Device Measures Apple’s Crispness

article image Kim Goh
A crisp apple makes for a delicious snack.

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

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.”

According to
Mohr, the WABP team’s results confirm the company’s internal findings and
provide a solid basis for wider adoption of the technology throughout the
horticultural research community and industry.

Mohr Digi-Test
Series computerized penetrometers include the MDT-1 and the new MDT-2
instrument planned for release in early 2011. The instruments can measure
numerous fruit quality parameters. Standard software and fixtures enable
accurate high-volume testing of fruit and other agricultural products.
Available features include automated report generation, barcode scanner
integration, and custom fixtures for general materials testing. To learn more
about the MDT-1, visit the Mohr and Associates website.

Established in
1982, Mohr and Associates develops innovative test and measurement
instrumentation for a wide range of applications. Visit the Mohr and Associates‘ website for more information.