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Mead & wine

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Questions for the panel:

1. Relating to mead/wine:
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. Question: 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?
- Oskaar

Response:
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.

Clayton Cone.

2. Relating to mead/wine:

I've been reading that yeasts like nitrogen from different sources during different phases in the early stages of fermentation. I've seen recommendations for using DAP at the end of the lag phase and Fermaid-K at the 1/3 sugar depletion phase. Does this play a bigger role than
supplementing YANC and FAN already present in the must to ensure optimal fermentation dynamics? I generally work i
n ten to twenty gallon batches, what is the proper dosing of DAP to use when preparing the must for introduction of the yeast, and at the end of the lag phase?

Response:

I wish that there was a universal protocol for the addition of nutrients to all fermentations, but there isn't. There are too many caveats:
1. Wild yeast spoilage organisms are the main problem that must be addressed. They can consume many times their requirement of minerals and vitamins during the early hours of the fermentation leaving the must deficient for the added yeast when they get through their lag phase an into their growth phase. So it is not wise to add a well balanced nutrient such as Fermaid K at the beginning of fermentation when there is the potential for the presents of wild spoilage organisms such as you may find in fresh crushed apples for cider and whole berries, fresh or frozen juice.

With good cleaning and sanitary practices, there is very little problems of spoilage yeast with honey and concentrates. So, it is safe to add the well balanced nutrient at the beginning of the fermentation when the yeast needs all the nutrients and will not have to share them with spoilage organisms. Then add DAP in increments during the growth phase and into the beginning of the stationary phase. Yeast like a fresh source of nitrogen during the growth phase and will reward you with minimum production of H2S and a healthy cell through out the entire fermentation.

2. How much nutrient to add is the next problem to be addressed. For all practical purposes, honey, apple juice, corn and cane syrup contain no nutrients for the yeast. So, 2 pounds of a well balanced nutrient such as Fermaid K and 2 pounds of Fermaid 2133 (autolysis yeast) and 4 pounds of DAP / 1000 gallons of must.
Grape juice concentrate contain very little nutrients for the yeast. A lot of the nitrogen and minerals and vitamins have been removed during the preparation for evaporation. So for insurance, it is best to assume that there are little to no nutrients available for the yeast and follow the above recommendations.

FAN or YAN in fresh grape juice can vary over a wide range depending on the grape varietal, vineyard practices and season from 40 PPM YAN to well over 500 PPM YAN. If you have the YAN analysis, these are our recommendations: http://www.lallemandwine.us/products/nutrient_strains.php

If you do not have a YAN analysis you should add 2 - 4 lbs. of DAP over the first 1/3 of the fermentation and 1 - 2 lbs of Fermaid K after 1/3 of the sugar has been converted to alcohol.3.

Oxygen should be considered as a yeast nutrient, so make sure that the yeast gets enough O2 near the end of its growth phase.

4. Potassium is a nutrient requirement that should be taken into consideration in honey, corn and cane sugar and grape concentrate fermentation. 1/2 to 1 lb of potassium carbonate should take care of this requirement added with in the first 12 hours of the fermentation.

Clayton Cone