Progress Report for Project ID number J-000379. P020-BCFGA- Canadian Tree Fruit Products Development - Activity 4: Update on Improving Ambrosia™ Apple Quality after Long Term Storage
Toivonen, P.M.A. and Cliff, M.A. 2017. Progress Report for Project ID number J-000379. P020-BCFGA- Canadian Tree Fruit Products Development - Activity 4: Update on Improving Ambrosia™ Apple Quality after Long Term Storage February 2017. AAFC Agri-Innovations Project Annual Activity Report, 16 pp.
A broad spectrum of related experiments were either conducted in 2016-17 or were part of an ongoing multi-year experiment in order to understand the issues around ensuring good sensory quality for Ambrosia apples after long term storage of up to 8 months. Ongoing work evaluating reflective row covers was completed in 2016-17, showing that the woven white polyethylene Extenday™ can be applied as little as two weeks before estimated harvest to induce good blush color development on Ambrosia apples. However, a reduced time for row cover application does not reduce the amount or color intensity of the blush and so there is no opportunity to manage the level of blush color for Ambrosia apple when using this particular reflective row cover. In a sensory study there was a documented systematic decline in sweetness and ‘Ambrosia’ flavor with storage time. While ‘Ambrosia’ flavor could be enhanced by having a later harvest, overall it was reduced with 5 and 8 months controlled atmosphere storage for all harvest maturities. Crispness, hardness, juiciness, skin toughness were found to be acceptable at 5months of controlled atmosphere storage, however, they deteriorated greatly by 8 months. Starch clearing index was found to be influenced by temperature profiles in orchards or between seasons, as well as by nitrogen nutrition in the Ambrosia orchard and is therefore considered to be unstable as an index for maturity. In contrast after two years study under this report, it has become apparent that the IAD index is insensitive to both seasonal and location differences in temperature profiles and also to nitrogen nutrition in the Ambrosia orchard. It was also shown to provide a good prediction of firmness retention over long term CA storage. Dynamic Controlled Atmosphere (DCA) storage did not yield large improvements in quality retention in comparison to conventional Controlled Atmosphere (CA) storage of Ambrosia apples. A part of this can be attributed to the late harvest maturity of apples used in this study and also to the fact that all of the apples were treated with 1-methylcyclopropene. A better control of the harvest maturity will be implemented in the 2016 harvest season and only half of the apples will be treated with 1-methylcyclopropene to ensure that the potential effects of DCA can be better identified when apples are evaluated in 2017.
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