Observation
I examined the consistency change of the milk when it was left out of the refrigerator for four days.
Hypothesis
The hypothesis is that the higher temperature affects the bacteria growth in the milk, hence changing the milk’s consistency.
Experiment and Procedure
A list of materials used in the experiment: a thermometer, 3-4 small clean cups, fresh milk, a refrigerator, paper, and a pencil to record the results. First, I added the same amount of milk and a similar type of milk to two cups. Secondly, I put a lid on them and placed one of the cups in a refrigerator and the other one out of the fridge, in a place with average room temperature. I turned off the air conditioner to as not to affect the average room temperature. Next, I examined the samples three times a day for four days and recorded the results. I inspected the pieces by first smelling them and then tasting them. I used the different spoons for each tasting to prevent the development of one sample from affecting another. I repeated this process for four days and, on the last day, concluded my observation.
Variables
The independent variable of this experiment is the milk storage temperature. The dependent variable is the condition of the milk and the time it takes for the milk to change its consistency. Controlled variables are the type and amount of the milk.
Data Collection and Conclusion
On the first day of the experiment, I did not observe any significant changes in both samples. On the second day, I noticed that the milk at the warm place had a distinct taste and bad smell. By the third day, milk had formed the lumps and bubbles in the milk left out of the refrigerator. As the days progressed, the regular temperature milk developed a worse taste and smell. Meanwhile, the refrigerator milk did not have any distinct smell until the fourth day of the experiment. This experiment confirms my hypothesis that leaving the glass of milk out of the refrigerator for four days has significantly changed its consistency as it formed more lumps, bubbles, yellow shade, and sour tastes. The warmer temperature facilitates the formation of lactic acid by the lactic acid bacteria in the milk, which causes milk spoilage (Lakade et al. 702). Therefore, under the warm temperature, the consistency of the milk changes due to the formation of lactic acid.
Work Cited
Lakade, Ankita Jagannath, et al. “Nanomaterial-Based Sensor for the Detection of Milk Spoilage.” LWT, vol. 75, 2017, pp. 702–709., doi:10.1016/j.lwt.2016.10.031.