Home Wine Industry Spotlights Rewrite the Rules of Yeast Rehydration

Rewrite the Rules of Yeast Rehydration


Introducing a New Cold Water Process

For the past 20 years, the wine industry has been taught that the best way to rehydrate active dried yeast is to use warm water and a rehydration nutrient. Because yeast can be temperature shocked if pumped directly into cold juice or must, this process requires very slowly dropping the temperature of the rehydrated yeast before inoculation.

As such, the process can take over an hour which is inconvenient during the busiest time of year. Nevertheless, winemakers were taught to follow this rule scrupulously or court disaster by way of stuck or sluggish fermentations.

Let’s speed it up

Go-Ferm Sterol Flash™, the newest addition to Lallemand Oenology’s line of Go-Ferm nutrients, gives winemakers a next-generation technology that allows them to safely break the traditional rules of yeast rehydration. Because Go-Ferm Sterol Flash can be used with cellar temperature water (15ᵒC/60ᵒF) instead of warm water, the slow acclimatization process can be skipped and inoculation can happen much faster.

Scott Laboratories tested the time required of Go-Ferm Sterol Flash against its predecessor, Go-Ferm Protect Evolution™ – Like most rehydration nutrients, Go-Ferm Protect Evolution uses warm water and takes an hour or more to go through the multiple acclimatization steps. Go-Ferm Sterol Flash drops that time to just 20 minutes and uses half as much water.

Dr. Nichola Hall, the General Manager of the Fermentation and Enology Department at Scott Laboratories, explains how the Lallemand R&D team transformed this longstanding principle:

What’s happening during rehydration?

During rehydration, the membranes of active dried yeast cells are reforming so they can function properly as protective layers. When rehydrated in cool water, the membrane does not fully re-form and leaves the cell vulnerable to the stressful conditions of fermentation.

Why use a rehydration nutrient?

Let’s start with sterols, the essential lipids in the yeast cell membrane. These sterols (mainly ergosterol) maintain membrane integrity by optimizing their structure. Without sterols, yeast will not adapt as well to fermentation stressors, such as high sugar or ethanol, and will be more susceptible to sluggish or stuck fermentations.

While yeast cells can produce these sterols themselves, rehydration nutrients are a much more efficient way to incorporate sterols into the cell membrane. “We use the term nutrient, which means nourish,” says Hall, “but sterols are actually protectors, shielding the yeast from the higher sugars and heat during fermentation. Some rehydration nutrients also contain vitamins, minerals and amino acids, so you do get some nourishment as well.”

Rehydration nutrients exploit a narrow window of time during rehydration when yeast cannot control what goes in and out of the cell. This means that the good things in rehydration nutrients (vitamins, minerals, and sterols) are easily and directly incorporated.

So, what’s the science behind Go-Ferm Sterol Flash?

Go-Ferm Sterol Flash is made from a unique yeast autolysate with an extremely high concentration and bioavailability of ergosterol. It is produced in a micro-agglomerated form via a proprietary process that results in a larger particle size. This larger particle size means it disperses instantly and is low-dusting, addressing some challenges with using previous Go-Ferm™ products.

Previous Go-Ferm products also required hot water to release their sterols into solution. On the other hand, Go-Ferm Sterol Flash quickly releases sterols into solution even at cool temperatures. Furthermore, the extremely high concentration of sterols released help overcome the typical issues with rehydrating yeast in cool water.

“Winemakers are practitioners,” says Hall. “They know what they like and what works for them. We are asking them to make a leap and ignore everything we have taught them for decades. But our new science has given us new knowledge that will disrupt the normal fermentation process. At Scott Laboratories, we depend on science to ensure the winemaking process works every time.”

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