Photos and article by Glenn Hale*

A ‘snapshot’ of the eating quality of Australian cherries shows them to be firmer, sweeter and tastier than those from other competing export countries.

The cool chain plays an important role in preserving the quality, freshness and visual appearance of cherries in Vietnam.

Phytosanitary irradiation is an efficient and chemical-free process that is applied to horticultural products to prevent the introduction or spread of quarantine pests and diseases. Currently, more than 60 countries treat food with irradiation while many countries already import irradiated food from Australia (DAFF, 2023).

Export trade in the irradiation treatment of fresh fruit and vegetables is on the increase. As Ben Reilly (fresh produce manager at Steritech) described in May 2023, “this is the largest year to date for irradiated Australian produce, which also includes us treating over 60 different horticultural crops. Almost two-thirds of our business is geared towards exports”.

Irradiation is one of the fastest ways to safely access international markets (e.g., Vietnam) as produce can be on supermarket shelves within 72 hours from harvest, hence it is a suitable option for high-value and highly perishable fruits such as cherries (DAFF, 2023).

Prior to the global pandemic, Agriculture Victoria assessed and reported on the variability of cherry quality purchased from several different outlets in Saigon, Vietnam (Australian Tree Crop, Aug–Sep. 2022). Earlier this year, Agriculture Victoria returned to Saigon to conduct a similar ‘snapshot’ on quality that also included a shelf-life trial due to limited information being published on the post-harvest performance of exported cherries.

Four batches of cherries were sourced from different retail outlets (Bato AuSales, Grove Fresh and US Mart) and Ben Thanh market in Saigon in January 2023 (Fig. 1).

Overall, the appearance, packaging type and fruit quality in terms of fresh weight, size, colour and maturity was highly variable between country of origin (Fig. 2 and Table 1). On average, irradiated fruit from Victoria was firmer, sweeter by more than 3°Brix, and of higher eating quality than untreated cherries from NZ.

Unlike in previous years, stems were less green on cherries purchased from Ben Thanh market, even though produce was stored in an upright refrigerator.

A short shelf-life trial conducted on one batch of irradiated cherries (cv. ‘Regina’) from Victoria showed a similar loss of fruit weight each day. Over the four days of shelf-life at approximately 20°C, cherries lost a total of six per cent fresh weight and six per cent in flesh firmness (Fig.3).

Cherry colour based on IAD (index of absorbance difference) as measured with a DA meter, increased by 10 per cent, from 1.71 to 1.88 (i.e., more intense red colour).

Surprisingly, cherry stems browned very quickly during daily shelf-life assessments which highlights the importance of storing cherries below 4°C and high relative humidity to maintain green stems and prevent dehydration so that cherries are visually more appealing to consumers.

Quality assessment on cherries (cv. ‘Regina’) purchased from Bato AuSales in Saigon, Vietnam in January 2023.

^Australian cherry colour guide; *Australian cherry export quality specifications (www.cherrygrowers.org.au). Range for Colour and SSC shown in parenthesis.

Reference

Department of Agriculture, Fisheries and Forestry (DAFF). Irradiation insights: Food irradiation for Australian producers. (Available online).

Acknowledgement

The ‘Building capacity in irradiation – pathways to export’ project is funded by the Hort Frontiers Asian Markets Fund (Project AM19002), part of the Hort Frontiers strategic partnership initiative developed by Hort Innovation, with co-investment from the Department of Jobs, Precincts and Regions (Victoria), Steritech, NSW Department of Primary Industries, SA Research and Development Institute, NZ Plant and Food Research, Aerial (France) and the Australian Government.

*Glenn Hale is a research scientist, Agriculture Victoria AgriBio Centre, Bundoora. Contact Glenn Hale on glenn.hale@agriculture.vic.gov.au