When University of Queensland Ph.D. candidate Edward Kerr submitted his paper on brewing, he didn’t expect another experiment and an even bigger paper to come out of it. But, one of the reviewers asked for clarification.
“I was looking at barley protein changes during the mashing stage of beer brewing when one of the paper's reviewers asked if the changes were caused by temperature or time spent mashing the barley," Kerr explained.
There was no denying it was a good question but Kerr was stuck. To find out the answer, he’d need to brew a whole extra batch of beer, which would take an additional three months.
“To be honest, I was feeling a little lazy, so decided to see if I could do the same experiment on a much smaller scale,” Kerr said.
And that’s when the surprise happened. During this experiment, Kerr found that he could accurately replicate the beer brewing process using only a single barley seed in a 1.5 mL tube—as opposed to the 5 kg of malt and 23 L of brew that was traditionally considered the minimum. More often than not, in fact, these experiments occurred at a much larger scale up to 100 L.
So, somewhat by accident, Kerr successfully decreased the scale of the experiment from 100 L to a mere 1.5 mL— a proverbial drop in the ocean.
“It has always been thought that testing how barley varieties perform in brewing had to be done at a similar scale to actual beer production," Kerr explained. "When breweries are trying out a new beer recipe, they also want to make enough of it to be able to easily test it by drinking. But this discovery brings together large-scale industrial beer producers and research scientists, who are used to high-precision and sensitivity."
Brews big and small
The brewing process starts with barley seeds being malted before they go through the mashing process, which extracts sugars and proteins into smaller sugars. Wort, the soluble portion of the mash, is then boiled with hops before fermentation, filtering, aging and carbonation.
Kerr’s experiment, published in Scientific Reports, compares protein and peptide levels between a 1 mL micro-mash—performed using a common benchtop shaker/incubator—and a traditional 23 L Braumeister mash.
Much to Kerr’s surprise, all levels were consistent. Looking at the abundance profile of each protein, every single one was similar at both the 23 L and 1 mL mash scales. Examining of proteolysis products released from barely seeds revealed the same results—very similar between mash scales, with only slight differences detected at lower temperatures early in the mash.
The researchers then turned to LC-MS/MS for metabolic analysis. Multiple reaction monitoring LC–MS/MS analysis showed that the fermentable sugar profiles after mash and boil were also similar at the two scales. Lastly, LC–MS/MS revealed wort from the 1 mL micro-scale mash contained very similar concentrations of free amino acids as its 23 L counterpart.
Back to the initial question that kicked off this nano-brewing experiment: are protein changes during mashing temperature- or time-dependent? The answer is both. For proteolytic forms of one abundant peptide family, protein increases were both temperature- and time-dependent. Meanwhile, proteolytic forms of a different protein family showed increases based on temperature only.
Kerr’s team said the new nano-method could speed up the quality testing of newly bred barley varieties.
“Now that we only need a tiny amount of malted barley, we can quickly and easily ensure new varieties are of high quality,” explained Benjamin Schulz, associate professor and co-author of the paper. “This could encourage breweries to be adventurous with their brewing conditions and may very well lead to new styles of beer.”
Additionally, with climate change begetting a warmer world and more severe weather, the researchers think this method can help ensure a steady supply of high-quality barley—regardless of drought or wildfire-destroyed crops.
“We're also hoping to use this approach in undergraduate practical courses in chemical engineering associated with the upcoming University of Queensland Nanobrewery,” Schulz said. “It's a great opportunity to bring process experimentation and optimization into the student experience.”
Photo: Ed Kerr (left) and Ben Schulz (right) have shrunk critical beer experiments, potentially leading to new beer varieties. Credit: Ho Vu