Session Six Postharvest quality, outturn New Zealand and Australia Avocado Grower s s Conference 05 20-22 22 September 2005 Tauranga,, New Zealand
Is Ripening and Post Harvest Quality Affected by Fruit Water Status? Jonathan Dixon, Toni Elmsly, Fiona Fields, Derek Smith, Henry Pak and Jonathan Cutting Avocado Industry Council Ltd FRST contract no. AVIX0201
Introduction The incidence and severity of disorders increases when pick to pack times exceed 48 hours Observed in library trays Stem end rot and body rot (brown patches) are the main disorders affected
Quality and Delays Before Storage 120 100 Quality disorders Sound fruit Brown patches 4.5 4.0 3.5 Incidence (%) 80 60 40 20 Stem end rot Brown patches Stem end rot 3.0 2.5 2.0 1.5 1.0 0.5 Severity (%) 0 4 72 4 72 4 72 4 72 4 72 Hours after picking before packing 0.0
Introduction The amount of water loss after harvest may be inducing earlier ripening because: High water loss rates - faster ripening (Bower and Cutting, 1988; Lallu et al, 2002, 2003, 2004) Low water loss rates slower ripening (Dixon et al, 2003, 2004)
Ripening time and rots Incidence of Unsound fruit (%) 100 80 60 40 20 0 0 1 2 3 4 5 6 Ripening time (days)
Introduction Conducted a series of experiments looking at quality in relation to ripening and water loss We manipulated ripening by: Increasing water loss after harvest Decreasing water loss after harvest Adding water to the fruit (imbibing) at different physiological stages
Water loss after harvest Weight loss before storage (%) 2.4 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 days 4.5 4.6 Bags Trays Bags Trays Bags Trays Bags Trays 4 hours 72 hours 4 hours 72 hours Time after picking before storage days 3.9 3.8 120 100 80 60 40 20 0 Incidence of sound fruit (%, 5% threshold)
Weight loss Instead of removing water what happens if we add water to the fruit? Do we get the opposite results to water loss?
Experimental To see if we could slow down ripening water was imbibed into freshly harvested fruit
Ripeness stages Weight change (%) 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0-0.2-0.4-0.6-0.8-1.0 Non-stored fruit Inhibition Pre-climacteric Climacteric Ripening stage Imbibed Non imbibed
Ripeness stages Ripening time (days) Stage Inhibition Preclimacteric Climacteric Imbibed 10.6a 9.7a 11.7a Non-imbibed 9.4b 10.3b 10.2b Sound fruit (%, 5% threshold) Stage Inhibition Preclimacteric Climacteric Imbibed 79.3 93.3 90.0 Non-imbibed 91.7 87.3 96.2
Imbibing What else does the amount of water imbibed tell us? Amount of water imbibed may measure fruit water potential how readily water moves into the fruit indicate fruit water status may explain some of the variation in quality disorders
Experimental Factors that affect fruit water status may be: Irrigation Rainfall
Irrigated vs Non Irrigated fruit 1.6 1.4 1.2 Dawn Mid PM Increase in weight (%) 1.0 0.8 0.6 0.4 0.2 0.0 Irrigated Non-irrigated Irrigated Non-irrigated
Irrigated vs Non-Irrigated Fruit Time of Day Imbibed Non-imbibed Irrigated Non-irrigated Irrigated Non-irrigated Ripening time (days) Mid PM 4.4 4.1 4.7 3.6 Incidence of sound fruit (%, 5% threshold) Mid PM 55.9 71.7 75 95
Effect of rain Weight change (%) 2.2 2.0 1.8 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0-0.2-0.4-0.6-0.8 Ripening time (days) 6 5 4 3 2 1 Incidence sound fruit (%, 5% threshold) 80 70 60 50 40 30 20 10 Imbibed Non-imbibed -1.0-1.2 Pre Rain Post 0 Pre Rain Post 0 Pre Rain Post
Conclusions The loss in quality with delays before packing is more because the fruit increase in ripeness rather than due to weight loss The fruit water status at harvest affects ripening which influences the amount of ripe rots This means what happens to the fruit before harvest and how the fruit are handled after harvest and by the packer affects final fruit quality
Acknowledgements Thanks to the following avocado growers for fruit for the various trials: Hugh Moore Graham Body Dan & Rose Cook Kevin Holley Drew Skowrup Kim Crocker Debbie Fleming
Library Trays a powerful tool in fruit quality management Dr Henry Pak Dr Jonathan Dixon Dr Jonathan Cutting Avocado Industry Council
Introduction Cornerstone of quality improvement programme export focus Feedback on fruit quality Improve quality on-orchard Runs in parallel with out-turn monitoring Initially best practice, now compulsory Over several seasons has successfully identified quality issues and contributing factors
Methods ~ 20 fruit sample after grading Each PPIN, every 2 nd picking round Coolstored 28 days 5 C 1 st assessment = external quality on removal from coolstorage Ripened at 20 C 2 nd assessment = internal quality at eating ripe Entered into central database
Number of fruit sampled 2001/2 30,023 2002/3 22,192 2003/4 23,882 2004/5 25,873 101,970
Main quality disorders
Brown patches
Fuzzy patches
80 onshore library trays incidence (%) 70 60 50 40 30 20 2001 2002 2003 2004 10 0 SER BP VB Fuzzy disorder
Seasonal trends
Fuzzy patches 80 70 60 2004/5 2003/4 2002/3 2001/2 incidence (%) 50 40 30 20 10 0 Aug Sep Oct Nov Dec Jan Feb Mar Harvest month
Flesh temperature audits 60.0 50.0 frequency (%) 40.0 30.0 20.0 10.0 0.0 < 3.0 3.5 4.5 5.5 6.5 7.5 8.5 >9 Temperature( ºC) Before 1st Dec After 1st Dec
80 out-turn monitoring 70 incidence (%) 60 50 40 30 20 2001 2002 2003 2004 10 0 SER BP VB Fuzzy Disorder
Fruit Age
60 50 40 30 20 10 0 Fruit Age 26 28 30 32 34 36 38 40 42 44 Fruit age when ripe (days) incidence (%) of unsound fruit (5% threshold)
Pick to Pack Time
50 45 40 35 30 25 20 Pick to Pack Time 0 1 2 3 days stem-end rot incidence (%)
Wet Fruit
60 influence of rain on stem-end rots 50 incidence (%) 40 30 20 10 0 0 1-5 5-10 11-15 16-20 >20 rainfall (mm)
Regional comparisons
25 Regional differences stem-end rot incidence (%) 20 15 10 5 0 Far North Whangarei Bay of Plenty
Packer Reports
Shed averages incidence brown patches 100 90 80 70 60 50 40 30 20 10 0 a d g h n p f c j u r b t q i k e m l s o
Grower comparisons
Conclusions Provides framework for quality improvement - feedback Successfully identified quality issues and causal factors over several seasons Allows remedial action within season