Why Magnums Reign Supreme

Every bottle of our Cotswold sparkling wine is made using the revered Traditional Method, a process of second fermentation in the bottle that creates a fine, persistent fizz. But does the size of that bottle actually matter?

The Science Behind Our Sparkling Wines

We add a very specific amount of sugar and yeast to kick off the second fermentation. Once the yeast has consumed all the sugar and created the bubbles, it dies off.

Following this is the crucial, slow aging process. The yeast cells undergo a process called autolysis—a slow, controlled breakdown. This releases Manno proteins, which later interact with the residual sugars (from the final dosage) in a process called the Maillard reaction. This is the key to developing those delicious, well-known, and much-loved toasted aromas and flavours that are the hallmark of fine traditional method sparkling wine.

Size Matters: Fermentation Kinetics and the Magnum

While the standard 75cl bottle is our most popular format, we pay close attention to how the wine behaves in different sizes. When we look at larger format bottles, such as the Magnum (1.5L), the science of fermentation becomes critical.

A larger bottle means more wine, more sugar, and consequently, a higher population of yeast. Yeast produces heat as it ferments. This means the temperature of the fermentation will increase the more yeast cells are metabolising the sugars. This fluctuation in stability and temperature is referred to as fermentation kinetics.

Ideally, the yeast should digest the sugars at a rate of approximately 1 bar of pressure per week, wrapping up around week six, all while maintaining an ambient temperature of between 12–14 degrees. Not too fast, and not too slow.

Numerous studies have investigated this behaviour, and they all point to the same conclusion: the Magnum format offers the most stable and optimum conditions for this precise, slow fermentation.

In brief, for the best possible sparkling wine, the Magnum is the answer. Despite the extra logistical effort and cost in the winery, the superior, stable fermentation makes it worth every ounce of effort. And let’s not forget - they make the perfect showpiece for any celebration too!

A number of our sparkling wines are currently available in the Magnum format - take a look at them here.