Cheese Lab Write Up
Hayden Shaffer
08.30.2017
9th Grade Biology and Biotechnology
INTRODUCTION1. The purpose of this lab was to find the most efficient way to make cheese with different curdling agents to record the curdling times.
2. The purpose of the second part of this lab was to change one component of the previous procedure and observe how the results differed.
3. The purpose of the third part of this lab was to test the cheese for protein, starch, glucose, and lipids and see which of these macromolecules were in the cheese.
HYPOTHESIS1. I hypothesize that milk mixed with the curdling agent FPC will curdle quickest.
2. I hypothesize that if we double the amount of FPC we are putting into the milk, the mixture’s curdle time will be half as long as the previous curdling time.
3: I hypothesize that if the cheese underwent the process of the lab, the cheese will have all 4 macromolecules for which we are testing.
PROCEDURE1. Label four 6ml tubes with the type of curdling agent group member.
2. Use a large pipet to transfer 3 ml of milk into each of the 6ml tubes.
3. Use a small pipet and transfer the entire contents of the tubes of fermentation produced chymosin, natural bovine chymosin, and buttermilk to the different labeled tubes containing the milk. For water, fill the small transfer pipet to the bottom of the bulb and add to the labeled tube containing the milk.
4. Cap the tubes, invert them three times and then transfer to 37°C water bath or place at body temperature (armpit) for incubation.
5. Set a timer and check for curdling every 5 minutes, by gently inverting the tube and examining for curds.
6. Record the time (in minutes) when the milk begins to curdle (small or large lumps) or solidify.
7. If the milk had not curdled in 30 minutes, check for curdling every hour.
8. In a data table, record the time (in minutes) when the milk begins to curdle (small or large lumps) or solidify.
9. Upon return to the lab, during the next work period, determine the amount of curds produced by each treatment.
10. For each treatment, weigh a paper cone and record the empty cone weight.
11. Transfer the entire contents of a tube into a labeled filter paper cone over a suitable collection vessel. Once all liquid has drained through, dry the filter paper with curds overnight.
12. Weigh the dry cone with dry curds. Subtract the dry cone weight. Record the weight of the curds (in mg) by multiplying the mass in grams by 1000.
13. Repeat with each treatment.
14. Create a data table that reports the Rate of Curd Production (weight/time) by each Curdling Agent.
15. Create a bar graph that shows the Rate of Curd Production by each Curdling Agent.
Part 2
1. Label four 6ml tubes with the amount of FPC agent for 2 group members.
2. Use a large pipet to transfer 3 ml of milk into each of the 6ml tubes.
3. Use a small pipet and transfer the entire contents of the tubes of fermentation produced chymosin(FPC) and label the tubes with the amount.
4. Cap the tubes, invert them three times, and then transfer to 37°C water bath or place at body temperature (armpit) for incubation.
5. Set a timer and check for curdling every minute, by gently inverting the tube and examining for curds.
6. In a data table, record the time (in minutes) when the milk begins to curdle (small or large lumps) or solidify.
7. Upon return to the lab, during the next work period, determine the amount of curds produced by each treatment.
8. For each treatment, weigh a paper cone and record the empty cone weight.
9. Transfer the entire contents of a tube into a labeled filter paper cone over a suitable collection vessel. Once all liquid has drained through, dry the filter paper with curds overnight.
10. Weigh the dry cone with dry curds. Subtract the dry cone weight. Record the weight of the curds (in mg) by multiplying the mass in grams by 1000.
11. Repeat with each treatment.
12. Create a data table that reports the Rate of Curd Production (weight/time) by each Curdling Agent.
13. Create a bar graph that shows the Rate of Curd Production by each Curdling Agent.
Part 3
-Monosaccharide indicator test
1.Test for glucose: In a test tube, mix 2 ml of cheese solution with 2 ml of benedict’s solution. Heat for 2 minutes in boiling hot water bath (100 ml of water in a 250-ml beaker at 100 degrees C) record all color changes and the length of time for each color change to appear.
-Polysaccharide test
2. Test for starch: In a test tube, mix 2 ml of well-mixed cheese solution with 0.25 ml of
Lugol’s Iodine. Gently swirl to mix. DO NOT HEAT. record the color change.
-Protein test
3. Test for protein: place 2 ml of cheese solution in test tube. Wearing goggles and gloves, add 0.5 ml of 10% NaOH and gently vortex to mix. Add 0.25 ml of 5% copper sulfate (CuSO4) and gently mix. The NaOH and CuSO4 mixture is called biuret reagent. Mix well. Record color change after 30 seconds.
-Lipid test
4. Test for lipids): Sudan IV. add 6 microliters of Sudan IV to 2 ml of cheese sample. Gently mix, red is negative for lipid test orange is positive test.
DATA
Curdling AgentCurdling Time Weight of Cone and Curds Weight of Cone Weight of Curds Rate
Chymosin
FPC
5 minutes
4.69 g
1.15 g
3.54 g
708 mg/m
Chymosin
NCB
24 hours
2.94 g
1.15 g
1.79 g
1.24 mg/m
Buttermilk
24 hours
2.8 g
1.15 g
1.65 g
1.14 mg/m
Water
24 hours
2.36 g
1.15 g
Jhuuuuuuuuu 1.22 g
.84 mg/m
Data pt.2Curdling agent
Weight of cone and curds
Weight of cone
Weight of curdes
Rate
Curdling time
FPC 100ml
3.16 g
.75 g
2.4 g
204 mg/m
10 min
FPC 200ml
3.15 g
.75 g
2.41 g
482 mg/m
4 min
Data pt.3Standard
Indicator used
Description + controle
Description - controle
Prescense
Glucose
Benedict's Solution
yellow-dark red
blue
Yes
Starch
Lugols Iodine
Black
Red
No
Protein
Biuret Reagent
Purple
Light blue
Yes
Fat/Lipids
Paper test/ sudan IV
Orange
Red
Yes
ANALYSIS1. The data tables and graph above represent the data collected in the cheese lab. The data from part one represents the weights of the different curds, how fast the different mixtures curdled, and the rate at which the curdling of each mixture occurred. My hypothesis was correct because I predicted the cheese mixed with FPC to curdle quickest and it did. We ran out of time at the end of the period for the first day so the curdle time is faster than the data shows for the NCB, buttermilk, and water. This error could be fixed by starting the curd recording process earlier with a larger block of time set aside for collecting data. We could investigate further by adding more of a curdling agent (specifically FPC) to milk and comparing the curdling time to the previous time.
