Hypothesis #1 | Colour

We think that the more sugar there is in the dried fruit we use to make fruit yeast water, the darker the quick bread will be when we bake it.

We visited a website that shows nutritional information, and we looked up the dried fruits we wanted to use to make our fruit yeast water. We found:

• Dried figs: 70 grams have 33.6 grams of sugar
• Dried apricots: 70 grams have 37.1 grams of sugar
• Dried mango: 70 grams have 46.2 grams of sugar

Since dried mangos have the most sugar, we guessed that it would make the quick bread with the darkest crust.

Our first hypothesis is that quick bread made from mango fruit yeast water will make the darkest quick bread of all three when compared to the sour dough quick bread.

Hypothesis #2 | Taste

We think that the sugar in the dried fruit used to make the yeast water will change the taste of the quick bread.

We visited a website that shows nutritional information, and we looked up the dried fruits we wanted to use to make our fruit yeast water. We found:

• Dried figs: 70 grams have 33.6 grams of sugar
• Dried apricots: 70 grams have 37.1 grams of sugar
• Dried mango: 70 grams have 46.2 grams of sugar

Since dried mangos have the most sugar, we guessed that it would make the sweetest tasting quick bread.

Our second hypothesis is that quick bread made from mango fruit yeast water will taste the sweetest of all three when compared to the sour dough quick bread.

Hypothesis #3 | Rise

We think that the sugar in the dried fruit used to make the yeast water will change how high our quick bread rises.

We visited a website that shows nutritional information, and we looked up the dried fruits we wanted to use to make our fruit yeast water. We found:

• Dried figs: 70 grams have 33.6 grams of sugar
• Dried apricots: 70 grams have 37.1 grams of sugar
• Dried mango: 70 grams have 46.2 grams of sugar

Since dried mangos have the most sugar, we guessed that it would make quick bread that rises the highest.

Our third hypothesis is that quick bread made from mango fruit yeast water will rise the highest of all three when compared to the sour dough quick bread.

Background Research

After brainstorming science fair project ideas, and deciding to research yeast and bread, we found out from our science fair mentor (Ms. Marshall) that you can extract yeast from fruit. An article that Ms. Marshall sent us mentioned that you can use different types of dried and fresh fruit to make fruit yeast water, so we decided to try using dried mangos, dried apricots, and dried figs. To figure out how to ferment the dried fruit, we watched a video that showed the process, provided a recipe and listed the instructions.

During our research phase, we also watched a video that showed how yeast and different amounts of sugar react to create gas by blowing up balloons. The video showed that the balloon on the bottle with the most sugar blew up the most. This made us think that the dried fruit with the most sugar in it will feed the yeast most (in our dried fruit yeast water) and produce the most waster, which will make that bread rise the highest.

We also watched a video about how sugar affects bread dough, in which a man bakes four loaves of bread with different sugar content levels in them. The bread with the highest sugar content had the darkest crust, and the bread with the lowest sugar content had the lightest crust. We think that the bread made with the fruit yeast water with the highest sugar content will have the darkest crust.

We visited a website where you can research nutritional values of foods. We searched our dried fruits to see how sugar is in them:

• Dried mangos: 70 grams have 46.2 grams of sugar
• Dried apricots: 70 grams have 32.1 grams of sugar
• Dried figs: 70 grams have 33.6 grams of sugar

We think that bread made with mango yeast water will rise the highest because it has the most sugar in it, and that it will have the darkest crust. Food with more sugar in it often tastes sweeter, so we think that bread made with mango fruit yeast water will taste the sweetest.

Our controlled variables for the bread were:

• flour
• sugar
• baking soda
• baking powder
• salt 
• canola oil

Our controlled variables for the dried fruit yeast water were:

• distilled water
• sugar

Our manipulated variables for the bread were:

• Sour dough starter
• Fruit yeast water

Making dried fruit yeast water:

Ingredients:

• 750 ml glass jars (3)
• 15 grams sugar (x3)
• 500 ml distilled water (x3)
• 70 grams dried mangos
• 70 grams dried apricots
• 70 grams dried figs
• 3 pieces of plastic wrap

Instructions to make fruit yeast water (all three kinds):

• Measure 500 ml of distilled water. Pour into glass jar.
• Use a digital scale to measure 15 grams of sugar and 70 grams of dried fruit. Add sugar and dried fruit to glass jar.
• Close the lid on the glass jar and cover the top with plastic cling film.
• Shake the jar until all the sugar crystals dissolve.
• Put the jar in a warm place out of direct sunlight.
• For five days you need to open and close the lid of each jar (to release pressure) and shake it gently. Do this twice per day.
• At the end of day five, strain out the fruit so you just have the fruit yeast water left. It should be bubbly/foamy and smell like alcohol.

