2,3-Dimethylpyrazine (3DP) and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) generated by the Maillard reaction in foods affect autonomic nervous activity and central nervous activity in human

Figures & data

Figure 1. The chemical structures of 3DP and DMHF.

Figure 2. The location design of a measurement channel of a probe holder in near-infrared spectroscopy.

Figure 3. POMS 2® scores for air (control) and odor inhalation.

Mean±SE (n = 26) of (a) the Maillard reaction sample, (b) 3DP, (c) DMHF. AH: anger-hostility; CB: confusion-bewilderment; DD: depression-dejection; FI: fatigue-inertia; TA: tension-anxiety; VA: vigor-activity; F: friendliness. *: p < 0.05; ^§: p < 0.001, vs. before inhalation, compared by paired t-test.

Figure 4. Effect of the odor of the Maillard reaction sample, 3DP, and DMHF on physiological parameters.

Mean±SE (n = 26) of (a) miosis rate of the pupillary light reflex, (b) fingertip temperature, (c) flicker frequency value. ^§: p < 0.001; ^‡: p < 0.005; ^††: p < 0.00001 by paired t-test.

Table 1. Changes in oxy-Hb concentration (mM/mm) before and during odor inhalation of the Maillard reaction sample, DMHF, and 3DP (n = 26).

	Maillard reaction sample			3DP^1			DMHF^2
Channel no.^3	⊿Mean^4	SE^5	p^6	⊿Mean	SE	p	⊿Mean	SE	p
1	−0.1999	0.0096	3.88E-64	−0.1476	0.0064	2.27E-72	−0.1311	0.0068	1.04E-57
2	−0.0910	0.0084	6.88E-24	−0.1098	0.0066	2.79E-46	−0.0759	0.0050	2.05E-40
3	−0.2182	0.0094	5.78E-74	−0.1195	0.0057	2.53E-64	−0.0985	0.0046	7.72E-66
4	−0.1342	0.0086	2.66E-42	−0.1442	0.0079	1.97E-53	−0.1044	0.0071	2.44E-38
5	−0.0748	0.0067	2.92E-25	−0.1152	0.0070	9.32E-46	−0.0458	0.0048	2.12E-19
6	−0.1540	0.0105	2.06E-38	−0.1224	0.0077	1.67E-43	−0.1207	0.0073	4.06E-46
7	−0.0872	0.0083	1.02E-22	−0.1349	0.0091	3.08E-39	−0.1237	0.0079	6.08E-43
8	−0.0509	0.0063	1.34E-14	−0.0431	0.0061	9.17E-12	−0.0344	0.0044	8.71E-14
9	−0.1016	0.0086	2.95E-27	−0.1286	0.0082	6.71E-43	−0.0617	0.0048	5.08E-31
10	−0.1112	0.0086	1.96E-31	−0.1440	0.0088	4.27E-45	−0.0806	0.0063	1.55E-31
11	−0.0900	0.0073	5.27E-29	−0.0913	0.0065	1.70E-36	−0.0166	0.0042	1.02E-04
12	−0.1282	0.0090	1.43E-36	−0.1333	0.0087	5.32E-41	−0.0420	0.0052	1.25E-14
13	−0.1578	0.0094	3.77E-47	−0.1450	0.0092	8.59E-43	−0.0864	0.0067	2.01E-31
14	−0.0807	0.0065	1.53E-29	−0.0971	0.0059	3.79E-46	−0.0346	0.0047	1.17E-12
15	−0.1715	0.0081	4.89E-65	−0.1763	0.0082	1.61E-66	−0.0885	0.0055	1.39E-44
16	−0.1653	0.0080	1.09E-62	−0.1576	0.0063	1.48E-81	−0.0792	0.0053	2.91E-39

¹2,3-Dimethylpyrazine.

²2,5-Dimethyl-4-hydroxy-3(2H)-furanone.

³The channel number of a measurement probe holder in NIRS (see Figure 2).

⁴Difference in oxy-Hb concentration between sample odor inhalation and air inhalation (control).

⁵Standard error.

⁶Significance level.

Figure 5. Illustration of changes in oxy-Hb concentration (hemodynamic responses) by NIRS.

Mean of (a) the Maillard reaction sample, (b) 3DP, (c) DMHF for 2 min before odor inhalation and 2 min during odor inhalation. Red color represents an increase in oxy-Hb concentration, and blue color represents a decrease in oxy-Hb.