Fruit enzymatic browning

Delay non-enzymatic browning of fruits and some vegetables. 

To prevent non-enzymatic browning, the fruit can be dipped in a 5% solution of citric acid (or in lemon juice). This is especially advisable in the case of sliced and diced apples where the acid content is low. The acid allows the light colour to be retained, while at the same time improving the taste of the pieces of apple. The colour of the fruit can be made even lighter by adding ascorbic acid to the dip. 

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... 

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. 

Edible film Controlled moisture transfer between food and the surrounding environment Controlled release of antimicrobial substances Controlled release of antioxidants Controlled release of nutrients, flavors, and drugs Reduction of oxygen partial pressure Controlled rate of respiration Temperature control Controlled enzymatic browning in fruits Reverse osmosis membranes... 

Stadtman, E. R. 1948. Non-enzymatic browning in fruit products. Advances in Food... 

Some reactions are very fast, for example neutralization and precipitation reactions (Chapter 1). Other reactions are slow, for example the enzymatic browning of fruits (Chapter 26), and some very slow, for example rusting (see Figure 6.1b, and Chapter 9). 

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. 

Amiot, M.J. et al., Influence of cultivar, maturity stage and storage conditions on phenolic composition and enzymatic browning of pear fruits, J. Agric. Food Chem., 43, 1132, 1995. 

Sucrose helps minimize earthy tastes of vegetables, while enhancing inherent flavors and aromas, and preserving color and texture (37). Addition of sucrose inhibits enzymatic browning of canned and frozen fmits, and prevents loss of color, flavor, and aroma from fruit during processing (38). 

Thermal pre-treatment can be carried out before the fruits enter the dryer. This reduces both the initial microbial count of the fruit and the degree of enzymatic browning. The cells in the pieces of fruit that are heated break up, thus accelerating the subsequent drying process. 

Phenol oxidases belong to the so-called monooxygenases, since they catalyze the incorporation of one atom of oxygen into the substrate. Phenol oxidases are present in all fruit and vegetable products and can affect the flavour and colour by the well-known browning reaction [23]. The enzymatic browning reaction involves the hydroxylation of plant phenolic compounds into the dihydroxy... 

Phenol oxidases Enzymatic browning Fruits, beverages... 

Polyphenol oxidase Mushroom, grape, pear, kiwi, sago, tea, potato, strawberry, olive, beet, cocoa Enzymatic browning (pig-ments),ripening of fruits, flavour formation, colour e.g. strawberries) formation... 

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