Handheld devices could determine brix levels
Two handheld devices are being tested to determine if they can help citrus growers test the maturity of fruit and brix levels before harvest to ensure high quality fruit and to meet export market specifications.
Professor Kerry Walsh from the Central Queensland University presented his work on testing two handheld devices, the F-750 Produce Quality Meter and the Sunforest H-100C, to measure brix and dry matter in mango at the recent 2017 Citrus Technical Forum and Field Day and their potential for the citrus industry.
Both devices can be used in the orchard. The devices are placed in contact with the fruit, shining infrared light into the fruit to obtain a brix estimate in a few seconds.
To start, the devices are calibrated by destroying the fruit and taking an actual brix (or dry matter measurement for some fruit types). Once calibrated the devices can be used across an orchard measuring many pieces of fruit to get a full picture of the maturity level of fruit within any block.
Professor Walsh’s work has shown that the F-750 meter is accurate at measuring dry matter in mango – a useful guide to fruit maturity and an index of ripened fruit eating quality.
The F-750 has allowed growers to measure dry matter of fruit in their orchards periodically throughout the season (without destroying the fruit), assisting to determine the optimal time to harvest.
A web app displays where samples have been taken across farm blocks and provides information on block average and time to reach the specification target.
Both devices have potential for application in citrus, but citrus’s thicker skin means further testing is required to determine the devices’ usefulness in the industry because both rely on penetrating the fruit’s skin with light.
The new Sunforest model has been designed for application in citrus but it hasn’t been tested locally yet, while preliminary testing on the F-750 is looking promising.
“Our testing is ongoing in citrus,” said Prof Walsh. “The older model F-750 didn’t perform as well as we had hoped, but a newly released model has performed better. A preliminary trial of the Sunforest was also promising, although results were poorer when fruit were in full sun.”
Currently the industry uses destructive methods to measure brix, which limits the amount of fruit that can be tested.
It’s accurate but may not be representative of fruit maturity across an entire block given the limitation on the number of fruit sampled.