Short Protocol No. 10 I July 2014 Thiobarbituric Acid Number (TAN) Analysis in Beer using an Eppendorf BioSpectrometer® Introduction Objective This assay measures the level of oxidation in your beer, which has a dramatic impact on both the taste and shelf life of the brew. Principle Wort or beer reacts with a solution of thiobarbituric acid and acetic acid which results in a yellow color than can be read on using the Eppendorf BioSpectrometer at an absorbance of 488 nm to determine the TAN. Protocol 1. Clarify beer or wort by filtration if necessary. 2.For the blank: Dilute 1 mL wort or beer in 9 mL distilled water. Add 5 mL 90% acetic acid to the dilution. 3.For the sample: Dilute 1mL wort or beer in 9 mL distilled water. Add 5mL 20 mM thiobarbituric acid in 90% acetic acid to the dilution. 4.Place the blank and samples in a 70 ºC water bath for 70 minutes. 5.Immediately cool the blank & samples to room temperature and read on the BioSpectrometer. 6.On the BioSpectrometer: Under Main Groups select the Absorbance folder. Under Sub Groups select Single λ. Under Methods select Single λ. 7.Select the soft key Edit to change the parameters. Parameters: Cuvette: 10 mm Wavelength: 448 nm 8. Select the soft key Next. 9.Transfer 100 μL of the blank to a cuvette optically clear at 570 nm. 10.Insert the cuvette with blank so that the arrow is pointing towards you and the clear side is facing you. 11.Measure blank by pressing the round Blank key. 12.Insert the cuvette containing 100 μL of the sample in the same orientation as the blank cuvette. 13.Measure the sample by pressing the round Sample key. TAN is a dimensionless number. Higher absorbance at 448 nm indicates oxidation, aging and a reduced shelf life likely due to thermal effects. Reference Li-Chan, E. C. Y., Griffiths, P. R. and J. M. Chalmers. “Applications of Vibrational Spectroscopy in Food Science, Volume 1, Instrumentation and Fundamental Applications” John Wiley and Sons, Chichester, UK, 2010 Short Protocol I No. 10 I Page 2 Ordering Information Description BioSpectrometer basic – 230 V/50–60 Hz, mains plug for Europe, additional mains/power connections available – 120 V/50–60 Hz, mains plug for North America BioSpectrometer kinetic – 230 V/50–60 Hz, mains plug for Europe, additional mains/power connections available – 120 V/50–60 Hz, mains plug for North America BioSpectrometer fluorescence – 230 V/50–60 Hz, mains plug for Europe, additional mains/power connections available – 120 V/50–60 Hz, mains plug for North America Your local distributor: www.eppendorf.com/contact Eppendorf AG · 22331 Hamburg · Germany [email protected] · www.eppendorf.com www.eppendorf.com Eppendorf®, the Eppendorf logo® and Eppendorf BioSpectrometer® are registered trademarks of Eppendorf AG, Germany. U.S. Design Patents are listed on www.eppendorf.com/ip. All rights reserved, including graphics and images. Copyright © 2014 by Eppendorf AG. Methods are intended for molecular research applications. They are not intended, verified or validated, for use in the diagnosis of disease or other human health conditions. Order no. international Order no. North America 6135 000.009 6135 000.017 – 6135000017 6136 000.002 6136 000.010 – 6136000010 6137 000.006 6137 000.014 – 6137000014
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