Cyclodextrin bitter taste

Not only analytical or preparative separations can be performed on cyclodextrin polymer columns, but also undesired components can be removed from aqueous solutions, bitter tasting substances (narin-gin, limonin) can be removed or at least their concentration can be strongly reduced after treatment of citrus juice with cyclodextrin polymers in batch or column process (65,66). Phenylalanine can be eliminated from dietetic protein hydrolysates (67), water-soluble organic substances (e.g. polychlorinated biphenyls (68), 2-naph-talenecarboxylate or phenol can be removed from aqueous solutions (e.g. from pharmaceutical wastewater) by polystyrene-cyclodextrin derivatives (69), by 8-cyclodextrin immobilized on cellulose (70) or by 6-cyclodextrin-polyurethane polymer (71). 

Funasaki, N. Kawaguchi, R. Ishikawa, S. Hada, S. Neya, S. Katsu, T. Quantitative estimation of the bitter taste intensity of oxyphenonium bromide reduced by cyclodextrins from electromotive force measurements. Anal. Chem. 1999, 71 (9), 1733-1736. 

It is also well known that sweet and bitter tastes interact. It is the case for the inhibition of sucrose sweet taste by inhibitors like lactisol or methyl-4, 6-dichloro-4,6-dideoxy-galactopyranoside which was attributed to their hydrophobic character and their bitterness (Mathlouthi et al., 1993). Bitter taste was foimd to be suppressed by sweeteners such as sucrose (Bartoshuk, 1975). The masking of unpleasant taste by pleasant (sweet) stimuli is greatly sought after in pharmaceuticals. For example, cyclodextrins were described to have the ability of masking the bitterness of drugs like propantheline... 

Funasaki, N., Uemura, Y., Hada, S., and Neya, S. Reduction of the bitter taste intensity of propantheline bromide by cyclodextrins as predicted by surface fension measurements, /. Phys. Chem., 100, 16298, 1996. 

Szejtli J, Szente L (2005) Elimination of bitter, disgusting tastes of drugs and foods by cyclodextrins. Eur J Pharm Biopharm 61 115-125... 

The P-cyclodextrin molecule is a cylinder (Fig. 4.11) which has a primary hydroxyl (C6) rim on one side and a secondary hydroxyl (C2, C3) rim on the other. The surfaces made of pyranose rings are hydrophobic. Indeed, the water of hydration is very easily displaced from this hydrophobic cavity by sterically suitable apolar compounds, which are masked in this way. In food processing, P-cyclodextrin is therefore a suitable agent for stabilizing lipophilic vitamins and aroma substances and for neutralizing the taste of bitter substances... 

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