Adding Yeast to the Fermenter



I see that wine makers are adding their yeast inoculum through the manway in their fermenters to give the yeast a head start on any already present microbes/flora.

 

Does the introduction of the yeast into the fermenter as the juice is filling the tank add value to other roles as well such as aeration, and does it accelerate the growth dynamics of the yeast?

 

Would this be beneficial for smaller scale production in the ten to twenty gallon range for us home mead/wine makers?



You are right about adding the yeast to the fermenter ASAP to give them a head start on the already present micro flora.

 

This is especially true when it takes a long time to fill the fermenter. It is not uncommon for some wineries to take 10 to 48 hours to fill their fermenters. Some people have proposed to add the yeast at the crusher or even in the gondolas as the grapes are being harvested. It take most active dry wine yeast several hours to begin their growth phase.

 

During this lag phase the wild micro flora are in their active growth phase. So the longer you wait to add your yeast to the must the more spoilage organisms you have. The yeast do benefit from the splashing and oxygen uptake. However, they benefit from the oxygen much more at about the 36th hour. Many of the spoilage organisms die off or at least reach their stationary phase at 2 - 5% alcohol.

 

So the sooner the added yeast can get through their lag phase and start growing and producing alcohol the sooner they will overwhelm the spoilage organisms and minimize their production of aromas and flavors. Some of these spoilage organisms produce compounds that add to the complexities of the wine when they are present in trace quantities but can become off flavors and aromas and even toxic to the added yeast if the added yeast does not over whelm them soon enough. The sooner you get the added yeast through its lag phase and into its growth phase the safer you are.

 

The added yeast produces 30+ times as much alcohol per yeast cell during its growth phase than it does during the stationary phase. You can keep it in its growth phase longer by proper rehydration (Go Ferm), nutrient addition and minimizing spoilage micro flora growth. This information does not necessarily translate directly to all 5 – 10 gallon operations. However the principle of getting the adding yeast into the must or mead ASAP holds true.

 

With good equipment cleaning and sanitizing practices, honey and grape concentrate offer very little spoilage micro flora problems. However, with frozen juice and whole berries there is always the possibility of spoilage organism problems.



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