Browning of fruits and vegetables

Additionally, the enzyme is also responsible for the detrimental enzymatic browning of fruits and vegetables [10] that takes place during senescence or damage at the time of postharvest handling, which makes the identification of novel tyrosinase inhibitors extremely important. Nevertheless, besides this... 

These two processes are also referred as cresolase activity or monophenolase activity and diphenolase activity, respectively. Such reactions represent the initial steps of vertebrate pigmentation (melanin biosynthesis) and the browning of fruits and vegetables.Catechol oxidases (EC 1.10.3.1) are ubiquitous plant enzymes, which also catalyze the oxidation of a broad... 

Corse, J. (1964). Enzymatic browning of fruits and vegetables. In Phenolics in Normal and Disease Fruits and Vegetables. (V.C. Runeckles, ed.). p.41. Pergamon Press, New York. 

Tyrosinase also has applications in the food industry, as it is responsible for the browning of fruits and vegetables. Interest in the enzyme has been demonstrated by tannin oil companies due to the role that it plays in melanogenesis. Also, it has been considered for use in melanin-related disorders, such as albinism, vitiligo, and melanoma [9],... 

Delay non-enzymatic browning of fruits and some vegetables. 

PPO catalyses the dependent oxidation of phenolics to quinones. The secondary reactions of quinones lead to the formation of polymeric brown or black pigments, which are responsible for significant post-harvest losses of fruits and vegetables [72]. Finally, induced PPO activity consists of both systemic and localized components. Systemic induction of PPO in tissues in response to all types of injuries may represent a broad, defensive role for PPO in protection of juvenile tissues from subsequent attack by a broad spectrum of pathogens and pests [71]. 

Maxie, E. C., Sommer, N. F., Brown, D. S., Radiation Technology in Conjunction with Postharvest Procedures as a Means of Extending the Shelf Life of Fruits and Vegetables, U. S. Atomic Energy Commission, Research and Development Rept. UCD-34P80-2 (1964). 

L-ascorbic acid (AA) and its isomer D-erythorbic acid (EA) (also called D-isoascorbic acid) have been used as inhibitors of enzymatic browning in fruit and vegetable products for at least 50 years, (15-17). These compounds prevent quinone accumulation and subsequent pigment formation by reducing the 0-quinones generated from the phenolic substrates of PPO back to O-dihydroxyphenolic compounds (17-18). AA also can act as a PPO inhibitor (19-20). AA and EA are used interchangeably although there are indications that AA is more effective in some systems (21-22). 

Studies reviewed herein have demonstrated the potential ability of several new approaches to control enzymatic browning in fruit and vegetable products the use of novel AA derivatives, polyphosphates and (5-cyclodextrin as browning inhibitors the application of browning inhibitors to cut fruits and vegetables by pressure infiltration and the use of cvs. having a low tendency to brown. It is likely that one or more of these approaches will be useful as an alternative to sulfites to control browning in affected commodities. 

---