The objective of this study was a quantitative and qualitative profile of pectin substances in fruit of the Asian pear trees. An investigation material for the study was fruit of the three pear cultivars: Shinseiki, Hosui, and Chojuro from an experimental orchard of the Horticulture Department of PPO – SGGW. The study was conducted using fruit instantly after the harvest (during a phase of the fruit harvest ripeness) and after the three months of cold storing in an ambient air atmosphere. A preparation of alcohol-insoluble substances was made of fruit tissues (the so called AIS – Alcohol Insoluble Solids). Pectins contained in AIS were extracted with use of different extracting agents, i.e. water, oxalates, hydrochloric acid, and NaOH; the four pectin fractions were obtained from the extractions performed. For those four fractions of pectins, galacturonic acid content was determined. The AIS obtained constituted 2.1% to 3.2% of fresh fruit pulp used in the investigations, i.e. 0.61% to 0.78% of pectins. In the phase of the harvest ripeness, the lowest amount of AIS was obtained from the Shinseiki cultivar fruit (20.6 g/1000 g) and the highest amount was obtained from the Chojuro cultivar fruit (28.8 g/1000 g). As for the Shinseiki and Chojuro fruit, it was stated an increase in AIS obtained after the three month storage. The galacturonic acid content, a basic component of the pectins, oscillated between 211.8 mg/g AIS and 171 mg/g AIS (in the phase of the harvest ripeness) and depended on the cultivar. Owing to the storage, the amount of galacturonic acid in the AIS dropped, and this drop was different for each cultivar. The highest changes were stated in the Shinseiki cultivar fruit and the lowest – in the Hosui cultivar pears.
Asiatic pear, pectin, AIS, galacturonic acid