Butyric flavour

Methionine can be obtained from enzymatic protein hydrolysates or from petrochemical sources. To a lesser extent than cysteine, it is a raw material in Maillard reactions for the preparation of process flavours and it can also be utilised as a precursor for the chemical preparation of the sulfide methional, which is an important flavour constituent for potato, malt, seafood and many other flavours. Methional can be reduced to methionol, which can be esterified with organic acids to, for instance, methionyl acetate and methionyl butyrate, which are useful compounds for pineapple and other fruit flavours (Scheme 13.16). 

Using the same approach, we can combine all other important volatile ingredients of a strawberry to form specific bases. All fruity esters like ethyl butyrate, ethyl caproate or ethyl isobutyrate can be combined to a fruity base , and all caramel-like ingredients to a caramel base , and so on. Finally, all major flavour characters of a strawberry can be obtained by appropriate combination of only a few bases. 

Flavour and off-flavour compounds of black and white pepper (P. nigrum L.) were evaluated by Jagella and Grosch (1999a,b). Enantioselective analysis of optically active monoterpenes indicated ( )-linalool, (+)-a-phellandrene, (-)-limonene, myrcene, (-)-a-pinene, 3-methylbutanal and meth-ylpropanal as the most potent odorants of black pepper. Additionally, 2-isopropyl-3-methoxypyrazine and 2,3-diethyl-5-meth-ylpyrazine were detected as important odorants of the black pepper sample from Malaysia, which had a mouldy, musty off-flavour. Omission tests indicated a-and (3-pinene, myrcene, a-phellandrene, limonene, linalool, methylpropanal, 2- and 3-methylbutanal, butyric acid and 3-meth-ylbutyric acid as key odorants. A storage experiment revealed that for ground black pepper, losses of a-pinene, limonene and 3-methylbutanal were mainly responsible for deficits in the pepper-like, citrus-like, terpene-like and malty notes after 30 days at room temperature. The musty/mouldy off-flavour of a sample of black pepper was caused by a mixture consisting of 2,3-diethyl-5-methylpyrazine (2.9pg/kg) and 2-isopropyl-3-methoxypyrazine (0.2 (xg/kg). 

Lipolytic rancidity is normally enzymatic, the enzymes responsible usually coming from bacteria or moulds. The effect of lipolytic rancidity is that the level of free fatty acid rises. The effect of this on the product depends very much upon the nature of the free fatty acid liberated. Low levels of free butyric acid from milk fat tend to enhance a toffee by giving it a more buttery flavour, whereas lipolysis of a lauric fat such as HPKO gives free lauric acid, which is an ingredient of, and tastes of, soap. This effect is very unpleasant. 

Lipase splits fatty acids from glycerol to produce free fatty acids, for example, butyric acid. If the original fat is butterfat then at low levels this produces a buttery or creamy flavour. As the free fatty acid content is increased, this strengthens the flavour to cheesy . Normally in toffees free butyric acid is not a problem at any practical level, possibly because of losses during cooking. Other free fatty acids have different flavours. Laurie acid, which is found in nuts, tastes of soap. This is not too surprising as soap often contains sodium laurate. Laurie fat sources, such as hardened palm kernel oil, are often used as a substitute for butter another potential source is nuts, which are sometimes combined with toffee. In any of these cases, lipolytic activity can shorten the shelf life of the product or render it totally unacceptable. 

Keywords prediction, simulation, pervaporation, flavour, ethyl butyrate. 

Flavouring substances that cause only taste impressions are defined as substances that are usually non-volatile at room temperature. Therefore, they are only perceived by the taste receptors [7]. Examples are sucrose (sweet) or caffeine (bitter). Flavouring substances causing odour impressions are volatiles that are perceived by the odour receptors [7]. Examples are ethyl butyrate or dimethyl sulfide. Some flavouring substances are perceived by taste and odour receptors (e.g. acetic acid, butyric acid). 

There are two principal ways for utilization of microorganisms (yeasts, fungi, bacteria) for the production of flavouring substances, i.e. fermentation (de novo biosynthesis) and biotransformation (Tab. 3.7). Fermentation products are usually complex (see 3.2.2.4.). Nevertheless, there are some single flavouring substances that are produced by fermentation, such as acetic, butyric, and propionic acids and others (Tab. 3.8). For biotransformations by microorganisms, suitable substrates are necessary. Some examples are given in Tab. 3.9 and Fig. 3.5. 

