BIO250 Lab 6. docx

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Lab 6 Food Microbiology BIO250L ” Student Name: MA ERICKA RENEE SAUVE Access Code (located on the lid of your lab kit): UAWQHC Lab Report Format Expectations Utilize college level grammar and professional formatting when completing this worksheet. Submissions without proper formatting, all required photos or sufficient responses will be rejected. Pre-lab Questions 1. In this lab, you will conduct two experiments that will demonstrate aspects of bacteria as they pertain to food. What concepts are these two labs trying to convey to you as a microbiology student? Why do you think they are important in the context of food production and food safety? This lab aims to convey the importance of bacteria in food preservation and production. Experiment 1 determines how refrigeration affects food quality. It slows bacterial growth, emphasizing food safety. Experiment 2 determines beneficial bacterial activity in yogurt production, showcasing their role in food transformation. Both are crucial for understanding how microbes influence food safety, shelf life, and the creation of nutritious, fermented products. 2. Escherichia coli is one of the most common causes of foodborne illness, yet it is also a common microorganism found within the human gut. Explain the difference between the types of E. coli . Some types of E. Coli possess virulent factors, which are considered foreign structures. This virulence is responsible for causing infections in the host. 3. There are several foods and beverages listed in this lab that are created through the actions of microorganisms. Name five foods and the specific microorganisms (with genus and species) that are used to make each of them. Pre-Lab, Table 1: Microorganisms Used to Produce Food Food Microorganism(s) 1. Cheese. Lactococcus. 2. Yogurt. Lactobacillus. 3. Fruit. E.coli

Lab 6 Food Microbiology BIO250L ” 4. Bread Saccharomyces cerevisiae 5. Milk. Listeria monocytogenes 4. Using an online research tool such as the A-Z index on the CDC website , explain why Listeria monocytogenes is a major threat to pregnant women and their developing fetuses, who are ten times more likely to get sick than other demographic groups. This is major threatening condition for pregnancy because this illness can be based through placenta and it can harm the fetus. EXPERIMENT 1: THE EFFECT OF REFRIGERATION ON FOOD QUALITY Introductory Questions 1. What is the objective of Experiment 1? Broadly describe the steps that you will take in this experiment. The Main objective of experiment 1 is to observe how refrigeration effects the rate of spoilage and bacterial growth on food, Steps involved are comparing refrigerated samples with the sample at room temperature over time. 2. How long do you anticipate this experiment will last? What is your plan to check samples regularly such that you obtain useful data? The experiment will last days to weeks. Regular observations and assessment like microbial counts or spoilage signs will be recorded and noted 3. What are your predictions for the outcome of Experiment 1? Explain your reasoning. Refrigerated samples are expected to spoil at slow rate due to reduced bacterial activity at lower temperature 4. What is the purpose of methylene blue in this experiment? How does it accomplish this task? Methyline blue serve as indicator of bacterial activity it can be accomplished by observing changing in colour which chsnges woth different oxygen concention in the environment

Lab 6 Food Microbiology BIO250L ” Data and Observations Report your observations from the experiment in the table below. Table 1: Time Required for Methylene Blue Color Change Milk Sample Start Time/Date (Step 10) End Time/Date (Step 11) Time Elapsed (End Time-Start Time) 0 hours 6:00 AM 6:30 AM 30 minutes 1 hour 6:00 AM 7:00 AM 1 hour 3 hours 6:00 AM 9:00 AM 3 hours 4 hours 6:00 AM 10:00 AM 4 hours Insert a photo of your test tubes at the end of your experiment. The test tubes should not be initial photos, but rather the final photos after the majority of the methylene blue has been converted. Your handwritten name must be in the photo in order to earn credit for this lab. Results and Discussion

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Lab 6 Food Microbiology BIO250L ” 1. On average, which sample took the least time to become white? Why do you think this was the case? Zero hour sample because it was at optimum temperature On average, which sample took the most time to become white? Why do you think this was the case? .4 hour sample took least time because it was at room temperature for linger period. 2. What does this experiment show you about the effect of refrigeration on the number of bacteria present in milk? Refrigerstion effect on number of bacteria because ot lowers the temperature and bacteria don't thrive in cold environment. 3. How does pasteurization affect the number of bacteria present in milk? It destroys pathogenic bacteria because at extremse condition of pasteurization bacteria can't grow. 4. What differences, if any, would this assay show if performed using raw (unpasteurized) milk? The colour and taste of milk would change at faster rate EXPERIMENT 2: PREPARATION OF YOGURT VIA LACTOSE FERMENTATION Introductory Questions 1. What is the objective of Experiment 2? How does it demonstrate the fermentation of lactic acid? The obejctive of experiment is to demonstrate how lactic acid bacteria ferment lactose into lactic acid, transforming milk into yogurt. 2. What do you expect to see when you check the pH at each step as time continues? As fermentation happen to occur, a drop in pH is expected, which indicates the increased acidity due to lactic acid production. 3. What will cause any changes in pH during this experiment? Microbial activity leading to lactic acid production will change the pH during experiment 4. What was the purpose of step 7 in this experiment? It involves a critical part of the fermentation process which is monitoring changes which help identifies any change which meed to be made

Lab 6 Food Microbiology BIO250L ” Data and Observations Provide the pH from each sample in the table below. Table 2: Yogurt pH Results Sample (Step #) pH 2 7. 6 7. 10 6. 14 5. 15 4. Graph the pH values in your above table that details the pH at each step, based on your tabulated values above. Your handwritten name must be included in this graph. If computer generated, ensure your name is present and incorporated organically into the graph title. Insert a photo of your pH test strips and the pH scale you used to determine the pH of the strip after sampling the yogurt. The photo must clearly depict the pH values that correspond to the values you denoted in Table 1 , above.

Lab 6 Food Microbiology BIO250L ” Results and Discussion 1. Interpret the data you provided. How did the pH change during the experiment? pH decrease as the lactose degenration produce H ions which cause the acidic pH . 2. What is causing the change in pH of the milk in this experiment? Lactose degenerating bacteria. 3. What attributes did the lactic acid confer on the yogurt? Lactic acid make yougurt. This yogurt made is soft in texture and taste as well. 4. How did the consistency of the milk change during the production of yogurt? What facilitates this change? Milk thickened when lactic acid is added during production . 5. What are the breakdown products of lactose? Glactose and glucose

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