Food Biochemistry and Food Processing

4 Browning Reactions 77

antibrowning agents. Honey (Chen et al. 2000);
papaya latex extract (De Rigal et al. 2001); banana
leaf extract, either alone or in combination with
ascorbic acid and 4-hexylresorcinol (Kaur and Ka-
poor 2000); onion juice (Hosoda and Iwahashi
2002); onion oil (Hosoda et al. 2003); solutions con-
taining citric acid, calcium chloride, and garlic ex-
tract (Ihl et al. 2003); Maillard reaction products
obtained by heating of hexoses in presence of cys-
teine or glutathione (Billaud et al. 2003, Billaud et
al. 2004); resveratrol, a natural ingredient of red
wine possessing several biological activities, and
other hydroxystilbene compounds including its ana-
log oxyresveratrol (Kim et al. 2002); and hexanal
(Corbo et al. 2000) are some examples of natural
inhibitors of PPO. In most cases, the inhibiting
activity of a plant extract is due to more than one
component. Moreover, a good control of enzymatic
browning may involve endogenous antioxidants
(Mdluli and Owusu-Apenten 2003).
Regulation of the biosynthesis of polyphenols
(Hisaminato et al. 2001) and the use of a commer-
cial glucose oxidase–catalase enzyme system for
oxygen removal (Parpinello et al. 2002) have been
described as essential and effective ways of control-
ling enzymatic browning.

Commonly, an effective control of enzymatic

browning can be achieved by a combination of anti-

browning agents. A typical combination might con-

sist of a chemical reducing agent such as ascorbic

acid, an acidulant such as citric acid, and a chelating

agent like EDTA (ethylenediaminetetraacetic acid)

(Marshall et al. 2000).

A great emphasis is put on research to develop

methods for preventing enzymatic browning, espe-

cially in fresh-cut (minimally processed) fruits and

vegetables. Technological processing including mi-

crowave blanching alone or in combination with

chemical antibrowning agents (Severini et al. 2001,

Premakumar and Khurduya 2002), CO 2 treatments

(Rocha and Morais 2001, Kaaber et al. 2002), pre-

treatments employing sodium or calcium chloride

and lactic acid followed by conventional blanching

(Severini et al. 2003), high-pressure treatments com-

bined with thermal treatments, and chemical anti-

browning agents such as ascorbic acid (Prestamo et

al. 2000, Ballestra et al. 2002) have been employed

to prevent enzymatic browning in foods.

The use of edible whey protein isolate–bees wax

coating (Perez-Gago et al. 2003), a high-oxygen

atmosphere (e.g., 70% O 2 ) (Jacxsens et al. 2001),

or an atmosphere of 90.5% N 2 7% CO 2 2.5%

Table 4.2.(Continued)

Inhibition

Inhibition Targeted toward the Substrate Targeted toward the Products

Removal of Oxygen Removal of Phenols

Processing Complexing agents Reducing agents

1. Vaccum treatment 1) Cyclodextrins 1) Sulphites


2. Immersion in water, syrup, brine 2) Sulphate polysaccharides (SO 2 ,SO 3 2-, HSO 3 - ,S 2 O 5 2-).


3. Chitosan 2) Acorbic acid and analogs


4. Cysteine and other thiol
   compounds

Reducing agents Enzymatic modification Amino acids, peptides and
proteins

1. Ascorbic acid 1) O-methyltransferase


2. Erythorbic acid 2) Protocatechuate 3, Chitosan


3. Butylated hydroxyanisole (BHA) 4-dioxigenase


4. Butylated hydroxytoluene (BTH) Maltol


5. Tertiarybutyl hydroxyquinone


6. Propyl gallate