What characteristics in sake are believed to give it more ageing potential?

The belief that higher levels of sugar and acidity in sake contribute to its ageing potential is supported by several factors. When sake has increased acidity, it helps preserve the beverage by acting as a natural preservative, similar to how acidity aids in the longevity of certain wines. A higher sugar content also provides additional nutrients that can enhance the complexity of flavor development as the sake ages.

As sake matures, various chemical reactions occur, including oxidation and the alteration of flavor compounds, which can lead to the emergence of more complex and subtle flavors over time. The presence of both sugar and acidity creates a balance that can help sustain the sake’s character as it evolves, allowing it to develop a rich depth of flavor while maintaining its freshness.

The other options do not reflect the same potential for ageing. For instance, lower acidity might not provide the necessary structure for longevity, while large grain size and high alcohol content alone do not necessarily guarantee that a sake will benefit from ageing. Therefore, the combination of higher sugar and acidity represents a more conducive environment for the ageing process in sake.