Flavors grapefruit

Food colorants play an important role in quality perception. Color is often the first notable characteristic of a food and it influences the expectations of consumers buying the product and also influences food handlers who make quality-related decisions, for example, during visual inspections." More specifically, color predetermines our expectations and perceptions of flavor and taste. " Color is interrelated with flavor intensity (detection threshold), with sweetness and salinity sensations, and also with our susceptibilities to and preferences for products. For example, consumers perceived a strongly red-colored strawberry-flavored drink to be sweeter than a less colored version, and yellow was associated with lemon and pink with grapefruit, but by reversing the colors, flavor perception changed." If food color is not appealing, consumers will not enjoy the flavor and texture of the food. ... 

A good example is l-p-mcnthene-8-thiol the (R) enantiomer is an important flavor component of grapefruit juice, having a very low olfactory threshold of... 

The major source of lycopene is tomato products but it also occurs in water melons, guavas, pink grapefruit, and in small quantities in at least 40 plants.14 The structure of lycopene is shown in Fig. 8.2. It is a long chain conjugated hydrocarbon and its structure suggests that it would be easily oxidized in the presence of oxygen and isomerized to cis compounds by heat. Both of these reactions occur in purified solutions of lycopene but in the presence of other compounds normally present in tomatoes, lycopene is more stable. Actually the absorption of lycopene in the human gut is increased by heat treatment probably because the breakdown of the plant cells makes the pigment more accessible. Preparations from tomatoes are widely used in pizza, pasta, soups, drinks and any product compatible with the flavor and color of tomatoes. 

In an attempt to influence flavor characteristics, CHS antisense and overexpression constructs were introduced into grapefruit by Agrobacterium tumefaciens [16, 59]. CHS overexpression constructs were shown to lead to morphological abnormalities and frequently to death, while a number of CHS antisense constructs resulted in a statistically significant reduction in flavonoid content in the transgenic plants even though there was a large variation in the flavonoid concentration [16]. 

Grapefruit, typically, has harsher flavor notes. Similar to other citrus oils, grapefruit oil is predominately composed of terpenes. There have been 206 volatile compounds identified in grapefruit juice. However, the flavor impact compounds are more dominant. Nootkatone and l-p-methene-8-thiol are the major compo-... 

Demole, E., Enggist, P., and Ohloff, G. 1982. 1 -p-Menthene-8-thiol A powerful flavor impact constituent of grapefruit juice (Citrus paraadisi Macfayden). Helv. Chim. Acta 65 1785-1794. 

Thiol synthesis. A powerful flavor-impact constituent of grapefruit juice is 1 -p-menthene-8-thiol (3). It has been synthesized by reaction of thiourea with the epoxide I to give 2 followed by reduction with LiAlH4. 

NHD has also been found to suppress naringin bitterness (26). It was suggested as being especially useful in upgrading the flavor of low B/A, early-season grapefruit juice (27). 

Bitterness is a generally undesirable flavor component and is usually detrimental to the quality of citrus products. Any bitterness in orange or tangerine products reduces their quality, whereas, a little bitterness is actually desirable for grapefruit products. However, it has been shown (35) that as the concentration of bitter materials increase, flavor scores and overall product acceptability decrease. Thus, excessive bitterness is usually considered objectionable and the Florida Department of Citrus has enacted regulations which limit the amount of naringin which may be present during the early weeks of the season (36). 

Importance of Selected Volatile Components to Natural Orange, Grapefruit, Tangerine, and Mandarin Flavors... 

In this chapter, we present some specific evidence on certain components important to citrus flavor. The interrelationship of certain volatile components to orange flavor is described and the flavor of grapefruit and the importance of specific compounds to the flavor of mandarin and tangerine are related to recent taste panel studies at our laboratory. 

Although nootkatone is a flavor impact compound in grapefruit, it does not by itself provide the full-bodied flavor provided by good quality cold-pressed grapefruit oil. The proper blend of nootkatone, aldehydes, other as yet unidentified components, and perhaps esters is necessary for full-bodied grapefruit flavor. 

Moshonas, M. G. Analysis of carbonyl flavor constituents from grapefruit oil. J. Agric. Food Chem., 1971, 1 , 769-770. 

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