When fermenting any kind of sugar water solution then there are small quantities of by-products such as methanol produced.
For the most part, this is no issue, however when you distill and concentrate the alcohols in the wash (including methanol) then it can become an issue. This will be removed in the first portion of distillate.
Distilling with fruit
When using fruits as a fermentation base, we can't guarantee the amount of methanol in the finished distillate, however discarding the first 50ml is good practice and will get rid of most of the methanol that may have been produced.
Methanol is produced during fermentation from fruit pectin, which is contained in fruit skins mainly. By taking care to not introduce too much fruit skins in the fermentation substrate, there won't be any issues at all.
If making gin (by soaking/steaming berries) or adding any other types of fruit in the boiler, there's absolutely no risk of adding methanol since the berries don't undergo the fermentation process. You shouldn't expect frothing issues either, unless the fruits are full of sugar.
Note: When doing multiple runs, for the second and third run it typically does not produce methanol depending on the unit you're using.
If you're concerned about the safety of consuming homemade spirits, read more here.
If you wish to distil other mixtures in a Pot or Reflux Still, then methanol could be produced. Here is a bit more information on distilling with Still Spirits stills:
Air Still
Methanol is produced as a by-product of fermentation rather than distillation. It is particularly higher in fruit washes as opposed to sugar washes. The reason why you don't need to discard the first 50ml when using the Air Still is that the yeast in the Air Still Fermentation Kit is actually the Turbo Pure Yeast strain. This is a very clean fermenting yeast strain which produces little to no methanol at all. Technically most of our Turbo Yeast range makes little to no methanol but if you want to use Classic 6, 8 or Fast, you should discard the first 50ml.
When using any alternative yeast, it is safe practice to discard the first 50ml.
T500 Reflux Still
A simple rule of thumb for this is to always discard the first 50 ml you collect. There is a risk that methanol can be present in your batch of spirits. However, the methanol comes off first from the still so it is easily segregated and discarded, and easily observed via changes in vapour temperature.
T500 Pot Still
A simple rule of thumb for this is to always discard the first 50 ml you collect. There is a risk that methanol can be present in your batch of spirits. However, the methanol comes off first from the still so it is easily segregated and discarded, and easily observed via changes in vapour temperature.
Alembic Pot Still
A simple rule of thumb for this is to always discard the first 50 ml you collect. There is a risk that methanol can be present in your batch of spirits. However, the methanol comes off first from the still so it is easily segregated and discarded, and easily observed via changes in vapour temperature.