Bioaccessibility and Cellular Uptake of β-Carotene Encapsulated in Model O/W Emulsions: Influence of Initial Droplet Size and Emulsifiers.

Wei Lu,Alan Kelly,Song Miao

doi:10.3390/nano7090282

Abstract

The effects of the initial emulsion structure (droplet size and emulsifier) on the properties of β-carotene-loaded emulsions and the bioavailability of β-carotene after passing through simulated gastrointestinal tract (GIT) digestion were investigated. Exposure to GIT significantly changed the droplet size, surface charge and composition of all emulsions, and these changes were dependent on their initial droplet size and the emulsifiers used. Whey protein isolate (WPI)-stabilized emulsion showed the highest β-carotene bioaccessibility, while sodium caseinate (SCN)-stabilized emulsion showed the highest cellular uptake of β-carotene. The bioavailability of emulsion-encapsulated β-carotene based on the results of bioaccessibility and cellular uptake showed the same order with the results of cellular uptake being SCN > TW80 > WPI. An inconsistency between the results of bioaccessibility and bioavailability was observed, indicating that the cellular uptake assay is necessary for a reliable evaluation of the bioavailability of emulsion-encapsulated compounds. The findings in this study contribute to a better understanding of the correlation between emulsion structure and the digestive fate of emulsion-encapsulated nutrients, which make it possible to achieve controlled or potential targeted delivery of nutrients by designing the structure of emulsion-based carriers.

Highlights

Carotenoids are a class of natural pigments abundant in plants and fruits that can have many health benefits when consumed at proper levels
Emulsions showed a reduced droplet size with increasing homogenization pressure (HP) used during their preparation (Table 1), which was as observed in many previous studies [15], and no significant difference in droplet size of emulsions stabilized by whey protein isolate (WPI), sodium caseinate (SCN) and Tween® 80 (TW80), processed at similar homogenization pressures, was observed
Droplets of WPI- and SCN-stabilized emulsions were negatively charged, which is mainly attributed to the protein molecules being negatively charged at pH (7.0), which is higher than their isoelectric point

Summary

Introduction

Carotenoids are a class of natural pigments abundant in plants and fruits that can have many health benefits when consumed at proper levels. Several potential mechanisms have been proposed to explain these biological activities, e.g., scavenging free radicals and preventing oxidative damage, altering transcription activity or functioning as precursor of vitamin A [3]. Β-carotene is a representative member of the carotenoids family and has been widely studied due to its high pro-vitamin A activity. Extreme water insolubility and instability greatly limit the health benefits of β-carotene. The delivery of β-carotene requires an encapsulation and protection mechanism. Emulsions are ideal carriers for lipophilic nutrients, such as β-carotene, due to their ease of operation, maintenance of chemical stability, controlled release and potential for target delivery of encapsulated compounds [4]

Methods

Results

Conclusion