What was it all about?

Running from 2015 to 2018, this investment was tasked with assisting Australian summerfruit producers in harvesting peaches and nectarines at the optimum maturity, to allow the fruit to continue development and ripening throughout storage and handling systems – resulting in greater customer satisfaction.

The key message from the work was that the physiological stage of fruit at harvest is paramount to its development after harvest, and that any fruit harvested without having reached physiological maturity (defined as the onset of ethylene production) is incapable of developing the full sensorial characteristics that are typical of the cultivar, and that are expected by consumers.

To assist in the decision-to-pick process, the researchers conducted experiments to monitor and identify physiological maturity in stonefruit cultivars using a non‐destructive chlorophyll content index (the index of absorbance difference, or I_AD, measurable with a DA meter) correlated with ethylene production. Other factors – such as soluble solids concentration, firmness and titratable acidity – were monitored as well as volatile organic compounds (VOCs), to gain a better understanding of the effects of fruit maturity on aroma during fruit development. As part of this, the project established a new technique to collect ethylene and VOCs using evacuated vials.

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The project produced tools and knowledge to help growers in the decision-to-pick process. This included developing DA meter maturity profiles for peach and nectarine cultivars, and the dissemination of materials about using this non-destructive approach to measuring fruit maturity. These resources are available on the Horticulture Industry Networks website here.