Estimation of carotenoid accessibility from carrots determined by an in vitro digestion method

Objective: To develop an in vitro digestion method to assess the impact of heat treatment, particle size and presence of oil on the accessibility (available for absorption) of alpha- and beta-carotene in carrots. Design: Raw and cooked carrots were either homogenized or cut into pieces similar to chewed items in size. The carrot samples, with or without added cooking oil, were exposed to an in vitro digestion procedure. Adding a pepsin - HCl solution at pH 2.0 simulated the gastric phase. In the subsequent intestinal phase, pH was adjusted to 7.5 and a pancreatin-bile extract mixture was added. Carotenoids released from the carrot matrix during the digestion were extracted and quantified on high-performance liquid chromatography (HPLC). Results: Three percent of the total g-carotene content was released from raw carrots in pieces. When homogenized (pulped) 21% was released. Cooking the pulp increased the accessibility to 27%. Addition of cooking oil to the cooked pulp further increased the released amount to 39%. The trends for alpha-carotene were similar to those for beta-carotene. Conclusion: The described in vitro digestion method allows a rapid estimation of carotene accessibility in processed carrots, which may reliably predict in vivo behavior.