates with the inhibition of angiotensin-converting enzyme (ACE) activity (Mullally, Meisel, & FitzGerald, 1997; Otte, Shalaby, Zakora, Pripp, & EI-Shabrawy, * Corresponding author. Tel.: þ55 21 3622 9622. E-mail address: caroline.mellinger@embrapa.br (C. Mellinger-Silva). Contents lists available at ScienceDirect International Dairy Journal journal homepage: www.elsevier.com/locate/idairyj http://dx.doi.org/10.1016/j.idairyj.2015.01.016 0958-6946/© 2015 Elsevier Ltd. All rights reserved. International Dairy Journal 48 (2015) 73e79