What is the main effect of a low temperature during malting?

In malting, temperature plays a critical role in enzymatic activity and the development of the grain. A low temperature during the malting process primarily slows down the rate of protein breakdown. This is crucial because the breakdown of proteins into peptides and amino acids is an integral part of the malting process that affects the flavor, body, and foam stability of the beer.

At low temperatures, enzymatic reactions, including those involving proteinases and peptidases, are inhibited. Consequently, this helps maintain a greater proportion of proteins within the grain, which can later contribute to positive aspects of beer quality, such as mouthfeel and head retention.

In the context of the other options, aiding in enzyme activation pertains more to optimal temperatures rather than low temperatures, as enzymes typically need specific, often warmer, conditions to become fully active. Encouraging rapid germination would ideally require warmer temperatures to expedite the sprouting process. Lastly, the process of facilitating husk removal typically relates to the milling stage and factors affecting husk integrity, rather than directly being influenced by malting temperatures. Thus, the main effect of low temperatures during malting is accurately characterized by the slowing of protein breakdown.