Sunlight flavor

The effect of sunlight, ie, the sunstmck flavor in beer, is caused by the formation of mercaptans. The portion of sunlight that is photochemicaHy active is the blue-green region of the visible spectmm (420—520 nm). 

There are two main methods of drying herbs either suspended in bunches, or lying flat on racks or trays. For the enthusiast, electric dryers are available. It is best to dry each type separately, as they tend to dry at different rates. Choose a dark, clean, dry, well-ventilated spot, free from dust and insects. Always dry herbs out of direct sunlight, which causes loss of color and flavor. 

Bassette and Keeney (1960) ascribed the cereal-type flavor in dry skim milk to a homologous series of saturated aldehydes resulting from lipid oxidation in conjunction with products of the browning reaction. The results of Parks and Patton (1961) suggest that saturated and unsaturated aldehydes at levels near threshold may impart an off-flavor suggestive of staleness in dry whole milk. Wishner and Keeney (1963) concluded from studies on milk exposed to sunlight that C6 to Cn alk-2-enals are important contributors to the oxidized flavor in this product. Parks et al. (1963) concluded, as a result of quantitative carbonyl analysis and flavor studies, that alk-2-4-dienals, especially... 

Patton, S. 1954. The mechanism of sunlight flavor formation in milk with special reference to methionine and riboflavin. J. Dairy Sci. 37, 446-452. 

The plant (Piper methysticum) grows best near sea level in areas like the Solomon and Fiji Islands, Samoa, Tahiti and New Guinea. With sufficient sunlight, it can reach twenty feet. The psychic components reside within the root—which after three or four years attains a thickness of three to five inches. The roots in older plants become heavy and knotted, accumulating strength and flavor. After six years, such roots may weigh twenty pounds after twenty years they may be as heavy as a hundred pounds. 

Creamy flavors in butter have been associated with 4-cis heptenal produced for autoxidation of isolinoleic acid (Begeman and Koster, 1964). Drier flavor in foam spray-dried milk has been associated with 6-rra x-nonenal, which has a flavor threshold in fresh milk of 0.07 pg/kg (Parks et al., 1969). Bassette and Keeney (1960) implicated a homologous series of autoxidation-derived saturated aldehydes, together with products of Maillard browning, in cereal-type off-flavors in powdered skim milk. Staleness in dry whole milk may be associated with saturated and unsaturated aldehydes (Parks and Patton, 1961). 2,4-Decadienal has been reported to be the principal compound responsible for the off-flavor associated with spontaneously oxidized milk (Parks et al., 1963). Oxidized flavors in sunlight-exposed milk are commonly related to C6 to Cn alk-2-enals... 

Light-induced oxidation of proteins has been shown to lead to off-flavors and destruction of essential amino acids in milk. Patton (1954) demonstrated that sunlight attacks methionine and converts it into methional (( -methylmercaptopropionaldehyde), which can cause a typical sunlight off-flavor at a level of 0.1 ppm. It was later demonstrated by Finley and Shipe (1971) that the source of the light-induced off-flavor in milk resides in a low-density lipoprotein fraction. 

C. Lumiflavin and lumichrome edso catalyze oxidation of lipids (to Upid peroxides) md methionine (to methional), resulting in the development of an unpleasant flavor - the so-called sunlight flavor. 

The distinctive flavor and bouquet (aroma) of each wine are determined by many factors. Prominent among these are the strain of grape vine used and its growing conditions (e.g., the mineral content and drainage of soil and the amount and intensity of sunlight). 

This is one dark beer. When held up to sunlight in a clear glass, I couldn t see through it at all Auktor Bock is strong. It has a thick, beige head (a bottle cap floats on it ), a pungent, malty aroma, and a rich flavor. This beer could be considered chewable. The hops add enough bitterness to balance the malty flavor. 

This section deals with those reduction defects attributable to vine sprays containing elemental sulfur and various fungicides or insecticides. The risk of sulfur compounds developing due to thermal or photochemical mechanisms ( sunlight flavor ) is also discussed. 

The decrease in redox potential produced by lamps with a solar emission spectrum, or fluorescent tubes, corresponds to the bleaching of white wines by reducing vitamin B2 to its (colorless) form (Figure 8.29). The redox potential of a Champagne may drop by over 100 mV. The confusion between reduction flavor and sunlight flavor is, therefore, quite legitimate. 

Fig. 8.29. Photochemical reduction of riboflavin involved in sunlight flavor ...

These molecules include sulfur amino acids, which play an essential role in sunlight flavor . This phenomenon is directly linked to the appearance of methanethiol and dimethyldisulfide in wines exposed to light, which give them cooked cauliflower or wet wool smells. 

Investigation of the reaction mechanism (Maujean and Seguin, 1983) showed that sunlight flavor was mainly due to the oxidative photodegradation of methionine (Figure 8.30). It was observed that methional was the primary product of oxidative photolysis of the amino acid. 

Fig. 8.30. Sequence of reactions involved in the development of sunlight flavor ( 3 indicates that the oxidized riboflavin reacts in triple state.)...

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