In Vitro Assessment of the Impact of Industrial Processes on the Gastrointestinal Digestion of Milk Protein Matrices Using the INFOGEST Protocol

Abstract

The goal of this study was to determine the impact of industrial processes on the digestion of six milk protein matrices using the harmonized INFOGEST in vitro static digestion protocol. First, this method was optimized to simple protein matrices using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion chromatography (SEC) to compare the intestinal protein hydrolysis obtained with increasing quantities of pancreatin. Similar results were achieved with the originally required pancreatin amount (trypsin activity of 100 U.mL−1) and with a quantity of pancreatin equivalent to a trypsin activity of 27.3 U.mL−1, which was thus used to perform the in vitro digestion of the milk matrices. Molecular weight profiles, peptide heterogeneity from LC-MS/MS data, calcium, free amino acid, and peptide concentrations were determined in the gastric and intestinal phases to compare the milk protein digests. Results showed that the industrial process affected not only the protein distribution of the matrices but also most likely the protein structures. Indeed, differences arose in terms of peptide populations generated when the caseins were reticulated or when their calcium concentrations were reduced.

In Vivo and In Vitro Comparison of the DPP-IV Inhibitory Potential of Food Proteins from Different Origins after Gastrointestinal Digestion

“…Dietary proteins were digested following simulated gastrointestinal digestion (SGID) using the INFOGEST protocol [ 35 ] adapted to proteins alone [ 36 ]. The digested proteins and blank digestion (blk SGID) samples were assayed for their ability to inhibit DPP-IV activity at the enterocyte level using live Caco-2 cells.…”

“…Interestingly, all of the proteins except caseins decreased plasma DPP-IV. Caseins are classified as slow-digesting proteins because of their ability to form poorly soluble structures which are prone to gelling at the low pH conditions in the stomach, thereby slowing down digestion [ 36 ]. Indeed, the plasma DPP-IV activity was measured 30 min after oral administration to fasted rats.…”

“…Before starting the in vitro experiments, protein powders were digested according to the INFOGEST harmonized protocol [ 35 ] adapted for protein alone [ 36 ]. In brief, 2 g protein was solubilized in 8 mL ultrapure water and mixed with 8 mL simulated salivary fluid at pH 7.0 for 2 min.…”

An Exploratory Study of the Role of Dietary Proteins in the Regulation of Intestinal Glucose Absorption

“…For in vitro and ex vivo experiments, protein samples were first digested in vitro according to the INFOGEST harmonized protocol ( 12 ) adapted for protein alone ( 13 ). Briefly, 2 g of protein sample (adjusted to % protein content) was solubilized in 8 ml of water and added to the reactor containing 8 ml simulated salivary fluid (SSF – Table 2 ) at pH 7.0, for 5 min.…”

Extraction and Characterization of Protein Concentrates from Limpets (Patella vulgata) and Peptide Release Following Gastrointestinal Digestion

“…The LPC was digested according to the INFOGEST modified protocol. 26 In brief, 8 mL of reconstituted LPC [6% (w/v) protein] was mixed in triplicate with 8 mL of simulated salivary fluid for 2 min at pH 7.0. However, α-amylase was not used in this in vitro digestion experiment as it was desired to examine the effect on protein digestion during the gastrointestinal transit.…”