PHENOLIC COMPOSITION AND BROWNING SUSCEPTIBILITY OF VARIOUS APPLE AND PEAR CULTIVARS AT MATURITY

The main phenolic compounds in cortex tissues of apples and pears are hydroxycinnamic derivatives (HCD) and flavanols (FLA). Phenolic content (initial and residual) was determined by HPLC. The degree of browning was determined by the simultaneous measurements of soluble (absorbance at 400 nm) and insoluble (lightness L*) brown pigments. In apples, the sum of absorbance and lightness, expressing the extent of browning, is closely correlated to the amount of phenolics (HCD and FLA) degraded. Maturity does not appear to play a major role in the ability of apples to develop browning. In pears, no correlation was found between these sums and the amount of phenolics (initial or degraded). However, L* was correlated with the amount of two flavanols. The extent of browning seemed to depend on the maturity of pears. A better control of browning would probably consist firstly in a selection of cultivars with a low content in chlorogenic acid. Secondly, flavanol content and the relative balance of HCD and FLA are of great importance in the susceptibility to browning.