For many years, it was believed that only amino acids, dipeptides, and tripeptides could be absorbed and thus reach the bloodstream. Nowadays, the bioavailability of oligopeptides is also considered possible, leading to new research. This pilot study investigates the activity of brush border enzymes on undigested whey protein hydrolysate (WPH) and on simulated intestinal digested (ID) whey hydrolysate and the subsequent absorption of resultant peptides through the proximal jejunum of a 7-week old piglet setup in an Ussing chamber model. Amongst all samples taken, 884 oligopeptides were identified. The brush border peptidase activity was intense in the first 10 min of the experiment, producing several new peptides in the apical compartment. With respect to the ID substrate, 286 peptides were detected in the basolateral compartment after 120 min of enzyme activity, originating from β-lactoglobulin (60%) and β-casein (20%). Nevertheless, only 0.6 to 3.35% of any specific peptide could pass through the epithelial barrier and thus reach the basolateral compartment. This study demonstrates transepithelial jejunum absorption of whey oligopeptides in an ex vivo model. It also confirmed the proteolytic activity of brush border enzymes on these oligopeptides, giving birth to a myriad of new bioactive peptides available for absorption.

Whey is well-known for the functional and bioactive properties of its proteins and peptides, which are of great interest to food and nutraceutical industries. The aim of this study was to investigate the effect of four different commercial proteases (Novo ProD® (NPD), Alcalase® (ALC), Pancreas Trypsin® (TRY), and Flavourzyme® (FLA)) in the generation of hydrolysates with emulsifying and antioxidant activities. Hydrolysis processes were carried out for 5 h, reaching maximum degrees of 18.5, 15.5, 9.2, and 8.7% for NPD, ALC, TRY, and FLA, respectively. All tested enzymes generated very diverse, but conservative peptide profiles when comparing the treatments along the time, with the main enzymatic actions up to 120 min-reaction. An increase in the in vitro antioxidant activity was found for all treatments, achieving 46%, 40%, 40% and 22% for ALC, TRY, NDP and FLA, respectively. TRY hydrolysate maintained or slightly increased its emulsifying capacity along the time, however, a decrease in emulsifying capacity was found for ALC and NPD hydrolysates when compared to the non-hydrolyzed whey protein concentrate (WPC). All tested enzymes generated hydrolysates with enhanced antioxidant and/or emulsifying activities, which may be used as food ingredients and the choice of the enzyme will depend on the need.