EFFECT OF CALCIUM AND SOME ANTIOXIDANTS TREATMENTS ON STORABILITY OF LE CONTE PEAR FRUITS AND ITS VOLATILE COMPONENTS

Abstract

The possibility of calcium nitrate and / or some antioxidants i.e. citric acid and ascorbic acid as preharvest treatment alone or in combination to control decay and its role in improvement the quality of Le Conte pear fruits as well as volatile components under cold storage condition and marketing period during to successive seasons 2007 and 2008. Le Conte pear trees were foliar spraying twice with calcium nitrate at concentration of (1700 ppm), citric acid at concentration of (50 and 100 ppm) and ascorbic acid at concentration of (50 and 100 ppm), ten treatments were used including control. All treated and untreated pear fruit were stored at 0 ± 1ºC and 85 – 90% relative humidity (RH) for 75 days and additional one week at room temperature (20-24ºC) as simulated marketing period. Fruit quality assessments i.e. weight loss and decay percentage, fruit firmness, total soluble solids %, total acidity %, total sugars, fruit calcium content and volatile components were evaluated. Results showed that treated and control fruits withstand free from chilling injury and pathogenic rot up to 45 days of cold storage. While, almost treatments prevented chilling injury symptoms and fruit deterioration up to 60 days of cold storage. Totally 27 volatile components were identified: 15 esters, 8 alcohols, 3 aldehydes and one terpene. Volatile components varied considerably both quantitatively and qualitatively between fresh and stored samples. The best treated samples at fresh were calcium nitrate + citric acid at 50, 100 ppm compared to the control treatments. Although all samples retain in good quality during storage period calcium nitrate, ascorbic acid at 50 ppm, calcium nitrate + citric acid at 50, 100 ppm, and calcium nitrate + ascorbic acid at 50 ppm treated samples were the best compared to the control samples because of in highest content of esters which exhibit it more fruity aroma and cause it more acceptable for consumer.