The impact of the Maillard reaction on the in vitro proteolytic breakdown of bovine lactoferrin in adults and infants

Abstract

The Maillard reaction has been proposed as a natural pathway to functionalize proteins and modulate their proteolysis. Nevertheless, gaps in understanding the digestive fate of Maillard reaction products (MRPs) still exist, especially regarding bioactive proteins such as lactoferrin (LF). UV absorbance and SDS-PAGE were used to monitor reaction progression under mild thermal processing (60 °C, 79% RH). Dynamic light scattering showed that MRPs had increased colloidal size and turbidity at 3 < pH < 10. FRAP analysis and in vitro digestion experiments demonstrated that MRPs possessed improved antioxidant capacity and higher susceptibility to proteolysis to varying extents under adult conditions compared to infant conditions. Proteomic analyses of MRP digesta revealed altered enzymatic cleavage patterns with no pronounced changes in the formation of known bioactive peptides. These also indicated that MRPs may breakdown in the gastro-intestinal tract to potentially form novel bioactive peptides. Overall, this work highlights that the Maillard reaction could be harnessed to modify the extent of proteolysis and bioactivity of proteins.

Physicochemical properties of β-carotene emulsions stabilized by chlorogenic acid–lactoferrin–glucose/polydextrose conjugates

“…As control samples verified that lyophilisation and physical mixing did not have significant influences on the molecular weight of the protein, analyses were focused on native LF, CA-LF conjugate and CA-LF-Glc/PD conjugates. Initially, intensely colored bands were visible at 80 kDa, corresponding to native LF, which was in agreement with a recently published report (Moscovici et al, 2014). After the incubation of LF with CA, higher molecular weight species were formed, as denoted by the appearance of new bands at molecular weights exceeding that of native LF.…”

Glycosylation improves the functional characteristics of chlorogenic acid–lactoferrin conjugate

“…26 Unheated LF, CA-LF conjugate and mixtures of CA-LF conjugate and Glc/PD were prepared under the same condition, and served as controls. Each sample was adjusted to pH 7.0 and then frozen-dried.…”

Digestibility of glycated milk proteins and the peptidomics of their in vitro digests

“…One‐day glycation of β ‐Lg with glucose at 90 °C generated enormous aggregates with a crosslinked structure, which particularly reduced the sensitivity of glycated protein to digestive proteases . Contrarily, conformational changes in glycated proteins may expose more accessible cleavage sites for digestive proteases, thus increasing protein digestibility . Therefore, effects of glycation on protein digestibility are related to glycation extent and type of heat treatment.…”

“…Although there have been many studies reporting the digestibility of glycated milk protein, most have focused on measuring degree of hydrolysis (DH), showing sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS‐PAGE) images of digests. Detailed information on the digests such as the composition of peptides and glycation information have only been revealed in a few studies . The peptide composition after digestion of a protein is closely related to its nutrition value, bioactivity and effects on gut flora .…”