A comparative study concerning the inhibition of the enzymatic browning in Red
delicious apple juice stored for 24 h at 4. 25, and 35 °c was carried out between the
thiol containing compounds; cysteine , glutathione· and Maillard reaction products
(MRPs) derived by heating aqueous solutions containing cysteine with glucose or
ribose (Cys/G or Cys/R) and those commercially applied such as: sodium
me\abisulfile . ascorbic acid and 4.hexyl resorcinol. The efflciency of all antibrowning
agents was determined in terms of absorbance and colour measurements. The
obtained results confirmed the presence of a proportional relation between
concentration of antibrowning agents and their inhibitory effect. whereas the increase
in storage temperatures showed an opposite trend. The inhibitory eHect of the thiol
containing compounds was comparable with 4-hexyl resorcinol and being significantly
(P < 005) higher than ascorbic acid under all experimental conditions. The MRPs
derived from cysteine I glucose model system were more active than their counterpart
derived from cysteine I ribose model system. However, each of them could be
considered as potential natural inhibitor having technological and commercial benefits
10 be applied in processed fruilS. The degree of browning was determined by
measuremenl of soluble (A.20) and nonsoluble brown pigments. showing high
correlation (r = 0.9454) with the percent of degraded phenolic compousnd during
storage of apple juice samples treated with various antibrowning aqents.