Fruit pigment formation

Fujikawa, S. et ah. Brilliant skyblue pigment formation from Gardenia fruits, J. 

The berry or the small fruits consist of strawberry, raspberry, blackberry, black currant, blueberry, cranberry and elderberry. The volatiles responsible for the flavour of small fruits are esters, alcohols, ketones, aldehydes, terpenoids, furanones and sulfur compounds (Table 7.3, Figs. 7.1-7.7). As fruit ripen, the concentration of aroma volatiles rapidly increases, closely following pigment formation [43]. 

SC, sulfite, bisulfite, metabisulfite), which inhibit PPO and may combine with quinones or reduce quinones to phenols, thereby preventing pigment formation (4, 9-10). Sulfites can produce acute allergic reactions in some asthmatics, however, with serious if not lethal consequences (11-12). Therefore, the Food and Drug Administration has banned the use of sulfites in fruits and vegetables served or sold raw to consumers (13) and has proposed restrictions on the use of sulfites in certain fresh potato products (14). 

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). 

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]. 

The formation of the normally present cyclic carotenoids is Inhibited. The transformation of the acyclic lycopene to the monocyclic gamma-carotene Is partially inhibited and further cyclizatlon to the bicyclic beta-carotene is totally Inhibited. However, when the treatment of the entire tree which Is sprayed with 2,000 ppm MPTA Is conducted preharvest at the fully mature stage of fruit development [2], the carotenoid composition of the endocarp reflects a net synthesis of the cyclic pigments and differs from the pattern seen in the peel as shown in Table II. 

The formation and transformation of pigments during fruit development and ripening... 

MiNGUEZ-MOSQUERA MI and HORNERO-MENDEZ D. 1994c. Formation and transformation of pigments dnring the fruit ripening of Capsicum annuum cv Bola and Agridulce. J Agric Food Chem 42 38 4. 

Fruits ripen in two major ways climacteric and non-climacteric. The former type involves both autocatalytic evolution of ethylene and a rise in respiration whereas the latter shows no increase in ethylene formation and downward drifts in respiration [14]. In both types, fruit ripening is characterized by many biochemical and physiological changes such as chlorophyll d radation, pigment accumulation, textural modification and the production of volatile aromatic compounds. 

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