As an experienced sommelier and brewer, I can confidently say that yes, you can mash out for too long. While it is important to allow the mash to convert the starches into fermentable sugars, leaving it for an extended period can have negative effects on the quality of the beer.
During the mashing process, enzymes present in the malt break down the complex starches into simpler sugars that yeast can ferment. This enzymatic activity is time-sensitive, with the majority of the conversion taking place in the first 60 minutes. After this point, the efficiency of the enzymes begins to decline.
Leaving the wort in the mash for over 24 hours can lead to the development of off-flavors and potential sourness. This is because the longer the wort sits, the more time bacteria and wild yeast have to take hold and produce unwanted byproducts. While some brewers intentionally use extended mashes for certain beer styles, such as sour beers, this is a controlled process that involves specific strains of bacteria or yeast.
In my personal experience, I once forgot about a batch of wort that was left in the mash tun for over 24 hours due to a sudden emergency. When I returned to it, I noticed a distinct sour aroma and taste. The prolonged exposure to microorganisms had caused the wort to sour, resulting in a beer that was not enjoyable to drink.
To avoid mashing out for too long, it is important to plan your brewing process carefully and set a timer to monitor the mashing duration. While it is generally recommended to mash for at least 60 minutes to ensure full conversion of starches, there is no need to exceed 120 minutes as the majority of enzyme activity occurs within the first hour.
Mashing out for too long can lead to sourness and off-flavors in the beer. It is crucial to monitor the mashing process and avoid leaving the wort in the mash for more than 24 hours. By being mindful of the timing and ensuring proper fermentation conditions, you can produce high-quality beers with optimal flavors and aromas.