Comparison of static and dynamic in vitro digestibility and bioaccessibility of palm-based emulsions and correlation to a human study: effects of triacylglycerol crystallinity

Abstract

The static and dynamic TIM-1 in vitro digestibility of similarly sized Span 60 o/w emulsions containing either liquid palm olein droplets (PO) or palm stearin (PS) droplets tempered to contain different levels of crystallinity (i.e., PS-SE (maximum), PS-SE-INT (intermediate), and PS-LE (undercooled)) were explored. Static in vitro digestion experiments included particle size analysis, and emulsion digestibility and bioaccessibility were compared between the static and dynamic models, respectively. β-carotene (BC, 0.1 wt%) was also incorporated in the emulsions to determine the influence of triacylglycerol (TAG) crystallinity on BC bioaccessibility and stability during storage under accelerated lighting conditions. TAG crystallinity altered the colloidal fat crystal network properties and ultimately impacted lipid digestion, attenuating early static in vitro lipolysis for the PS emulsions compared to the PO emulsion. This correlated well with TIM-1 bioaccessibility trends and with results from our results of a previous human study wherein the rise in postprandial TAG was delayed when healthy men consumed PS-SE versus PS-LE. The presence of crystalline TAG modestly accelerated BC degradation, and did not improve preservation nor alter BC in vitro bioaccessibility.