Volatile compounds affecting

Lawrence, W. C., Volatile Compounds Affecting Beer Flavor, Wallerstein... 

Aparicio, Morales, M.T., Luna, G. and Aparicio-Ruiz, R. (2000) Biochemistry and chemistry of volatile compounds affecting to consumers attitudes of virgin olive oil, in Flavour and Fragrance Chemistry (eds V. Lanzotti and O. Taglialatela-Scafati), Kluwer Academic Press, Dordrecht, The Netherlands, pp. 3-14. 

Volatile Compounds Affecting the Aroma of Vitis vinifera L. cv. Scheurebe... 

Vanhaelen, M., R. Vanhaelen-Fastr6, and J. Geeraerts Isolation and characterization of trace amounts of volatile compounds affecting insect chemosensory behaviour by combined pre-concentration on Tenax GC and gas chromatography. J. Chromatogr. 144, 108—112(1977). 

Hplc techniques are used to routinely separate and quantify less volatile compounds. The hplc columns used to affect this separation are selected based on the constituents of interest. They are typically reverse phase or anion exchange in nature. The constituents routinely assayed in this type of analysis are those high in molecular weight or low in volatility. Specific compounds of interest include wood sugars, vanillin, and tannin complexes. The most common types of hplc detectors employed in the analysis of distilled spirits are the refractive index detector and the ultraviolet detector. Additionally, the recent introduction of the photodiode array detector is making a significant impact in the analysis of distilled spirits. 

Therefore, CL and die depolymerized product from which CL is regenerated contain various impurities which are present in widely fluctuating amounts depending on the reclamation processes involved. In particular, the presence of cyclohexanone, cyclohexanone oxime, octahydrophenazine, aniline, and other easily oxidized compounds affects die permanganate number. Also volatile substances such as aniline, cyclohexylamine, cyclohexanol, cyclohexanone, nitrocy-clohexanone, and aliphatic amines may also be present in the CL.22... 

The trapping efficiency of polymeric, microporous adsorbents [e.g., polystyrene, polyurethane foam (PUF), Tenax] for compound vapors will be affected by compound vapor density (i. e., equilibrium vapor pressure). The free energy change required in the transition from the vapor state to the condensed state (e.g., on an adsorbent) is known as the adsorption potential (calories per mole), and this potential is proportional to the ratio of saturation to equilibrium vapor pressure. This means that changes in vapor density (equilibrium vapor pressure) for very volatile compounds, or for compounds that are gases under ambient conditions, can have a dramatic effect on the trapping efficiency for polymeric microporous adsorbents. 

Although many physiological and biochemical processes In plants are affected by various allelochemicals, In most Instances the details of the mechanism of action of a particular allelochemical have not been elucidated. Because soil mediates the transfer of most allelochemicals (except perhaps volatile compounds) from a donor to a receiver, plant roots are often the first tissues to contact an allelochemical. Thus, It Is not surprising that root growth and development are Inhibited In many Instances of allelopathy (1.-3) One of the primary physiological functions of plant roots Is the absorption of mineral nutrients. Therefore, It Is logical that the Influence of allelopathic Interactions on mineral absorption by plant roots has been Investigated. 

Experiment II. Volatile compounds from leaves and bulbs Volatiles (terpenoids, ethylene and other compounds) can be released from the leaves and other plant parts and consequently can affect the germination of seeds, growth and development of neighbouring plants in ecosystems. 

Exchange of volatile compounds across the air-water interface, e.g., oxygen (reaeration that affects aerobic or anaerobic conditions) and release of odorous substances Release of odorous substances to the urban atmosphere and change of reaeration due to a lower atmospheric oxygen concentration Extent of the processes... 

Escriche, I., Fuentes, C., Gonzalez, C., and Chiralt, A. 2001b. Development of medium volatility compounds in Machego type cheese as affected by salt content and salting method. J. Food Composition Anal. 13, 827-836. 

Compositional differences in the pea seeds influence the quality of the end products. Pea flours have been used for protein enrichment of a number of cereal-based products however, undesirable sensory characteristics may limit their use, in spite of improved functional effects in food systems. The production of volatile compounds during cooking and baking of foods with pea supplementation affects their acceptability. Enzyme systems active in unheated pea flours may contribute to their functional properties, but adversely affect the sensory quality of the food. 

The effect of temperature on the solubility of 5b was investigated in a series of experiments at the same CO2 density (p = 0.75 gcm ). The temperature that generally may affect the solubility of volatile compounds in compressed fluids has only a minor impact on the solubility of the relatively low volatile complex 5b in the investigated range (Fig. 12). At temperatures between 313 and 333 K, approximately the same quantities of 5b are extracted. 

Many factors affect the volatile composition of fruit and vegetables, e.g. genetics, maturity, growing conditions and postharvest handling. Furthermore, preparation of the fruits and vegetables for consumption and the method for isolation of volatile compounds may change the volatile profile and key aroma compounds compared to non-processed fruits and vegetables. 

The four key features of PTR-MS can be summarised as follows. First, it is fast. Time dependent variations of headspace profiles can be monitored with a time resolution of better than 1 s. Second, the volatile compounds do not experience any work-up or thermal stress, and very little fragmentation is induced by the ionisation step hence, measured mass spectral profiles closely reflect genuine headspace distributions. Third, measured mass spectral intensities can be directly related to absolute headspace concentrations, without calibration or use of standards. Finally, it is not invasive and the process under investigation is not affected by the measurements. All these features make PTR-MS a particularly suitable method to investigate fast dynamic process. 

ODOR. An important property of many substances, manifested by a physiological sensation caused by contact of their molecules with the olfactory nervous system. Odor and flavor are closely related, and both are profoundly affected by submicrogram amounts of volatile compounds. Attempts to correlate odor with chemical structure have produced no definitive results, Objective measurement techniques involving chromatography are under development. Even potent odors must be present in a concentration of 1,7 x I07 molecules/cc to be detected. It has been authentically stated that the nose is 100 times as sensitive in detection of threshold odor values as the best analytical apparatus. 

Almost all classes of compounds non-selective Flame ionization detector Non-halogenated volatile compounds (EPA 8015) Phenols (EPA 8041) PAHs (EPA 8100) —All other chemical compounds present in the sample will interfere with the target analytes. —TPH analyses are affected by naturally occurring organic compounds in soils with high humic substance content. 

Figure 4 shows pesticide volatilization as affected by soil depths of 1, 5, and 10 cm with water evaporation (E) equal to 0.25 cm/d. Since the concentration is inversely proporational to the depth of soil containing the 1 kg/ha of pesticide, the ratio of the concentrations roughly explains the initial relative volatilization rates. The very water soluble (Category III) compounds appear to approach a constant volatilization rate regardless of depth because their volatilization is controlled by diffusion of the chemical through the boundary layer above the soil surface as well as by the rate of movement upward to the soil surface. 

Compared to other classes of organic compounds, ethers have relatively low toxicities. This characteristic can be attributed to the low reactivity of the C-O-C functional group arising from the high strength of the carbon-oxygen bond. Like diethyl ether, several of the more volatile ethers affect the central nervous system. Hazards other than their toxicities tend to be relatively more important for ethers. These hazards are flammability and formation of explosive peroxides (especially with di-isopropyl ether). 

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