--- title: Bread rising: yeast at work — a lesson of Mova's school · trees and pragmatics description: «Bread rising: yeast at work», a lesson of the chemistry course of Mova's primary school, sentence by sentence with dependency trees and pragmatics. It begins: Mum leaves a bowl of bread dough by the radiator, and an hour later it has puffed up to twice its size. --- [Mova](https://md.mova.elamur.ai/free/en/) · [this page in HTML](https://mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/) [home](https://md.mova.elamur.ai/free/en/) / [corpora](https://md.mova.elamur.ai/free/en/corpora/) / [school](https://md.mova.elamur.ai/free/en/corpora/school/) / [Chemistry](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/) / Bread rising: yeast at work # Bread rising: yeast at work Lesson 21 of the chemistry course of Mova's primary school: 19 sentences, each with its syntax tree and pragmatics. The lessons are written for Mova, and their agreed trees are part of Mova corpus 0.4 (CC BY-SA 4.0). How Mova does on its tests: [the lesson at school](https://md.mova.elamur.ai/free/en/school-run/chemistry/21-bread-rising-yeast-at-work/). - [0](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/0/) — Mum leaves a bowl of bread dough by the radiator, and an hour later it has puffed up to twice its size. - [1](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/1/) — The dough is full of yeast, a tiny living fungus, which eats sugar and breathes out carbon dioxide gas. - [2](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/2/) — Kneading pulls the dough's gluten proteins into long stretchy strands, like a net of tiny balloons. - [3](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/3/) — They trap the gas, so the dough swells, and every hole in a slice of bread is where a bubble once was. - [4](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/4/) — In the hot oven the outside browns into a crust, as sugars and proteins react with heat, while the inside stays soft because its water keeps it below 100 °C. - [5](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/5/) — Not all bread needs yeast: pitta and tortillas are flat, and pitta puffs up only because water inside turns to steam. - [6](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/6/) — Cakes rise with baking powder or whisked eggs instead. - [7](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/7/) — And yeast has a cousin nobody invited: the fluffy mould on old bread. - [8](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/8/) — Yeast is a tiny living fungus; in dough it eats sugar and gives off carbon dioxide gas that puffs the dough up. - [9](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/9/) — Warmth makes yeast work faster, so dough is left somewhere warm; in a cold fridge it rises very slowly, which bakers use to make it tastier. - [10](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/10/) — Kneading lines up gluten proteins into long stretchy strands that trap the gas like balloons. - [13](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/13/) — Flatbreads like pitta and tortilla are made without yeast; pitta gets its pocket because water inside turns to steam in a hot oven. - [14](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/14/) — Yeast in warm sugary water wakes up, eats the sugar and foams; water that is too hot kills yeast. - [15](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/15/) — Sourdough uses wild yeast and bacteria; the bacteria make acids that give the sour taste, and a starter can be kept alive and fed for many years. - [16](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/16/) — Bread goes stale as its starch slowly lines up and squeezes out water; warming it in the oven softens it for a while. - [17](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/17/) — The crust browns as sugars and proteins react with heat; the inside stays soft and pale because its water keeps it below 100 °C. - [18](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/18/) — Cakes rise without yeast, using baking powder or whisked eggs to trap gas that expands in the oven heat. - [19](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/19/) — A soufflé sinks soon after leaving the oven because the air inside cools and shrinks. - [20](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/21-bread-rising-yeast-at-work/20/) — Mould is a fungus related to yeast that grows from spores on damp bread; penicillin, a life-saving medicine, was first found from a mould, but mould on bread can be harmful, so mouldy bread goes in the bin. - ← previous: [Gases all around: breath and balloons](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/20-gases-all-around-breath-and-balloons/) - next →: [Milk, cheese and yoghurt](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/22-milk-cheese-and-yoghurt/) - ↑ back to [Chemistry](https://md.mova.elamur.ai/free/en/corpora/school/chemistry/)