AcUu, M. and Zaror, C. Enzymatic Synthesis of Ethyl Butyrate in Water/Isooctane Systems Using Immobilized Lipases. In Progress in Flavour Precursor Studies (Schreier, P. and Winterhalter, P., eds.). Allured Publishing, pp. 483-486 (1993)... 

A professional description of flavours uses as precise descriptors as possible. Chemical analytical results are combined with sensory analysis of the identified components to assess the relative importance and contribution to the flavour profile. Key ingredients or character impact compounds (CIC) are important components sine qua non to impart the typical, product characteristic, flavour, e.g. anethol for anise, eugenol for clove, 3-methyl butyl acetate for banana or ethyl butyrate to improve the juiciness of orange juice. 

CIC (E)-2-hexenal, (E)-2-hexenol, (E)-2-hexenyl acetate and hexanal are responsible for the fresh, green-fruity basic flavour. Ethyl-2-methyl butyrate, hexyl acetate support the fruity-estery note and additional compounds like 3-methyl butyl acetate, hexyl-2-methyl butyrate, damascenone, linalool impart the specific species character. Benzaldehyde intensifies the pip note. 

Lipases release free fatty acids from milk lipids to generate a rancid, butyric, cheesy, fatty, soapy flavour. Most important are the even numbered acids C4 to C20. In cheeses from goats and sheep 4-methyl octanoic acid imparts a strong animal, goaty character. 

The three compounds presented in Table 6.34 are the key odorants of butter [63]. A comparison of the odour profiles of five samples of butter (Table 6.35) with the results of quantitative analysis (Table 6.34) show that the concentrations of these three odorants, which were found in samples 1 and 2, produce an intensive butter aroma. In samples 3 and 5, the concentration of 2,3-butanedione is too low and, therefore, the buttery odour quality is weak. In sample 4, the excessively high butyric acid concentration stimulates a rancid off-flavour. 

The principal constituents of brandy are acetic, butyric, cen.an.thic, and valerianic esters, acetic acid, volatile oil, tannin, and colouring matter. The flavour is due to the cenanthic ester. 

Rum contains a high proportion of volatile acids, and owes its flavour mainly to a mixture of esters, chief among them being ethyl butyrate, formate, and acetate the colouring matter employed consists of caramel. When new, rum has rather a disagreeable odour, but the true... 

Natural fruit aromas are mixtures of certain organic compounds and esters. Synthetic aromas prepared in laboratories are simple mixtures of these same esters and organic compounds. They are used in perfumes, foods and drinks to give taste and pleasant smells. Ethyl acetate, for example, is a colorless liquid with an apple flavour it is known as apple ester and is used in perfumery as a fruit essence. Propyl acetate has the smell of pears, isopentyl acetate that of bananas and ethyl butyrate smells of pineapples. All are colorless liquids. Higher molar mass esters are odorless. 

Rum, which is made by fermenting treacle or molasses, and twice distilling the product, owes its flavour to formic and butyric esters, and is coloured either by ageing in wood, or artificially by means of caramel. 

Japan ND (No. 505) (Cox et al., 1978) is 7 million times the estimated daily intake of methionyl butyrate when used as a flavouring agent. 

Volatile fatty acids p resent in wine may derive from the anabolism of lipids, resulting in compounds with even number of carbon atoms, by oxidative decarboxylation of a-keto acids or by the oxidation of aldehydes. Volatile fatty acids synthesised from a-keto acids are mainly propanoic add, 2-methyl-l-propanoic acid (isobutyric acid), 2-methyl-l-butanoic acid, 3-methyl-l-butanoic acid (isovaleric acid 3-methylbutyric add) and phenylacetic add. From lipid metabolism, the following fatty acids are reported butanoic add (butyric), hexanoic acid (caproic), odanoic acid (caprylic) and decanoic add (capric) (Dubois, 1994). Although fatty adds are charaderized by unpleasant notes (Table 1), only few compounds of this family attain its perception threshold. However, their flavour is essential to the aromatic equilibrium of wines (Etievant, 1991). 

Olives Grey, brown or yellow +++ Off flavour, butyric acid... 

Feijoa are very aromatic fruit they have their best aroma and flavour after natural abscission, but during storage they lose their special flavour. Shaw et al. (1983) reported a decrease in several volatiles, mainly ethyl butyrate, and an... 

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