Bitter/astringent flavors

Definition From Acacia catechu Properties Bitter astringent flavor Uses Natural flavoring agent in foods and beverages... 

Orange sweet (Citrus sinensis (L.) Osbeck, syn. C. aurantium var. dulcis L. Rutaceae). The oil is pale yellow to orange, clear liquid that may become cloudy when chilled. It has a mild bitter, astringent flavor, yield of 0.3-0.5%. Orange oil is generally used in orange flavors and many other natural flavors. 

It has been shown that the aroma of tea is affected by the heat treatment received. Tea aroma and flavor are greatly influenced by catechins and proceeds by more than one pathway. The catechins influence tea aroma and flavor in three ways. First, catechins have a bitter, astringent taste. Second in order to reduce the level of soluble catechins (i.e. in var. assamica), a second heat treatment is required. This refiring produces a stronger roast aroma. Third catechins strongly influence the pyrolysis of B-carotene and L-theanine. 

Acetylpyrrole is characterized by an astringent, bitter, roasted flavor (Winter et al., 1976f). 

Special care should be taken in maintaining wooden barrels. New barrels must be conditioned to eliminate any bitter, astringent off-flavors (Section 13.9.1), by cleaning with steam or boiling water, or by keeping the barrels full of slightly sulfured cold water for a few days. 

The feeding behavior of herbivores is strongly influenced by the secondary products which determine texture, taste, flavor and palatability of plants. Many secondary compounds either deter or attract grazing herbivores in most cases because they have a characteristic (bitter, astringent, aromatic etc.) taste and flavor. Many of the repellent secondary products reduce the fitness if ingested (Table 74). They may be divided into two groups ... 

In addition to their effect on VOO stability and human health, phenolic and volatile compounds are the main responsible for the sensory attributes of VOO (e.g., bitter, astringent, pungent, throat catching), providing this oil with its delicate and unique flavor highly appreciated by costumers [6, 82, 83]. Recent studies showed that the sensory intensity of the bitterness attribute in VOO is associated mainly to secoiridoid derivatives of hydroxytyrosol, particularly 3,4-DHPEA-EDA and... 

The natural moisture of the cocoa bean combined with the heat of roasting cause many chemical reactions other than flavor changes. Some of these reactions remove unpleasant volatile acids and astringent compounds, partially break down sugars, modify tannins and other nonvolatile compounds with a reduction in bitterness, and convert proteins to amino acids that react with sugars to form flavor compounds, particularly pyrazines (4). To date, over 300 different compounds, many of them formed during roasting, have been identified in the chocolate flavor (5). 

Noble, A., Why do wines taste bitter and feel astringent In Wine Flavor (eds A.L. Waterhouse and S. Eberler), American Chemical Society, Washington, DC, 1998, p. 156. 

Phenolic compounds are important components of many fruits, vegetables, and beverages, to which they contribute to flavor, color, and sensory properties such as bitterness and astringency. Recent interest in functional foods and the medicinal use of phenolic compounds have also stimulated interest in their chromatographic separation. 

The complexities and interaction of composition on the quality perception of vermouth is illustrated with wild-apricot-based vermouth (Figs. 8.5-8.7). It shows that sweetness, flavor, and astringency are preferred at a sugar content of 8%, whereas body, appearance, and aroma were preferred at 12% sugar (Fig. 8.5). Body, flavor, aroma, and total acidity were scored better at an alcohol content of 19% (Fig. 8.6). The spice concentration preferred for volatile acidity, total acidity, flavor, and bitterness was 5% (Fig. 8.7), whereas body, sweetness, appearance, and astringency were preferred at a 2.5% level (Joshi et al, 201 la,b). 

Phenolic compounds also contribute directly to the flavor due to their astrin-gency and bitter taste characteristics [11]. In fact, astringency is believed to be due to the interaction between tannins and salivary proteins, resulting in the formation of protein-tannin aggregates in the mouth, as discussed in more detail below [12-15],... 

The manipulation of the cap, the length of time the juice is kept in contact with the skins, and the temperature of fermentation are three important variables available to the enologist to produce a wine of the depth of color and flavor, degree of astringency and bitterness, and general texture and longevity that he wishes his wine to have. Later in the process there are additional variables but none is more important than these three. 

Hydrolytic rancidity results from the hydrolytic degradation of milk lipids. The hydrolysis is catalyzed by lipases and produces free fatty acids (FFAs), some of which have a low flavor threshold and can cause unpleasant flavors in milk and milk products. These flavors are variously described as rancid, butyric, bitter, unclean, soapy or astringent. The lipases involved are of two types indigenous milk enzyme(s) and enzymes of microbial origin. 

Classical liquid-liquid, liquid-solid and fractional crystillization can also be used before preparative and analytical HPLC to concentrate trace flavor active components. Huang et al. (59) used these classical techniques to isolate a nonvolatile bltter/astringent fraction from soy flour. The bitter fraction was further separated using preparative HPLC. Seven peak fractions were separated and the flavor characteristics of each collected peak determined. The reverse phase analytical separation of the bitter peak fraction produced six well resolved peaks. These peaks were further collected and identified using UV and NMR spectroscopy. 

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