Volatile compounds wheat

For estimating the contribution of volatile compounds to bread aroma Rothe and coworkers (S) defined "aroma value" as the ratio of the concentration of some volatile compounds to the taste threshold value of the aroma. This concept was further developed by Weurman and coworkers (9) by introducing "odor value", in which aroma solutions were replaced by synthetic mixtures of volatile compounds in water. These mixtures showed the complexity of the volatile fractions of wheat bread, because none of them resembled the aroma of bread. Recently two variations of GC-sniffing were presented (10-11), in which the aroma extract is stepwise diluted with a solvent until no odor is perceived for each volatile compound separately in the GC effluent. The dilution factors obtained indicate the potency of a compound as a contributor to the total aroma. 

The first comprehensive investigation of the volatiles of wheat bread was carried out by Mulders et al. (11. 16-18). After a qualitative analysis (16-18) which led to the identification of 90 compounds, the authors attempted to get an insight into the sensory relevance of the major components which were found in the headspace extract of white bread. A mixture of the main compounds identified was prepared in water to match the gas chromatogram obtained from the bread sample (11,). The odor of the synthetic mixture resembled that of the fermented dough but not that of wheat bread. 

Crackers are generally subdivided into three basic categories saltines or soda crackers (also known as cream crackers in the United Kingdom), sprayed crackers, and savory crackers (Hoseney, R.C. Wade, P. Findley, J.W. 1988 Soft wheat products in press). They are a class of baked product with a unique flavor and texture. Crackers are usually made of wheat flower, water, fat, yeast and salt by a process that combines fermentation, baking and dehydration to yield a thin low moisture product. Saltines are the simplest cracker with a typical "cracker-like aroma. This paper reviews the basic flavor chemistry of saltine crackers and presents preliminary data on the extraction of volatile compounds from these crackers. 

Volatile Compounds from Vegetative Tobacco and Wheat Obtained by Steam Distillation and Headspace Trapping... 

The purpose of this investigation was to characterize volatiles and study their biogenesis in stalk of burley tobacco and wheat during active growth. A comparision was made of volatile compounds obtained by steam distillation and headspace... 

Our previous results (15) on the composition of wheat SDE volatiles are shown in Table IV. These results support a direct precursor-product relationship between a fatty acid and a specific steam distilled volatile compound, because hexanal and trans 2-nonenal (which presumably originate from their linoleic acid precursor C18 2) account for a larger proportion of the total oil from steam distillates of tobacco stalk than is the case for wheat plants (cf. Table I and Table IV). On the other hand, trans 2-hexenal and the sum of nonadien-aldehydes and alcohols (which presumably originate from linolenic acid C18 3) account for a larger proportion of the oil of wheat than of tobacco stalk. 

Volatile Compounds from Wheat Plants Isolation, Identification, and Origin... 

Volatile compounds have been reported to stimulate germination, in vitro and in vivo, of spores of the fungal pathogens which cause wheat rust diseases. 

The most thorough studies of promotion of fungal development by volatiles was done by French and co-workers (4-6) who showed that volatile compounds in solution or their vapors were effective promotors of rust spore germination. Rusts are diseases found on many species including crop plants such as wheat, corn, beans and others. They are caused by fungi whose life cycle includes multiple development steps with the formation of rust colored uredospores in... 

HAM1LT0N-KEMP AND ANDERSEN Volatile Compounds from Wheat Plants 195... 

Identification of compounds and origin. The volatile compounds isolated by steam distillation-extraction of a wheat sample are listed in Table I. 

Table I. Volatile Compounds Isolated from Vegetative Wheat Tissue...

HAMILTON-kemp and andersen Volatile Compounds from Wheat Plants 199... 

Hansen, B. and Hansen, A. 1994b. Volatile compounds in wheat sourdoughs produced by lactic acid bacteria and sourdough yeasts. Z. Lebensm. Unters. Forsch 198, 202-209. 

Con 1 A number of allelopathic agents besides phenolic acids have been identified in wheat tissue/residues, for example, organic acids, hydroxamic acids, and volatile compounds (Patrick 1971 Lynch 1977 Willard and Penner 1976 Tang and Waiss 1978 Buttery et al. 1985 Shilling et al. 1985 Niemeyer et al. 1989 Blum et al. 1991 Wu et al. 2001 Macias et al. 2005 Mathiassen et al. 2006). A number of these are just as or more phytotoxic than simple phenolic acids. 

Andersen, R.A., T.R. Hamilton-Kemp, P.D. Fleming and D.F. Hilderbrand. 1986. Volatile compounds from vegetative tobacco and wheat obtained by steam distillation and head-space trapping. In Biogenesis of aromas (T.H. Parliment and R. Croteau, eds.). Amer. Chem. Soc. Symp. Series S17i 99-111. 

LOXs are of agricultural significance In so far as they apparently play an Important role In the biogenesis of a number volatile flavor and aroma constituents that can affect food quality. Wheat leaves are particularly active in the generation of volatile compounds and were therefore Investigated to determine the role of LOXs In the generation of these compounds. 

Figure 8 Total ion current chromatograms of volatile compounds isolated from a stored wheat grain sample characterized by a musty-earthy off-odor. The upper chromatogram was acquired in scan mode, whereas the lower one was acquired in multiple ion monitoring mode (see Sec. II). IPMP, 2-methoxy-3-isopropylpyrazme IBMP, 2-methoxy-3-isobutylpyrazine MIB, 2-methylisobomeol TCA, 2,4,6-tri-chloroanisole GEO, geosmin.

Solid-phase microextraction proved to be an efficient and robust method for the isolation of microbial volatile compounds in wheat grain. Matrix... 

Volatiles and cuticular extracts of the wheat stem sawfly, Cephus cinc-tus Norton (Hymenoptera Cephidae), were analyzed. The bifunctional 9-acetyloxynonanal gave the strongest EAD response. Additional EAD-active compounds included 13-acetyloxytridecanal, aldehydes with 9—16 carbon chain lengths, acids with 8—10 carbon chain lengths, and pheny-lacetic acid. The odor of phenylacetic acid was detected instantly by human... 

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