How does a low mash temperature of 140-150°F affect beer?

A low mash temperature of 140-150°F typically leads to a lighter-bodied beer that is more attenuative. The reason behind this is that lower temperature mashing favors the production of fermentable sugars over dextrins. At these temperatures, enzymes like alpha-amylase become more active, breaking down starches into simpler fermentable sugars, which yeast can easily convert into alcohol and carbon dioxide. This results in a beer with a light mouthfeel and higher attenuation, meaning a lower final gravity and a drier finish.

By contrast, higher mash temperatures (around 156-162°F) would yield more unfermentable sugars, creating a fuller-bodied beer. Therefore, the choice that accurately reflects the impact of low mash temperatures on beer is that it produces a lighter-bodied, more attenuative beer.