Phenols flavour compounds

Vanbeneden, N., Gils, R, Delvaux, R, Delvaux, R R. (2008). Formation of 4-vinyl and 4-ethyl derivatives from hydroxycinnamic acids occurrence of volatile phenolic flavour compounds in beer and distribution of padl-activity among brewing yeasts. Food Chemistry, 107, 221-230. http //dx.doi.Org/10.1016/j.foodchem.2007.08.008. 

Conjugates of flavour compounds were also found in milk phenols can be liberated by /i-glucuronidase, arylsulfatase and acid phosphatase from their respective precursors [57]. 

Protein-rich rape seed residues from biodiesel production plants are rich in phenolic compounds, glucocinolates and phytic acid. Phenolic compounds and phytic acid could be used as potent antioxidants in cosmetic and pharmaceutical formulations (Shamsuddin, 1995 Amarowicz and Shahidi, 1994 Wanasundara et al., 1996 Oatway et al., 2001). Derivatives from glucosinolate hydrolysis, including isothiocyanates, thiocyanates and nitriles, could be used as anticarcinogenic agents, biopesticides and flavour compounds (Halkier and Gershenzon, 2006). 

King, B.M., Solms, J. (1982). Interactions of volatile flavour compounds with propyl gallate and other phenols as compared with caffeine. J. Agric. Food Chem., 30, 838-840. 

The smell and taste of plants rely on aroma and fragrance compounds, many of which (besides fhe terpenoids) are derived from phenylpropanoid metabolism. In food and cosmetic industry, such fragrance and aroma compounds play an important economical role. Simple phenolic fragrance compounds are, e.g., eugenol, isoeugenol or (methyl)chavicol (Fig. 4.2), the biosynthesis of which has been clarified recently more complex compounds are phenolic esters. Evolutionary aspects of the bios)mthesis of flavours and scents have been reviewed by Gang (2005). 

CIC Vanillin, the main component in vanilla flavour is the basic key ingredient for the creamy, sweet character. All other volatile flavouring compounds have been identified only in small traces. Among them 2-methoxy phenol and 2-methoxy-4-vinyl phenol are responsible for the phenolic, smoky odour. 4-Methoxy benzalde-hyde, 3,4-methylene-dioxy-benzaldehyde, methyl benzoate and methyl ciimamate impart the warm, powdery, aromatic floral character. Vitispirane adds a fruity, floral topnote. Natural vanilla extract blends very well with other flavourings and it has been modified in different directions ethyl vanillin is used to increase the sweet, creamy vanillin aspect. Tonka beans and coumarin add a full, dried hay, slightly caramel-like custard aspect, supported by the butter notes of diacetyl and 4-hydroxy-decanolide. 

Off-flavours may arise from the activities of all the wild yeasts encountered. Pichia and Candida species will oxidize ethanol in a vessel exposed to air to produce acetic acid, while Saccharomyces diastaticus will attack malto-tetraose and often dextrins to produce ethanol. There are also differences between culture yeast and wild yeast with respect to the production of esters, fusel alcohols, organo-sulphur compounds, hydrogen sulphide, vicinal diketones and other products important in beer flavour. Phenolic flavours are known to be produced by certain wild yeasts. [95]. 

A huge variety of biologically active phenolic compounds containing one or more aromatic rings are found naturally in plant foods, where they provide much of the flavour, colour and texture. The simpler phenolic substances include ... 

EtOH extraction was the most efficient way to improve the flavour of the phloem. A solvent/solid ratio of at least 10 1/kg was needed to achieve a significant change in the taste. The loss of catechins was approximately 27% and that of lignans was 35%. All the catechins and lignans were found from the EtOH extract. Losses of lignans and catechins were smaller with other sovents, but either the taste was not modified or the cost of solvent treatment would be too high. Phenolic compounds like lignans and catechins also have a bitter taste and some improvement in flavour may have occurred because of the lower concentration of these. The disappearance of the characteristic... 

Fig. 7.5 Some phenols and related compounds that are important for the flavour of fruits and...

