Ultrafine bubble generator and ultrafine bubble generation method

A method for generating ultrafine bubbles, comprising:

• (a) the step of adding
• (A) a sophorolipid containing acidic sophorolipid and lactonic sophorolipid in a ratio (mass ratio) of 78:22 to 100:0,
• (B) a free fatty acid or salt thereof, and
• (C) a gas generation component
• to water with a hardness of 30 to 200 mg/L to allow these three to coexist in the water;
• and
• (b) the step of generating bubbles in the water.

An ultrafine bubble-containing liquid, comprising the following (A), (B), (c), and (d):

• (A) a sophorolipid containing acidic sophorolipid and lactonic sophorolipid in a ratio (mass ratio) of 78:22 to 100:0,
• (B) a free fatty acid or salt thereof,
• (c) fine bubbles that are formed from at least one gas selected from the group consisting of carbon dioxide gas, oxygen gas, hydrogen gas, and chlorine gas, and that have an average number particle size of less than 1000 nm;
• and
• (d) water.

A method for producing an ultrafine bubble-containing liquid, comprising:

• (a) the step of adding
• (A) a sophorolipid containing acidic sophorolipid and lactonic sophorolipid in a ratio (mass ratio) of 78:22 to 100:0,
• (B) a free fatty acid or salt thereof, and
• (C) a gas generation component
• to water with a hardness of 30 to 200 mg/L to allow these three to coexist in the water;
• and
• (b) the step of generating bubbles in the water.