FERMENTATION

The Cascade Bohemian Yeast seems to be slower than other home brew yeasts. What are the differences?
What temperature should I ferment at?
How do I get the correct temperature to start my fermentation?
How do I control my fermentation temperature?
How do I know when my fermentation is finished?
Why didn't my fermentation start?
Why is my fermentation taking so long?
Why has my beer stopped fermenting?
Sometimes my brew smells "off" during fermentation or when I bottle. Why is that?
Where can I find the Cascade Home Brew Performance Specifications?

Q. The Cascade Bohemian Yeast seems to be slower than other home brew yeasts. What are the differences?

The Cascade Bohemian Yeast has been specially selected because it gives a steady, measured fermentation that results in a very clean tasting beer. (In brewing "fast" does not necessarily mean "better".) The speed of the fermentation and associated properties are different from many of the home brew yeasts that you may have used. It is important to understand these differences so that you make the correct decisions when brewing.

Do not expect signs of fermentation within a few hours. Cascade Bohemian Yeast may take a day to acclimatise before fermentation starts. This compares to some yeasts that start foaming within a few hours of pitching. Therefore don’t think that nothing is happening or that the yeast is dead - it is determinedly preparing itself for fermentation.

You may speed up the start of fermentation using a "Yeast Starter" culture. A yeast starter is made by stirring the yeast into a nutrient solution at a suitable temperature, allowing it to acclimatise, and then adding the starter into the fresh wort in the fermenter. The following is one of many good ways of making a starter.

1. Ensure the equipment is sanitised and rinsed with cooled boiled water.
2. About three hours before starting to brew, add 500 mL of water to a saucepan and stir in two tablespoons of malt extract (from the home brew can or another liquid or powder).
3. Boil for 20 minutes, cover with aluminium foil and cool to 25°C.
4. Add the yeast and stir well.
5. Keep at about 25°C for two hours, occasionally swirl.
6. When the fermenter has been made to 23 L, pour in the starter and gently stir.

There will not be a huge amount of froth and foam. Cascade Bohemian Yeast will often produce less than 1 cm of foam and the foam may not cover the entire surface.

Do not rely on watching for bubbles in your airlock to determine if fermentation is under way. Despite your best efforts you may have a leak in your fermenter seals through which the CO₂ is escaping. With many faster yeasts the CO₂ may escape through both the leak and the airlock. Because Cascade Bohemian Yeast ferments at a steadier rate the CO₂ may only escape through the leak and thus there may be few or no bubbles seen going through the airlock. One home brewer told me that he definitely had no leaks and had not seen any bubbles in the airlock in the five days since fermentation should have started. He concluded that nothing had happened and he was going to throw the whole brew out. I asked him to take an hydrometer reading first and that revealed the fermentation had gone nicely to completion the gravity had dropped from 1040 to 1006). As well, the hydrometer sample was gassy and foaming which visually demonstrated that fermentation had occurred. Similarly you may only need to pour some of the brew out of the tap into a glass and look, smell and taste. Is there foam? Is there gas? Is it tasting something like beer? If you have any further doubts you may risk a peek inside the fermenter. Streams of bubbles coming to the surface will indicate that there is fermentation.

The full fermentation time for Cascade Bohemian Yeast may be a couple of days longer than with other yeasts.

SAFETY NOTE: Do not assume that the Cascade brew will take the same time as other yeasts and package too early. If you do you will risk extra fermentation occurring in the bottle resulting in the very dangerous risk of explosion. Only rely on hydrometer readings to determine when fermentation has finished - make sure that you have the same hydrometer reading on two consecutive days and that the reading is what you expect (e.g. about 1006 with a 1.7 kg kit plus 1 kg of dextrose or sugar in 23 L).

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Q. What temperature should I ferment at?

This is a very important question. Temperature is vital.

Please follow the brew kit instructions.

If the temperature is too low the fermentation will slow and maybe stop prematurely as the yeast drops to the bottom.

If this happens it may be possible to retrieve the situation by warming the fermenter and stirring the yeast into solution. However brewing yeast is a very fussy organism and if the temperature is changed dramatically there may be off-flavour development.

If you ferment at too high a temperature the fermentation rate will increase markedly but you may end up with significant off-flavour development.

If the temperature is even higher the yeast may die resulting in both off-flavours and an unfinished fermentation.

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Q. How do I get the correct temperature to start my fermentation?

This is sometimes tricky but it is vitally important that you get it right.

Buy a thermometer that covers 15-30°C.

Use very hot/boiling water to dissolve the sugars and the tin of Cascade Master Craftsman extract - 2 L should be enough.

Add water at a temperature of 15-20°C and your final temperature will be about right.

In my home normal cold tap water addition to a final volume of 23 L gives a final temperature of 22-24°C, which is ideal.

You need to determine what the conditions are in your home (and water temperature may change significantly between summer and winter).

Initially you may wish to fill to a few litres short of 23 L, check the temperature and add cold or hot water accordingly up to 23 L.

The following formula may assist in calculating the temperature required for the water to be added:

• if the malt extract and adjunct occupy 1 L, then 22 L of water is needed
• if 2 L of boiling water is used (at 100°C)
• if the overall temperature of the 22 L of water is to be 23°C
• therefore 20 L of water is required at a temperature of T°C

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Q. How do I control my fermentation temperature?

Firstly start with a temperature of 19-26°C (ideally 22-24°C).

You need to assess your environment (which may change seasonally).

If your environment is going to be in the low 20°s for the next week special control procedures are not required.

If the temperature is going to be in the high 20°s put the fermenter in the coolest room of the house.

