University of California

Ask the Produce Docs (General)

How is fresh apple fruit pressure measured?

Category
  • Quality Evaluation
Question

I work in the quality inspection of imported fresh fruits. We are importing various fresh fruits from different origins. I would like to understand how exactly Fresh Apple Fruit Pressure is measured at destination. If you can give us any variety wise / origin wise details of Apples pressure it would be very helpful to me. Presently we are focusing on imported apples from USA, China, RSA, Italy & NZ. (V.J.)

Answer

Apple firmness (sometimes referred to as pressure) is measured with a penetrometer using an 11-mm round tipped probe. A very thin slice of the skin is removed on two sides of the fruit at the equator, and the probe is pressed into the flesh to obtain the reading.  The measurement is made the same for all types of apples.  You can see some examples of penetrometers on the following website http://www.qasupplies.com/firtes.html. For a guide to apple firmness levels, please refer to this linked PDF document by Philip Schwallier.  These values are recommendations for harvest firmness for storage, so your values may be somewhat lower upon arrival in your market.          
                                         -Beth Mitcham

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