Abstract:
The major phenolics of 'd' Anjou' pear (Pyrus communis L.)
tissues were chlorogenic acid and arbutin. Chlorogenic acid
inhibited mycelial growth and spore germination of Penicillium
expansum and mycelial growth of Mucor piriformis. Slight increases
in radial growth and spore germination of Botrytis cinerea occurred
on chlorogenic acid media. Chlorogenic acid had no effect on M.
piriformis spore germination. Arbutin inhibited spore germination
of P. expansum, and inhibited both mycelial growth and spore
germination of M. piriformis and B. cinerea. The effect of arbutin
on radial growth of P. expansum was not significant.
Decay susceptibility of 'd' Anjou pear fruit increased as fruit
approached maturity. Ethanol extracts from the fruit increased
radial growth of the fungi, but had no effect on spore germination.
Fruit firmness and polygalacturonase inhibitor activity correlated
significantly with percent decay. The relationship between
phenolics and fruit decay was not significant. The location of
fruits on the trees had no effect on decay, firmness, fungal radial
growth, fungal spore germination, polygalacturonase inhibitor
activity and amount of phenolics.
Late maturing 'd' Anjou' pear fruits were more susceptible to
storage decay than the pre- and optimum mature fruits. Immature
fruit was firmer than optimum and late mature fruit at harvest and
throughout the storage period. Extractable juice (EJ) of unripened
fruit was maintained at a constant level throughout the storage
period. EJ of ripened fruit declined substantially, but gradually
increased after late sampling period. Soluble solids (SS) varied
among different harvest groups and during the storage period.
Fruits increased SS upon ripening. Immature fruits had higher
titrable acids (TA) than optimum and late mature fruit. TA
decreased during the storage period and also upon fruit ripening.
Superficial scald developed on the ripened fruit in December, 1982
and increased thereafter. Immature fruits showed higher incidence
of scald development than the optimum and late mature fruit in
December, but all fruits developed scald symptoms after February,
1983. Optimum mature and late mature fruit developed acceptable
flesh texture, juiciness, and flavor upon ripening until February,
1983. Immature fruit was incapable of developing an acceptable
flavor upon ripening throughout the sampling period.