If the ambient temperature is going to be below 20°C, I sometimes wrap a thick towel around the fermenter. This helps maintain the initial heat and also helps maintain the heat generated by the fermentation.

Better ways of control in lower temperature environments are the use of a heating strap or, even better, an immersion control heater (which I often use instead of a thick towel). You can find these at a home brew shop.

A temperature-indicating strip on the outside of the fermenter is very helpful (but note that it may read 1-2°C lower than the fermenting beer).

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Q. How do I know when my fermentation is finished?

Depending upon temperature a fermentation should take between 4 to 8 days. I define fermentation as complete when the gravity is less than 1007° and the gravity is the same on two consecutive days. (Note that this applies to normal brews of 1.7 kg of hopped malt extract and 1 kg of dextrose or sugar in 23 L - other brews may differ.)

Obviously you must use an hydrometer to take these gravity readings.

SAFETY NOTE: Some brewers watch their airlock for signs of CO₂ bubbling out. They assume that when bubbling stops the fermentation has ceased. Sometimes the fermenter seals (the lid's O-ring and the airlock grommet) may not be working and the CO₂ is escaping through leaks rather than through the airlock. They bottle the beer erroneously believing that all fermentable sugars have gone. However fermentation of wort fermentables continues in the bottle along with the priming sugar fermentation. The CO₂ pressure can become so great that a faulty bottle may explode. This is a dangerous situation.

This same danger can be created if the fermentation stops prematurely due to low temperature and you judge the end of fermentation from CO₂ ceasing to go through the airlock rather than by using an hydrometer.

Be very careful - always make decisions based upon an accurate hydrometer reading.

You can support the gravity measurements by tasting the beer. Try following the flavour development by tasting each day through fermentation. Note how the sweetness decreases until there is a balance with bitterness. Your tasting skills will quickly develop.

Also see the FAQ: "The Cascade Bohemian Yeast seems to be slower than other home brew yeasts. What are the differences?"

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Q. Why didn't my fermentation start?

This is not a common occurrence but there are some possible simple reasons.

You forgot to add the yeast (this happened to me once on a bad day!).

The yeast is dead. Is it very old? Has it been stored in a very hot environment?

The wort temperature is far too high and a large part, or all, of the yeast was killed on pitching.

The wort temperature was too low. The yeast may drop to the bottom. There is a chance of saving the day by warming the wort and stirring up the yeast. There are risks that fermentation shall not proceed normally and spoilage organisms may take over.

Fermentation has actually started but you have seen no signs - see the question "The Cascade Bohemian Yeast seems to be slower than other home brew yeasts. What are the differences?"

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Q. Why is my fermentation taking so long?

The longest a fermentation should take is about 7 or 8 days (that is, the time to get to a gravity below 1007° and to be at the same gravity for two consecutive days).

Sometimes a fermentation may start off well but tail off a bit at lower gravities.

Often the reason may be too low a temperature - the brew may have started at too low a temperature, or the temperature may have dropped during fermentation.

It is possible that not all the yeast was pitched - you may have left a lot in the sachet. However the 7 g of yeast in the sachet is more than enough to do the job and lack of yeast is an unlikely cause.

Some brewing texts might suggest that you should aerate the wort by agitation or else fermentation will be slow. However with our style of home brewing the wort gets sufficient aeration during normal preparation.

Always make sure that you have at least 1.7 kg of malt extract per 23 L. This is because malt extract contains natural amino acid nutrients required by the yeast for fermentation. If the malt extract concentration is too dilute the concentration of amino acids may become too low to promote a healthy yeast population. The fermentation may be slow or it may cease prematurely.

If hydrometer readings indicate that the gravity is still dropping, albeit slowly, let the fermentation continue even if it passes 8 days. Note that the longer it continues at a slow rate then the more chance there is of spoilage organisms taking over. However if all cleaning has been properly done then spoilage is unlikely.

Note that if a non-standard recipe is used, the true final gravity may be higher than 1006°. This will certainly be the case if more than 1.7 kg of malt extract is used and/or a maltodextrin adjunct is used. Consult your home brew shop about the likely final gravity.

Also see the question "The Cascade Bohemian Yeast seems to be slower than other home brew yeasts. What are the differences?"

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Q. Why has my beer stopped fermenting?

The most likely reason is that the temperature has been allowed to drop too low and the yeast has fallen to the bottom of the fermenter. 18-20°C should be targeted as the lowest temperatures for reasonable fermentation.

However don't be fooled into thinking that your beer has stopped fermenting based upon lack of bubbles in the airlock. It is possible that the gas is escaping through a leak and the beer is still fermenting quite well. Hydrometer readings are the most reliable means of determining the rate of fermentation.

There are further possible reasons. These are fully covered under the question "Why is my fermentation taking so long?".

The beer may still actually be fermenting - see the question "The Cascade Bohemian Yeast seems to be slower than other home brew yeasts. What are the differences?"

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Q. Sometimes my brew smells "off" during fermentation or when I bottle. Why is that?

It is possible that you are detecting sulphur compound odours. Different yeasts may produce them at different rates. Some people are especially sensitive. The odours may resemble so-called "rotten egg gas" or the smell in town gas. They are normally formed in various amounts during fermentation and occasionally they may occur in noticeable quantities. They normally dissipate during maturation (and this is one of the reasons why maturation is a standard brewing process). The home brewer will find that if these odours are noticeable at the end of fermentation they should disappear during bottle maturation leaving a clean tasting beer. Two weeks should be enough but if still present leave for another week or two.

Alternatively (but hopefully not) the smell could be due to infection from beer spoilage organisms as a result of inadequate cleaning and sanitation.

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Q. Where can I find the Cascade Home Brew Performance Specifications?

The performance specs can be found here.

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