With Breaking Bread - The Panel, FoodFaith’s discussion on the history, culture and sustainable future of bread on October 9th as part of the Sydney friends of Good Food Month, today, we’re taking a look at yeast. One of the key components in baking for thousands of years, but did you know that yeast isn't actually a plant?

In fact, yeast, or Saccharomyces Cerevisiae, is a member of the fungus kingdom and shares some characteristics with plants. With over 1500 species currently known today, the two most common strains, bakers and brewers yeast, still have an important role in cooking, medicine, and history.

Cultural Uses:

Yeast has been used for thousands of years across many different cultures, and may be one of the first organisms domesticated by humans! Early grinding stones and baking chambers used for bread with yeast have been discovered in Egyptian archaeological sites, along with 4000 year old drawings of breweries and bakeries.

In Australian colonial history, domestic, or homemade, yeast was often used to make bread, with recipes dating back to the 1830’s. Australia’s first beer brewer, James Squire, began brewing as a convict in the 1730’s, which has become one of Australia’s most popular beer brands and recently recreated the world’s oldest yeast using ale found in a shipwreck from the 1790’s.

Before the development of the granulated yeast found in supermarkets today, yeast was only available fresh, in a liquid or cream form. Granulated yeast was developed during WWII to not need refrigeration, unlike liquid yeast, and to have a longer shelf-life and faster rising time.

In 1923, Vegemite, a spread made from brewer’s yeast, was developed in Australia only 20 years after the British equivalent, Marmite, was invented. Both spreads use yeast extract, which is the leftover yeast from brewing beer. British soldiers were even issued with Marmite during WWI as part of their rations, and Marmite was more popular than Vegemite in Australia until the 1930’s!

Medicinal Uses:

Medicinally, brewer’s yeast has been used more than bakers yeast to treat a wide range of medical conditions. Taken orally, yeast has been used to treat respiratory problems, allergies, diarrhea, PMS, skin problems, and type 2 diabetes. While only early research has been conducted into the effectiveness of yeast for these treatments, it has been found that yeast could be used to lower blood sugar in diabetics, and may be effective in treating PMS, although it can take months for positive effects to be felt.

In the 1920’s, yeast cakes, cubes of yeast with a similar consistency to stock cubes, were also part of a popular health trend in America, and were promoted for their vitamin B content and their ability to cure a range of diseases, prevent obesity, and even make people smarter! But, many of these health claims were found to be false and the trend ended in the 1930’s.

However, some negative effects of using brewer’s yeast have also been found recently, such as itching and swelling in those with yeast allergies, a potentially increased risk of blood infections in those with weakened immune systems, and can worsen the effects of Crohn’s disease and cause blood sugar levels to drop too low for diabetics who already take medication to lower blood sugar. For more information regarding the short and long-term use of brewer’s yeast you should consult your doctor.

Culinary Uses:

Yeast is mostly used in cooking as a leavening or raising agent in bread-making, and as a fermenting agent in brewing of beer, cider, wine, and non-alcoholic drinks, including kombucha, root beer, and kefir. As a source of B vitamins, not including B12, protein, and low levels of fat and sodium, yeast is also often used as a nutritional supplement and a cheese substitute in vegan meals.

Yeast works by consuming sugars such as glucose in flour, fructose and glucose in honey, molasses, and fruits, and converting these sugars into carbon dioxide gas. In bread, baker’s yeast is used and the carbon dioxide gets trapped in the dough and causes it to rise. The yeast then dies during baking, giving the bread a soft and spongy texture. In brewing, the sugar gets converted into ethanol by brewer’s yeast, giving beer and other beverages their alcoholic content.

Interested in trying out some recipes with yeast for yourself? Have a look through some of these:

Rare Brews, collection of historical beer recipes, The University of Sydney Library

Aus day yeast extract damper, ABC radio

1 hour cinnamon rolls, Life Made Simple

Milk Kefir, Kombucha Kamp

Growing Facts:

While typically grown in laboratory environments, yeast has been cultivated at home for hundreds of years. Nowadays, there are several ways to source and grow your own yeast, from capturing yeast from the air or using fruits and vegetables to creating yeast starters, jars of malt extract and hops similar to those made for sourdough starters.

Yeast grows best in a warm environment with a low pH and a food source, usually sugar. When pickling, a white, thread-like yeast can grow as a result of air exposure, but this should be removed as it can introduce bad flavours.

While baking bread is just one of the many ways to use yeast, it has played a role in bringing people together across and within many cultures. To find out more about bread and its importance across the community, you can attend Breaking Bread - The Panel in October, where a panel of speakers will share their knowledge and you can even taste some different kinds of bread. Get your tickets here today!