WSU Apple Breeding Program Picks Unique Taste-Testing Device

An apple’s crispness is rated among its most important qualities by consumers, but the apple industry has not yet established a reliable automated method for measuring fruit crispness, instead relying primarily on subjective and labor-intensive taste-testing. But, new research has confirmed the capabilities of a unique texture-testing instrument that could change the way apple crispness is rated.


Researchers with the Washington State University Apple Breeding Program (WABP), led by associate professor Kate Evans, compared the sensory attributes of a variety of apples, rated by an expert taste-testing panel, with measurements obtained by the Mohr MDT-1 penetrometer. According to their report, the researchers found a significant correlation between the MDT-1’s crispness measurements and the apples’ crispness and overall eating quality.

The MDT-1 is a next-generation replacement for the hand-operated Magness-Taylor penetrometer the industry has used for decades to measure fruit firmness, and the researchers conclude that MDT-1’s unique measurements are likely more informative than other penetrometer tests or acoustic resonance techniques. The report also says that the WABP intends to use the MDT-1’s measurements to reduce the need for taste-testing as they develop new apple varieties.

“Think of the MDT-1’s plunger as a mechanical tooth,” says Brandt Mohr, Mohr’s chief technologist. “The MDT-1 measures the energy released by the crunch of the apple as the plunger advances in a way that is repeatable and operator-independent. Fruit firmness alone is not adequate, because a firm apple is not necessarily a crisp apple.”

For more information on the MDT-1, go to