Device Measures Apple’s Crispness

Richland,
Washington – Everybody knows a good apple when they bite into one, and it turns
out that an apple’s crispness is rated among its most important qualities by
consumers. However, despite the size and economic importance of the U.S. apple
market, an estimated 231 million bushels in 2009, the industry has not
established a reliable automated method for measuring fruit crispness, instead
relying primarily on taste-testing that is both subjective and labor-intensive.
Now, new research confirming the capabilities of a unique texture-testing
instrument suggests this is about to change.

Researchers with
the Washington State University Apple Breeding Program in Pullman, led by Associate Professor Kate
Evans, compared the sensory attributes of a variety of apple selections, rated
by an expert taste-testing panel, with measurements obtained by the Mohr MDT-1
penetrometer.

According to
their report published in the December 2010 issue of HortTechnology, the
researchers found a significant correlation between the MDT-1’s Crispness (Cn)
measurements and the apples’ crispness and overall eating quality. The MDT-1 is
a next-generation replacement for the hand-operated Magness-Taylor (MT)
penetrometer the industry has relied on for decades to measure fruit firmness,
manufactured by Mohr and Associates.

The researchers
conclude the MDT-1’s unique measurements are likely more informative than
standard MT penetrometer tests or acoustic resonance techniques with which the
industry has more recently experimented. The report goes on to state that the
WABP intends to use the MDT-1’s Cn measurements to reduce the need for labor-intensive
taste-testing as they develop new apple varieties.

According to
Brandt Mohr, Mohr’s chief technologist, the MDT-1 measures some of the same
fruit characteristics as a consumer.

“Think of
the MDT-1’s plunger as a mechanical tooth,” Mohr says. “The MDT-1
measures the energy released by the crunch of the apple as 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.”