High Methoxyl Pectin Consistently Reduces β-Carotene Bioaccessibility Across Various Gastrointestinal Digestion Conditions.

Dietary fiber could inhibit β-carotene bioaccessibility by restricting its release from the food matrix, interfering with digestive enzyme activities, binding bile salts, or modifying viscosity and other physicochemical properties of the digesta. In this study, we investigated whether high methoxyl pectin (HMP), a soluble dietary fiber found in fruits/vegetables and an additive for the food industry would impact β-carotene bioaccessibility under various physiological digestive conditions, following the INFOGEST gastrointestinal model. Concentrations of pancreatin plus bile salts and shear forces (simulated by varying water bath rounds/min. and glass bead addition) were modified in the presence (1.15 mg/mL digesta) and absence of HMP. Endpoints measured in the digesta included β-carotene bioaccessibility, surface tension, viscosity, micelle size, zeta potential, and triglyceride lipolysis. Adding HMP reduced overall bioaccessibility of β-carotene from 32.1±6.2% to 24.1±5.7% (p<0.001). All other parameters also had a significant impact on the bioaccessibility of β-carotene, that is, bile/pancreatin concentration (p<0.001), water bath shaking speed (p<0.001), and glass beads (p = 0.001). Surface tension, viscosity, and micelle size were less strongly affected by HMP addition (p<0.05), though not triglyceride lipolysis. The inhibitory effect of HMP varied depending on bile/pancreatin concentration and shear-forces, with strongest reductions when β-carotene bioaccessibility was highest at onset.