Experimental Data Analysis
For Research Methods I formulated the question, if the old saying is that we should eat an apple a day, what is on the surface of our apple a day?
Abstract
This experiment was to determine if E. coli was present on the surface of apples purchased at a local grocery store, both before and after washing with water as recommended by the Food and Drug Administration. Four varieties were chosen from different regions and washed with distilled water that had been boiled. The results were inconclusive as there were no positive results.
Introduction
Good health is essential to good quality of life and yet the Center for Disease Control reports that childhood obesity has more than doubled in children and more than tripled in adolescents in the last 30 years. Over one-third of adults in the United States are considered obese, with an annual estimated medical cost of $147 billion. (Ogden 2012) Obese is defined as having a body mass which is calculated by height versus weight, according to the National Institute for Health. It is an approximate estimate of body fat and is meant to help gauge the risk of diseases associated with having additional body fat. Having a lower income, lower education and sometimes being a member of a minority group increases the likelihood of obesity. (Health, United States, 2011, With Special Features on Socioeconomic Status and Health, 2011)
What causes obesity? Other than a medical condition, such as hypothyroidism, obesity is caused by eating too many calories and not getting enough exercise. Both children and adults are exposed to the easy availability of food high in calories but low in nutritional value. (Causes of Obesity, Mayo Clinic 2013)
Personal experience has shown it generally takes more cost, time and effort to prepare healthy food, plus access to a food preparation area and refrigeration. Unrefrigerated fresh produce also has limited freshness, while Twinkies have a shelf life of 45 days. (Isidore 2013) Peer pressure and the behaviors modeled at home also play a role, but making healthy decisions is a series of steps towards building a lasting healthy pattern. Choosing better food for snacks is a necessary part of that pattern. It is part of modern life to be on the run, not near a kitchen or healthy source of snack food. Ideally, a better choice for a snack would be a food that has a reasonable amount of calories rather being a calorie dense processed food. It would be an even better choice if it had good nutrition, fiber, was sturdy enough to survive being packed in a lunch bag or briefcase and stayed fresh under a variety of conditions.
An apple that weighs 182g contains approximately 95 calories, 31g of fat, no cholesterol, 4.4g of dietary fiber and 157g of water. While apples usually taste sweet they also have a low glycemic index, so they only raise blood sugar by a small amount, with vitamins C, A, K, E, B-6, thiamin, riboflavin, niacin, iron, magnesium, phosphorus, choline, betaine, copper, manganese, zinc, potassium, and more. (Coila 2011) Under ideal conditions, apples can stay fresh for up to 6 months when stored with 90-95% humidity at 0 degrees C.
Before recommending an apple a day, it might be good idea to check and see if the apple has unwanted added organisms lurking on the surface. According to the Mayo Clinic, there are many strains of E.coli but only a few trigger diarrhea. The O157:H7 produces a powerful toxin that damages the small intestine lining. Exposure can come from food, water or from another person. Rainwater runoff from livestock farms can contaminate fresh produce. (Goyal 2007)
Hypothesis
In any food unwanted organisms can be present. Both children and adults have a tendency to “grab a snack” now and then, which may contain a strain of E.coli which would cause diarrhea. According to the federal Food and Drug Administration, washing produce with water will remove the majority of any E.coli that may be present. I hypothesize that tests made before and after washing will show the results of the washing process as having removed or noticeably lowered the presence of the E.coli organisms.
Materials List
Four varieties of four apples each were chosen. The four varieties were Braeburn from Chile, Zestar from New York, Jonagold from Washington and Jazz from New Zealand and all are commonly used for “hand-eating” according to the Apple Journal’s current list of varieties and their uses. All four varieties were available from local grocery stores.
Materials for testing were 3M Petrifilm tests, transfer pipettes, sterile swabs, and condiment cups. Washing materials included Bounty brand paper napkins and distilled water.
Procedure
Four different varieties of apples were obtained from a local grocery store. The apples were chosen from the back of the display to minimize organisms that might have been introduced by the general public. The apples were placed in a plastic produce bag obtained in proximity to the apple display and remained in the plastic bag until testing.
