Produce Degradation Pathways and Prevention

Mechanisms of Food Additives, Treatments, and Preservation Technology 313

Removal of polyphenols could be used during the processing of clear juices, which
could be filtered through adsorbents or adsorbents could be added to the juice and
removed by filtration. Polyphenols form complexes with β-cyclodextrins. Cyclodex-
trines when added to juice form complexes with polyphenols that cannot be oxidized
by PPO^ (Osuga et al., 1994). The production-scale application of such treatment is,
however, limited because of price and efficiency. Exclusion or removal of oxygen
is widely used during the processing of fresh produce to prevent browning and other
undesirable reactions described in other parts of this review. Heat inactivation of
enzymes, including the PPO (blanching), is very often used as the first step in the
technological processing of fruits and vegetables. This important treatment is dis-
cussed below.

Aromatic and phenolic acids:
Benzoic
Kojic
Coumaric
Ferulic

Competitive inhibition of PPO

(binding to active sites)

With exception of kojic acid,

very weak effect

4-Hexylresorcinol and other
substituted 4-resorcinols

Competitive inhibition of PPO Effective inhibitor of black-spot

formation in shrimps, effective

for mushrooms PPO, very low

or no effect to apple and grape

PPO

NaCl, NaF, CaCl 2 Chelating effect

Phosphoric acids,
polyphosphates

Chelating effect; acidification

Sodium or calcium hypochlorite Inhibition of enzyme (partial
denaturation of protein)

Proteases
Isolated natural proteases or
juices of natural sources:
Ficin or fig extracts
Papain or papaya juice
Aktinidin or kiwi juice
Bromelain or pineapple
juice, etc.

Inhibition of enzyme

Sources: Soliva, R.C. and Martin-Belloso, O., Trends Food Sci. Technol., 14, 341, 2003; Martinez, M.
and Whitaker, J.R., Trends Food Sci. Technol., 6, 195, 1995; Osuga, D. et al., in Protein Structure-Function
Relationships in Foods, Blackie, 1994, p. 62; and Son, S.M. et al., Food Chem., 73, 23, 2001.

TABLE 10.6
Antibrowning Additives (continued)

Antibrowning Additive

Mechanisms of Action

(Proposed) Limitations of Use