Behavior of Malondialdehyde and Its Whey Protein Adducts duringIn VitroSimulated Gastrointestinal Digestion

Abstract

The behavior of malondialdehyde and its whey protein adducts in aqueous buffer and fully hydrogenated coconut oil-in-water emulsions stabilized by Tween 20 or by whey protein was studied during in vitro gastrointestinal digestion. The malondialdehyde levels during in vitro digestion depended upon the kind of sample, the location of the whey protein, and the extent of adduct formation before digestion. During gastric digestion, degradation of acid-labile malondialdehyde–whey protein adducts as well as formation of new malondialdehyde adducts with hydrolyzed whey protein was suggested to occur, in addition to the earlier described equilibria with respect to the aldol self-condensation of malondialdehyde and its hydrolytic cleavage. After in vitro digestion, both malondialdehyde and its adducts were present in the digest with malondialdehyde recoveries varying between 55 and 86% depending upon the model system studied. To conclude, the reactivity of malondialdehyde toward (hydrolyzed) proteins does not stop at the point of ingestion.

Influence of Proteins on Bioaccessibility of α-Tocopherol Encapsulation within High Diacylglycerol-Based Emulsions

“…Moreover, only low-molecular-weight- peptides could be observed after the gastric digestion. SPI showed no resistance to pepsin and caused this result [ 61 ]. In the initial SC-coated emulsion, the bands were mainly concentrated in 25–35 kDa, which was the main component of casein ( β - and α s -casein) [ 62 ].…”

“…In the end of the gastric digestion, the oil droplets' surface of SC-coated emulsions was coated with small-molecule peptides (below 10 kDa), which was similar to the SPI-coated emulsion. caused this result [61]. In the initial SC-coated emulsion, the bands were mainly conc trated in 25-35 kDa, which was the main component of casein (β-and αs-casein) [62].…”