Flavor significance

Patton, S., Barnes, I. J. and Evans, L. E. 1959. n-Deca-2,4 Dienal, its origin from lino-leate and flavor significance in fats. J. Am. Oil Chemists Soc. 36, 280-283. 

Quantitatively, the major path of degradation of the Amadori or Heyns Intermediate 1s a dehydration reaction which yields furfural and hydroxymethylfurfural. Of greater flavor significance are the minor pathways which can result in both aromatic products as well as reactive Intermediates. These Intermediates can undergo a retro-aldollzatlon reaction to produce alpha dicarbonyl compounds, such as pyruvaldehyde and diacetyl as well as reactive monocarbonyls, such as glycolaldehyde and glyceraldehyde. 

These observations are in accord with the results of a previous study which demonstrated that the aglycons from a Chardonnay glycosidic fraction wre not a significant source of added arona to the wine fran vrfiich it had been obtained ( ). The present work emphasises the inportance of mild acid hydrolysis and the associated chemical pathways to yield flavor significant volatiles in these non-floral varieties. 

Commonly, the fatty acids in food lipids are exposed to heat during oil processing and food manufacture. Once peroxides are formed, they can decompose and generate free radicals, and the rate of peroxide decomposition increases with temperature. Such reactions are of extreme importance to both consumers and processors, because of their flavor significance, and under frying conditions they can affect the physical, nutritional, and toxological properties of the fried food. 

E. N. Frankel, Chemistry of Autoxidation, Mechanism, Products and Flavor Significance, Flavor Chemistry of Fats and Oils, American Oil Chemists Society Publication, Peoria, Illinois, 1985. 

There are many reports of Pseudomonas cultures producing musty, earthy, and potato-like odors ( l-6). The work of Morgan et al. (T) established 2-methoxy-3-isopropyl pyrazine to be partially responsible for these odors. Subsequently, 2-methyoxy-3-isopropyl pyrazine was found in bell peppers (8), a similar compound 2-methoxy-3-secbutyl pyrazine was identified in galbanum oil (9), and several 2-methoxy-3-alkyl pyrazines were identified in various raw botanicals (10). The odor threshold exhibited by 2-methoxy-3-isobutyl pyrazine (1 part in 10 indicates flavor significance for these compounds even at the exceptionally low concentrations in which they occur in foods and other natural products Producing these compounds from microbial fermentations could be an economical source of flavor for the food industry. 

Frankel, E.N. (1985) Chemistry of autoxidation Mechanism, products and flavor significance, in Flavor Chemistry of Fats and Oils (eds D.B. Min and T.H. S mouse), AOCS Press, Champaign, IL, pp. 1-37. 

Microbial activity can produce off-flavors in several ways the production of undesirable primary metabolites, incidental conversion of food constituents of otherwise little flavor significance, or through residual enzyme activity after cell death [62],... 

The sensitivity of taste or odor panels can be measured by the ability of individuals to detect sensory characteristics. Threshold values are measures of the least concentrations of volatile compounds detected in a food matrix (oil or water) or minimum detectable level by at least 50% of the panelists. This definition is, however, now commonly used to refer to detection by 100% of the panelists. There is a considerable difference in the flavor significance of volatile decomposition products formed in oxidized or rancid lipids. Hydrocarbons have the highest threshold values ranging from 90 to 2150 ppm, and the least impact on flavor. Substituted furans with threshold values of 2-27 ppm, vinyl alcohols with threshold values of 0.5-0.3 ppm, and 1-alkenes... 

Table 5.5. Flavor significance of volatile compounds in oxidized soybean oil (peroxide value 9.5) ...

A large number of volatile compounds have been identified in beef fat (Table 11.17). The flavor significance of individual volatile compounds can be calculated on the basis of their threshold values. Thus, two of the carbonyl compounds formed in the smallest concentrations, c/5-4-heptenal and rran, tran5 -2,6-nonadienal, were the most flavor significant. More sensitive GC-MS analyses reported odor threshold values of 1260 ppb for cw-4-heptenal and 1231 for tra 5, d5 -2,6-nonadienal found among fish oil volatiles (Section E.3 and Chapter 5). On the other hand, the most abundant carbonyl, 2-decenal, was the least flavor significant. 

Carbonyls (in order of concentration) Flavor threshold Flavor significance... 

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