Lactones flavoring from

It should be stressed that it is a prerequisite of successful flavor precursor studies that the contribution of the odorant under investigation to a food flavor or off-flavor has been established. Sometimes the structure of a precursor can be assumed on the basis of structural elements in the odorant. In such cases, additions of the respective isotope-labelled precursor to the food system is commonly used to elucidate the precursor and to clarify reaction pathways governing the formation of the odorant. This method has been frequently applied, especially, in studies on the enzymatic generation of odor-active aldehydes (e.g., (Z)-3-hexenal in tea leaves) or alcohols (e.g., l-octen-3-oI in mushrooms) [cf. reviews in 84, 85] as well as lactones [86] from unsaturated fatty acids. 

Lactones derived from oak constitute an important flavorant in most wines aged in barrel. However, because sherries are aged in cask that are rarely emptied or cleaned, they derive few lactones from the wood. Their detection is possible only in stages containing the oldest wine (Chatonnet et ah, 1990). 

Natural food flavors such as terpenes, hydrocarbons, alcohols, aldehydes, ketones, esters, acids, lactones, amines, sulfur compounds are enzymatically produced in fruits and vegetables. On the contrary, processed food develops its characteristic acceptable flavors from chemical reactions within its components at temperatures far below those at which its major components, i.e., lipids, proteins and carbohydrates pyrolyze. 

Figure 7-25 Flavor Character of Some Lactones. Source From R. Teranishi, Odor and Molecular Structure, in Gustation and Olfaction, G. Ohloff and A.F. Thomas, eds., 1971, Academic Press.

Whereas the glucose ester 9 has been identified for the first time as a natural wine constituent, glycoconjugates of its reduced form, i.e. of the monoterpene diol 11, are known Riesling wine constituents (2). Under acidic conditions, diol 11 was partially converted into the bicyclic ether 12, the so-called dillether (2). In analogy to the formation of ether 12 from terpene diol 11, a likely formation of lactone 10 from acid 9A could be be expected (cf. Fig. 5). This so-called wine-lactone 10, first identified as an essential oil metabolite in the Koala (55), has recently been established by Guth (34) as a major aroma contributor in two white wine varieties. The 35,3a5,7aR-configured isomer of 10, which has been identified in wine, is reported to possess an unusual low flavor threshold of 0.01-0.04 pg/L of air and a sweet, coconut-like aroma (55). 

The importance of aliphatic lactones as aroma components in foods is based on their characteristic organoleptic properties. Due to their mostly low odor thresholds averaging about 0.1 ppm (572), lactones often have a high flavor value. Detailed reports 128, 162, 425, 688) exist on the formation of lactones, especially from glycerides, higher fatty acids and short-chain functionalized aliphatic compounds as their precursors. Whereas y-lactones preferentially occur in plants, 5-lactones are mainly found in animal products. Thus, considerable quantities of 5-lactones... 

Do et al. [74] investigated flavor development in peaches as influenced by harvest maturity and artificial ripening. Peaches obtain most of their characteristic flavor from lactones, and of course, these lactones increase as stage of maturity advances. Artificial ripening of the peaches does not result in similar levels of lactones in the ripe fruit. Artificially ripened peaches contained only about 20% of the total lactone content of tree ripened peaches. Benzaldehyde and total esters in the artificially ripened peaches reached only 20% and 50% of their respective concentrations found in tree-ripened fruit. 

Threonine was discovered by Rose in 1935. It is an essential amino acid, present at 4.5-5% in meat, milk and eggs and 2.7-4.7% in cereals. Threonine is often the limiting amino acid in proteins of lower biological quality. The bouillon flavor of protein hydrolysates originates partly from a lactone derived from threonine (cf. 5.3.1.3). 

A. Mosandl, U. Hener, U. Hagenauer-Hener and A. Kuster mann, Stereoisomeric flavor compounds. 33. Multidimensional gas chromatography dkect enantiomer separation of -y-lactones from fr uits, foods and beverages , 7. Agric. Food Chem. 38 767-771 (1990). 

Flavor volatQes from beef and pork fat can be concentrated up to 30-fold by extracting with small quantities of SC-CO2 at low pressure. SC-CO2 concentrated volatile fractions from heated beef tallow have greater numbers of terpenoids, more high molecular weight ketones, more lactones, more esters, more phenols and more branched cyclic and unsaturated aldel des than similar extracts from heated pork fat, but the latter has more 2,4-dienals and higher concentrations of aldel des. 

