Experimenting With Yeast

All of our food comes from the living world around us. Most of it it is made from plants and animals, but other living things go into our food, too. Today, we’re going to explore one of these other ingredients, called fungus (if there’s only one, we call it fungus; if there are many, they are fungi). Fungi are found nearly everywhere and play important roles in our world. They can help break down dead plants and animals, returning them to the earth. Some fungi can cause diseases. And there are some fungi that we eat, like mushrooms. 

About the Experiment

For this experiment, we’re going to learn about a very small fungus, called yeast. You can’t see a single yeast with your eyes, but if you put a lot of yeast together, you can get a gooey lump (if they’re wet) or a powder (if they’re dry). Yeast are one of the most important ingredients in bread. Let’s find out how this special fungus helps us make bread.

	Details Ages - 4-8
	Time - 3 hours (30 mins active)
	Difficulty - Medium

 What You'll Need

• Measuring cups and spoons, bowls, mixing spoons, 2 baking pans, oven
• Active dry yeast
• Flour
• Warm (not hot!) water
• Sugar
• Salt
• Butter or similar product to grease pans

Let's Do This!

The yeast you buy in stores is alive. It may not seem like it because it’s just a dry powder, but the yeast are just resting, until we tell them it’s time to wake up and get going. How do we do that? Just add a little water – and sugar.

1. Begin by preheating your oven to 450 degrees.
2. Activate the yeast by mixing it with ¼ cup of warm water and a teaspoon of sugar, then wait for about 15 minutes. In a second bowl, add just the yeast and water, but no sugar. Does the yeast react the same way with or without the sugar? Why do you think this is happening? (After observing the two mixtures, discard the one without the sugar)
3. Mix 2 tsp of yeast with 3 cups of flour and 2 tsp of salt. Add another cup of warm water. Stir until it’s all combined into a doughy blob. If needed, add a little more warm water until the mixture sticks together. In a separate bowl, mix the same ingredients – but without the yeast.
4. Cover both bowls and leave them out at room temperature for 2-3 hours. The room should be warm, at least 70 degrees. What happens to the mixture in each bowl at the end of the time?
5. Sprinkle some flour on a table or surface to shape the dough, then place the dough on top of it. Fold the dough into a round shape, then push down on it to squeeze out the air bubbles. Do this once or twice more. Repeat with the other dough.
6. Grease the inside of the pans with butter or a similar product and place the loaves into the pans. Note which pans have the dough with and without the yeast.
7. Bake for 30-40 minutes, checking periodically to see how the loaves look. Watch their color and take them out when they begin to turn golden brown. Let them cool for about 10 minutes before cutting into them. What does each loaf look like when you cut into it? How does it taste?

What Did You Learn?

1. What happened to the loaves with and without the yeast? Why?
2. Did the two loaves taste different? What about their texture (how they felt)? Would you want to eat bread made without yeast?
3. Is what happened to the bread the same as what happens when soda or other drinks have bubbles in them? How is it the same or different?
4. What the yeast did with the sugar and the water is a process called fermentation. The yeast changed the sugar into a kind of gas, called carbon dioxide. Do you think any of the other foods that you eat are made using fermentation?

Resources

To see how else scientists are experimenting with yeast, check out the resources below.

It’s not just for food – some scientists are using yeast to make fuel for cars too.

Yeast might even help feed astronauts in space.

Where does the yeast we use in baking come from?

Scientists are exploring whether foods made with fermentation are especially good for us, by helping to feed the bacteria in our stomachs. Bacteria are living things that are too small to see, but all around us.

Preventing The Problem of Plastic Pollution

Plastic … it's a modern day fact of life and it's everywhere, particularly single-use plastic containers. You might not give it much thought but products like toothpaste, shampoo, condiments, carryout containers, and even water nearly always come in packaging that we use once and then throw away. These single-use containers fill up our landfills and can last many years, with some plastics taking hundreds of years to degrade. If not disposed of properly, plastics can litter our landscapes and spill into our oceans. For this reason, researchers are working to replace these plastics with materials that are biodegradable and earth friendly.

One approach to eliminating plastic packaging is to use plant-based fiber to create products that are environmentally harmless but provide similar results to plastic. ARS researchers have developed techniques to make fiber packaging from materials like wheat straw, bamboo, and cotton.  Learn more.

Fish as Feed/Fish as Food

Anglers call carp “trash fish” because of their many tiny bones. The U.S. government calls carp an invasive species because it can take over and devastate every watery environment they enter.

“Invasive carp (bighead, black, silver, and grass carp) outcompete native fish for food and space, starting at the base of the ecosystem,” said Wendy Sealey, fish physiologist with ARS. Sealey conducts her research at the Bozeman Fish Technology Center, in Bozeman, MT.

