prior to activating the rise in the batter.

01:30 Aug 24, 2016 

But as soon as the baking powder is stirred into a wet dough or batter, the two ingredients begin to react, releasing bubbles of CO2 and causing chemical leavening.
http://phys.org/news/2014-05-difference-soda-powder.html#jCp

So the word "rise" is really a synonym for "leavening" here, and the translation for leavening is in fact levadura, but, since the text doesn't specify whether the recipe uses yeast or baking powder, I believe a better translation for "to activate the rise" might perhaps be "leudar" (to leaven).

01:23 Aug 24, 2016 

Hi Juan. As far as I can tell, the use of the word "rise" when cooking with yeast doesn't refer to the yeast itself, but to the fermentation it causes.

RISING (FERMENTATION)
Once the bread is mixed it is then left to rise (ferment).
As fermentation takes place the dough slowly changes from a rough dense mass lacking extensibility and with poor gas holding properties, into a smooth, extensible dough with good gas holding properties.
The yeast cells grow, the gluten protein pieces stick together to form networks, and alcohol and carbon dioxide are formed from the breakdown of carbohydrates (starch, sugars) that are found naturally in the flour.
http://www.bakeinfo.co.nz/Facts/Bread-making/Science-of-brea...

Baking soda and baking powder (a slightly different thing) also produce this rising or leavening, but through a chemical process, an acid-alkali reaction.

All baking powders contain sodium bicarbonate (just like baking soda). But baking powder also contains two acids. One of these acids is called monocalcium phosphate. Monocalcium phosphate doesn't react with the sodium bicarbonate while it's dry.

00:22 Aug 24, 2016 

De acuerdo Robert. Básicamente hay tres productos que se usan en pastelería: el polvo para hornear, el bicarbonato y la levadura. Su función es parecida aunque no tienen ni el mismo sabor, ni la misma fuerza. El caso es que la palabra "rise" en un diccionario de cocina se refiere a la levadura, los otros son "baking soda". También se podría considerar "rise" simplemente como un sustantivo equivalente a elevar, esponjar, aumentar la masa/volumen, que se logra simplemente con dejarlo reposar o mantenerlo en un ambiente templado adecuado.

00:01 Aug 24, 2016 

That doesn't sound right to me, the recipe might call for bicarbonate of soda instead of yeast, which would also make the batter rise. Batter can often be made to rise by leaving it wrapped and standing in a warm environment.

18:07 Aug 23, 2016 

Sounds like there is yeast in the batter, which makes the batter/dough rise. I think they are using rise and yeast synonymously.