MDT Series Penetrometer and Texture Analyzer

Sophisticated fruit testing in a rugged portable package

Mohr Digi-Test (MDT) Series instruments are portable materials testers designed to accurately characterize the texture and firmness of fruit, vegetables, and other agricultural produce in the field, packing house, and the laboratory.

The MDT-1 is in active use by prominent fresh produce industry and research organizations. The new MDT-2 builds on the capabilities of the MDT-1 with a number of next-generation enhancements.

MDT-2 Key Features

  • Constant rate, Creep, and Crispness testing
  • Eliminates operator and transcription errors
  • Tension and compression modes
  • 5 mg (1x10-5 lb.) force sensitivity (24-bit ADC)
  • ±30 kg (±65 lb.) standard load cell range
  • 0.001 mm (1x10-5 in.) distance precision
  • Precision external scale / automated calibrator
  • 2+ GB storage, enough for thousands of tests
  • USB host/client, 10/100 Ethernet
  • Lightweight with bright color touchscreen
  • Barcode scanner integration

MDT for Fruit Testing and other Agricultural Testing

Save a lot of time, effort, and money

The MDT is optimized for fruit and vegetable testing -- we have specialized probes and testing routines for apples, pears, grapes, cherries, kiwi, tomatoes, potatoes, watermelon, and many other agricultural products. You will save at least 50% of the time you spend testing and managing data when you use the MDT. For organizations with high-volume testing (most growers, packing houses, and retailers), this can translate to major cost and efficiency savings. Here are a few ways you will save time and effort:

  • Fast testing: The MDT can test faster than you can physically keep up (25+ tests/minute).
  • Automated reports: All data is immediately tabulated and exported in customizable reports, viewable anywhere over a LAN or the internet.
  • Barcode scanning: No more writing or entering information, including identification info! This can all be barcoded and is handled automatically by the MDT.
  • Diameter / weight: The MDT records these parameters automatically.
  • Integrated test data: MDT software allows any kind of fruit test data to be barcoded in (titrable acidity, soluble solids, color, etc.) with the same high efficiency as MDT test data. These are included in your automated reports, too.
  • Network integration: Fruit test data is available immediately over the network.
  • Portability: The MDT is lightweight, battery powered and designed to be used anywhere. Use it in the lab and then throw it in your truck for field use or carry it into the packing house.
  • Ease of Use: We know you are busy and don't have the time or energy to figure out a new instrument. One button press gets you testing.

Get more meaningful test results

The interior portion of an apple, which contains most of the edible material but is generally not tested by convential fruit firmness testers, is actually one of the most important portions of the fruit to test. This is because fruit maturation progresses at a different (and often accelerated) rate within the interior of the fruit. A normal external fruit pressure value can mask a overly mature fruit interior. Discarding this important data leads to lower market share and dissatisfied consumers. Using this data gives your organization the edge in timing picking, optimizing storage parameters and shipping times, and in managing sales. The MDT gives you better data in a number of ways:

  • Repeatable, accurate results: Effegi and Magness-Taylor fruit tester data is easy to "fudge" and even with careful use can vary widely from operator to operator. The MDT is always accurate to within 0.01 lb, no matter who is using it.
  • Complete fruit maturity data: The MDT gives you external fruit pressure, internal fruit pressure, crispness (analagous to the crunch you experience when biting a fruit), and creep deformation (how viscous the fruit material is under constant pressure, indicating loss of cellular integrity), and also gives you the Quality Factor (QF), a weighted summation of all these test parameters, customized for each fruit type and scaled to 100 for optimum picking and 0 for the limit of consumer acceptability. For a complete description of MDT test parameters, please read the paper referenced below on Apple Maturity.
  • Instant statistics: Ever wonder what the "bell-curve" of your fruit looks like? The MDT gives you mean and standard deviation you as you test. Follow along on the MDT Server desktop software and see the histogram of fruit quality from multiple different testers.

Important MDT documents for agricultural users:

The Mohr Digi-Test (MDT) Computerized Agricultural Penetrometer as an Apple Maturity Tool. MDT test results described in detail.

Apple Quality Testing in Five Market Centers Using the MDT-1 Agricultural Penetrometer. Describes a comprehensive retail fruit quality test program carried out in a multistate region using the MDT.

MDT FAQ for agricultural users

MDT for General Materials Testing and Texture Analysis

The MDT has a wide range of test capabilities and features that few other instruments offer. From its ability to perform complicated velocity and position-dependent tests (such as creep strain and thixotropic viscosity measurements) with sampling rates up to 1 kHz to its integrated barcode scanning and Ethernet capability, the MDT is in a class by itself. Read below for more information.

