Esters flavoring from

Many esters have fragrant odors and contribute to the flavors of fruits. For example, benzyl acetate, CH3COOCH2C6Hs, is an active component of oil of jasmine. Other naturally occurring esters include fats and oils. For example, the animal fat tristearin (12), which is a component of beef fat, is an ester formed from glycerol and stearic acid. 

The IUPAC rules name esters as alkyl alkanoates. That is, the portion of the ester derived from the alcohol is named as an alkyl group. The portion of the ester that is derived from the carboxylic acid is named as the conjugate base of that acid. It is easy to distinguish these parts. The half derived from the carboxylic acid has the carbonyl group. Pentyl ethanoate, or pentyl acetate, is one ester used as artificial banana flavoring. Figure 11.51 shows three ester nomenclature examples. 

Esters formed during heating of lipids are contributors to pork flavor. Raw pork contains only a small number of esters, while cooked pork contains significantly more, and acetates are the most prominent volatiles. Esters of cooked pork are derived from C1-Ci0 acids, which impart a fruity sweet note to pork meat (J16). Beef contains a higher proportion of esters derived from long chain fatty acids which possess a more fatty flavor character (16). The characteristic odor of mutton is believed to be due to the evolution of 4-methyloctanoic acid, 4-methylnonanoic acid and similar compounds during heating (17). 

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. 

Butter Flavors. Technologies for the hydrolysis of butter fat to produce and concentrate the free fatty acids to enhance the butter flavor of products have been available for decades. More recently, biotechnologists have developed methods for producing a variety of fairly pure enzymes, economically and in large quantities. The increased availability of lipases (glycerol ester hydrolases) from microbial... 

Esters are colorless, volatile liquids that often have pleasant odors. Many occur naturally in flowers and fruits. Isoamyl acetate (Fig. 7.27a) is generated in apples as they ripen and contributes to the flavor and odor of the fruit. Benzyl acetate, the ester formed from acetic acid and benzyl alcohol (see Fig. 7.27b), is a major component of oil of jasmine and is used in the preparation of perfumes. 

That many chemical substances are not soluble in sc carbon dioxide permits selective extraction.100 It is often used with foods, for which it eliminates the possibility of leaving toxic residues of solvents such as methylene chloride. It also avoids the hydrolysis that might occur when esters (for flavors or fragrances) are recovered by steam distillation. It has been used to extract the flavor from hops, the caffeine from coffee, fat and cholesterol from foods,101 pecan oil,102 lavender oil (for which hydrolysis of linalyl acetate could occur in steam distillation), 103 ginseng (from which it does not extract pesticide residues),104 ginger,105 microalgae,106 cooked chicken,107 ethanol from cider,108 and many others. One method used with aromas and con-... 

Other interesting examples were reported on the use of SILM for the selective separation of the substrates and products of transesterification reactions. The biosynthesis of organic esters commonly used in the perfumery and flavor industries can be carried out by transesteriflcation from vinyl esters and alcohols catalyzed by enzymes in non-conventional media (i.e., n-hexane [88] and IL [90]) at low water content. When the biochemical reaction reaches the equilibrium, the reaction medium could consist of a mixture of alcohol, vinyl ester, organic acid, and alkyl ester (flavor ester). The possibility of using SILMs for the selective separation of these reaction mixtures has been extensively analyzed [30,88,91-93]. 

At present, over a thousand synthetic and natural flavors are available. The majority of these are concentrates or extracts from the material whose flavor is desired and are often complex mixtures of from tens to hundreds of compounds. A number of ester flavoring agents are synthesized industrially. Many have flavors very close to the target flavor, and adding only one or a... 

We can recognize many organic functional groups in compounds we use every day. Pesticides and Freons often contain chlorinated hydrocarbons. Many fruits get their aromas and flavors from aldehydes, ketones, and esters. The sour taste in foods is because of carboxylic acids, and the many rotting smells are due to amines (6.4-6.13). 

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. 

