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The o-quinones, themselves, are colorless, however they react with other phenolic compounds and can self-polymerize to form compounds which produce the brown color associated with apple oxidation (Nicolas et al.). This oxidation process forms a thin brown layer on the exposed surface of the apple.
The rate of browning in different apple types is dependent on both the concentration of polyphenol oxidase and polyphenols within the apple (Nicolas et al.). Decreased levels of either component within the oxidation reaction can slow the browning process. Apples which exhibit slow browning are often specifically chosen by farmers and the food industry, leading to a genetic selection of fruits with lower or less active polyphenol oxidase and polyphenols (Nicolas et al.). The activity of polyphenol oxidase can also be perturbed by thermal denaturation via heating or by coating the exposed apple with ascorbic acid, thus lowering the pH (Nicolas et al.). Ascorbic acid is also an effective...
The enzymatic oxidation can similarly be slowed by placing the apple within a colder environment.
Limiting the exposure of the apple to oxygen will also slow oxidation. Preventing diffusion of oxygen to the sliced or punctured apple will consequently limit the presence of oxidizing agent needed to generate the modified and polymerized o-quinones (Nicolas et al.). Placing a cut apple within an anoxic environment or within water will prevent oxygen from gaining rapid access and will thus slow the reaction (Nicolas et al.). Coating the apple with honey or syrup may accomplish a similar effect (Nicolas et al.).
Works Cited
Kotz, John C., Paul Treichel, and John R. Townsend. Chemistry and chemical reactivity. Cengage Learning, 2008.
Nicolas, JJ et al. "Enzymatic browning reactions in apple and apple products." Critical Reviews in Food Science and Nutrition 34.2 (1994):…
Works Cited
Kotz, John C., Paul Treichel, and John R. Townsend. Chemistry and chemical reactivity. Cengage Learning, 2008.
Nicolas, JJ et al. "Enzymatic browning reactions in apple and apple products." Critical Reviews in Food Science and Nutrition 34.2 (1994): 109-157.
2005). The rules for deep-sea life are different than those for terrestrial species. Stratification plays an important role in species classification in vent environments. As the chimney grows in height the environment changes. Tarasov and associates believe that deep-sea vents have a longer evolutionary history then shallow vents found closer to the surface. This is an important factor in understanding how hydrothermal vents are connected to early life on planet
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Chocolate: Behind Its Bad Rap In today's society, chocolate is everywhere. It seems that people have developed a love-hate relationship with chocolate. According to the U.S. Department of Commerce, in 1997, the average American ate 11.7 pounds of chocolate. American adults ranked chocolate as the most-craved food and as their favorite flavor by a three-to-one margin. (Mustad, 2001) Throughout the world, exists a society of chocolate lovers. While Americans consume, on average,