Frequently Asked Questions
1.What is ethyl carbamate?
2.How do Phyterra's yeast prevent the formation of ethyl carbamate?
3.Are any of Phyterra's yeasts genetically modified organisms?
4.Do different yeast strains really affect the flavor attributes of wine?
5.How does changing the fermentation temperature change a wine's flavors?
6.Can you mix strains in a fermentation?
7.What kind of technical support does Phyterra provide?
8.What is the optimal way to rehydrate and add yeast to grape juice?
9.What are your suggested inoculation rates?
10.How should I store my yeast?
11.Can an open package of dry yeast be resealed and used later?
12.Can I use yeast that has gone past the expiration date?
13.What will happen to my wine if I do not add enough yeast?
14.Ethyl Carbamate
15.About Yeast?
1.What is ethyl carbamate?
Ethyl Carbamate (also known as EC or urethane) is a well known, potent carcinogen sometimes used in pesticides. EC in high doses can cause tumors within months. In March 2007, the World Health Organization reclassified EC from a Group 2B possible human carcinogen to a Group 2A probable human carcinogen. The US National Toxicology Program cites clear evidence linking EC to breast, lung, liver, ovarian and stomach cancer in animals Ethyl carbamate is found in wine and other fermented foods in low concentration as a naturally occurring by-product of the fermentation process. Canadian government has set mandatory EC limits for wines and spirits. Other countries including the USA may soon set limits as well. In October 2006, four wines were pulled off Canadian store shelves for exceeding ethyl carbamate limits.
2.How do Phyterra's yeast prevent the formation of ethyl carbamate?
During fermentation, yeasts break down arginine, an amino acid, into urea and ornithine
Yeast cells can then either
- further degrade urea into ammonia for a nitrogen source OR
- excrete urea.
Urea reacts with ethanol + time + heat to form ethyl carbamate
Phyterra wine yeast strains favor urea degradation over excretion. Without a urea source, ethyl carbamate can not be formed.
3.Are any of Phyterra's yeasts genetically modified organisms?
All Phyterra yeasts have non-GMO status according to EU regulations, the most relevant jurisdiction regarding this subject.
4.Do different yeast strains really affect the flavor attributes of wine?
Yes. Every strain is a little different. Some emphasize varietal character, some make more neutral flavored wines, some are better at extracting tannins.
5.How does changing the fermentation temperature change a wine's flavors?
Lower temperatures tend to allow retention of natural fruit flavors, much like storing an apple in the refrigerator keeps it fresher longer
6.Can you mix strains in a fermentation?
While you can, most commercial winemakers choose a single strain. Mixed strains tend to produce unpredictable fermentations, and sometime unpleasant wines. Some winemakers will use different strains on separate lots, then blend later.
7.What kind of technical support does Phyterra provide?
Phyterra wants you to make the best wine possible. Please contact us with any question you may have by clicking here
8.What is the optimal way to rehydrate and add yeast to grape juice?
Instructions:
- Dissolve 1g yeast to 10mls water (a 7g package in 70 mls or 3 oz, a 500g package in 5 liters or 1.3 gallons)at 38-41 C
- Let stand 15 minutes without stirring, then stir to suspend yeast.
- Add immediately to juice.
Alternatively, you can add the suspended yeast to an equal amount of juice, wait an additional 20 minutes, then add to juice.
9.What are your suggested inoculation rates?
Standard rate is 25g/100 liters (2lbs/1000 US gallons)
For home winemakers, our 7g package can make up to 28liters (7 gallons).
10.How should I store my yeast?
Store at room temperature or refrigerate. Dry yeast will always lose some of its viability and activity over time but at colder temperatures these losses are less than at warmer temperatures.
11.Can an open package of dry yeast be resealed and used later?
We advise to use opened yeast within a week to ensure good performance. Air and moisture affect viability.
12.Can I use yeast that has gone past the expiration date?
For best results, use yeast prior to the expiration date. There is no guarantee that it will perform as well as yeast within its expiration date.
13.What will happen to my wine if I do not add enough yeast?
Not enough yeast will result in a slower start, with a higher risk of wild yeasts overtaking the fermentation, as well as slower and sometimes stuck fermentations.
14.Ethyl Carbamate
15.About Yeast?
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