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The objectives of this study were to determine the optimal extraction condition of cassava pulp and their effects on mercury bioaccessibility and bioavailability. The extraction process requires the starch be separated from the fiber by enzyme application. The enzyme reaction conditions for the solubilization were optimized via a response surface methodology (RSM). The selected dependent variable was percentage of neutral detergent fiber (NDF). The highest NDF (79.68%) of crude dietary fiber could be gotten from enzymatic digestion condition of 0.1% of α-amylase (w/v), 0.1% of amyloglucosidase (v/v) and 1% of neutrase (v/v). In addition, NDF affecting the mercury bioavailability was estimated by using in vitro digestion and Caco-2 human intestinal cell model system. In vitro digestion (bioaccessibility) showed that the fiber could reduce mercury bioaccessibility to 2-57% compared with the control (0-1000 mg of NDF in 1 g of fish tissue) in a dose dependent manner. The effect of fish tissue amount (0 - 4 g) on mercury quantification when 500 mg of NDF was added in digestion model test showed that the NDF did assist with reduction of mercury amount in fish tissue from 39% to 21% compared with control (the control lacks NDF). Furthermore, the Caco-2 cell was utilized for evaluation of intestinal cell accumulation and supporting reliable estimating bioavailability. The results showed that the mercury transfer to intracellular range from 9.07-5.97% for control and 6.54- 4.63% in the media containing 500 mg NDF. In conclusion, this study suggests that NDF prepared from cassava pulp could decrease mercury bioavailability by inhibiting the mercury transfer to the aqueous fraction and could be applied in functional food and dietary supplement products. [ABSTRACT FROM AUTHOR]

The ability of modified dietary fiber (MDF) generated from cassava pulp to modulate the bioaccessibility and intestinal absorption of heavy metals may be helpful to mitigate health risk associated with select foods including select fish high in methyl mercury. Using a coupled in vitro digestion/Caco-2 human intestinal cell model, the reduction of fish mercury bioaccessibility and intestinal uptake by MDF was investiaged. MDF was prepared from cassava pulp, a byproduct of tapioca production. The highest yield (79.68%) of MDF was obtained by enzymatic digestion with 0.1% α-amylase (w/v), 0.1% amyloglucosidase (v/v) and 1% neutrase (v/v). MDF and fish tissue were subjected to in vitro digestion and results suggest that MDF may reduce mercury bioaccessibility from fish to 34% to 85% compared to control in a dose-dependent manner. Additionally, accumulation of mercury from digesta containing fish and MDF was only modestly impacted by the presence of MDF. In conclusion, MDF prepared from cassava pulp may be useful as an ingredient to reduce mercury bioavailability from food such as fish specifically by inhibiting mercury transfer to the bioaccessibile fraction during digestion., (© 2016 Institute of Food Technologists®)