Will the lower or upper end of the recommended temperature ranges for fermentation, give better results?

Our recommendation is generally fermenting at the lower end.

This is because yeast will produce heat of their own throughout fermentation but this also depends on the outcome you wish to achieve.

The lower end of the temperature range tends to give cleaner flavours, but fermentation will often take longer.

However, at the higher end of the range fermentation finishes faster but more esters and higher alcohols are produced.