Testing the apples as they came directly from the bag:
A 100 ml beaker of distilled water was heated to boiling and allowed to cool (figure 1).
Figure 1. Heating the distilled water in a beaker in the microwave 1.5 minutes on high.
Using a transfer pipette, 1.5ml of the water was placed in a condiment cup. A sterile swab was then dampened in the water and the majority of the surface of the apple was swabbed starting with the identifying label, using a “pole to pole” motion from stem to blossom end. The swab was placed back into water in the condiment cup for 3 seconds and then discarded. The transfer pipette was then used to take the remaining water and inoculate the test according to the directions on the package. The condiment cup, pipette and swab were discarded after being used for one apple. After each test the apple was placed to the side of the plastic bag and when all of one variety were completed they were placed back into the plastic bag. The tests were marked using a black Sharpie pen with the date and time they were placed into the incubator at 37-40 degrees Celsius and checked at intervals of 24 hours for 4 days. All four varieties were tested in this manner. (Figure 2)
Figure 2. Incubator temperature settings.
Washing the apples was accomplished by pouring the distilled/boiled water into a 50ml graduated cylinder. Removing one napkin from the package, 10 ml of the water was poured onto the napkin. Each apple was rubbed all over with the damp napkin starting at the label and rotating to make sure all surfaces were included in the process. This took 20 seconds per apple, timed with an iPhone 4. After washing each apple was dried with another napkin and both napkins discarded after each apple. The dried apple was then placed on another napkin. When all four apples of one variety had been washed the E.coli tests were repeated according to the procedure listed above.
The completed tests were then placed into the incubator on the wire shelf, 8 tests per stack. (Figure 3)
Figure 3. E.coli tests stacked in the incubator
Results
All of the E.coli tests before and after washing showed negative results according to the instructions and illustrations provided by 3M. (Figures 4-10)
With no test positive test results, the analysis of these test results allow for three possibilities. The first is that the apples had no E.coli present. This is certainly possible, as a grocery business would want to make sure their products were safe and attractive to the consumer. The produce manager of the grocery store was interviewed and he stated that the apples were refrigerated but they were not washed. The apples went from the truck in packing house boxes to the refrigerator and from there they were stocked into the various bins. If the apples were washed prior to being received at the store, then the process was completed at the apple packing facility.
The second possibility is that the tests were defective. Since there were no positive results this is also possible. The tests have specific instructions for use and storage clearing printed on the exterior foil. The instructions state that the package should be refrigerated until opened, and once opened it should not be refrigerated. The shelf life, once the package is opened, is 30 days. So it is possible the tests may not have been shipped under the correct conditions and/or they may not have been stored correctly.
The third possibility is that the procedure for testing was flawed. Annie Johnson of 3M technical support was consulted as to the recommended method of testing the surface of apples for E.coli. She suggested that the apples be rubbed all over with 1ml of water and then the water tested for the presence of E.coli. She also mentioned that apples are slightly acidic and so are naturally resistant to E.coli. Recalling that other research papers had shown bottled water may not be completely free of E.coli, as part of the process used for these tests; distilled water was obtained and kept sealed until it was used for these tests. The water was boiled and allowed to cool, so that any results obtained on the tests would be from the apples and not from the water.
Conclusions
The final conclusion, based on these test results is inconclusive. Since there are no positive results at all, so there is no way to tell if the apples are clean or the tests or the testing process was defective.
Short-comings, suggested improvements
To do this and achieve meaningful results, the tests need to be used with a substance that confirms the test is not defective and produces a positive result. The 3M Petrifilm tests would have to be shipped according to manufacturer’s guidelines and then verified that the instructions for storage were followed at the receiving facility.
The water is also a potential source of E. Coli. The distilled water was purchased and kept sealed until it was used for these experiments, but the water should be tested by itself as well.
Four varieties were tested, two from within the United States and two from outside the United States, but if all the apples went through a standardized process of washing at the apple packing houses then it would be reasonable to assume that regardless of variety or origin, the likelihood of the surface of the apples being contaminated with E.Coli is the same between all varieties processed through that packing house.
