Project Detail
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Optimization of RLOS protocol for superficial scald prevention on Packham’s Triumph pears
Objectives and Rationale
Repeated low oxygen stress (RLOS) can prevent superficial scald incidence on Packham’s Triumph during long term storage. In certain seasons the alcohol build-up during the stress periods in the pear is higher than the prescribed maximum levels of 100-150 ppm which can lead to off-tastes. The aim of this project is to optimize the RLOS protocol to control superficial scald on South African ‘Packham’s Triumph’ pears.
Methods
Three treatments (RLOS+ULO, RLOS+CA and RA) were applied to optimum harvested Packham’s Triumph. A minimum of one stress and a maximum of 9 stress periods were applied over the storage period of 10 months. Fruit quality evaluations were done after each shelf life period.
Key Results
RLOS+ULO and RLOS+CA was effective in preventing superficial scald on optimum Packham’s Triumph up to 10 months with 7 day shelf life, irrespective of the number of stress periods that was applied in 2017. In the second season, RLOS+CA was only effective up to 8 months. For 10 months storage, at least 7 stresses needed to be applied for effective storage. Both RLOS treatments resulted in fruit with good firmness and green skin colour retention. In 2017 the alcohol concentration in the fruit stored under RLOS+ULO was higher than the recommended maximum levels after the stress periods, but still there were no off-tastes detected after shelf life. The alcohol concentrations were much lower in the second season. No off-tastes was also found in 2018.
Key Conclusions of Discussion
The RLOS+ULO treatment is effective to control superficial scald for 10 months with only one stress period at the beginning of storage. When RLOS+CA is used with only one stress period it is recommended to not store longer than 8 months. The alcohol concentration build-up differed between seasons. Application of monthly stress periods resulted in high alcohol concentrations in the RLOS+ULO treatment in 2017. Hhowever, the fruit did not have any off-tastes after shelf life, whether it was stored with or without a bag
For Final Report, please contact:
anita@hortgro.co.za