I. Blank, S. Devaud, W. Matthey-Doret, Ph. Pollien, F. Robert, C. Yeretzian Nestlé Research Centre Lausanne, Switzerland

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1 I. Blank, S. Devaud, W. Matthey-Doret, Ph. Pollien, F. Robert, C. Yeretzian estlé Research Centre Lausanne, Switzerland Weurman 22 / IBk

2 Pyrolysis C, Shigematsu (1976), Mills & Hodge 1 s h (1976), Debrauwer et al. (1991), Yaylayan et al. (1987, 1994, 1996), and others Boiling Autoclave, Huyghues-Despointes et al. (1994), SDE Weenen & van der Ven (21) Results Volatiles More than 1 compounds identified dorants o article dealing with odour impact Weurman 22 / IBk

3 dorants formed from fructosyl proline Identification with focus on odour-active compounds Formation kinetics of key odorants Quantification of four key odorants upon time (GC-, GC-MS) (IDA, SMPE) Formation/degradation kinetics of non-volatile products Quantification of precursors and Maillard intermediates (HPAEC) Dynamic changes of volatile components Qualitative on-line measurements (PTR-MS) Weurman 22 / IBk

4 Reaction conditions Precursors Glucose/L-proline (1:1), Fru-Pro (.2 mol) Buffer Phosphate (5 ml,.2 M, ph 5-8) Temperature Boiling (reflux) Time Up to 7 h Clean-up GC: Solvent extraction, acidic and basic fraction Dionex: Dilution, direct analysis Weurman 22 / IBk

5 Acidic fraction H H H H H CH 3 CH H HCH H H H H H H Basic fraction H H Weurman 22 / IBk

6 Fru-Pro: Caramel-like, roasty Glc/Pro: Roasty, popcorn-like Compound Identification dor quality dor intensity RI (DB-Wax) MS Fru-Pro Glc/Pro Diacetyl 98 + Buttery 2 2 Acetic acid Acidic, pungent 3 3 Furaneol Caramel-like 3 2 Homofuraneol Caramel-like 1-3,4-Dimethyl Caramel-like cyclopentenol-1-one Sotolone Seasoning-like Acetyl-1-pyrroline Roasty, popcorn-like Propionyl-1-pyrroline Roasty, popcorn-like Acetyltetrahydropyridine Roasty, popcorn-like Unknown Roasty 2 2 Weurman 22 / IBk

7 ph K Fru-Pro Glu/Pro Reaction conditions: Glc+Pro or Fru-Pro (.2 mol each) + phosphate buffer (5 ml,.2 M), boiling ph ph Weurman 22 / IBk

8 ph K Fru-Pro Glu/Pro H Reaction conditions: Glc+Pro or Fru-Pro (.2 mol each) + phosphate buffer (5 ml,.2 M), boiling ph ph Weurman 22 / IBk

9 Concentration (mmol/l) ph 7. ph Time (min) (.2 mol Glc +.2 mol Pro + 5 ml phosphate buffer,.2 M, boiling) Weurman 22 / IBk

10 ph K Fru-Pro Glu/Pro Reaction conditions: Glc+Pro or Fru-Pro (.2 mol each) + phosphate buffer (5 ml,.2 M), boiling ph ph Weurman 22 / IBk

11 ph K Fru-Pro Glu/Pro H Reaction conditions: Glc+Pro or Fru-Pro (.2 mol each) + phosphate buffer (5 ml,.2 M), boiling ph ph Weurman 22 / IBk

12 m/z=126: 2-Acetyl-1,4,5,6-tetrahydropyridine HS conc. [ppbv] Reaction time [min] Glu/Pro Fru-Pro m/z = 57: 1-Hydroxy-2-propanone HS conc. [ppbv] Glu/Pro Fru-Pro Reaction time [min] (Schieberle et al., 2) Weurman 22 / IBk

13 HS conc. [ppbv] HS conc. [ppbv] H m/z= 129, Furaneol Reaction time [min] m/z= 145, 3,5-Dihydroxy-2,3-dihydro-6-methyl-4H - pyran-4-one Reaction time [min] H H HS conc. [ppbv] Glu/Pro Fru-Pro HS conc. [ppbv] m/z= 87, 2,3-Butanedione Reaction time [min] m/z= 89, 3-Hydroxy-2-butanone Reaction time [min] Weurman 22 / IBk H

14 Key odorants identified in Fru-Pro are those known in Glc/Pro Furaneol, sotolone, acetic acid, diacetyl, 2-AP, ATHP, etc. Fru-Pro favours formation of furaneol and acetic acid Acetic acid (1-3 mol%), furaneol (.4-.2 mol%) Glc/Pro favours formation of -heterocyclic odorants ATHP (up to.4 mol%), 2-AP (up to.5 mol%) Formation of Fru-Pro is favoured at ph 7 as compared to ph 6 Continuous formation at ph 6, maximum at ph after 1 h of reaction PTR-MS provides new insight into dynamic changes of volatile components Particularly useful in combination with quantitative data Weurman 22 / IBk