Altering the level of calcium changes the physical properties and digestibility of casein-based emulsion gels

Abstract

Casein-based emulsion gels prepared with different types of lipid (i.e. milk fat or rapeseed oil) were formulated with high (774 mg Ca per 100 g) or low (357 mg Ca per 100 g) calcium levels by blending acid and rennet casein. Their physicochemical characteristics (i.e. composition, texture, microstructure & water mobility) and in vitro digestibility were compared to conventionally formulated high-calcium (723 mg Ca per 100 g) emulsion gels made from rennet casein with calcium chelating salts (CCS). CCS-free, high-calcium emulsion gels were significantly (p ≤ 0.05) softer than those with low calcium levels (possibly due to their shorter manufacture time and higher pH) and showed the highest rates of disintegration during simulated gastric digestion. Despite having a higher moisture to protein ratio, the high-calcium emulsion gels containing CCS had broadly similar hardness values to those of high-calcium concentration prepared without CCS, but had higher cohesiveness. The high-calcium matrices containing CCS had quite a different microstructure and increased water mobility compared to those made without CCS and showed the slowest rate (p ≤ 0.05) of disintegration in the gastric environment. Gastric resistance was not affected by the type of lipid phase. Conversely, fatty acid release was similar for all emulsion gels prepared from milk fat, however, high-calcium emulsion gels (CCS-free) prepared from rapeseed oil showed higher lipolysis. Results suggest that food matrix physical properties can be modified to alter resistance to gastric degradation which may have consequences for the kinetics of nutrient release and delivery of bioactives sensitive to the gastric environment.

Controllable Viscoelastic Properties of Whey Protein-Based Emulsion Gels by Combined Cross-Linking with Calcium Ions and Cinnamaldehyde

“…However, a lower Ca 2+ ion level was needed to form the solid emulsion gels in this case. Previous studies have reported that heat treatment increased the gel strength of milk in the presence of CaCl 2 , which can be attributed to unfolding and cross-linking of the thermally denatured proteins. , …”

“…Previous studies have reported that heat treatment increased the gel strength of milk in the presence of CaCl 2 , which can be attributed to unfolding and cross-linking of the thermally denatured proteins. 23,24 Overall, both cinnamaldehyde incorporation and heat treatment affected the texture of Ca 2+ -induced WPI-based emulsion gels. There might be several reasons for this phenomenon.…”

Gastrointestinal Fate of Fluid and Gelled Nutraceutical Emulsions: Impact on Proteolysis, Lipolysis, and Quercetin Bioaccessibility

“…Previous studies have also reported that trapping oil droplets in protein gels can inhibit their lipolysis. 33,34 When the gellan gum content was raised from 0.1 to 0.2%, the rate of lipolysis gradually decreased, which may be attributed to oil droplets being incorporated in more compact gel structures at higher polysaccharide concentrations. In addition, some oil droplets were trapped in polysaccharide-rich zones for the systems containing 0.2% gellan gum (Figure 5), which may also have slowed the access of bile salts and/or lipase to the corn oil.…”

“…We thus monitored the gastrointestinal behavior of nutraceutical emulsions containing 0, 0.1, or 0.2% gellan gum. Gelled emulsions after acidification for 12 h were cut into ∼5.0 mm cubes to simulate oral breakdown, , and then fluid and gelled emulsion samples were taken for lipolysis, proteolysis, and bioaccessibility measurements. Prior to analysis, these samples were diluted with distilled water, so that they had initial corn oil contents of 2.5 wt % (for lipolysis analysis) and 5 wt % (for proteolysis and bioaccessibility analysis), respectively.…”

Nucleic Acids Delivery Into the Cells Using Pro-Apoptotic Protein Lactaptin

“…We have also observed that Ca 2+ stabilizes complexes of RL2 with nucleic acids. It is known that at low concentration divalent cations like Ca 2+ and Mg 2+ promote the condensation of CPP particles into agglomerates (McIntyre et al, 2017). Next, to study the plasmid protection outside the cells and intracellular release of cargo, we confirmed the pDNA release from the complexes by heparin displacement.…”