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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 third in the series describing these new devices.

Atago’s PAL-BX|ACID5 is able to measure the soluble solid content (SSC) and the titratable acidity (TA) of the same sample. The master kit, besides the main unit, includes a scale, plastic pipettes, plastic beakers and an attachment for the main unit (see below).

atago 1

Getting started

There are two different methods on how the TA content can be measured.

Method 1: with scale
  1. Place the beaker in the scale and set it to zero.
  2. Pour 1 g of juice into the beaker.
  3. Add distilled water until the total weight is 50 g.
  4. Stir the sample for at least one minute.
  5. Transfer at least 0.6 ml of the diluted sample onto the sensor of the main unit and start the measurement.

atago 2

Method 2: without scale
  1. Place the attachment onto the main unit.
  2. Pour at least 0.2 ml of juice onto the attachment.
  3. Fill the attachment with distilled water (10 ml) until you reach the mark (line).
  4. Stir it well for at least 30 seconds (be careful not to scratch the sensor).
  5. Start the measurement.

atago 3

During our testing, the first method (with scale) showed an accuracy of approximately 88%. Without using the scale the accuracy dropped to 69%. Therefore, the second method should only be used for a rough estimation.

Link to the manufacturer

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Ines Hanrahan

Washington Tree Fruit Research Commission


Washington State University