This process was repeated three times for the three experiments.

Making quick bread using fruit yeast water:

We made the bread using the same recipe that only varied on the use of fruit yeast water versus instant yeast starter. The recipes are as follows:

Plain Quick Bread Recipe Using Fruit Yeast Water

Prep Time: 10 minutes
Cook Time: 45 minutes
Yield: 1 loaf

Ingredients:

• 240 ml fruit yeast water (active and bubbly)
• 250 g all-purpose flour
• 25 g sugar
• 1/2 teaspoon baking soda
• 1 teaspoon baking powder
• 1/4 teaspoon salt
• 60 ml canola oil

Instructions:

1. Preheat Oven: Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line it with parchment paper.
2. Mix Dry Ingredients: In a large bowl, whisk together the flour, sugar, baking soda, baking powder, and salt.
3. Combine Wet Ingredients: In a separate bowl, mix the fruit yeast water and oil.
4. Blend Together: Pour the wet ingredients into the dry ingredients and stir gently until just combined. Avoid overmixing to maintain a tender texture.
5. Pour into Pan: Pour the batter into the prepared loaf pan and smooth the top with a spatula.
6. Bake: Bake for 45 minutes.
7. Cool: Let the bread cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely.

Plain Quick Bread Recipe Using Sour Dough Yeast Starter

Prep Time: 10 minutes
Cook Time: 45 minutes
Yield: 1 loaf

Ingredients:

• 240 g active yeast starter (100% hydration, bubbly and fed)
• 120 ml water
• 250 g all-purpose flour
• 50 g sugar
• 1/2 teaspoon baking soda
• 1 teaspoon baking powder
• 1/4 teaspoon salt
• 60 ml canola oil

Instructions:

1. Prepare Sourdough Starter: Make sure your sourdough starter is active and bubbly before beginning.
2. Preheat Oven: Preheat your oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line it with parchment paper.
3. Mix Dry Ingredients: In a large bowl, whisk together the flour, sugar, baking soda, baking powder, and salt.
4. Combine Wet Ingredients: In a separate bowl, mix the sourdough starter, water, and oil. Add vanilla extract if using.
5. Blend Together: Pour the wet ingredients into the dry ingredients and stir gently until just combined. The batter should be thick but pourable. Avoid overmixing.
6. Pour into Pan: Pour the batter into the prepared loaf pan and smooth the top with a spatula.
7. Bake: Bake for 45 minutes.
8. Cool: Let the bread cool in the pan for 10 minutes, then transfer it to a wire rack to cool completely.

When we made our batches of bread, we observed the following:

Fig bread:

• 1st sweetest
• 2nd darkest
• 2nd lowest rise
• 2nd smoothest
• Spongy
• Smells like cinnamon/BBQ
• Feels cooked
• 4.9 cm tall
• Sweet dry dense bread

Apricot bread:

• 2nd lightest colour
• Smoothest
• 3rd lowest rise
• Smells like cake
• Feels cooked
• Very dense
• Tastes like sponge cake
• 4.8 cm tall

Mango bread:

• Lightest colour
• Bumpy texture
• Lowest rise
• Doesn't feel cooked
• Has a lot of holes 
• 4.5 cm tall

Control bread (sour dough starter):

• Spongy/squishy
• Moist and tastes like bread
• Is light in colour on the sides
• 1st highest rise
• 1st darkest in colour
• Has a lot of holes
• 6.2 cm tall

For batches 2 and 3, all of the attributes listed above were the same for each bread. The only differences were in heights/rise. They heights for each experiment are listed below by batch one, two, and three:

Fig: 5.0 cm, 5.0 cm, 4.9 cm

Apricot: 5.1 cm, 5.0 cm, 4.8 cm

Mango: 4.8 cm, 4.6 cm, 4.5 cm

Control: 6.7 cm, 6.3 cm, 6.2 cm

Hypothesis 1: Incorrect

We guessed that mango would be the darkest bread because of the high sugar content in mangoes. 

