Mrs. Knapp’s 2 nd and 3 rd Period Class Stella Brockman, Manteca, California April 24,2004

Summary We are going to talk about : Yeast Fermentation Citrus Fruits Set Up Results

Yeast & Fermentation Yeast is a living organism People use to bake Fermentation allows them to live, using sugars. Citric Acid is poisonous to them Fermentation is digesting sugars without oxygen. Carbon Dioxide is also produced We got the citric acid from the citrus fruit, such as lime & grapefruit.

Problem/ Hypothesis Our class investigated the type of citrus juice that yeast can ferment. To do this, we measured level of carbon dioxide. Our hypothesis is that yeast likes fruits that have a lot of sugar and has less citrus acid, so it will like something sweet like an orange, therefore, yeast will produce the most carbon dioxide in orange juice.

Methods Juice from 4 citrus fruits was added to one gram of yeast and 3ml of water. We then mixed 3ml of the yeast solution and 5 ml of fruit juice in the labeled test tubes. We used a pipette bulb to take up 1ml of the solution. The reading was checked and written immediately after about 5 hours.

Materials

Conclusion The water and the yeast did not ferment because there was no sugar to eat/absorb. The sugar and the yeast have the most sugar therefore the yeast ferment the most on the yeast/sugar tube. Yeast in high sugar and low citric acid ferments the best.

Acknowledgements Thanks to our classmates in Mrs. Knapps class. Thanks to Debbie Walker, UOP Department of Biology, for the supplies used in the experiment.

Me!