Acetaldehyde is one of the several precursor compounds produced by yeast during fermentation. It has a green apple-like aroma and flavors and is common in young beer and mead.

Glucose >> Pyruvic Acid >> Acetaldehyde >> Ethanol

Although Acetaldehyde is a natural precursor to ethanol formation, its residual levels in the finished brew is not desirable. At excessive levels, it might even give a paint solvent/ nail polish smell. Here are the few causes for this off-flavor:

1. Insufficient healthy yeast count. Many home brewers end up with old or improperly stored yeast. Also to save cost and time some brewers sprinkle the dry yeast on their wort. Making a vigorous starter batch and ensuring adequate oxygen and nutrients reach the yeast.
2. Fast Pressure Brewing. A brewery under pressure to churn batches as quickly as possible tries to ferment alcohol as fast as possible. This does not give yeast enough time to metabolize the precursor compounds completely. This problem is larger for lagering than for ale.
3. Another reason for acetaldehyde is fermenting inverted sugar instead of natural unpasteurized honey during mead making. Adulterated packaged honey is therefore avoided by mead makers.

Remedy

• 48 hours of Diacetyl rest for lagers and ales. Slightly warm conditioning and patience are all it takes for the yeast to complete its task.
• In mead tasting like acetone: Allow it to age for at least 6 months. High sugar and natural compounds in honey prevent yeast activity. Hence it takes it longer to clear up.

Solvent: are aromas and flavors of higher alcohols (fusel alcohols). Similar to acetone, lacquer varnish and paint thinner aromas. It is an indication of stressed yeast and is undesirable. Cheap distilled liquor (where the last portion of the distillate is not discarded) often gives these notes. Reasons for the stress could be inadequate healthy yeast count, high gravity (too much sugar), high temperature accelerated fermentation, etc.
In mead, the common reason is the use of inverted sugars or adulterated packaged honey.

Typically 4-12 days but it depends on a lot of factors:

1. Fermentation temperature. Higher the temperature faster the fermentation is (but beware of the off-flavors produced in yeast fermented at above 25 degrees Celsius)
2. Yeast dosage. although 1gm/liter is recommended. Increasing it to 3gm/liter can produce wine in 2-3 days (50% reduction in time)
3. Availability of yeast nutrients. Grape and fruit juices don’t have enough natural proteins for the yeast to multiply fast. Adding 0.5-1gm per liter of yeast nutrient is sufficient to establish a healthy yeast colony and fast fermentation. Mead is notorious for being slow to ferment and produce nail polish like off-notes because of a lack of nutrients.
4. Sugar concentration: 18-25% w/v of sugar concentration is ideal for fermenting with wine yeast. However higher the concentration, the more time it will take for the yeast to finish its job and produce ethanol.

Yes, they need lots of yeast nutrients (0.5-1gm per liter compared to 0.25gm per liter in case of homebrew beer). The reason is that honey and apple/fruit juice don’t have enough proteins and nitrogen. With a low YAN (simply put nitrogen that yeast can use) the fermentation tends to get stuck and is prone to infection. To compensate that we use 2-4 times more yeast nutrient. This helps establish a healthy yeast colony, prevent infection, stuck fermentation and off-flavors

Wine is typically made from grapes that are 20-50/- a kg. Cider are made from other fruits which are usually in 50-100/- price range. However pure forest honey is 800-1000/- a kg. A wine typically takes 4 weeks to clear up for drinking, mead takes as long as 6 months to become clear.

Not only the ingredients cost more, but also the processing time is higher. Hence the higher cost for mead. If you want to know more about Indian forest honey the read the link.

Mead are very mild flavored. They will have hints of the flowers and the fauna from which the honey was extracted. The color of mead is also dependent on the types of honey being used.

Typically most people like their mead to be slightly sweet so that the floral aromas are best complimented. However you can get mead in variety of flavors from dry to full bodied. Often brewers add flowers and spices in the mead to increase the flavors. However most mead are very strong and are supposed to be consumed in moderation (a glass maximum two only).

Mead are typically aged for long. It takes 6 months before the mead clears up. So longer you age it the better it becomes. Like most wines they don’t have an expiry date and don’t go bad if stored properly.

It is ok to get a slight tart lactic acid taste in the mead. However getting acetone or kerosene flavors is not OK.

Theoretically you can convert mead into acetic acid vinegar. However that would be sacrilege to the effort by the honey bees in making your honey.

Similarly nobody distills mead to make brandy. On the contrary some brewers have made fortified mead by adding distilled grape wine to it. (20% ABV as against a traditional 13-15% strong mead.

Mead is a very rare and priced beverage. It is rarely sold in the wine shops and most gifted. Mead has an 8000-year-old tradition behind it. So if someone gifts you a bottle of authentic mead, please be grateful to the bearer.

1. Clarity: Mead takes longer to ferment and even longer to clear out. We recommend a minimum 6 months of ageing (1 month if cold crashed) for it to clear out.
2. Fusel Alcohol: Mead also produces some fusel alcohol which makes fresh fermented honey taste like acetone. By aging these off flavors are removed and floral flavors gets enhanced.
3. Complexity: By aging for ~6 months complex biochemical reactions happen. This mellow down the hasher flavors and enhances the more delicate flavors. Aging works best for sweet mead. The 1:1 Mead (one part honey one part water) needs to be aged for 2-3 years to get the best flavors. As compared to that the 1:3 Mead (one part honey, 3 parts honey) is ready in 3-6 months.
4. Boasting Rights: The older is the bottle that you gift, the more it will be valued and appreciated by your friends and family.