Caseinglicomacropeptide allows the design of smart emulsions undergoing pH-dependent gelation.

MORALES, ROCÍO; MARTINEZ, MARÍA JULIA; PILOSOF, ANA M. R.

Leeds

Congreso; 17th Food Colloids Conference : Application of Soft Matter Concepts; 2018

Caseinglicomacropeptide (CMP) is a valuable peptide for its bioactive as well as for its technological properties. One of the more relevant properties of this peptide is its ability to self-assemble in solution by decreasing the pH below 4.5, leading to gel formation.The objective of present work was to evaluate if CMP based oil/water emulsions may undergo a pH-dependent gelation, thus allowing the design of smart gelled emulsions that could protect bioactive compounds during storage and gastric transit (acid pH). The properties of gelled CMP or CMP/co-emulsifier emulsions (polysorbate (Tween 80, Tw), lecithin, sodium caseinate, gelatin and Arabic gum) and their effect on in vitro lipolysis were studied.The gelation of emulsions was performed by decreasing pH to 2 and 3 with the addition of 1 N HCl, and the gel time was determined. After 24 hours the gelled emulsions were diluted in buffer to pH 6.5 to reverse to the liquid state. The droplet size of the emulsions was determined before and after the reversal of gelation, to evaluate the degree of flocculation or coalescence. Additionally, interfacial studies of CMP and CMP/co-emulsifier were performed in a drop tensiometer to understand the emulsions behaviour.By lowering the pH, the gelation of CMP emulsion was achieved; however, during the acidification necessary to promote gelation the emulsion partially coalesced. Among the co-emulsifiers studied, Tw proved to be the right co-emulsifier for the formation of stable gelled CMP emulsions. It was determined by dynamic light scattering that the formation of a complex between CMP and Tw occurred in the bulk that would adsorb at the oil/water interface leading to stable emulsions. Tw´s molecules would dominate the interfacial behaviour, as determined by the interfacial drop technique. A synergistic interaction between both emulsifiers appears as the basis of this improvement in which Tw would contribute to steric stabilization of oil droplets, hindering the coalescence when decreasing pH.The presence of Tw did not alter the free fatty acid release from CMP-Tw emulsions during an in vitro gastroduodenal digestion model, showing a high degree of lipolysis, similar to single CMP emulsions, even if Tw dominated the oil/water interface. This can be attributed to the interaction between CMP and Tw that hinders the possibility of Tw to interact with bile salts and decrease their availability to remove the lipolysis products from the interface.In conclusion, smart stable CMP based emulsions undergoing a reversible pH dependent sol-gel transition could be designed, allowing a high bioavailability.