pH Determination of Milk and Milk Products
Smartphone-based determination of pH after reaction with a chemically bound pH indicator
Introduction
pH-indicator strips provide an easy and cost-effective tool to determine the general pH of milk and milk products such as yogurt, cream and butter milk. With MQuant® StripScan app, you can even take the guesswork out of your work. Designed to complement MQuant® pH 0-14 Universal Indicator strips, our free, innovative app guides you through the test process, reads results via your mobile camera, then saves and visualizes your measurements. Using MQuant® StripScan app in combination with the MQuant® pH 0-14 Universal Indicator strips, you can get quick semi-quantitative results for direct in-process control with instant results for fast decision making.
The following application note describes the determination of the pH level of milk and milk products using the MQuant® pH 0-14 Universal Indicator strips in combination with the MQuant® StripScan App.
Experimental Method
Special indicator dyes that are covalently bound to the reagent papers, change their color depending on the pH value of the sample.
- Measuring range
pH 0 – 14 - Sample material
Milk and milk products
Reagents, Instruments and Materials
Reagents
- MQuant® pH-indicator strips 0-14 Universal indicator (1.09535)
Accessories
- MQuant® Card (provided with the test strip box)
- MQuant® StripScan App (can be downloaded via Apple App Store or Google Play Store)
Sample preparation
The sample can be analyzed in its original form.
Sample analysis
For the analysis, follow the below steps:
- Start the App.
- Get your MQuant® pH indicator test strip and the MQuant® Card ready.
- Dip the test strip into the undiluted sample (15 – 25 °C) for approx. 2 seconds, ensuring that the reaction zone is completely immersed.
- Remove the strip from the sample and if necessary, quickly rinse the reaction zones with distilled water to remove adherent sample, e.g., if yogurt is used.
- Shake off excess liquid from the strip and dry the backside of the strip using a paper towel.
- Select the parameter pH (1.09535) in the app. Wait for 15 seconds, till the color of the pH strip completely develops (a countdown is displayed on the screen, which begins immediately after selecting the parameter pH).
- Just before the end of the countdown, place the test strip on the MQuant® Card.
- After the waiting time has elapsed, place the MQuant® Card with the test strip within the viewfinder on your phone screen, and align the camera along the reference points.
- The picture is captured automatically by the camera of the smartphone.
- The result is displayed on the screen.
Results
Comparison with visual evaluation, Reflectoquant® pH test (1.16894), and pH electrode seen in Table 1.
Table 1. Comparison of StripScan, visual, and reflectometric pH strip readout with pH electrode reading for milk and milk products (dairy products)
Conclusion
The MQuant® pH strip in combination with the MQuant® StripScan app provides quick and easy determination of pH of milk and milk products. The measured values are comparable to those measured with the Reflectoquant® system and the pH electrode.
For more information
- MQuant® StripScan see SigmaAldrich.com/mquant-stripscan
- MQuant® pH Indicator Test strips see SigmaAldrich.com/phtests
- Applications see SigmaAldrich.com/wfa-applications
- Article: Beverage Testing with the MQuant® StripScan Mobile App
References
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