Determination of Calcium in Beer

PHOTOMETRIC DETERMINATION WITH PHTHALEIN DERIVATIVE

Introduction

Calcium plays a crucial role in the beer brewing process, affecting various aspects such as enzymatic activity, pH stabilization, protein precipitation, and yeast health. Derived mainly from brewing water and enhanced with calcium salts, its presence has a significant impact on the flavor, clarity, and stability of the finished beverage. As a result, accurate measurement of calcium levels is essential for ensuring a consistent and quality product.¹ 

Here, we outline a photometric analysis of calcium levels in beer using the Spectroquant^® photometric system with the Calcium Test Kit.

Content Overview

• Experimental Method
  
• Reagents, Instruments and Materials
• Analytical Approach
• Analysis
• Related Literature
• Reference

Experimental Method

Calcium ions react with phthalein purple to form a violet colored complex. The intensity of the color produced is directly proportional to the concentration of calcium ions present. The absorbance of the colored solution is measured photometrically, providing a reliable quantification of calcium.

Reagents, Instruments and Materials

Instruments

• Spectroquant^® VIS Spectrophotometer Prove 100 (173016)
  
• Spectroquant^® UV/VIS Spectrophotometer Prove 300 (173017)
• Spectroquant^® UV/VIS Spectrophotometer Prove 600 (173018)

Test Kits

• Spectroquant^® Calcium Test: photometric, 0.20–4.00 mg/L (Ca) (1.00049)

Materials

• Rectangular cells 10 mm (1.14946) and/or
• Rectangular cells 20 mm (1.14947) and/or
• Rectangular cells 50 mm (1.14944)
• Water for analysis (1.16754)

Analytical approach

Sample preparation

Fill 100 mL of beer in a 600 mL beaker. Stir in order to drive off the CO₂ for about 1 hour with a magnetic stirrer. Alternatively, you can also use an ultrasonic bath. Attention! Foams strongly.

Expected original beer concentration [mg/L]	Volume of sample [mL]	Filling up in a volumetric flask with x volume [mL]	Dilution factor
4-25	8	100	1+9
25-75	4	100	1+24
75-150	2	100	1+49
150-400	1	100	1+99

Therefore pipette x mL of this solution into a 100-mL volumetric flask and fill up to volume with water for analysis to the mark
(= diluted beer sample).

Analysis

Determine the Ca content with the above mentioned test kit against a reagent blank (water for analysis (instead of beer) + reagents).

The method is preprogrammed on the Prove instruments, but has to be calibrated for each batch.

For details, see Prove manual.
It is recommended to perform a calibration with 5–10 measurement points over the entire measuring range. The calibration should be checked regularly using standard solutions.

Related Literature

• Manual Analysis Methods for the Brewery Industry

  Spectroquant^® Prove - Analysis Methods for the Brewery Industry

• New Fast and Innovative Detection of Beer Spoilage Organisms

  Hybriscan^® an Innovative Screening Method for Beer Spoilage Organisms Based on the Detection of rRNA

• Sulfur Dioxide in Beer

  Photometric Determination with Ellmann’s Reagent
  
  

Reference

1. West DB. 1976. Methods for the Determination of Calcium in Beer. 59(3):678-679. https://doi.org/10.1093/jaoac/59.3.678