Color development during aging

Finally, we try to develop a chemical interpretation for the color of red wine—i.e., the specific role of different substances and the changes they undergo which cause the evolution of wine color, especially during aging. 

Figure 18 Stabilization of an SIS HMA color development during oven aging at 150°C (300°F).

Excessive or insufficient acid development during manufacture can produce variability in the moisture content of cheese and defects in flavor, body, texture, color, and finish (Van Slyke and Price 1952). The rate of lactose fermentation varies with the type of cheese, but the conversion to lactic acid is virtually complete during the first weeks of aging (Van Slyke and Price 1952 Turner and Thomas 1980). Very small amounts of lactose and galactose may be found in cheese months after manufacture. (Huffman and Kristoffersen 1984 Turner and Thomas 1980 Harvey et al. 1981 Thomas and Pearce 1981). Turner and Thomas (1980) showed that the fermentation of residual lactose in Cheddar cheese is affected by the storage temperature, the salt level in the cheese and the salt tolerance of the starter used. 

The phenolic compounds extracted from the fruit contribute to the development and stability of the wine s red color. The color evolution during vinification and aging is mainly due to chemical transformations to the phenolic compound derived from the fruit. Anthocyanins, responsible for the purple-red color of young wines, participate in reactions with other phenolic compounds to generate other, more chemically stable molecules. These changes involve oxidation, polymerization, and other... 

Aromatic amines, such as phenyl- -naphthylamine or condensation products of diphenylamine with acetone condensates, are excellent antioxidants and antiozonants but cause color development. From the sterically hindered phenols, monocyclic phenols, such as 2,6-di-teit-butyl-p-cresol, are less effective antioxidants but remain white and nontoxic during aging. They are, however, volatile and provide poor protection at elevated processing temperatures. Polycyclic phenols, such as 2,2 -methylene-bis (4-methyl-6-teit-butylphenol), are relatively nonvolatile, but become discolored by oxidation to a conjugated system. O Shea... 

An oxidative phase during aging is indispensable to ensure normal color development, particularly in red wines (Ribereau-Gayon et ai, 1983). Excessive oxidation in any type of wine, however, results in an organoleptic defect known as flatness (Section 8.2.3). 

DEVELOPMENT OF THE PHENOLIC CHARACTERISTICS OF RED WINES (COLOR AND FLAVOR) DURING AGING... 

Figure 3 shows the performance during static oven aging at 170°C (338°F) of a stabilized EVA polymer. The base stabilization of the EVA polymer by the producer using AO-1 provided an unsatisfactory level of stability. The presence of skinning and a more pronounced level of discoloration in the base AO-1 stabilized EVA requires additional antioxidant to meet the performance needs of a HMA. Upon the addition of AO-2 to the base polymer, it is clear that the stability of the EVA is improved significantly, skin formation is not observed, and color development is reduced substantially. The formation of insoluble gel as a result of cross-linking is also reduced dramatically with the addition of AO-2, as shown in Fig. 4. 

The lens grows with age, and colorations or opacities may develop and interfere with vision. Cataract formation may be enhanced by some miotics, steroids, and phenothi-azines. Aldose reductase inhibitors, which prevent the conversion of sugars to polyols, appear to prevent or delay diabetic cataract. Levels of glutathione and other compounds drop during the formation of some types of cataracts.The pharmacokinetics of delivery and penetration of such compounds into the crystalline lens is currently of great interest. 

Some of the earliest examples of glazed pottery appeared in India during the Harappan period. (They did not appear in other countries, such as Mesopotamia, until about 1500 yr later.) The use of terracotta was also well known in early India. With the coming of the Indo-Aryans and the Vedic age, pottery became refined in shape, size, color, and strength, indicating an increasing awareness of the quality control needed to develop utensils for use. 

During bottle aging, wines develop in a reducing environment, tending towards greater organoleptic quality than they initially possessed. Besides changes in color, this process results in an increase in the complexity and finesse of aroma and flavor. The time necessary to attain this optimum... 

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