The vertebrate olfactory system recognizes and discriminates between thousands of structurally diverse odorants. Detection of odorants in mammals is mediated by odorant receptors, which comprise the largest superfamily of G-protein coupled receptors (GPCRs). As with other GPCRs, OR ligands are able to serve as both agonists and antagonists. To understand the correlation of the function of odorant receptors and human olfaction, we examined effects of antagonists of human odorant receptors for odor intensity in sensory evaluation. Screening of odorant receptors for Hexanoic acid revealed that five ORs -OR2W1, OR10A6, OR51E1, OR51I2 and OR51L1- responded to Hexanoic acid dose-dependently, and also some antagonists that inhibited the response of Hexanoic acid-receptors were identified. Next, sensory evaluation was performed to examine whether antagonists of Hexanoic acid-receptors could decreased the Hexanoic acid-odor. As a result, it was found that antagonists weakened Hexanoic acid-odor, suggesting the link between the function of ORs at peripheral level and human olfaction at cognition level.

Modified starches play an important role in producing the texture of processed foods. Main modified starches for food are divided in starch to prevent retrogradation and crosslinking starch to improve stability of viscosity. To add “mochimochi (glutinous, sticky)” texture to food, low-amylose starch or tapioca starch are main choices. Furthermore, to add “sakusaku” (crisp) texture to food, degradable starch is effective. To make fish products more “puripuri” (gelatinous, springiness), oil coated starch can be selected. To keep “funwari” (Soft) texture in bread or cake, pregelatinized starch which contains vegetable oil is preferable. Selecting proper kinds of basic starches or modified starches is important to make the special texture of processed foods.

Menthol is frequently formulated in cooling products as a cooling agent. Menthol elicits a cooling sensation improving thermal comfort. However, high concentration of menthol is known to induce unpleasantness stimulation such as burning sensation. Therefore, to find more comfortable concentration of menthol, we established method to evaluate cooling sensation using neck area of sensitive volunteers. By using this method, we found the sex difference in menthol sensitivity of the subjects, and positive effects of sweating on cooling sensation. Moreover, we discovered the mentholinduced sensory irritation was inhibited by concomitant application of 1,8-cineole, by using Ca²⁺-imaging method focusing on TRP channels.

Many drugs have a bitter taste, which makes them difficult or unpleasant to take medicines for patients, giving rise to noncompliance and thus decreasing therapeutic efficacy. Especially, children, elder people and patients with dysphagia cannot swallow tablets, so powder and liquid formulations and orally disintegrating tablets are preferable as a dosage form for such peoples. However, bitter drugs in solution or dissolved rapidly in saliva from these preparations are directly contact with gustatory cells on tongue, evolving bitterness. Therefore, it is of great importance from a viewpoint of compliance to mask bitterness of the drugs in pharmaceutical fields. In general, physical barrier coating, chemical modification and sensory masking are employed as taste-masking techniques. Among chemical modifications, cyclodextrin (CyD) complexations provide an effective means for masking bitterness of drugs. CyDs are known to form inclusion complexes with various guest molecules in aqueous solution and in solid state and to alter physicochemical properties of the guests through the com plexation. Therefore, the CyD complexation is successfully utilized for improvement of pharmaceutical properties of drugs. This review is concerned with the current application of CyDs to the masking of bitterness and disgusting tastes of drugs and with the mechanism by which CyDs suppress the unpleasant taste. The present information will be useful in design of dosage forms and formulations of drugs with bitter/irritating tastes.