“…Much research has been carried out on the transport of bioactive peptides in Caco-2 cells (Foltz et al, 2007;Iwan et al, 2008). Opioid peptides (Iwan et al, 2008;SienkiewiczSz1apka et al, 2009a), ACE inhibitors (Chua, Jois, Sim, & Go, 2004;Foltz et al, 2008;Zhu et al, 2008) and anti-hypertensive peptides (Quiró s, Dá valos, Lasunció n, Ramos, & Recio, 2008;Sun, Liu, Li, & Qin, 2009) have been shown to cross the epithelial cell monolayer. These studies found that the method of transport was not only dependent on the size of the peptide but also on charge, molecular weight, hydrogen bonding and hydrophobicity (Iwan et al, 2008;Pauletti, Okumu, & Burchardt, 1997;SienkiewiczSz1apka et al, 2009a).…”