What was it all about?

Avocado fruit quality in shops can be improved by identifying and adopting measures that lessen or, ideally, eliminate flesh bruising.  This project, which ran from 2016 to 2018, set out to investigate if there are characteristics of the fruit that make them more or less likely to be damaged during handling. In addition, researchers tested tools that shoppers and retail staff could use to determine fruit ripeness without squeezing.

A key finding from the study was that fruit was found to be more resistant to bruising when it was cooled rapidly after harvest. Links were also found between greater bruising susceptibility and low dry matter content, advancing ripeness, post-harvest temperatures above 5°C and post-harvest storage durations of one week or more.

Pre-harvest factors leading to differences in fruit robustness were evidently important contributors to both bruise susceptibility and body rot upon ripening. For example, one of the studies found that a high ratio of nitrogen to calcium (N/Ca) in the fruit was linked to more body rots, although not bruise susceptibility.  More work is needed to tease out the relationship between nutrition and poor quality at retail.

The study confirmed that shoppers are major contributors to avocado bruising as they apply compression forces typically ranging from three to 30 Newtons (N) to firm-ripe avocados when assessing ripeness. A ‘slight’ thumb compression of 10N applied to a firm-ripe fruit is enough to cause bruising, expressed within 48 hours at 20°C. It’s here where the use of in-store decision-aid technologies can come into play. The team reviewed 16 tools for assessing avocado ripeness with four evaluated for reliability, ease of operation and maintenance.  All were able to discriminate between different avocado stages of ripeness for both ‘Hass’ and ‘Shepard’ fruit.  The devices included a handheld FruitFirm meter, a bench top Sinclair IQä Firmness Tester, a Digital Firmness Meter, and a prototype decision aid tool dubbed the ‘Readycado’ developed under project AV12009.  In-store consumer testing suggested that the ‘Readycado’ device could be well-received by shoppers. 

Knowledge generated by the project was shared with other researchers and with industry stakeholders, including growers, packers, ripeners, retailers, consumers and AAL. Indications are that more can be done to protect fruit from damage during handling.

Grower recommendations

• Cool fruit to 5-12°C and pack within 24 hours after harvest
• Avoid impact damage during harvest and packing
• ‘Hass’ avocado fruit should be harvested at more than 23 per cent dry matter, which is the current industry recommendation
• Fruit should pass through the supply chain as quickly as possible
• Drop heights be kept below 10 cm for fruit at the rubbery to softening ripeness stages
• Fruit be handled carefully without dropping or excessive squeezing from firm-ripe stage onwards
• Ripened ‘Hass’ avocado fruit should be maintained at 5°C
• Regularly monitor avocado fruit quality at retail to gauge effectiveness of bruise-reduction measures.

ACT NOW

• See slides from the team’s presentation to AAL regional grower meetings in 2018
  
  
• Read these articles on the Avocados Australia website:
  • Factors affecting avocado flesh bruising susceptibility
  • Best practice handling to reduce flesh bruising
  • Whether impact injury at harvest increases body rots at retail
  • Reducing bruising
    
    
• Remember that all project findings have been incorporated into the industry’s Best Practice Resource (BPR).

This project was part of a broader supply chain quality-improvement program that has also involved the now-completed Supply chain quality improvement – retailer point of purchase improvements (AV15011) and Supply chain quality improvement – cool chain best practice guidelines (AV15010).