What process occurs simultaneously during multiple parallel fermentation in sake brewing?

In sake brewing, multiple parallel fermentation refers to the unique process where saccharification (the conversion of starch to sugar) and fermentation (the conversion of sugar to alcohol) occur simultaneously. This is a distinctive aspect of sake production that differentiates it from other alcoholic beverages.

During this process, the koji mold is introduced to steamed rice, which breaks down starches into sugars. At the same time, yeast is added to the mixture, which ferments the sugars produced into alcohol. This dual process allows for a more efficient fermentation since both necessary conversions happen concurrently rather than sequentially.

The correct answer indicates the simultaneous nature of these conversions, highlighting the importance of both starch conversion and sugar fermentation happening together in the same environment. This is integral to producing sake, as it influences the flavor profile and quality of the final product, contributing to the rich umami characteristics that sake is known for.

The other choices focus on either one specific conversion process or a subsequent action (like pressing), which do not capture the essential simultaneous fermentation aspect that defines this stage in sake brewing. Therefore, the answer reflects the unique and vital nature of multiple parallel fermentation in the making of sake.