But his scepticism was leavened with humour and appreciation of paradox, in which he found the stuff of poetry.
en.wikipedia.org In some ways, leavened bread is a foam, as the yeast causes the bread to rise by producing tiny bubbles of gas in the dough.
en.wikipedia.org In addition to flour, doughnuts may also include such ingredients as water, leavening, eggs, milk, sugar, oil/shortening, natural flavors and/or artificial flavors.
en.wikipedia.org Some flatbreads, such as naan, use leavening agents; others, such as matzo, do not.
en.wikipedia.org