Odor saturated fatty acid

Determining the threshold value is difficult because subthreshold levels of one compound may affect the threshold levels of another. Also, the flavor quality of a compound may be different at threshold level and at suprathreshold levels. The total range of perception can be divided into units that represent the smallest additional amount that can be perceived. This amount is called just noticeable difference (JND). The whole intensity scale of odor perception covers about 25 JNDs this is similar to the number of JNDs that comprise the scale of taste intensity. Flavor thresholds for some compounds depend on the medium in which the compound is dispersed or dissolved. Patton (1964) found large differences in the threshold values of saturated fatty acids dissolved in water and in oil. 

Properties Light amber liquid sour odor. Mp below —40C, bp 120-140C (1 mm), d 1.38 (20C), pH absolution) 1.15. Very corrosive. Miscible with water and saturated fatty acids. 

Several alkyl-branched fatty acids were found to be powerful and characteristic food flavors. 2-Methylbutyric acid is an important constituent of the aroma of cranberry Vaccinium vitis-idaea L.) (77). 3-Methyl-valeric acid and isovaleric acid were identified in tobacco leaves and found to contribute to the distinct sensory properties of Turkish tobacco smoke 590). Isovaleric acid, which has the lowest flavor threshold (0.7 ppm) 522) of all saturated fatty acids, is regarded as an essential flavor component of Limburger cheese (575). ( )-3-Methyl-2-hexenoic acid was recognized as the malodorous component of schizophrenics sweat (579). The undesirable odor of mutton can be attributed to branched-chain and unsaturated fatty acids having 8 to 10 carbon atoms. The 4-methyl-branched acids and in particular 4-methyloctanoic and 4-methyl-... 

Autoxidation of saturated hydrocarbons is, like autoxidation of saturated fatty acids, important at higher temperatures (around 150 °C). The final odorous products formed are mainly fatty acids, their lactones, alcohols and ketones with fewer carbon atoms in the... 

Fish oil contains both high levels of fast drying acids and non-drying acids (saturated and mono-unsaturated acids). As a result it dries more slowly than linseed oil and gives a softer film because of the plasticizing saturated fatty acids present. Fish oil can impart an undesirable odor. 

The hydrogenation step following hydroformylation serves two important purposes. It reduces the aldehyde intermediate product to the desired primary alcohol functional group, which is the primary site of reactivity of the polyol with isocyanates. It also reduces the residual olefins in the FAMEs to saturated hydrocarbons, thus eliminating the pathway to Hock degradation and odor development, which is inherent to other processes that leave fatty acid unsaturation in the polyols. This step eliminates the typical vegetable oil odor from the final namral oil polyols of this process. 

Oil-containing adhesives might emit fatty acid oxidation products like saturated and unsaturated aldehydes which can contribute to odor (Wilke, Jann and Brodner, 2004). Adhesives on a phenol resin base have been found responsible for odor annoyance in several office buildings in former East Berlin. Alkyl-substituted phenols, methyl, dimethyl and ethyl phenols, some of which have very low odor thresholds, have been detected in indoor air as well as in different floor samples and were most likely responsible for the off-odor (Kirchner and Pernak, 2004). 

The relevance of this chemistry is demonstrated by the sensory impressions of linseed-oil based linoleum. Jensen, Wolkoff and Wilkins (1995) studied the autooxidation products emitted from linoleum and identified saturated and unsaturated aldehydes and fatty acids. An odor evaluation of the identified 2-alkenals and the fatty acids as contributing most to odor intensity (Jensen, Wolkoff and Wilkins, 1995), although many odorous products may not be quantified by traditional analytical methods (Knudsen et al., 2007) Knudsen et al. (2007) showed that linseed oil based products exhibited a more negative sensory perception than similar product not containing linseed oil, and that the negative perception persisted for at least a year. 

Canola Oil occurs as a light yellow oil. It is typically obtained by a combination of mechanical expression followed by n-hexane extraction, from the seed of the plant Brassica juncea, Brassica napus, or Brassica rapa (Fam. Cruciferae). The plant varieties are those producing oil-bearing seeds with a low erucic acid (C22 i) content. It is a mixture of triglycerides composed of both saturated and unsaturated fatty acids. It is refined, bleached, and deodorized to substantially remove free fatty acids phospholipids color odor and flavor components and miscellaneous, other non-oil materials. It can be hydrogenated to reduce the level of unsaturated fatty acids for functional purposes in foods. It is a liquid at 0° and above. 

Canola Oil Canola oil is obtained from low erucic acid, low glucosinolate rapeseed. The unique polyunsaturated fatty acid and low saturated composition of canola oil differentiates it from other oils. It has a higher oleic acid (18 1) content (55%) and lower linoleic acid (18 2) content (26%) than most other vegetable oils, but it contains 8-12% of linolenic acid (18 3) (58). Canola oil is most widely used in Canada and is considered a nutritionally balanced oil because of its favorable ratio of near 2 1 for linoleic to linolenic acid content. Unlike most other edible oils, the major breakdown products of canola oil are the cis, trans- and tram, trans-2,4-heptadienals with an odor character generally described as oily, fatty, and putty. Stored canola oil shows a sharp increase in the content of its degradation products, which are well above their odor detection thresholds. The aroma is dominated by cis, tram-, tram, frani-2,4-heptadienals, hexanal, nonanal, and the cis, trans- and... 

Greenish-brown oil. Odor characteristic of green coffee bsans. d 0,9653. ng 1.4790. Iodine no. (Wjjs) 100,72. Seponification no. 195.53 Reichert-Meissl no. 0.36. Saturated acids 33.60%. Unsaturated fatty acids 38.02%, Unsa-ponifiable matter 12.63%. 

In recent years, other saturated and unsaturated aldehydes also attracted considerable attention, because many of them are highly odorous and suspected to be irritative to the eyes and mucous membranes. Such aldehydes are typical oxidative degradation products of unsaturated fatty acids, which are components of many building products for indoor use. In recent years, a variety of analytical techniques have been developed or modified for the simultaneous determination of formaldehyde and higher aldehydes in ambient air. 

Lactones occur as natural odorants in aU major food commodities, including meat and meat products, milk, dairy products, cereals, fruits, vegetables and various beverages, such as tea, wine and spirits. Odour-active compounds in foods are y-and 5-lactones derived from aliphatic saturated and unsaturated y-hydroxycarboxyHc and 5-hydroxycarboxylic acids derived from fatty acids or sugars, but some lactones also arise from other precursors (e.g. mint lactone is a terpenoid compound and pantolactone is produced by hydrolysis of pantothenic acid via pantoic acid). Some lactones derived from aromatic hydroxycarboxyhc acids are also common compounds. The most important representatives of these compounds are phthahdes that are 3fL-isobenzofuran-l-ones (8-98) and coumarins (8-99) that are 2fL-l-benzopyran-2-ones (5-lactones of 2-hydroxycinnamic acids). 

Glycerides are extensively used as butter and lard substitutes in foods, but they must be modified by hydhogenation before being used. This allows control of the melting point and removes impleasant odors. Table 3.15 lists several important unsatirrated fatty acids and the corresponding saturated derivatives. 

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