Abstract: Vegetables are the primary carotenoid contributors in the human diet. The relatively low bioaccessibility of carotenoids limits their potential health benefits. In recent years, studies have shown that the particle size of excipient emulsion and processing methods are the important factors affecting the bioaccessibility of carotenoids in vegetables. Therefore, the effect of different particle sizes (200, 500 nm and 10 μm) of excipient emulsion and processing methods (raw and blanching) on the bioaccessibility of β-carotene from spinach were studied using a simulated gastrointestinal tract (GIT) model. The results showed that physical properties (particle size and ζ-potential), microstructure, oil digestibility and bioaccessibility of β-carotene in small-particle-size (~200 nm d3,2) emulsion/spinach mixed system during simulated GIT digestion were significantly different from those in large-particle-size (~10 μm d3,2) emulsion/spinach mixed system (P < 0.05) but not from those in medium-particle-size (~500 nm d3,2) emulsion/spinach mixed system (P > 0.05). The bioaccessibility of β-carotene in the mixed systems containing small- and medium-particle-size emulsions was 28.78% and 28.65%, which was significantly higher than that in the one containing large-particle-size emulsion (12.80%) (P < 0.05). The bioaccessibility of β-carotene during the simulated digestion of spinach in the presence of small-particle-size excipient emulsion was significantly affected by the processing method used (15.66% in blanched spinach, vs 28.78% in raw spinach) (P < 0.05). These results indicate that controlling the particle size of the excipient emulsion and selecting a reasonable way to process fruits and vegetables is of great significance for improving the bioaccessibility of β-carotene in fruits and vegetables.

Key words: excipient emulsion, β-carotene, simulated gastrointestinal tract digestion, bioaccessibility