Vanilla flavour is not only determined and characterised by the vanillin molecule, but also by many more phenolic compounds and vanillin derivatives. Two examples of molecules that recently obtained FEMA-GRAS status are vanillyl ethyl ether and vanillin 2,3-butanediol acetal (Scheme 13.11). Vanillin can be hydrogenated to form vanillyl alcohol, which is also used in vanilla flavours. Vanillyl alcohol can be reacted with ethanol to form vanillyl ethyl ether. Vanillin can also form an acetal with 2,3-butanediol (obtained by fermentation of sugars) catalysed byp-toluene sulfonic acid in toluene. 

Reduction of the sodium chloride level can result in taste problems and flavour shifts. There are several approaches to maintain salt taste. Most often, potassium chloride is used, because it shows the most prominent salty taste of those applicable inorganic salts. Lithium chloride is the most salty salt but cannot be used for toxicological reasons. Most consumers, however, complain about the bitter, chalky taste of KCl-containing formulations. Development of sodium-reduced products using mineral salts is a challenge and the whole product formula has often to be adapted [25]. Therefore, the main focus of the research was the search for masking compounds or technologies to cover the bad taste of KCl, e.g. phenolic acids and derivatives [26] and lactisol [27]. 

The variety of suitable nucleophiles is far greater water, alcohols, phenols, amines and carboxylic acids are commonly used, but others including silanes or compounds with acidic C-H bonds such as malonates have been reported as well. The resulting products can, in some cases after further conversion, be used in many different applications, such as nonionic surfactants, emulsifiers, fragrances, flavouring agents, cosmetics and polymer components. 

An extension of our hypothesis to flavour-active nucleotides seems to be possible because these compounds also have negative charges at two different points of the molecule in addition to the acidic phosphate group, they also possess a phenolic hydrogen. 

Vanilla essence comes in two forms the actual extract of the seedpods and the far cheaper synthetic essence, basically consisting of a solution of synthetic vanillin in ethanol. Natural vanilla is an extremely complicated mixture of several hundred different compounds, versus synthetic vanillin which is derived from phenol and is of high purity. Many commercial vanilla extracts are now actually blends of natural and synthetic vanillin. The occurrence of several non-vanillin aroma and flavour components in minor or trace amounts in beans is the reason for their organoleptic superiority over synthetic vanilla and blends. Natural vanilla has a delicate, rich and mellow aroma and aftertaste, while the synthetic material is quite heavy, grassy and less pleasant. 

Hartman, T.G., Karmas, K., Chen, J., Shevade, A., Deagro, M. and Hwang, H. (1992) Determination of vanillin, other phenolic compounds, and flavours in vanilla beans. In Ho, C.-T., Lee, C.Y. and Huang, M.T. (eds) Phenolic Compounds in Food and Their Effects on Flealth I, ACS Symposium Series No. 506. American Chemical Society, Washington, DC, pp. 60-76. 

The composition of the volatile oil, which determines the odour and flavour characters, has been of particular interest to chemists. Ajowan oil is composed of phenols, terpenes and p-cymene. The essential oil contains more than 27 compounds, of which thymol (61%) is the major one, the others being paracymene (15.6%), y-terpinene (11.9%), (3-pinene (4-5%), dipen-tene (4-6%), camphene and myrcene. The essential oil composition of ajowan seed is given in Table 16.3. 

Unfortunately, uncontrolled MLF also presents a risk of wine spoilage by compounds that can produce off-flavours (including acetic acid, volatile phenols and mousiness) or that may be hazardous to human health (such as ethyl carbamate and biogenic amines). The most important aspects of the development of LAB and MLF in wines are dealt with in this chapter. 

Grape compounds which can enter the yeast cell either by diffusion of the undissociated lipophilic molecule or by carrier-mediated transport of the charged molecule across the cell membrane are potentially subject to biochemical transformations by enzymatic functions. A variety of biotransformation reactions of grape compounds that have flavour significance are known. One of the earlier studied biotransformations in yeast relates to the formation of volatile phenols from phenolic acids (Thurston and Tubb 1981). Grapes contain hydroxycinnamic acids, which are non-oxidatively decarboxylated by phenyl acryl decarboxylase to the vinyl phenols (Chatonnet et al. 1993 Clausen et al. 1994). 

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