Lastly, knowing the exact temperature on the incubator, rather than guessing at a range would ensure the tests were held at the correct temperature.
Works Cited:
Adult Obesity Facts. (2013, August 16). In http://www.cdc.gov. Retrieved October 2, 2013, from http://www.cdc.gov/obesity/data/adult.html
Childhood Obesity Facts. (2013, July 10). In http://www.cdc.gov. Retrieved October 1, 2013, from http://www.cdc.gov/healthyyouth/obesity/facts.htm
Coila, b. (2013, October 13). are apples a good snack for weight-loss. In www.livestrong.com. Retrieved October 13, 2013, from http://www.livestrong.com/article/375556-are-apples-a-good-snack-for-weight-loss/
Comprehensive Apple Variety List. (n.d.). In http://www.applejournal.com. Retrieved October 13, 2013
Goyal. (2007). Best Management Practices for Pathogen Control in Manure Management Systems. In http://www.extension.umn.edu. Retrieved October 9, 2013, from http://www.extension.umn.edu/distribution/livestocksystems/DI8544.html
How Are Overweight and Obesity Diagnosed?. (2012, July 13). In http://www.nhlbi.nih.gov/. Retrieved October 2, 2013, from http://www.nhlbi.nih.gov/health/health-topics/topics/obe/diagnosis.html
Isidore, C. (2013, July 9). New Twinkies will double their shelf life. In http://money.cnn.com/. Retrieved October 1, 2013, from http://money.cnn.com/2013/07/09/news/companies/twinkies-shelf-life/index.html
Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of obesity and trends in body mass index among US children and adolescents, 1999-2010. Journal of the American Medical Association 2012;307(5):483-490.
Raw Produce: Selecting and Serving it Safely. (2013, August 12). In www.fda.gov. Retrieved October 2, 2013, from http://www.fda.gov/food/resourcesforyou/consumers/ucm114299
For Research Methods I formulated the question, if the old saying is that we should eat an apple a day, what is on the surface of our apple a day?
Abstract
This experiment was to determine if E. coli was present on the surface of apples purchased at a local grocery store, both before and after washing with water as recommended by the Food and Drug Administration. Four varieties were chosen from different regions and washed with distilled water that had been boiled. The results were inconclusive as there were no positive results.
Introduction
Good health is essential to good quality of life and yet the Center for Disease Control reports that childhood obesity has more than doubled in children and more than tripled in adolescents in the last 30 years. Over one-third of adults in the United States are considered obese, with an annual estimated medical cost of $147 billion. (Ogden 2012) Obese is defined as having a body mass which is calculated by height versus weight, according to the National Institute for Health. It is an approximate estimate of body fat and is meant to help gauge the risk of diseases associated with having additional body fat. Having a lower income, lower education and sometimes being a member of a minority group increases the likelihood of obesity. (Health, United States, 2011, With Special Features on Socioeconomic Status and Health, 2011)
What causes obesity? Other than a medical condition, such as hypothyroidism, obesity is caused by eating too many calories and not getting enough exercise. Both children and adults are exposed to the easy availability of food high in calories but low in nutritional value. (Causes of Obesity, Mayo Clinic 2013)
Personal experience has shown it generally takes more cost, time and effort to prepare healthy food, plus access to a food preparation area and refrigeration. Unrefrigerated fresh produce also has limited freshness, while Twinkies have a shelf life of 45 days. (Isidore 2013) Peer pressure and the behaviors modeled at home also play a role, but making healthy decisions is a series of steps towards building a lasting healthy pattern. Choosing better food for snacks is a necessary part of that pattern. It is part of modern life to be on the run, not near a kitchen or healthy source of snack food. Ideally, a better choice for a snack would be a food that has a reasonable amount of calories rather being a calorie dense processed food. It would be an even better choice if it had good nutrition, fiber, was sturdy enough to survive being packed in a lunch bag or briefcase and stayed fresh under a variety of conditions.
