Effects of the Amino-Carbonyl Reaction of Ribose and Glycine on the Formation of the 2(or 5)-Ethyl-5(or 2)-methyl-4-hydroxy-3(2H)-furanone Aroma Component Specific to Miso by Halo-Tolerant Yeast

Screening of High-Level 4-Hydroxy-2 (or 5)-Ethyl-5 (or 2)-Methyl-3(2 H )-Furanone-Producing Strains from a Collection of Gene Deletion Mutants of Saccharomyces cerevisiae

“…Therefore, acetaldehyde might accumulate in the same manner as observed in a GPD1-overexpressing strain under conditions of fermentative and osmotic stress. Because adding NaCl to medium containing glucose increased HEMF production in Z. rouxii (16,24,25) and S. cerevisiae (data not shown), the HEMF production pathway, which might utilize acetaldehyde as a C 2 precursor, may serve as a pathway for eliminating the accumulated acetaldehyde under fermentative-and osmotic-stress conditions in yeast. On the other hand, the growth of the yeast cells appeared to be delayed in the HEMF production medium with acetaldehyde (see Fig.…”

“…A 2ϫ YPD medium (2% yeast extract, 4% Bacto peptone, and 4% glucose, pH 6.0) and HEMF production medium were used during HEMF production. The HEMF production medium (416 mM glucose, 200 mM glycine, 200 mM ribose, 7.3 mM KH 2 PO 4 , 20 mM MgSO 4 , and 0.5% yeast extract, pH 6.0) was prepared by heat sterilizing the mixture at 121°C for 15 min, as previously described (16). The HEMF production medium without glucose (HEMF-G medium) was prepared in the same way as the HEMF production medium, except that the glucose was omitted; it was used only during the acetaldehyde or ethanol addition experiments.…”

“…Sasaki et al proposed that the HEMF in soy sauce is biosynthesized by soy sauce yeasts from the sugar phosphates found in the pentose-phosphate cycle, such as D-xylulose 5-phosphate (10,15). However, Sugawara et al and Hayashida et al demonstrated that HEMF formation was promoted by cultivating halotolerant yeast in the medium, including the Maillard reaction products formed from ribose and amino acids, such as glycine (16), alanine (17), and glutamic acid (18), during heat sterilization. Furthermore, Ohata et al demonstrated that the five-member ring and the methyl group on the HEMF side chain were formed from a 5-carbon chemical compound generated by the amino-carbonyl reaction of ribose and glycine (the C 5 precursor) and that the ethyl group on the HEMF side chain was formed from a 2-carbon chemical compound generated by the glucose metabolism of yeast (the C 2 precursor) (19).…”

“…To improve the functionalities in soy sauce with HEMF, soy sauce yeasts that exhibit high-level HEMF production must be bred; however, this goal has not been attained because the HEMF formation pathway in soy sauce is not fully elucidated. S. cerevisiae, which is widely used to produce fermented food (e.g., alcoholic beverages), can generate HEMF under experimental conditions (10,16). Because S. cerevisiae and Z. rouxii are closely related (29,30) and because both can produce HEMF, they should share a fundamental HEMF formation mechanism.…”

Functional properties of soy sauce and metabolism genes of strains for fermentation

“…HEMF, 4‐hydroxy‐2, 5‐dimethyl‐3(2H)‐furanone (HDMF) and 4‐hydroxy‐5‐methyl‐3(2H)‐furanone (HMF) are also found to be antioxidants in soy sauce (Kataoka et al ., ; Nagahara et al ., ). HEMF is detected in the mixture of pentose and alanine, and HDMF instead of HEMF is found in the mixture of pentose and glycine (Sugawara et al ., ).…”