2. The data for part two shows that when twice as much FPC was added to the milk, the curdling rate (mg/minute) doubled meaning, meaning it curdled twice as fast as before. My hypothesis for part two proved to be correct because I predicted the curdling time to halve once twice as much curdling agent was used, and it did. As far as the data shows, there were no errors to the second part of the lab. My reasoning for this statement is that the amount of FPC used seems to be directly correlated with the curdling rate in such a way that when twice as much FPC is used, the rate doubles. It’s possible that this could only seem to be the case if an error occurred somewhere in the process, such as in the incubation process. An incubation error could be different clothing in between the armpit and test tubes, which could be fixed by having the same person incubate both tubes simultaneously while another team member times and a third member records the data. Another incubation error that might have occurred could be taking the test tubes out of the armpit for too long or taking one out for a different period of time than the other. This could be fixed for the most part by taking them out simultaneously for a very quick and almost negligible amount of time (something like 2 seconds) so that any cooling to occur would make little to no difference in the recording process.
3: The data for part three of the lab means that the cheese tested had glucose, protein, and lipids, but not starch. My hypothesis is incorrect because of the fact that we didn’t have starch. This means we only had 3 of the 4 macromolecules. We could have erred in mismeasuring or using one-time-use tools multiple times. We could fix these problems if we were more attentive and made sure we were following the procedure correctly. This could lead to other investigations such as searching for these macromolecules in other foods and comparing our findings to that of the cheese.
New concepts:
Macro-molecules: A molecule containing a very large number of atoms, such as a protein, nucleic acid, or synthetic polymer. The four main classes being carbohydrates, lipids, proteins, and nucleic acids. After making the cheese we checked to see what macro-molecules were present in the cheese corresponding to the agents. The understanding of what macro-molecules are were vital to this project because we needed to know what we were testing the cheese for.
Protein: a macro-molecule; a class of nitrogenous organic compounds that consist of large molecules composed of one or more long chains of amino acids and are an essential part of all living organisms. Proteins were present in the cheese that we made because of the tests we ran to confirm them.
Lipids/fats: Any of a class of organic compounds that are fatty acids or their derivatives and are insoluble in water but soluble in organic solvents. They include many natural oils, waxes, and steroids. Our cheese tested positive for lipids.
Carbohydrates: a macro-molecule that provides energy for the cell; two types- monosaccharides and polysaccharides; monosaccharides give the cell energy while polysaccharides store the energy.
CONCLUSION1. Our overall discovery was that we found FPC to be the quickest curdling agent. We put FPC, NCB, buttermilk and water into milk in different test tubes and incubated the mixtures. We checked for curdling and recorded data frequently until all solutions were curdled, and then we weighed the curds and created tables and graphs for our data. Evidence for this can be observed in the Data section of this report where weights, curdling times, and curdling rates for the different mixtures are listed. The evidence lays out clearly how fast the curds formed (rate), how long it took the curds to form (time), and how heavy the curds were. This is known in scientific theory as analyzing your results and drawing a conclusion. The evidence also shows water to be the least effective curdling agent which is proven by the water/milk mixture having the least heavy curds. This is also known in the scientific theory as analyzing your results and drawing a conclusion.
2. Our overall discovery for part two was that more FPC will make the mixture curdle quicker. We put 100 ml of FPC into one test tube of milk and 200 ml into the other. We incubated the tubes and recorded the weight, curdling time, and curdling rate for each mixture and compared them to each other. Evidence for this is shown in the Data section for part two where weights, curdling times, and curdling rates for the different mixtures are listed. The evidence lays out clearly how fast the curds formed (rate), how long it took the curds to form (time), and how heavy the curds were. This is known in scientific theory as analyzing your results and drawing a conclusion. From the data we can also conclude that doubling the amount of FPC used will halve the time it took for the solution to curdle. This also is known in scientific theory as analyzing your results and drawing a conclusion.
3. Our overall discovery for part three was that the cheese we tested contained the macromolecules glucose, protein, and lipids. We mixed certain chemicals with the cheese to test for glucose. We then completed a similar procedure with other chemicals being mixed into different test tubes, and based on color changes in the mixtures we concluded whether or not the presence of glucose, starch, proteins, and lipids were found in the cheese. This evidence of this is shown in our Data section for part three in a data table where you can see the indicator used to detect the macromolecule’s presence and the color change observed in the mixtures after 30 seconds. This is known in scientific theory as testing your hypothesis with an experiment. From the data table we can also easily see which macromolecules were present in the cheese. This means that glucose, protein, and lipids are in the cheese. This is known in scientific theory as analyzing your results and drawing a conclusion.
Reflection: I thought our procedure was very well written and we followed the directions well. Something that went poorly was we didn't get an accurate timing for the curdling time because the cheese didn't curdle within the time frame. I learned that when you create a procedure and stick to it super well you can save a lot of time from reducing errors. I learned that patience is really important when dealing with timing. I could have used research to figure out the curdling time of cheese with different curdling agents to save us time.