Impact of Protein Gel Porosity on the Digestion of Lipid Emulsions

Abstract

Abstract:The present study sought to understand how the structure of protein gels impacts lipolysis of gelled emulsions. The selected system consisted of an o/w emulsion embedded within gelatine gels. The gelatine gelled emulsions consisted of a discontinuous network of aggregated emulsion droplets, dispersed within a continuous network of gelatine. The rheology of the gelled emulsions was dominated by the rheological behaviour of the gelatine, at no point was yielding or brittle fracture observed suggesting a gelatine continuous structure rather than a bi-continuous gel. A direct relationship between the speed of fat digestion and gel average mesh size was found, indicating that the digestion of fat within gelatine gelled emulsions is controlled by the gels ability to slow lipase diffusion to the interface of fat droplets. Digestion of fat was facilitated by deposition of the gelatine network, which mainly occurred via surface erosion catalysed by proteases. Overall this work has demonstrated that protein gels can considerably slow the kinetics of lipolysis of gelled emulsions, key for the future development of structures to control fat digestion and or the delivery of nutrients to different parts of the gastrointestinal tract.Introduction:

In vitro digestion of Pickering emulsions stabilized by soft whey protein microgel particles: influence of thermal treatment

“…In particular, since lipid digestion is an interfacial process, largely controlled by the binding of lipase-colipase complex onto the surface of emulsified droplets, it seems possible to alter the kinetics and degree of lipid digestion by modification of the interfacial structures or controlling the transport of lipase [13][14][15] , and in turn to potentially control satiety. However, in most surfactant-and protein-stabilized emulsions, the adsorbed layers are displaced by biosurfactants, in particular bile salts [16][17][18][19][20] .…”

In Vitro Digestion of Lipids in Real Foods: Influence of Lipid Organization Within the Food Matrix and Interactions with Nonlipid Components

“…In this study, the higher gel structure forming capacity of the protein was related to the lower lipase diffusion capacity to the interface of fat droplets. As proteases facilitated the breakdown of the gel network, digestion of fat occurred (Sarkar et al., ). Therefore, the lipid‐protein interaction of our study could be explained in a physicochemical basis similarly.…”

Design principles of food gels

“…As gelation can slow down the diffusion of human digestive enzymes into gel matrices, the digestion of desired food materials can be delayed substantially by embedding them in suitably designed gels. Indeed, a direct relationship between the rate of oil digestion and the average mesh size of the gel is found when oil droplets are embedded in gelatin gels 112 . Beside food gels formed in vitro, some food biopolymers have been demonstrated to form intragastric gels, such as alginate 22 , low-acyl gellan 113 , whey protein-pectin 114 and so on.…”