Kombucha brewing improved by scientists

Kombucha’s popularity keeps growing, but here’s the problem: making good kombucha consistently has always been tricky. This fizzy fermented tea can turn out perfectly tangy one batch and disappointingly harsh the next.

Two chemistry professors from Shippensburg University decided to tackle this brewing challenge with some real science. What they discovered could change how we make this ancient drink.

The SCOBY struggle

Anyone who’s tried brewing kombucha knows the frustration. You start with SCOBY – that rubbery “Symbiotic Culture of Bacteria and Yeast” – add it to sweetened tea, and cross your fingers. Sometimes it works perfectly. Other times? Not so much.

The process seems simple enough. Yeast converts sugar into alcohol and carbon dioxide. Then bacteria transform that alcohol into acids that provide kombucha its signature tang. But since we’re dealing with living organisms, results vary wildly.

“Brewers typically see making kombucha as an art more than a science,” explains Jeb Kegerreis, the physical chemist who led this research. “When we’re doing a consultation, we walk the brewer through the biochemistry of what’s happening during fermentation.”

Kegerreis and his colleague John Richardson were determined not to rely solely on chance.

The silicone breakthrough

The discovery came from an unexpected tip. A fellow brewer told Richardson they’d been using silicone sous vide bags instead of glass jars, with faster fermentation and better acid production.

The team investigated and found something remarkable: kombucha brewed in silicone bags fermented twice as fast as traditional methods. Instead of waiting two weeks, brewers could finish a batch in just seven days.

The secret lies in silicone’s porosity. Unlike glass, these bags allow oxygen to seep through from all sides, giving bacteria exactly what they need to work efficiently. More oxygen means faster alcohol breakdown and increased acid production.

But speed wasn’t the only benefit. The silicone method produced more gluconic acid – a game-changer for flavor.

Better taste without the bite

“We think this acid will become more popular with brewers,” Kegerreis says about gluconic acid. “It provides acidity without the sour vinegar taste you get from acetic acid, and that may appeal to more tastebuds.”

This matters enormously. Traditional kombucha can taste harsh or overly vinegary, especially to newcomers. Gluconic acid delivers tang without the bite.

The researchers also noticed how SCOBY behaves differently in various containers. In glass jars, the characteristic pellicle only forms at the surface. In silicone bags, it spreads around the entire interior, creating much more surface area for fermentation.

Sugar science

The team also examined how different sugars affect the final product. While most brewers use table sugar, they tested pure glucose and fructose separately.

“During fermentation, yeast breaks sucrose into glucose and fructose,” explains student researcher Abbi Czarnecki. “We wanted to see how removing that first step affects the brewing process.”

Glucose produced kombucha with desirable gluconic acid and minimal alcohol. Fructose created sweeter brews but with more alcohol and acetic acid.

Real health benefits

This research validates kombucha’s wellness reputation. The fermentation process creates genuine health compounds: probiotics that support gut health, antioxidants that combat cellular damage, and B vitamins that provide gentle energy.

Even the iron released during fermentation potentially improves oxygen delivery throughout your body. These aren’t miracle cures, but measurable benefits from proper fermentation.

From art to science

“Brewing kombucha can still be creative,” Richardson says. “But when something goes wrong during fermentation, science can help make it right.”

This research brings scientific understanding to ancient brewing art, giving both home brewers and commercial producers tools for consistent results. The silicone bag method offers particular promise for anyone frustrated with unpredictable batches.

For the kombucha industry, these findings could be transformative. Consistency has always challenged commercial production, and these methods offer a path toward more reliable, higher-quality products.

The beauty lies in accessibility – you don’t need a chemistry degree to benefit from these discoveries.

Visit the ACS Spring 2024 program to learn more about the research.

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