Natural products are obtained directly from plant or animal sources by physical procedures. Nature-identical compounds are produced synthetically, but are chemically identical to their natural counterparts. Artificial flavor substances are compounds that have not yet been identified in plant or animal products for human consumption. Alcohols, aldehydes, ketones, esters, and lactones are classes of compounds that are represented most frequently in natural and artificial fragrances. 

In addition to mating-disruption pheromones, there are a number of naturally occurring, nonpheromonal attractants and repellents. Many are typically used as food additives or in cosmetics or perfumes, and are derived from diverse plant and animal sources. Capsaicin [44], the spicy component of chili peppers, is used in several bird, deer, and rodent repellents. Maple lactone [45], a common food additive and flavoring, is used in traps to attract cockroaches with its stale beer odor. Methyl... 

Heat-generated flavors, due to the formation of lactones and methyl ketones from hydroxy and keto add precursors, which occur in trace quantities in milk lai. These flavors arc considered to be desirable in fried and baked goods and are partly responsible for the unique condiment properties of butler in food preparation. However, they are undesirable in dried whole milk and evaporated milk where the objective is to make a bland product as much like fresh milk as possible. 

Mosandl, A., Hener, U., Hagenauer-Hener, U., and Kustermann, A. 1989. Stereoisomeric flavor compounds. XXXII. Direct enantiomer separation of chiral y-lactones from food and beverages by multidimensional gas chromatography. J. HighResolut. Chromatogr. 12 532-536. 

A very important lactone in wines is the so-called wine lactone," 3a,4,5,7a-tetrahydro-3,6-dimethyl-2(3H)-benzofuranone 5, which exists in four enantiomeric pairs. This compound was first identified and isolated from the urine of Koala bears (75TL1885, 97JAFC3027), from their diet of the leaves of the Eucalyptus punctata tree. And this shows that the wine lactone belongs to monoterpenoid flavoring ingredients, which have been converted into oxygenated forms. 

Molasses. A large number of volatile and nonvolatile compounds have been identified in the flavor fractions of various types of molasses (51-621. Compound classes identified include aliphatic and aromatic acids, aldehydes, phenols, lactones, amines, esters, furans, pyrazines, and sulfides. Most of these compounds can arise from carbohydrate degradation through a number of traditional pathways especially because residual nitrogen-containing sources are present. 

It is obvious that many of these volatiles contribute to the aroma generated from milk fat by heating. In 1967, Kinsella et al. emphasized the flavor capabilities of milk fat and outlined a scheme for their utilization (7). The lactones and methyl ketones are... 

The flavor constituents of plain and roasted cashew nuts have not been previously reported in the literature. In the present study, aroma compounds have been isolated from plain, oven-roasted and oil-roasted cashew nuts by simultaneous distillation extraction and by steam distillation followed by selective extraction, after pH adjustment. Compound identification was carried out by GC and GC-MS analyses. Esters and lactones are present in plain cashews whereas roasted samples also contain pyrazines. 

To sum up, the flavor constituents of plain and roasted cashew nuts are reported here for the first time. The mild flavor of cashew nuts can be attributed to the carbonyls, esters and lactones, especially to 5-heptene-2-one and 1,3-propanediol diacetate. Upon roasting, 2,6-dimethyl pyrazine, 2,6-diethyl pyrazine and the furanone are formed in larger amounts and from flavor profile also these compounds are likely to play a significant role in the characteristic aroma of roasted cashew nuts. 

There is increasing evidence that the interaction of lipids with the Maillard reaction is relevant to the generation of flavor in many cooked foods. For instance, the removal of lipids from coconut has been shown to cause flavor changes in the roast material (12). Uncooked coconut contained significant amounts of lactones as the main aroma components on roasting pyrazines, pyrroles and furans were also found in the aroma volatiles which added a strong nut-like aroma to the sweet aroma of the unroasted coconut. When ground coconut was defatted and then roasted, the sweet aroma due to lactones disappeared and the product possessed a burnt, nut-like aroma. A marked increase in the number and amount of Maillard reaction products, in particular pyrazines, was found. 

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