Spoiled milk hastening the degradation speed of fruit peels.

[trexzert]

I am stuck on how to measure the amount of bacteria in any type of liquid, more specifically milk. Is there some way that I can control how much bacteria, like adding a specific amount of bacteria into it.

[deleted-71417]

Hi,

This science Buddies Project describes how to estimate the number of bacteria in a liquid using a serial dilution technique:

https://www.sciencebuddies.org/mentorin ... p015.shtml

I hope this answers your question. If not, post another more specific question and we will try to help.

Best wishes for a very successful project!

Best regards,

Barrett L. Tomlinson

[trexzert]

RE-EDITTEED
I need help on improving my hypothesis if there is anything to be improved on.

Higher bacteria content in smaller amount of liquids will hasten the degradation of orange peels.

For my project, I am going to grow bacteria and put equal amounts of bacteria into 100ml,200ml,300ml, and 400ml tap water.
I will then apply them to each of the 4 containers that hold equal grams of orange peels.

Is there a good easy way to grow bacteria ?

Any suggestions is greatly appreciated.

[trexzert]

How can I control the amount of bacteria and show how much bacteria is grown in chicken broth?

[MelissaB]

Hi,

I think you might want to take a look at Science Buddies' microbiology guides, in the lower right-hand corner of this page: http://sciencebuddies.com/science-fair- ... l?From=Tab .

I believe that you may be able to buy bacteria in suspension at different concentrations, but I am not sure. You could take a look at Carolina Biological Supply's website or a similar website (note: Science Buddies does not endorse CBS) to see what they have. I think you will find it very difficult to put 'the same amount of' bacteria into different amounts of water, because amounts of bacteria are hard to measure without specialized equipment.

Make sure you boil the tap water and the containers first to reduce the amount of bacteria in/on them if you do go that route.

[trexzert]

Actually i changed my hypothesis, which is now

Higher ph content in liquid will hasten the degradation speed of organic substance.

First, I need a cheap (20 dollars or less) way to tell how much ph there is in liquids.

[carolinethorn]

Hi,

Did you know you can make your own pH indicator? There are instructions on the science buddies websites in the section on chemistry projects.
https://www.sciencebuddies.org/science- ... p041.shtml
https://www.sciencebuddies.org/science- ... p013.shtml

If you still want to buy something pre-made, have you tried doing a google search for pH paper?
I tried searching "ph paper school" - i found a couple of websites that seem to be aimed at home school or use by children rather than labs. I cannot say whether any of these websites are any good though.

http://www.xump.com/science/pHPaper.cfm
http://www.home4schoolgear.com/wiraphlpa1tu.html
https://www.indigoinstruments.com/test_ ... -1-14.html

I'm interested to hear more about how you are going to do your experiment and what you think may happen. What kinds of different solutions would you use to be the different pH contents? Do you think the pH of your test solutions may be changed at all by the fruit peel?

best of luck,
Caroline

[trexzert]

Thx

Now this is a rough draft of my procedures. Any comments or improvement tips are greatly appreciated.


Materials

-Red Cabbage Juice
-Four 1L Containers
-Orange Peels
-Electronic Scale
-Soil(STILL DECIDING)
-500ml of Pop
-500ml of Apple Juice
-500ml of Vinegar
-500ml of Water
-4 Small Containers of 200ml
-Strainer
-4 porous bags with string
-labels
PROCEDURE 1

TESTING OUT pH LEVEL OF LIQUID

1.Take 50ml from each of the 4 liquids and pour them separately into 4 of those 200ml containers.

2. Pour 50ml of Red Cabbage Juice into each of the four liquids. Use a strainer to remove any pieces of cabbage that pours out.

3.Now wait a while for the cabbage juice to spread out. You should now see a clear liquid that has a change in color.

4. A GENERAL IDEA OF pH LEVELS
pH Color
––––––––––––
2 Red
4 Purple
6 Violet
8 Blue
10 Blue-green
12 Greenish-yellow

5. Record the pH level of the liquids.

PROCEDURE 2

1. Collect exactly 400 gram of orange peels and put four amounts of 100 gram of orange peels into each porous bag. Now put a bag holding 100 grams of peels into each four 1L container.
2. Pour 350 ml of the 4 different liquids separately into each container. Be sure the leave the strings of the porous bag hanging out of the container.
3. Label the name of the liquid that is in each container ON THE STRING AND THE CONTAINER so that you do not get mixed up. Put a lid on all the containers.
4. After 1 week, take all the porous bag by the string and air dry each separately by using a blow dryer. It is recommended to blow dry each bag for at least 3 minutes.
5. Measure each bag’s weight using a electronic scale. Record.
6. Then put each bag of orange peels into those containers and wait for another week.
7. Repeat step 4. After 4 weeks, summarize findings.

[MelissaB]

This looks really good! I do have a few suggestions, though:

Will the orange peels be cut to a certain size? The size of the peels are going to affect the surface area the liquids can work on, so you want to be sure this is the same for all groups.

I am a little concerned that the apple juice and possibly the pop (which kind of pop? Cola?) will spoil after a week or so and the whole experiment will start to stink and maybe need to be thrown away! Can you keep the experiment outside or in a garage or something?

Otherwise, it looks good to me. Good luck!

[donnahardy2]

Hi Trexert,

How are you? I just noticed your post in the science buddies website and I remember your banana peel project from last year. I see that you are working on another hopefully prize-winning project. Your meticulous attention to detail will be an asset on this project as well.

Barrett and Melissa have given you some excellent suggestions, and I would like to add some comments as well.

First, Melissa’s comment about the size of the orange peel pieces is very important. You need to make sure the pieces in all of the bags are approximately the same size.

Next, I think you have too many variables. Your question is about pH, but each of your samples has differences other than pH. Soda pop, apple juice, vinegar, and water might have characteristics other than pH that would affect the degradation of the orange peels. And, all of your samples are acidic; you don’t have any high pH samples. If you are going to measure the effect of pH, you would need to use one sample and vary just the pH. The pH scale ranges from 0 to 14, so you would want to test between 3 and 5 pH levels. All other parameters would need to be identical. For example, you could use water, water with acetic acid (white vinegar) to lower the pH, and water with baking soda (sodium carbonate added) to raise the pH. You can experiment with the cabbage pH indicator to make samples with a range of pH levels.

Since you are studying the degradation of the orange peels over time, you need to add a mixture of bacteria that will start this process. Breakdown of plant materials requires a wide variety of organisms, and you can find these in compost, rich garden soil, or in manure from an animal that digests grass (cow, rabbit, goat, or horse). To keep the experiment controlled, you would need to add the same weight of the bacteria source to each sample.

I hope this helps. Please let us know if you have any other questions.


Donna Hardy

[trexzert]

Oh Wow, I never thought about that. If only I had known this earlier.
Another question is because apple juice is greenish, would this affect the outcome of the color when it is mixed with red cabbage juice?

[donnahardy2]

Hi Trexzert,

I’m sure the background color of the apple juice will interfere somewhat, but go ahead and see if it works well enough for you to see a color. Since you are using a large volume of cabbage juice, the purple color should show through.

Pure apple juice is acidic, with a pH of about 3.

http://wiki.answers.com/Q/What_is_the_PH_of_apple_juice

I saw the earlier discussion about measuring the bacteria in your sample, and I don't think you do need to measure the bacteria, since you will be weighing the orange peels. You still should add some bacteria added to the samples, but this will be one of your controlled parameters, since you will use the same source and quantity (soil).

Donna Hardy