Considerable knowledge has been accumulated on the biochemical processes occurring during ripening of Cheddar cheese, which in turn has major consequences on flavor and texture development. The present review outlines major metabolic pathways and agents involved in the modification of milk constituents in Cheddar cheese ripening. Mechanisms of volatile flavor and off-flavor production and recent developments in the analysis, both sensory and instrumental, of Cheddar flavor and flavor compounds are also detailed here.

/pdf/flavor-of-cheddar-cheese-a-chemical-and-sensory-perspective-1dwze8j5ek.pdf

Flavor of Cheddar Cheese: A Chemical and Sensory Perspective

Recent studies of the volatile compounds in tea

By application of the aroma extract dilution analysis on the volatile fraction isolated from a black tea infusion (Darjeeling Gold Selection), vanillin (vanilla-like), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel), 2-phenylethanol (flowery), and (E,E,Z)-2,4,6-nonatrienal (oat-flake-like) were identified with the highest flavor dilution (FD) factors among the 24 odor-active compounds detected in the FD factor range of 4−128 Quantitative measurements performed by means of stable isotope dilution assays and a calculation of odor activity values (OAVs; ratio of concentration to odor threshold in water) revealed, in particular, the previously unknown tea constituent (E,E,Z)-2,4,6-nonatrienal as a key odorant in the infusion and confirmed the important role of linalool and geraniol for the tea aroma An aroma recombinate performed by the 18 odorants for which OAVs > 1 were determined in their “natural” concentrations matched the overall aroma of the tea beverage In the black tea leaves, a total of 42 odoran

Characterization of the Key Aroma Compounds in the Beverage Prepared from Darjeeling Black Tea: Quantitative Differences between Tea Leaves and Infusion

The recovery of aroma compounds from waste streams has been accomplished in only a few commercial applications, the best known being the recovery of coffee or cocoa volatiles during processing. The limitation in application is economics. The waste stream must have an adequate concentration of volatiles and the volatiles must be of high value. Few processing operations meet these economic criteria at this time. In the future, the high costs of recovering flavouring materials from waste streams will be partially offset by the saving in disposal costs associated with environmental issues.

Flavour-Isolation Techniques

Application of aroma extract dilution analysis (AEDA) to the volatiles isolated from a commercial Japanese soy sauce revealed 30 odor-active compounds in the flavor dilution (FD) factor range of 8-4096, among which 2-phenylethanol showed the highest FD factor of 4096, followed by 3-(methylsulfanyl)propanal (methional), the tautomers 4-hydroxy-5-ethyl-2-methyl- and 4-hydroxy-2-ethyl-5-methyl-3(2H)-furanone (4-HEMF), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (4-HDF), and 3-hydroxy-4,5-dimethyl-2(5H)-furanone (sotolone), all showing FD factors of 1024. Thirteen odorants were quantified by stable isotope dilution assays, and their odor activity values (OAVs) were calculated as ratio of their concentrations and odor thresholds in water. Among them, 3-methylbutanal (malty), sotolone (seasoning-like), 4-HEMF (caramel-like), 2-methylbutanal (malty), methional (cooked potato), ethanol (alcoholic), and ethyl 2-methylpropanoate (fruity) showed the highest OAVs (>200). An aqueous model aroma mixture containing 13 odorants, which had been identified with the highest OAVs, in concentrations that occur in the soy sauce showed a good similarity with the overall aroma of the soy sauce itself. Heat treatment of the soy sauce resulted in a clear change of the overall aroma. Quantitation of selected odorants revealed a significant decrease in sotolone and, in particular, increases in 2-acetyl-1-pyrroline, 4-HDMF, and 4-HEMF induced by heating.

Characterization of the key aroma compounds in soy sauce using approaches of molecular sensory science

A compact and versatile distillation unit was developed for the fast and careful isolation of volatiles from complex food matrices. In connection with a high vacuum pump (5×10–3 Pa), the new technique, designated solvent assisted flavour evaporation (SAFE), allows the isolation of volatiles from either solvent extracts, aqueous foods, such as milk or beer, aqueous food suspensions, such as fruit pulps, or even matrices with a high oil content. Application of SAFE to model solutions of selected aroma compounds resulted in higher yields from both solvent extracts or fatty matrices (50% fat) compared to previously used techniques, such as high vacuum transfer. Direct distillation of aqueous fruit pulps in combination with a stable isotope dilution analysis enabled the fast quantification (60 min including MS analysis) of compounds such as the very polar and unstable 4-hydroxy-2,5-dimethyl-3(2H)-furanone in strawberries (3.2 mg/kg) and tomatoes (340 μg/kg). Furthermore, the direct distillation of aqueous foods, such as beer or orange juice, gave flavourful aqueous distillates free from non-volatile matrix compounds.

Solvent assisted flavour evaporation – a new and versatile technique for the careful and direct isolation of aroma compounds from complex food matrices

Wolfgang Bahr

Papers

Solvent assisted flavour evaporation – a new and versatile technique for the careful and direct isolation of aroma compounds from complex food matrices