Walter Matthey-Doret

Formation of methyl (methylthio)methyl disulfide in broccoli (Brassica oleracea (L.) var. italica)

Abstract Vapour cooking of fresh broccoli did not generate 2,3,5-trithiahexane (TTH) but cutting broccoli into pieces followed by cooking in water allowed the detection of this odorant. The formation of TTH was enhanced upon frozen storage of cut broccoli pieces for a few weeks. Cutting broccoli activates cysteine sulfoxide lyase transforming methylcysteine sulfoxide into methylsulfenic acid, which upon heating gives rise to dimethyl sulfide and dimethyl trisulfide that react to TTH. Thus, enzymatic reactions combined with thermal treatment may favour TTH formation.

Glycerol, an underestimated flavor precursor in the Maillard reaction.

The objective of the present work was to investigate in depth the role of glycerol in Maillard reactions and its potential to act as an active flavor precursor. Reactions using isotopically labeled compounds (various reducing sugars, proline, and glycerol) unambiguously demonstrated that, in addition to its role of solvent, glycerol actively contributes to the formation of proline-specific compounds in Maillard model systems. Additionally, rhamnose and fucose/proline/glycerol systems generated the 2-propionyl-1(3),4,5,6-tetrahydropyridines, known for their roasty, popcorn aroma. Their formation from such systems is unprecedented. The results presented here have direct implications for flavor generation during thermal processing of foods containing glycerol, which is a ubiquitous food ingredient and an underestimated flavor precursor.

The role of lipids in aroma/food matrix interactions in complex liquid model systems

Abstract The release of nine aroma compounds was investigated in complex liquid bouillon-type model systems containing various non-volatile constituents. The relative release was determined by static headspace GC-MS as a function of the bulk composition. Among the non-volatile food constituents studied, fat appeared to be very efficient in binding volatile aroma molecules. This retention by the fat was directly correlated with the intrinsic physical properties of the aroma compounds, such as the water/octanol partition coefficient. The individual effect of the major fat constituents was studied as well, indicating that, for example, even small amounts of phospholipids may effectively retain volatile compounds.

Impact of Boiling Conditions on the Molecular and Sensory Profile of a Vegetable Broth

Low-pressure cooking has recently been identified as an alternative to ambient and high-pressure cooking to provide food with enhanced organoleptic properties. This work investigates the impact of the cooking process at different pressures on the molecular and sensory profile of a vegetable broth. Experimental results showed similar sensory and chemical profiles of vegetable broths when boiling at 0.93 and 1.5 bar, while an enhancement of sulfur volatile compounds correlated with a greater leek content and savory aroma was observed when boiling at low pressure (80 °C/0.48 bar). Thus, low-pressure cooking would allow preserving the most labile volatiles likely due to the lower water boiling temperature and the reduced level of oxygen. This study evidenced chemical and sensory impact of pressure during cooking and demonstrated that the flavor profile of culinary preparations can be enhanced by applying low-pressure conditions.