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Report, 2012

Improvement of Organic Apple Quality and Storability

Tahir, Ibrahim;

Abstract

Improvements in yield and quality by increasing the light distribution and carbohydrate uptake (summer pruning and ground covering), optimizing the physiological state of harvested fruit (cultivar-specific harvesting indices), postharvest fruit protection (treatment with hot water and ethanol, respectively) and optimizing storage conditions (cultivar-specific CA and ULO storage procedures) were investigated in a set of eight organically grown apple cultivars. A combination of summer pruning and covering the orchard ground with white textile increased tree productivity, improved coloration at harvest, and increased contents of anthocyanin, ascorbic acid and total phenolic compounds in at least some of the cultivars. It also developed fruit resistance to Neofabraea spp. and Colletotrichum gloeosporioides which were the most common pathogens, causing fungal storage deseases. Analyses of various fruit ripening parameters showed that starch hydrolysis point and Streif index (firmness/(starch hydrolysis point * soluble solid concentration)) were corrlated with internal ethylene concentration (IEC) at harvest. Thus, the optimal harvesting time can be deduced from the starch index in some cultivars (Agra, Santana and Sultanat) while the Streif index is more accurate for other cultivars (Eir, Delorina and Zarya alatau). In yet others, titratable acidity and flesh firmness also produced important information and have to use as an additional index beside starch hydrolysis for Ella and Dayton respectively which showed only close correlation between starch hydrolysis and IEC. By contrast, soluble solids concentration and skin color are not useful due to their sensitivity to weather conditions and light intensity. Post-harvest hot water treatment (46º C for 120 seconds) decreased fungal decay during storage in only two cultivars (Dayton and Eir), whereas spraying the fruit with 10% ethanol decreased fungal decay in all six cultivars. Optimization of CA and ULO storage conditions maintained fruit quality and reduced amount of fungal decay. Storage of eight organic cultivars in a wide range of pCO2 achieved slight additional improvement in some cultivars, while flesh browning, causing by high CO2 can be expected. CA (2.0 kPa O2 and 2.0 kPa CO2 ) can be recommended for Agra, Eir, Ella and Delorina; ULO (1.0 kPa O2 and 1.0 kPa CO2 ) for Zarya alatau and (1.0 kPa O2 and 2.0 kPa CO2 ) for Dayton, Santana and Sultanat.

Keywords

Organic apple, quality, ULO storage, Antioxidants

Published in

Landskap, trädgård, jordbruk : rapportserie

2012, number: 2012-14
ISBN: 978-91-87117-13-8
Publisher: SLU - Fakulteten för landskapsplanering, trädgårds-och jordbruksvetenskap

Authors' information

Swedish University of Agricultural Sciences, Plant breeding and Biotechnology

UKÄ Subject classification

Plant Biotechnology

URI (permanent link to this page)

https://res.slu.se/id/publ/41845