Abstract: The present invention relates to a method for producing a cysteine-rich food material by maintaining a food material containing ?-glutamylcysteine at a ratio of at least 1 wt % to the solid content thereof at a temperature ranging from 50 to 120° C. and at a pH ranging from 1 to 7. This process is conducted in the absence of a sugar and in the presence of water. The present invention also relates to a method for producing a cysteine-rich food material by reacting the food material with a ?-glutamyl peptide hydrolase at a pH ranging from 3 to 9 and at a temperature ranging from 15 to 70° C. in the present of water. Further, the present invention relates to a method for producing a flavor-enhancing material for use in food, food products obtained by these processes, and yeast cells or extracts for use in food products.

Abstract: Herein is disclosed a flavor precursor composition comprising as an active ingredient a flavor precursor compound (flavor precursor compound A) in which a volatile flavor compound having a mercapto group in the molecule and a non-volatile compound having a mercapto group in the molecule are bound to form a disulfide structure, or a flavor precursor compound (flavor precursor compound B) which is an organic compound represented by Formula (1) shown below in which R1H is a non-volatile compound and R2H is a volatile compound having in the molecule a furan ring structure (including a structure where part or all of the carbon—carbon double bonds thereof are hydrogenated) or a thiophene ring structure (including a structure where part or all of the carbon—carbon double bonds thereof are hydrogenated), said Formula (1) being: R1—(S)n—R2 ??(1) which composition can preserve, and release, the flavor effectively and can be used in the fields of fragrances and foods.

Abstract: The present invention relates to a method for producing a cysteine-rich food material by maintaining a food material containing &ggr;-glutamylcysteine at a ratio of at least 1 wt % to the solid content thereof at a temperature ranging from 50 to 120° C. and at a pH ranging from 1 to 7. This process is conducted in the absence of a sugar and in the presence of water. The present invention also relates to a method for producing a cysteine-rich food material by reacting the food material with a &ggr;-glutamyl peptide hydrolase at a pH ranging from 3 to 9 and at a temperature ranging from 15 to 70° C. in the present of water. Further, the present invention relates to a method for producing a flavor-enhancing material for use in food, food products obtained by these processes, and yeast cells or extracts for use in food products.