In vitro gastrointestinal digestibility and peptidomic analysis of frankfurters as influenced by different forms of κ-carrageenan

We used peptide profiling to investigate the effects of different forms of κ-carrageenan (a typical hydrocolloid) on the in vitro gastrointestinal digestibility of frankfurters. All incorporated forms of κ-carrageenan were found to decrease the digestibility of meat proteins in the frankfurters, although the effects varied for some peptide fragments. Particle size analysis and super-resolution microscopy revealed that addition of κ-carrageenan in a water suspension resulted in the lowest protein digestibility for frankfurters, followed by κ-carrageenan in a powder form and in a brine suspension. Peptide profiling identified 63 peptides common to all frankfurters after gastrointestinal digestion. In addition, 9 new peptide fragments related to myofibrillar proteins and sarcoplasmic proteins were observed in digestion products from frankfurters that contained κ-carrageenan. Addition of the κ-carrageenan water suspension resulted in a unique pattern of peptide abundance after gastrointestinal digestion of the frankfurters. This pattern was not observed with the powder or brine suspension, both of which contained higher abundances of myosin peptides. However, it is still unclear how different forms of κ-carrageenan caused changes in specific digestion sites, and further investigation is needed to understand this phenomenon. These findings provide novel insights into the effects of various forms of κ-carrageenan on the digestibility of meat proteins in emulsified meat products.