Beverage Testing with MQuant® StripScan Mobile App

Saskia Neubacher, Product Manager Mobile Analytical Workflows


pH and nitrate content are two of the key parameters used to measure the quality and safety of food and beverages (F&B). Generally, pH measurements are carried out using pH strips, pH meters, or electrodes, whereas spectrophotometers or electrodes are used for measuring nitrate content. This article examines the use and efficiency of the MQuant® StripScan mobile app to measure the pH of orange juice samples and nitrate concentration of mineral water samples. The results indicate towards the possible use of the MQuant® StripScan mobile app as a viable alternative to more sophisticated and instrument-based methods for pH and nitrate measurements in food and beverage analysis.


Ensuring delivery of quality and safe food and beverage products is critical to the global F&B industry. pH plays an important role in preserving the color, flavor, texture, taste, and nutritional overall value of the product and significantly impacts the quality of final food and beverage product delivered. Moreover, maintaining the proper pH is a food safety issue.1 For instance, keeping the pH of canned or preserved food at 4.6 helps prevent the growth of toxic bacteria, such as Clostridium botulinum.2 Additionally, most microorganisms including bacteria, yeasts, and molds cannot survive or grow under very low or high pH values. In the food industry, monitoring the pH of raw materials is essential to prevent their deterioration, which in turn, can affect the shelf-life of the final product. For example, in juices and brews, measuring the pH of water before addition in food processing guarantees a good quality and safe end-product.3


MQuant StripScan App Product Group Dashboard


This is particularly important when the water source is a municipal water system, where quality can vary considerably over time.

The traditional method for pH measurement involves the use of a pH meter, which uses the difference in electrical potential between a pH electrode and a reference electrode to generate a reading. The logarithmic nature of pH scale makes even a small change very significant, with even a change of just 0.3 units denoting doubling of acid concentration.4 Additionally, pH measurements by electrodes are greatly influenced by factors like temperature, electrode stability (drift and hysteresis), the quality of the response slope/calibration curve, as well as the accuracy of the instrument.5

A novel method for measuring pH involves the use of the MQuant® StripScan mobile app in combination with test strips. This method provides pH measurements in a few seconds, and also offers additional benefits of automatic data storage, generation of graphs for further documentation, and an automatic data transfer to desktop devices.6

Nitrate (3--) is another compound that has a significant influence on the quality of F&B products. Although it occurs naturally as part of earth’s nitrogen cycle, various human activities contribute to its presence through agricultural operations (via excessive use of inorganic fertilizer), sanitation, diffusion from industrial processes, and disposal of solid waste.7

Consumption of food or beverages with high levels of nitrates can have adverse health effects. For example, it can generate carcinogenic nitrosamines upon reaction with amines or amides. Under some conditions, nitrates can also produce nitrite (NO2-) through bacterial reduction in the stomach, causing a rare blood disorder called methaemoglobinaemia, a serious condition resulting from impaired oxygen transport by red blood cells.8 For this reason, regulatory agencies have set safety limits for nitrate in food and beverages, as well as in water supplies. For example, the current acceptable daily intake (ADI) for nitrate set forth by the European Food Safety Authority (EFSA) is 3.7 milligrams per kilogram of body weight per day (mg/kg bw/day). The U.S. Environmental Protection Agency (EPA) has implemented a maximum contaminant level (MCL) for nitrate in water at 10 mg/L (as nitrogen; equivalent to 45 mg/L of nitrate).9 The Food and Drug Administration’s (FDA) allowable nitrate level in bottled water is the same as EPA, while in food, the level should not exceed 500 part per million (ppm) in the finished product.10

Different methods available for measuring nitrate content include spectrophotometric, chemiluminescence, electrochemical detection, chromatographic, capillary electrophoretic, and spectrofluorimetric methods.11 Although these techniques offer high sensitivity and selectivity, they also involve laborious chemical work, and require specialized and expensive instrumentation. To address these issues, rapid detection techniques based on test strips are gaining popularity. Combined with the MQuant® StripScan smartphone app, test strips are fast, affordable, non-hazardous for most measurements, and do not require the handling of liquid chemical waste.

In this article, we describe the use of MQuant® StripScan mobile app and test strips for measuring pH and nitrate content of food and beverage products.



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