The automation of the determination of Starch in beer samples

Skalar Analytical thanks
Mr. Helmut Klein (Laboratory Manager at BRAU UNION ÖSTERREICH AG)
for his valuable contribution in this research project.

The production of beer includes several steps. One of these is the conversion of starch to fermentable sugars by enzymes. The source for the starch is commonly malted barley, although other sources can also be used. By analyzing the concentration of starch, one can determine if this process of converting starch to sugars is completed.

For many years the determination of Starch (Iodine reaction) is done manually, which is not only time-consuming but also sometimes sensitive to errors. In close cooperation with Mr. Helmut Klein, Laboratory Manager of the BRAU UNION ÖSTERREICH AG, Skalar has successfully automated this application on the San++ Automatic Beer & Malt analyzer.

Skalar SAN++ Beer and Malt Analyzer
Figure 1: The Skalar Beer & Malt Analyzer

The method is based on the precipitation of dextrins and starch by addition of ethanol. After centrifugation the precipitate is dissolved in a buffer. Then a iodine solution is added which reacts with the dextrins and starch. The released iodine is colorimetrically measured at 580 nm. The calibration and stability tests show the suitability of this automation to analyze Starch.

Figure 2: Calibration and Reproducibility Figure 3: Typical calibration curve

Typical data of the method can be found in table 1:

TABLE 1: TYPICAL PERFORMANCE FOR STARCH ANALYSIS
Typical Range 0.13 - 2.60 Extinction
0.00025 - 0.005 % Starch
Linearity 0.99998
Reproducibility (CV) < 1%
Method Detection Limit < 0.00005 % (1% of maximum range)

In addition the automated method was compared to the manual method (MEBAK 2.3.2 "Photometrische Jodprobe") with real-life samples.

Figure 4: Correlation of the automated and manual method

TABLE 2: SAMPLE COMPARISON
  SKALAR San++
Extinction
MANUAL
Extinction
Beer A 0,29 0.32
Beer B 0,59 0.52
Beer C 0,86 0.54
Beer D 0,81 0.64
Beer E 1,45 1.02
Beer F 1,12 0.72
Beer G 1,56 1.06
Beer H 1,64 1.08
Beer I 1,02 0.68
Beer J 1,03 0.68

The good correlation between the new Skalar automated procedure and the standard MEBAK method as shown in table 2 and figure 4, proves that the automated method of the Starch determination using the Skalar San++ Beer and Malt analyzer can fully replace the laborious MEBAK method.

In addition to the well-known applications that are already automated on the Skalar San++ analyzer such as Bitterness, B-Glucan, Diacetyl, Total SO2, Free Amino Nitrogen, Skalar now adds the Starch application to its range of applications for the beer and malting industry.

If you require more information, do not hesitate to contact us.