Hypolipidemic and bifidogenic potentials in the dietary fiber prepared from Mikan (Japanese mandarin orange: Citrus unshiu) albedo.

The albedo is the white part of the citrus peel, which acts as a water reservoir for the juice sacs, seeds and leaves in times of drought. As the functionality of the albedo is unknown, we examined in this study the hypolipidemic and bifidogenic potentials of dietary fiber (DF) prepared from the Mikan (Japanese mandarin orange: Citrus unshiu) albedo. The albedo was obtained from Mikan harvested in Arida, Wakayama Prefecture, and total DF (TDF), water soluble DF (SDF) and water insoluble DF (IDF) were extracted. Albedo TDF contained arabinose (37.21%), galactose (16.05%), xylose (18.30%) and glucose (13.94%), but did not contain detectable amounts of galacturonic acid. Albedo SDF inhibited the enzymatic digestion of triolein by pancreatic lipase in vitro. The SDF, at a concentration of 80 mg per 6 mL of substrate solution, significantly inhibited the activity of this enzyme (>50%). As compared to a control group on a 5% cellulose diet, rats fed a diet containing 1% albedo TDF for 4 wk showed significantly decreased serum triacylglycerol concentrations, increased fecal lipid excretion, and no changes in hepatic lipid content (triacylglycerol, total cholesterol, and phospholipid) or serum concentrations of total cholesterol or phospholipid. Consumption of albedo TDF also increased the number of bifidobacteria in the cecum. In this report, we have demonstrated that consumption of albedo TDF increased the levels bifidobacteria in the rat cecum, and decreased serum triacylglycerol concentrations due to the accelerated lipid excretion into the feces caused by the inhibition of pancreatic lipase.