Physiological comparability of the harmonized INFOGEST in vitro digestion method to in vivo pig digestion

Abstract

Recently, a static in vitro digestion (IVD) protocol was published by Minekus and coworkers (Minekus et al., 2014) within the COST INFOGEST network. The protocol, concentrating on physiological enzyme activities had the main goal to improve the comparability of experimental data between labs. The protocol was validated in several inter-laboratory studies using skim milk powder (SMP) and indeed demonstrated improved harmonization compared with previous experiments with individual IVD protocols (Egger et al., 2016). Although the enzyme activities and salt concentrations of the harmonized protocol are based on available human in vivo data, confirmation of the protocol's physiological relevance has been lacking until now. The main goal of the study was therefore to compare the harmonized IVD protocol with data from in vivo digestion. Towards this aim, an in vivo pig experiment with the same SMP as used for the validation of the IVD protocol was performed followed by a comparison of protein hydrolysis between in vivo and in vitro results. Protein hydrolysis at different levels was analyzed with gel electrophoresis, mass spectrometry, high performance liquid chromatography, and spectrophotometric o-phthaldialdehyde determination of free amino acids. Principle component analysis was used for graphical data comparison. Milk proteins detected after gastric IVD corresponded to gastric and duodenal in vivo samples and intestinal IVD samples corresponded to distal jejunal in vivo samples. Peptides identified after the gastric phase of IVD, correlated with in vivo gastric samples (r=0.8) and intestinal IVD peptides correlated best with in vivo samples collected from the median jejunum (r=0.57). Free amino acids were in both systems mainly released during the intestinal phase of digestion. Protein hydrolysis in the harmonized IVD was similar to in vivo protein hydrolysis in pigs at the gastric and intestinal endpoints. Therefore, the harmonized static in vitro protocol is suited to study protein hydrolysis at these endpoints.

Gastrointestinally Digested Protein from the Insect Alphitobius diaperinus Stimulates a Different Intestinal Secretome than Beef or Almond, Producing a Differential Response in Food Intake in Rats

“…We worked with complex mixtures of dietary components that underwent a transformation during the digestion process. We simulated the in vivo digestion process with the INFOGEST harmonized protocol [32], which is very close to in vivo pig protein hydrolysis, as demonstrated by Egger et al [46]. It has been shown that protein hydrolysates have different effects on the enteroendocrine system, mainly due to the presence of specific peptides [47].…”

Gastrointestinal Digestion of Food Proteins under the Effects of Released Bioactive Peptides on Digestive Health

“…Authors suggested that despite data were inconclusive and more studies are still needed, there is some evidence indicating that differences in i) kinetics of protein hydrolysis, ii) amino acid composition, iii) rate of absorption, and iv) protein/food texture, may have an impact on metabolic aspects related to hunger including the post-prandial use of protein nitrogen, the flux of peptides and amino acids toward bloodstream, and the secretion of hormones and enzymes. [17] The identification of peptides in the gastrointestinal lumen during digestion of milk proteins has been documented in animals, [18][19][20][21][22] and humans, [23][24][25][26][27] . However, data are still scarce and there is a high diversity between these investigations regarding species, ingested products, dairy matrix, gastrointestinal compartments evaluated, and analytical techniques used.…”

Comparative peptidomic profile and bioactivities of cooked beef, pork, chicken and turkey meat after in vitro gastro-intestinal digestion

“…Therefore, with the aim to more closely simulate the in vivo human digestive conditions, we applied in this study, the harmonized basic static in vitro protocol developed within the COST action INFOGEST [16]. Despite its obvious limitation (in vitro static model vs in vivo dynamic digestion), the harmonized INFOGEST in vitro digestion protocol is suitable for the study of digestion of protein-rich food due to its similarity with in vivo digestion [17].…”