An apple that weighs 182g contains approximately 95 calories, 31g of fat, no cholesterol, 4.4g of dietary fiber and 157g of water. While apples usually taste sweet they also have a low glycemic index, so they only raise blood sugar by a small amount, with vitamins C, A, K, E, B-6, thiamin, riboflavin, niacin, iron, magnesium, phosphorus, choline, betaine, copper, manganese, zinc, potassium, and more. (Coila 2011) Under ideal conditions, apples can stay fresh for up to 6 months when stored with 90-95% humidity at 0 degrees C.
Before recommending an apple a day, it might be good idea to check and see if the apple has unwanted added organisms lurking on the surface. According to the Mayo Clinic, there are many strains of E.coli but only a few trigger diarrhea. The O157:H7 produces a powerful toxin that damages the small intestine lining. Exposure can come from food, water or from another person. Rainwater runoff from livestock farms can contaminate fresh produce. (Goyal 2007)
Hypothesis
In any food unwanted organisms can be present. Both children and adults have a tendency to “grab a snack” now and then, which may contain a strain of E.coli which would cause diarrhea. According to the federal Food and Drug Administration, washing produce with water will remove the majority of any E.coli that may be present. I hypothesize that tests made before and after washing will show the results of the washing process as having removed or noticeably lowered the presence of the E.coli organisms.
Materials List
Four varieties of four apples each were chosen. The four varieties were Braeburn from Chile, Zestar from New York, Jonagold from Washington and Jazz from New Zealand and all are commonly used for “hand-eating” according to the Apple Journal’s current list of varieties and their uses. All four varieties were available from local grocery stores.
Materials for testing were 3M Petrifilm tests, transfer pipettes, sterile swabs, and condiment cups. Washing materials included Bounty brand paper napkins and distilled water.
Procedure
Four different varieties of apples were obtained from a local grocery store. The apples were chosen from the back of the display to minimize organisms that might have been introduced by the general public. The apples were placed in a plastic produce bag obtained in proximity to the apple display and remained in the plastic bag until testing.
Testing the apples as they came directly from the bag:
A 100 ml beaker of distilled water was heated to boiling and allowed to cool (figure 1).
Figure 1. Heating the distilled water in a beaker in the microwave 1.5 minutes on high.
Using a transfer pipette, 1.5ml of the water was placed in a condiment cup. A sterile swab was then dampened in the water and the majority of the surface of the apple was swabbed starting with the identifying label, using a “pole to pole” motion from stem to blossom end. The swab was placed back into water in the condiment cup for 3 seconds and then discarded. The transfer pipette was then used to take the remaining water and inoculate the test according to the directions on the package. The condiment cup, pipette and swab were discarded after being used for one apple. After each test the apple was placed to the side of the plastic bag and when all of one variety were completed they were placed back into the plastic bag. The tests were marked using a black Sharpie pen with the date and time they were placed into the incubator at 37-40 degrees Celsius and checked at intervals of 24 hours for 4 days. All four varieties were tested in this manner. (Figure 2)
Figure 2. Incubator temperature settings.
Washing the apples was accomplished by pouring the distilled/boiled water into a 50ml graduated cylinder. Removing one napkin from the package, 10 ml of the water was poured onto the napkin. Each apple was rubbed all over with the damp napkin starting at the label and rotating to make sure all surfaces were included in the process. This took 20 seconds per apple, timed with an iPhone 4. After washing each apple was dried with another napkin and both napkins discarded after each apple. The dried apple was then placed on another napkin. When all four apples of one variety had been washed the E.coli tests were repeated according to the procedure listed above.
The completed tests were then placed into the incubator on the wire shelf, 8 tests per stack. (Figure 3)
Figure 3. E.coli tests stacked in the incubator
Results
All of the E.coli tests before and after washing showed negative results according to the instructions and illustrations provided by 3M. (Figures 4-10)
With no test positive test results, the analysis of these test results allow for three possibilities. The first is that the apples had no E.coli present. This is certainly possible, as a grocery business would want to make sure their products were safe and attractive to the consumer. The produce manager of the grocery store was interviewed and he stated that the apples were refrigerated but they were not washed. The apples went from the truck in packing house boxes to the refrigerator and from there they were stocked into the various bins. If the apples were washed prior to being received at the store, then the process was completed at the apple packing facility.
