Prepared by: Ines Hanrahan and Stefan Röder, Washington Tree Fruit Research Commission
Recently, several devices to assist in determining some of the commonly used fruit quality parameters such as firmness, soluble solids content (SSC), titratable acidity (TA), dry matter content (DMC), and skin color have been introduced to growers in the Pacific Northwest and elsewhere. The Washington Tree Fruit Research Commission (WTFRC) Internal Program, under the leadership of Ines Hanrahan, has tested several such devices. This article is the second in the series describing these new devices.
The Accuvin Titratable Acidity Test is a fast and easy to use tube test to estimate the titratable acidity (TA) concentration in apples. The price depends on the box size and starts at $1.82 per sample.
Using a sharp knife, make a small (1/2 inch deep) hole. Wait for juice to accumulate inside the hole (squeezing fruit enhances the process). Squeeze the upper sampler bulb and a take sample of pure juice avoiding small pieces of flesh. Remove any sample from the outside of the tube by wiping it on a paper towel.
Release the sample to the test reagent by squeezing the sample bulb once. After closing the tube, shake it well and wait for 30 seconds. Compare your result with the color chart provided with the kit.
This test showed an accuracy of approximately 73% when performed in our laboratory and is by far the easiest test to use and to train people on. Due to the low accuracy, this test can be used to track the change of the TA concentration prior to harvest or to compare different lots.
Link to the manufacturer
Tree Fruit Research Commission