MDT Server software allows all of your test data to be barcode-entered and tracked along with MDT texture test data in a single MySQL® relational database that can produce customizable automated reports ready to print, e-mail, or post to the web. Single or multiple users with either a notebook computer or an MDT can simultaneously view, add, and edit texture data in a central database.

Viscous liquid, semi-solid, and thixotropic materials -- MDT-2 is superior to traditional viscometers / viscosimeters

  • Jams, jellies
  • Custard, pudding, pie fillings
  • Catsup, mustard, other condiments
  • Glue, bonding agents
  • Cement, sand, asphalt mixtures
  • Grease
  • Oil
  • Biomedical samples

Solid materials

  • Candy, chocolate
  • Taffy, licorice
  • Bread, bagels, pretzels, pasta
  • Fruit, vegetables
  • Wood and paper products
  • Rubber, plastics
  • Fabric, other textiles

Fully programmable to perform a wide range of test protocols in any sequence

  • Constant velocity stress-strain
  • Constant load creep strain (including standard penetrometer mode)
  • Tension and compression modes
  • Surface finding
  • Diameter measurement
  • Repetitive thixotropic materials testing
  • Hysteresis
  • Real-time test protocol flow-control
    • Time
    • Displacement
    • Velocity
    • Force

MDT-2 Computerized Penetrometer and Texture Analyzer, Fruit Tester

MDT-2 with quick-load Teflon® base and external scale. Compared with the MDT-1, the MDT-2 features bright dynamic color graphics, touchscreen control, improved computational capabilities, longer battery life, enhanced USB and Ethernet connectivity, and a number of other new and/or improved features.

MDT quick-testing buttons for rapidly testing a fruit multiple times.

MDT Quick Buttons™. The MDT makes it easy to test a fruit multiple times. Press green to test a new fruit or press yellow to test the same fruit again. If you have trouble with a test, press red to abort. The MDT keeps track of everything and gives you individual and average test data for each fruit as you test.

MDT used in Research and Industry

The group of researchers currently led by Dr. Katherine (Kate) Evans at the Washington State University's Tree Fruit Research program use the Mohr MDT tester in their evaluation of new cultivars. Their most recent success is the WA 38, marketed as the Cosmic Crisp® apple.

Dr. James (Jim) Mattheis of the ARS Tree Fruit Research Laboratory in Wenatchee, WA used a Mohr MDT penetrometer during his team's research into the use of MCP to control post-harvest ripening of apples. For more details about this work, see:

Plungers, Fixtures, and other Attachments

There are a number of plungers and other attachments available for testing many different materials. Custom fixtures, plungers, and other attachments can be fabricated on an affordable time and materials basis. We also offer a range of load cell sensitivities for working in specific force ranges.

MDT probes.  Interchangeable fixtures for testing most types of fruits and vegetables.

Example MDT probes (L-R: general compression, 4.7 mm, 8 mm pear, 11 mm apple, cherry probes). Numerous interchangeable probes and fixtures make it easy to test anything: fruit, vegetables, other food products, plastics, textiles, etc.

MDT rheology plunger during testing of a thixotropic material (pie filling).  Test protocol involves measurement of viscosity hysteresis at multiple different shear rates.

MDT rheology plunger during testing of a thixotropic material (pie filling). Test protocol involves measurement of viscosity hysteresis at multiple different shear rates.

MDT using compression plunger to test a gumdrop candy.  This test protocol involved both creep strain deformation and constant-rate compression testing.

MDT using compression plunger to test a gumdrop candy. This test protocol involved both creep strain deformation and constant-rate compression testing.

MDT external scale / calibrator.  Use the scale to weigh fruit or place it under the test head and let the MDT-2 use the Weigh Station to calibrate itself.

MDT external scale / calibrator. Use the scale to weigh fruit or place it under the test head and let the MDT-2 calibrate itself.


42.0(H) x 17.8(W) x 20.3(L) cm.
(16.5 x 7.0 x 8.0 in.)


4.5 kg (10 lbs.)


Operating Temperature: 0°C to +50°C (typ. -10°C to +60°C)
Non-operating Temperature: -20°C to +60°C


CE compliance logo
Complies with all applicable EU directives, as specified by the Declaration of Conformity supplied with the instrument.

Complies with Canadian ICES-003.


pdf icon MDT-2 Datasheet (7/8/2019).

How to purchase

For purchasing options, please visit our How to Buy page.