Before baking bread, I take the sourdough starter out of the fridge and bring it to room temperature.
このパンはサワー種を使っているので、独特の酸味があります。
This bread has a distinctive tang because it uses a sourdough starter.
From English 'sour' and Japanese 種 (たね, 'seed/starter'). The reading サワーだね combines the loanword with the native Japanese word for starter.