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The Chemical Fingerprint of Beer from a Single Experiment with Minimum Sample Preparation – A Rapid Quantitive Analysis by 1H NMR Spectroscopy

by Beer, Benchtop NMR, Chemistry, Cider, Craft Beverage, NMR, NMR Test Methods, NMR Validation, qNMR Tagged: , , , , , ,

NMR Spectroscopy is the premier tool utilized by chemists to obtain detailed chemical information on molecular structure and is used extensively in molecular structure verification, chemical purity analysis, and complex mixture analysis. We have developed a quantitative NMR analysis that yields a chemical fingerprint that brewers can utilize to follow detailed variations in the chemistry observed in the various stages of the brewing process (malting, mashing, boiling, fermentation, ageing, and blending). The analysis observes all molecules in the beer at the same time and each molecular component (acids, alcohols, amino acids, malt-oligosaccharides) yields a unique spectral fingerprint pattern that is related to the structure of the molecule. Though the spectrum consists of a large number of overlapped individual fingerprints it is possible to identify and quantify individual components because many components have signals that appear at unique and specific points in the spectrum. The quantitative analysis is performed by comparing the area under the individual molecule signals to that of an internal standard (Maleic Acid 99%). Molecular components are quantified on a weight/volume basis in mg/L (parts-per million). Ethanol is also quantified on a %volume/volume basis.

The technique is not only applicable to the brewing process but is also being utilized to gain detailed chemical understanding of cider-making process, as well as the production of wine, mead, sake, spirits, and kombucha. Our laboratory has been developing this method with the help of a number of breweries following changes in batches of standard beers (Kolsch, Stout, Scots Ale, Barley Wine) as the brewing process is tweaked and changed over the course of 2 years. We have looked not just at finished beers but have studied dextrin solubility and chemistry of wort made from different malts, the effect of temperature on sour mashing, the effect of wild yeast and bacteria on various aspects of beer chemistry, as well as troubleshooting of “out of sensory target range” beers. The analysis requires very little sample preparation, has a large (orders of magnitude) linear concentration range of applicability and observes a large number of components in a single test that does not require constant re-calibration with expensive standards.

A poster was presented on this topic at the World Brewing Congress held August 1-17 in Denver Colorado – the poster can be downloaded here.

Beer and Cider Analysis – Example of Spectral Repeatability of Benchtop 60 MHz NMR System

by Beer, Benchtop NMR, Cider, NMR, qNMR Tagged: , , , ,

Here is an example of spectral reproducibility. We are doing a lot of beer NMR at the moment on our 300 MHz NMR and for “giggles” we are running many samples through the various bench-top systems in our lab. We have been quantifying small organic acids (lactic, acetic, succinic , malic, citric, etc.) as they can give some idea of yeast activities and health during fermentation. We are also quantifying  and studying the 1,4/1,6 linkage distribution of residual dextrins. The series of superimposed spectra below consists of 28 spectra of a freeze dried beer sample (a unique Belgian Dubbel. Each spectrum was 128 pulses and took approximately 30 minutes per spectrum. So the superimposed data represents a 14 hour continuous stability test.The data was automatically processed with 16K zero-fill and autophase.It looks pretty damn good.

Zoe Belgian Dubbel - Freeze Dried - 1H qNMR analysis. 128 superimposed spectra representing a 14 hour spectral reprodcibility and stability test.
Zoe Belgian Dubbel – Freeze Dried – 1H qNMR analysis. 128 superimposed spectra representing a 14 hour spectral reprodcibility and stability test.

 

We’ve been looking at a lot of sour beers – here is a home-brewed Flemish Red aged in an oak barrel – note the high lactic and acetic content.

Flemish Red Ale - Freeze dried - 1H NMR
Flemish Red Ale – Freeze dried – 1H NMR

We’ve also been analyzing a lot of hard ciders – commercial and home-brewed varitieties of various styles – very different from one sample to another in the small molecule and sugar chemistry.

Commercial Cider Example - Freeze Dried Sample - 1H NMR Analysis at 60 MHz
Commercial Cider Example – Freeze Dried Sample – 1H NMR Analysis at 60 MHz

 

Dry Basque Cider Example - Freeze Dried Sample - 1H qNMR Analysis
Dry Basque Cider Example – Freeze Dried Sample – 1H qNMR Analysis

 

1H qNMR at 300MHz or 60 MHz can be utilized to identify and quantify small molecule chemistry in fermentations. Below is an example of a quantitative chemistry report on a series of ciders.

Table - 1H qNMR - SMall Molecule and Sugars Analysis
Table – 1H qNMR – SMall Molecule and Sugars Analysis

 

Beer and Cider Analysis is offered with similar quantitative results is offered for $100 per sample in our analytical lab.

From Atoms to Flavour: The Chemistry of Beer

by Beer, Chemistry, Chemometrics, NMR, Process NMR, qNMR, Reaction Monitoring Tagged: , , , , ,

Adam DiCaprio (ex PNA) gave an excellent Science Cafe Talk under the auspices of the ACS North Carolina Section at the Busy Bee Cafe in downtown Raleigh on December 2, 2014. CHanging gears from his previous talks he centered the discussion on malt and hop chemistry as well as an start-to-finish NMR analysis of production runs of a bottled commercial tavern ale. If you are interested in having Adam give a detailed chemistry seminar on beer at your section meetings please contact him directly at adam@process-nmr.com.

A PDF version of his talk is available here …. ACS Science Cafe Talk – Dicaprio – Busy Bee Cafe – Raleigh NC – 12-2-14