Colour results:

• Darkest: fig
• Lightest: mango

Hypothesis 2: Incorrect

We guessed that mango would be the sweetest bread because of the high sugar content in mangoes. 

Sweetness results:

• Sweetest: fig
• Least sweet: apricot

Hypothesis 3: Incorrect

We guessed that mango would be the tallest bread because of the high sugar content in mangoes. 

Height results:

• Highest rise: apricot (although the control bread rose the highest of them all)
• Lowest rise: mango

Hypothesis 1: Colour

Our first hypothesis was that quick bread made from mango fruit yeast water would make the darkest quick bread of all three when compared to the sour dough quick bread. This hypothesis was incorrect. Our experiment showed that fig made the dakest quick bread.

Hypothesis 2: Sweetest

Our second hypothesis was that quick bread made from mango fruit yeast water would taste the sweetest of all three when compared to the sour dough quick bread. This hypothesis was incorrect. Our experiment showed that fig made the sweetest quick bread.

Hypothesis 3: Rise

Our third hypothesis was that quick bread made from mango fruit yeast water would rise the highest of all three when compared to the sour dough quick bread. This hypothesis was incorrect. Our experiment showed that apricot yeast water produced quick bread with the highest rise.

In the end, we found that if you want your bread to taste like regular bread then don't use fruit yeast water because the fruit yeast water makes your bread taste a little like cake. 

If you’re worried about your bread tasting different than you want it to taste, you could either find a fruit that makes your bread taste like normal bread or you could just use normal yeast to make your bread. This is because the fruit you use to make your fruit yeast water will change the taste of the bread you bake. And if you want your bread to rise really high, you might want to use yeast instead of fruit yeast water. This is because bread made with fruit yeast water won't rise as high as bread made with normal yeast. 

Another fruit we could try to make fruit yeast water with would be raisins. People make wine out of grapes, so they would probably work for this experiment.

Other fruits we could try include:

• dried bananas
• dried dragon fruit
• dried cherries
• dried apples
• dried blueberries

One of the videos we watched fermented thier fruit for 10 days. We only fermented ours for 5 days. If we could di it again, we could try it out, and see if it changes how our bread looks, tastes and rises.

Because our bread turned out so sweet, we think it would be best to make cake instead of bread with the dried fruit yeast water. The bread that rose the highest was our control bread. We think that if you want your bread to rise high, you should use normal sour dough yeast starter.

Some possible sources of error that could have impacted our experiments include:

• Cross-contamination when making our fruit yeast water, yeast starter, or our bread
• Overcooking/undercooking our bread
• The type of flour that we used may have impacted the outcome
• Our fruit yeast water may have gotten mold in it

Reference list:

“Fermentation of Yeast and Sugar.” YouTube, uploaded by The Sci Guys, March 16, 2016, https://www.youtube.com/watch?v=FYClCHVT00M

Hamel, PJ. (2020, Feb. 24). Baking Bread with a Yeast Water Starter. King Arthur Baking blog. https://www.kingarthurbaking.com/blog/2020/02/24/baking-bread-with-a-yeast-water-starter

“How Sugar Affects Bread Dough.” YouTube, uploaded by ChainBaker, Sept. 25, 2024,  https://www.youtube.com/watch?v=1GgRJ1Ye-2U.

Nutritionix. (n.d.). Dried apricot: 100 g. Retrieved Jan. 4, 2025, from https://www.nutritionix.com/food/dried-apricot/100-g

Nutritionix. (n.d.). Dried figs: 100 g. Retrieved Jan. 4, 2025, from https://www.nutritionix.com/food/dried-figs

Nutritionix. (n.d.). Dried mango: 100 g. Retrieved Jan. 4, 2025, from https://www.nutritionix.com/food/dried-mango

“Pablos ultimate yeastwater (sic).” YouTube uploaded by PG Baker, Aug. 22, 2017, https://www.youtube.com/watch?v=l8jbrE-BB9U.

“What is Yeast and How Is it Found?” YouTube, uploaded by Food Unwrapped, Sept. 25, 2021, https://www.youtube.com/watch?v=UoPi2gn81I8.