Chloroacetate esters are usually made by removing water from a mixture of chloroacetic acid and the corresponding alcohol. Reaction of alcohol with chloroacetyl chloride is an anhydrous process which Hberates HCl. Chloroacetic acid will react with olefins in the presence of a catalyst to yield chloroacetate esters. Dichloroacetic and trichloroacetic acid esters are also known. These esters are usehil in synthesis. They are more reactive than the parent acids. Ethyl chloroacetate can be converted to sodium fluoroacetate by reaction with potassium fluoride (see Fluorine compounds, organic). Both methyl and ethyl chloroacetate are used as agricultural and pharmaceutical intermediates, specialty solvents, flavors, and fragrances. Methyl chloroacetate and P ionone undergo a Dar2ens reaction to form an intermediate in the synthesis of Vitamin A. Reaction of methyl chloroacetate with ammonia produces chloroacetamide [79-07-2] C2H ClNO (53). 

Polyunsaturated fatty acids in vegetable oils, particularly finolenic esters in soybean oil, are especially sensitive to oxidation. Even a slight degree of oxidation, commonly referred to as flavor reversion, results in undesirable flavors, eg, beany, grassy, painty, or fishy. Oxidation is controlled by the exclusion of metal contaminants, eg, iron and copper addition of metal inactivators such as citric acid minimum exposure to air, protection from light, and selective hydrogenation to decrease the finolenate content to ca 3% (74). Careful quality control is essential for the production of acceptable edible soybean oil products (75). 

Yeast (qv) metabolize maltose and glucose sugars via the Embden-Meyerhof pathway to pymvate, and via acetaldehyde to ethanol. AH distiUers yeast strains can be expected to produce 6% (v/v) ethanol from a mash containing 11% (w/v) starch. Ethanol concentration up to 18% can be tolerated by some yeasts. Secondary products (congeners) arise during fermentation and are retained in the distiUation of whiskey. These include aldehydes, esters, and higher alcohols (fusel oHs). NaturaHy occurring lactic acid bacteria may simultaneously ferment within the mash and contribute to the whiskey flavor profile. 

Much work has been reported and summarized ia the Hterature on the matufing of various whiskeys ia charred or uncharred white-oak barrels (4—7). The early Hterature iadicates that total acids, aldehydes, esters, soHds, and color iacreased with aging time and that their concentrations were iaversely proportional to proof. Thus aging at higher proofs (over 127°) yields less color and flavor. The maximum allowable entry proof for straight whiskeys was iacreased from 110° to 125° by the U.S. Treasury Department ia 1962. 

The organoleptic properties of black tea depend to a considerable extent on the astringency resulting from the interaction of caffeine with the oxidized galloyl ester of the flavanols. The aroma components of black tea also constitute a unique flavor profile that blends well with the taste of the nonvolatile materials. The caffeine provides a moderate level of stimulation, which adds further to the appeal of the beverage, although tea has been shown to provide relaxation as well as revival of character.119... 

Paprika contains capsombin and capsanthin (Fig. 8.3) which occur mainly as the lauric acid esters, and about 20 other carotenoid pigments. Paprika is produced in many countries which have developed their own specialties. Cayenne or cayenne pepper, produced from a different cultivar of C. annum, is usually more pungent. C. frutescens is the source of the very pungent Tabasco sauce. Paprika oleoresin is produced by solvent extraction of the ground powder. Obviously paprika supplies both flavor and color and its use is limited to those products compatible with the flavor. The recent rise in demand for tomato products in the form of pizza, salsa, etc., has increased the demand for paprika. Paprika is used in meat products, soups, sauces, salad dressings, processed cheese, snacks, confectionery and baked goods.1018... 

Mosandl A, Schubert V, Stereoisomeric flavor compounds XXXVII Enantiomer separation of l-alken-3-yl esters and their chirality evaluation from essential oils using multidimensional gas chromatography (MDGC),/ Essen Oil Res 2 121— 132, 1990. 

Some esters play a central role In flavor changes during beer aging. (Adapted from Vesely et ah, 2003)... 

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