IFI Institute Fermentaciones Industriales

San Juan de la Rambla, Spain

IFI Institute Fermentaciones Industriales

San Juan de la Rambla, Spain

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Tavares T.G.,Catholic University of Portugal | Tavares T.G.,New University of Lisbon | Contreras M.M.,IFI Institute Fermentaciones Industriales | Amorim M.,Catholic University of Portugal | And 5 more authors.
International Dairy Journal | Year: 2011

The hydrolysis of bovine whey protein concentrate (WPC), α-lactalbumin (α-La) and caseinomacropeptide (CMP), by aqueous extracts of Cynara cardunculus, was optimized using response surface methodology. Degree of hydrolysis (DH), angiotensin-converting enzyme (ACE)-inhibitory activity and antioxidant activity were used as objective functions, and hydrolysis time and enzyme/substrate ratio as manipulated parameters. The model was statistically appropriate to describe ACE-inhibitory activity of hydrolysates from WPC and α-La, but not from CMP. Maximum DH was 18% and 9%, for WPC and α-La, respectively. 50% ACE-inhibition was produced by 105.4 (total fraction) and 25.6μgmL-1 (<3kDa fraction) for WPC, and 47.6 (total fraction) and 22.5μgmL-1 (<3kDa fraction) for α-La. Major peptides of fractions exhibiting ACE-inhibition were sequenced. The antioxidant activities of WPC and α-La were 0.96±0.08 and 1.12±0.13μmoltrolox equivalent per mghydrolysed protein, respectively. © 2011.


Tavares T.,Catholic University of Portugal | Tavares T.,New University of Lisbon | Contreras M.D.M.,IFI Institute Fermentaciones Industriales | Amorim M.,Catholic University of Portugal | And 4 more authors.
Peptides | Year: 2011

Whey protein concentrate (WPC) was subjected to enzymatic hydrolysis by proteases from the flowers of Cynara cardunculus, and the resulting angiotensin-converting enzyme (ACE)-inhibitory effect was monitored. The whole WPC hydrolysate exhibited an IC50 value of 52.9 ± 2.9 μg/mL, whereas the associated peptide fraction with molecular weight below 3 kDa scored 23.6 ± 1.1 μg/mL. The latter fraction was submitted to RP-HPLC, and 6 fractions were resolved that exhibited ACE-inhibitory effects. Among the various peptides found, a total of 14 were identified via sequencing with an ion-trap mass spectrometer. Eleven of these peptides were synthesized de novo - to validate their ACE-inhibitory effect, and also to ascertain their stability when exposed to simulated gastrointestinal digestion. Among them, three novel, highly potent peptides were found, corresponding to α-lactalbumin f(16-26) - with the sequence KGYGGVSLPEW, α-lactalbumin f(97-104) with DKVGINYW, and β-lactoglobulin f(33-42) with DAQSAPLRVY; their IC50 values were as low as 0.80 ± 0.1, 25.2 ± 1.0 and 13.0 ± 1.0 μg/mL, respectively. None of them remained stable in the presence of gastrointestinal enzymes: they were partially, or even totally hydrolyzed to smaller peptides - yet the observed ACE-inhibitory effects were not severely affected for two of those peptides. © 2011 Elsevier Inc.

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