Superior high-efficiency and high-throughput volatile flavor extraction of Japanese fermented seasonings by solvent-assisted stir bar solid extraction with reverse extraction.

Fermented seasonings have pleasant flavors that stimulate our appetite. Their flavoring properties change depending on factors such as their materials and fermented conditions. Therefore, a comparative analysis of their flavor is important when evaluating their quality.

Identification of key neoculin residues responsible for the binding and activation of the sweet taste receptor.

Neoculin (NCL) is a heterodimeric protein isolated from the edible fruit of Curculigo latifolia. It exerts a taste-modifying activity by converting sourness to sweetness. We previously demonstrated that NCL changes its action on the human sweet receptor hT1R2-hT1R3 from antagonism to agonism as the pH changes from neutral to acidic values, and that the histidine residues of NCL molecule play critical roles in this pH-dependent functional change.

Non-acidic compounds induce the intense sweet taste of neoculin, a taste-modifying protein.

Neoculin, a sweet protein found in the fruit of Curculigo latifolia, has the ability to change sourness into sweetness. Neoculin turns drinking water sweet, indicating that non-acidic compounds may induce the sweetness. We report that ammonium chloride and certain amino acids elicit the intense sweetness of neoculin.

Identification and modulation of the key amino acid residue responsible for the pH sensitivity of neoculin, a taste-modifying protein.

Neoculin occurring in the tropical fruit of Curculigo latifolia is currently the only protein that possesses both a sweet taste and a taste-modifying activity of converting sourness into sweetness. Structurally, this protein is a heterodimer consisting of a neoculin acidic subunit (NAS) and a neoculin basic subunit (NBS). Recently, we found that a neoculin variant in which all five histidine residues are replaced with alanine elicits intense sweetness at both neutral and acidic pH but has no taste-modifying activity.