Influence of Pear Variety and Drying Methods on the Quality of Dried Fruit

In this study, the impacts of two different pear cultivars, “Conference” and “Alexander Lucas”, on the kinetics and the final quality of samples dried by convection (CD) and microwave-convection (MCD) methods, were investigated. The quality of dried material was evaluated by the analysis of water activity, porosity, color, acoustic emission (AE) and mechanical and sensory properties. The required drying time to obtain 0.2 kg H2O/kg dry solid (d.s.) was longer for “Conference” than “Alexander Lucas” and was 20 min by CD and 5 min by MCD. The pear cultivar, in conjunction with the drying method (CD or MCD), affected the number of AE events and the work of breaking. The CD pear of the “Conference” cultivar was characterized by higher force, higher breaking work and stronger AE relative to the CD pear of the “Alexander Lucas” cultivar. There were no differences in taste or overall quality, but the hardness was higher for the CD “Conference” pear. A principal component analysis showed that panelists preferred dried fruit with good taste and overall quality but lower hardness. A positive correlation was found between the number of acoustic events and sensory hardness; thus, an acoustic method can be useful for effectively evaluating the texture of dried pears. These results show that the dried pear slices that generated fewer AE events upon breaking were perceived as better by the panelists.

Evaluation of susceptibility level of pear cultivars to fire blight (Erwinia amylovora) in the Czech Republic

Thirty-three pear cultivars and selections of potential interest to pear producers and plant breeders in the Czech Republic were tested for relative field susceptibility to the fire blight (Erwinia amylovora) over five years. Level of fire blight susceptibility was evaluated according to the extent of lesion development on the shoot tips after artificial inoculation in experimental plots under insect proof nets. Old cvs Alexander Lucas (as resistant standard), Conference (as moderately resistant standard) and Beurré Bosc (as susceptible standard) were included in the tests. The 33 pear cultivars and selections were tested, only one of them was highly resistant (3.0%), 3.0% were evaluated as resistant, 12.1% moderately resistant, 36.4% moderately susceptible, 18.2% susceptible and 27.3% highly susceptible. Breeding selection US 625-63-10 was the only highly resistant pear genotype (necrosis of shoots of 0–7.0%). Resistant genotype group (necrosis 7.1–13.0%) comprised US 625-63-4. Moderately resistant genotypes (necrosis 13.1–25.0%) included cvs Alexander Lucas, Alfa, Bohemica and HL 31-50-31. Highly susceptible genotypes (necrosis more than 80.1%) included cvs Vonka, Karina, Bona, Decora, Elektra, Milka, Regina, Alice and TE 4763. The remaining genotypes were moderately susceptible (necrosis 26.1–60.0%) and susceptible (necrosis 60.1–80.0%).