The second possibility is that the tests were defective. Since there were no positive results this is also possible. The tests have specific instructions for use and storage clearing printed on the exterior foil. The instructions state that the package should be refrigerated until opened, and once opened it should not be refrigerated. The shelf life, once the package is opened, is 30 days. So it is possible the tests may not have been shipped under the correct conditions and/or they may not have been stored correctly.
The third possibility is that the procedure for testing was flawed. Annie Johnson of 3M technical support was consulted as to the recommended method of testing the surface of apples for E.coli. She suggested that the apples be rubbed all over with 1ml of water and then the water tested for the presence of E.coli. She also mentioned that apples are slightly acidic and so are naturally resistant to E.coli. Recalling that other research papers had shown bottled water may not be completely free of E.coli, as part of the process used for these tests; distilled water was obtained and kept sealed until it was used for these tests. The water was boiled and allowed to cool, so that any results obtained on the tests would be from the apples and not from the water.
Conclusions
The final conclusion, based on these test results is inconclusive. Since there are no positive results at all, so there is no way to tell if the apples are clean or the tests or the testing process was defective.
Short-comings, suggested improvements
To do this and achieve meaningful results, the tests need to be used with a substance that confirms the test is not defective and produces a positive result. The 3M Petrifilm tests would have to be shipped according to manufacturer’s guidelines and then verified that the instructions for storage were followed at the receiving facility.
The water is also a potential source of E. Coli. The distilled water was purchased and kept sealed until it was used for these experiments, but the water should be tested by itself as well.
Four varieties were tested, two from within the United States and two from outside the United States, but if all the apples went through a standardized process of washing at the apple packing houses then it would be reasonable to assume that regardless of variety or origin, the likelihood of the surface of the apples being contaminated with E.Coli is the same between all varieties processed through that packing house.
Lastly, knowing the exact temperature on the incubator, rather than guessing at a range would ensure the tests were held at the correct temperature.
Works Cited:
Adult Obesity Facts. (2013, August 16). In http://www.cdc.gov. Retrieved October 2, 2013, from http://www.cdc.gov/obesity/data/adult.html
Childhood Obesity Facts. (2013, July 10). In http://www.cdc.gov. Retrieved October 1, 2013, from http://www.cdc.gov/healthyyouth/obesity/facts.htm
Coila, b. (2013, October 13). are apples a good snack for weight-loss. In www.livestrong.com. Retrieved October 13, 2013, from http://www.livestrong.com/article/375556-are-apples-a-good-snack-for-weight-loss/
Comprehensive Apple Variety List. (n.d.). In http://www.applejournal.com. Retrieved October 13, 2013
Goyal. (2007). Best Management Practices for Pathogen Control in Manure Management Systems. In http://www.extension.umn.edu. Retrieved October 9, 2013, from http://www.extension.umn.edu/distribution/livestocksystems/DI8544.html
How Are Overweight and Obesity Diagnosed?. (2012, July 13). In http://www.nhlbi.nih.gov/. Retrieved October 2, 2013, from http://www.nhlbi.nih.gov/health/health-topics/topics/obe/diagnosis.html
Isidore, C. (2013, July 9). New Twinkies will double their shelf life. In http://money.cnn.com/. Retrieved October 1, 2013, from http://money.cnn.com/2013/07/09/news/companies/twinkies-shelf-life/index.html
Ogden CL, Carroll MD, Kit BK, Flegal KM. Prevalence of obesity and trends in body mass index among US children and adolescents, 1999-2010. Journal of the American Medical Association 2012;307(5):483-490.
Raw Produce: Selecting and Serving it Safely. (2013, August 12). In www.fda.gov. Retrieved October 2, 2013, from http://www.fda.gov/food/resourcesforyou/consumers/ucm114299
