Data logger, oscilloscope, signal generator and more!

DrDAQ is a versatile instrument that connects to the USB port of any PC. Using the supplied PicoScope software it can be used as an oscilloscope, spectrum analyzer and signal generator.

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Measuring the pH of milk


This experiment looks at the changes in pH of milk as it goes sour. Milk is contaminated by bacteria even before it leaves the udder, although at this point they are harmless Educational data loggerand few in number. Processing and handling activities can introduce further microorganisms.

The two main groups of bacteria in milk are lactic acid bacteria (LAB) and coliforms. Lactic acid bacteria is the normal bacteria present in milk and dairy products. Coliforms are the main reason for milk spoilage.

This experiment demonstrates the changes in the pH of milk over a several day period (depending on room temperature).
It is suitable for ages 13 upwards.

Equipment required

  • DrDAQ data logger connected to a PC
  • One pH probe (DrDAQ Part no DD011)
  • A bottle or container of milk

Experiment setup

Allow the milk to reach room temperature without cooking and re-pasteurising it. Plug the pH probe into the DrDAQ BNC socket and insert the probe into the container of milk. Then run the PicoLog software.

Set PicoLog to take 1 sample per minute and a maximum sample of 10,000.

set up

Carrying out the experiment

Start PicoLog Recording the data and display the graph. Try and keep the experiment in a stable environment as the extremes in room temperature may give false readings.


Questions and discussion of results

1.Did you see a reduction of pH shortly after starting the experiment?

2.What causes the reduction in the pH of milk?

3.Does the speed of change in pH stay constant over the whole experiment period?

4.Calculate the extent of change in pH obtained in the process.

5. What would be the results of incubating UHT milk over the same time period?

Further study

Try repeating the experiment using unpasteurised or ultra heat treated milk.

Try keeping the container of milk at different temperatures (in the fridge or an incubator).


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    Rop Honnor
  • I have been using my 4224 PicoScope for years. I travel abroad so this has been ideal due to its physical size. Storage of waveforms on my Laptop is very easy allowing me to quickly email waveforms to my Colleagues.

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  • PicoLog TC-08: This is a very nice unit that works consistently and reliably.

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  • It is a great scope. I had a weird problem - it did not work on one of my PC’s. Customer service gave me first class service. If I could give 6 stars for customer service - I would do so.

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  • Perfect Partner for Development of Encoder controlled Stepper Motor Actuators. Since the included software is really stable, this type of device is a great tool for great tasks!

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  • A superb piece of equipment worth its weight in gold

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  • So simple to use & beats any other I have ever used hands down.

    John D Samsing
  • Rather than webcam our benchtop scope screen, it was suggested we use a PicoScope to share waveforms via screen share.

    We were a bit hesitant at first … but it worked flawlessly, and everybody is now out shopping for PicoScopes!

    T Lövskog • SVP of Innovation at Additude AB
  • Great functionality in a compact size. I really like moving the mouse pointer to a position and having the Time and Voltage display the values at that point. Calibration equipment is a breeze with that feature.

    Don Horein

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