10-4 |
Production and characterization of angiotensin I converting enzyme (ACE) inhibitory peptides from whey fermentation by lactic cultures |
J. E. AHN and B. H. Lee. Dept. of Food Science & Agricultural Chemistry, McGill Univ., Macdonald Campus, 21111 Lakeshore Rd., Sainte-Anne-de-Bellevue, QC H9X 3V9, Canada Peptides that inhibit angiotensin I converting enzyme (ACE), which plays an important role in peripheral blood pressure regulation, have been isolated from many different food protein sources. While many bovine casein-derived ACE inhibitory peptides have been extensively studied, the major whey protein fractions (a-lactalbumin and b-lactoglobulin), also appeared to contain peptides that inhibit ACE. However, such peptides have been derived mainly from enzymatic hydrolysis of whey proteins using commercial enzymes instead of fermenting them with lactic cultures, which release extracellular proteases and endopeptidases by lysis. The objective of the study was to select the lactic strains that produce the most potent ACE inhibitory peptides during whey fermentation, purify and identify the bioactive peptides. Whey media, supplemented with 1% glucose and 0.5% yeast extract, were fermented with various strains of lactic cultures for 48 h. The total water soluble peptides from whey fermentation were subjected to ACE inhibitory assay (in vitro) for screening. The selected fractions were injected to RP-HPLC, equipped with a Delta Pak C18 column (30 x 150 mm). Each peptide was purified by RP-HPLC on the same column using a binary gradient and subsequently tested for ACE inhibitory activity. Due to their high ACE inhibition rates, the total water soluble peptides produced by Lb. brevis, Lb. helveticus, and Lb. paracasei were selected. The RP-HPLC chromatograms obtained from these fractions showed 3 to 6 active peaks, with their inhibition rates ranging from 11.5% to 56.9%. The sequences of these potentially bioactive peptides were proposed. Though they do not have the inhibiting potency of synthetic drugs commonly used in the treatment of hypertension, these naturally occurring peptides may represent nutraceutical/functional food ingredients.
Session 10, International: Division Lecture and Paper Competition
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