Wayne B. Sherman

Quality characteristics of melting and non-melting flesh peach genotypes

A study was conducted to compare the quality characteristics of non-melting flesh (NMF) peach genotypes intended for fresh market use with the standard melting flesh (MF) peach genotypes, and to determine the effect of storage at 8 °C on the physical and chemical composition of the respective fruit types. In general, mesocarp firmness, skin L (lightness) and hue (red and orange components) decreased significantly with time in storage. This decrease was much more dramatic in MF genotypes than in their NMF counterparts. Water-soluble uronic acids increased significantly in both flesh types. Total soluble solids and total uronic acid content showed little or no change depending upon the genotype. NMF fruits had significantly higher hue and L values, firmness, soluble solids and total carotenes and xanthophylls than their MF counterparts. Water-soluble pectin content was significantly higher in MF genotypes.

Development of off-flavour in non-melting flesh peach genotypes†

Studies performed to investigate the development of off-flavour in some NMF peach genotypes revealed that there were certain chemical components that were consistently associated with the disorder. Generally there was a significant increase in total soluble phenolics, polyphenoloxidase (PPO) activity and ethanol with an increase in both the percentage of off-flavoured fruit and the degree of off-flavour with time in storage at 8 °C in NMF genotypes. Total soluble sugars and soluble solids decreased significantly during the storage period. These changes in chemical composition of NMF genotypes were not observed in MF and NMF genotypes that did not show off-flavour development. Highly significant linear correlations were detected between off-flavour development and soluble phenolics, PPO activity, ethanol, total soluble solids and soluble sugars in Fla 92-21C and USDA 87P285, lines with the highest percentage of off-flavoured fruit. Soluble phenolics, chlorogenic acid, PPO activity and ethanol were positively correlated but soluble sugars and soluble solids were negatively correlated with off-flavour development. The accumulation of soluble phenolics and ethanol and the reduction in soluble solids and sugars appear to be associated with the development of off-flavour in NMF peach genotypes.

Stone Fruit Genetic Pool and Its Exploitation for Growing under Warm Winter Conditions

Peaches, plums, apricots, and cherries are temperate fruit crops that generally require a cold winter to break dormancy and produce fruit on a yearly basis. As these stone fruit species have spread around the world, however, genotypes have been selected for adaptation to more marginal, and even extreme, local environments by farmers and researchers. In marginal environments such as in mild winter regions of the world, locally selected well-adapted cultivars often do not possess commercially acceptable fruit quality. Starting with these poor quality but adapted cultivars, fruit breeders have developed and are developing commercially acceptable stone fruit cultivars suited to a wide range of mild winter conditions.