To help curb their numbers, in 2013, researchers began testing whether carp could be used as a replacement for wild-caught fish in aquatic animal feeds. Fish meal is an important and expensive ingredient used in aquafeeds, with an annual production of approximately 5 million tons.

Not only can carp be used as a feed ingredient for hybrid striped bass and rainbow trout, targeted fishing lowered carp populations in the project areas. That’s important because there’s a new interest in the targeted fishing of carp, this time from the restaurant community.

Restauranteurs large and small are now serving up carp to their customers under the re-branded name of “copi.” Even the World Wildlife Fund is promoting carp as pet food. Reportedly, copi is a flavorful fish, despite its high number of fine bones.

“Projects like the initial ARS study are still relevant because the issue of invasive carp is ongoing and evolving,” Sealey said. “The collaborative approach of the research and resource agency groups displays hope for how the complex issues [of invasive carp] extend well beyond just the science and require diverse team/approaches to have true impact.”

The Insects Inside

We all know that insects surround us, but what about the ones that get closer to home – inside our homes? In this short video, ARS entomologist Tracy Leskey answers the most pressing viewer questions about household insects, including:

• How to make your home less attractive to ants, silverfish, and other insects
• What to do about stinkbugs – and why invasive insects are such a big problem
• Why spiders aren’t actually insects at all
• How to protect beneficial insects
• Saving your clothes from moths
• Electronic bug zappers
• What to do if your pet eats an insect and
• How to keep insects from getting into a home in the first place

Learn about all these issues, and more, in our video interview with Dr. Leskey.

Precision Agriculture

Applying the right resources in the right place at the right time can be a win-win for farmers and the environment. This approach, known as precision agriculture, lets farmers use cutting-edge tools to get specific, detailed information on individual bits of land or even plants in their fields. This knowledge enables them to apply only as much fertilizer, water, or other inputs as necessary – producing better results for them and their crops. Overall, researchers have found that using these methods costs no more than traditional approaches, but produces more consistent crop yields, and improves soil and water quality by reducing excess nutrient run-off from fertilizer. ARS conducts research on precision agriculture as part of its long-term agroecological research project, which has locations throughout the country.

The secret to precision agriculture is understanding that plants, and land, are not all the same; some parts of a field may require more or less fertilizer, for instance. By figuring out what is, or isn’t, needed, and responding appropriately, farmers use scarce resources like water most effectively.  Watch our video to learn more about this innovative new approach that’s helping farmers grow their crops more efficiently – and sustainably.

Taking the Ouch Out of Oxalate

If one of your parents or grandparents ever suffered from a painful kidney stone, you might want to tell them there's a bit of good news.

Oxalic acid, or "oxalate," is a naturally occurring plant chemical which, in the human diet, can react with calcium, iron, and other minerals to inhibit mineral absorption. Foods such as tea, beets, rhubarb, strawberries, spinach, and chocolate are known to increase oxalate in the urine and may contribute to kidney stone formation.

Spinach in particular contains higher concentrations of oxalate than most crops, but it is also considered healthful because it is rich in a number of key nutrients.

Scientists with the ARS's Crop Improvement and Protection Research Unit in Salinas, CA, and the University of Arkansas conducted a study analyzing the genetic code of 310 spinach varieties and identified 8 spinach varieties that have low oxalate levels, which is sometimes linked to better health.

If you'd like to learn more read, "Making Spinach with Low Oxalate Levels".

Tick Tactics: Scientists Are Finding New Ways to Fight an Old Foe

Ticks are one of the most troublesome insect pests, attaching themselves to humans, livestock, pets, and other animals. They can transmit many diseases, including Lyme disease, which can have devastating health effects. Currently, ticks infect over 300,000 Americans a year with Lyme disease, and infections are on the rise. One of the major ways that ticks travel is via unsuspecting deer, which can carry them long distances as they move around and search for food.

At ARS, researchers are working on new approaches to limit ticks’ ability to spread. One strategy is to target them while they’re traveling via deer. Watch this video to learn more about how researchers are using classic techniques applied in creative new ways to neutralize ticks.

ARS Pollinator Health in Southern Crop Ecosystems
Research Unit Outreach Event

The ARS Pollinator Health in Southern Crop Ecosystems Research Unit established a new apiary in Stoneville, MS with honey bee colonies decorated by students in the local community! The unit used this opportunity to engage with their community by connecting them through art by partnering with local art alliances (Delta Arts Alliance and Greenville Arts Council), bringing a splash of color to the apiary.

Dr. Pierre Lau and Sarah Dietrich gave presentations on bee biology, pollination, and agriculture at public, alternative, and private schools in the Mississippi Delta. Students, ranging from grades K-12, were instructed and tasked to paint honey bee boxes with something they learned or were inspired by in the presentations. The classes were also invited to tour the facilities. This was an activity used to involve the community and bring awareness of the ongoing research and opportunities in STEM.