Investigating Food Safety (Developed by SEPUP)
Consumers’ concerns over food safety are broad. They range from worries over the possibility of Salmonella poisoning to questions about pesticide residues on produce. This module introduces some of the issues associated with food safety. Students first explore food-borne illness as they investigate the growth of yeast, a common fungus that is used to model other effects of pathogenic microorganisms. They examine the different chemical additives, and their use in preventing microbial growth. Students then explore how chemical additives can be used to slow the oxidation of fresh fruit and to enhance the nutrient content of foods.
They also learn how foods can be tested for the presence of chemical residues, such as pesticides. Finally, the students evaluate the use of different food preservation techniques, which are intended to improve food safety. The embedded assessment system focuses on students’ ability to use evidence and identify trade-offs. THIS MODULE INCLUDES A TEACHER'S GUIDE
THIS MODULE REQUIRES 16 SEPUP TRAYS
- The causes of food-borne illness include bacteria, viruses, and parasites.
- Chemicals can be used to inhibit the growth of microorganisms, thus reducing the risk of food-borne illness.
- The concentration of a solution can be accurately determined through titration.
- Gathering relevant evidence is essential for thoughtful inquiry and good decision making.
- Making decisions about complex issues often involves trade-offs and evaluating issues requires an analysis of both risks (costs) and benefits.
Content List in Investigating Food Safety (Developed by SEPUP) is as follows:
|1||Teacher’s Guide with reproducible masters for Student Sheets|
|32||9 oz plastic cups|
|16||30 mL graduated cups|
|16||Bottles of "Lugol’s solution, dilute", empty|
|16||LAB-AIDS® measuring/mixing spatulas|
|8||Drop control bottles of Simulated Pesticide Test solution (2,000 ppm Iron [III] Nitrate)|
|8||Drop control bottles of Sodium Benzoate solution|
|8||Drop control bottles of Sodium Carbonate solution|
|8||Drop control bottles of "Ascorbic Acid, 10%", empty|
|8||Drop control bottles of Vinegar|
|8||Drop control bottles of Distilled Water|
|8||Drop control bottles of Liquid Starch solution|
|2||Vials of Ascorbic Acid, 25 g|
|2||Packets of Lemon drink, unsweetened mix|
|1||Roll of 2” wide plastic wrap|
|1||Bag of Apricots, dried, preserved using sulfur dioxide|
|1||Bag of Apricots, dried, preserved without using sulfur dioxide|
|1||2 lb container of Yeast|
|1||240 ml bottle of "Ascorbic Acid Stock solution", empty|
|1||240 ml bottle of "Lugol's (Iodine) Stock Solution", empty|
|1||20 ml bottle of Lugol’s (iodine) solution|
|1||180 ml bottle Bottle of Potassium Iodide solution|
|1||Package of Black-eyed peas|
|1||3 ml graduated pipet|
|MSDS (Material Safety Data Sheets)|
- Number of students
- Number of groups
- Maximum 8 groups per period
- Introducing Food-Borne Illness
- Students describe how they respond to situations involving food safety. They read articles that address some of the causes and the relative risks of food-borne illnesses.
- Optimum Conditions for Microbial Growth
- Students investigate the role microorganisms play in food spoilage and generate a list of conditions necessary for microbial growth. They explore the effect of varying amounts of food (sugar) on the growth of yeast, a common and safe fungus used to model other, more harmful, microorganisms. Students then observe a demonstration showing the effect of extremely high levels of sugar on yeast growth and discuss the optimum condition for yeast growth.
- Inhibiting Microbial Growth
- Students design an experiment to investigate the ability of chemicals to inhibit the growth of yeast. After conducting the experiment(s), they conclude that chemicals can be used to inhibit the growth of yeast– and by extension, other microorganisms – and that chemical food preservatives can be used to increase the safety of the food supply as well as to improve its cosmetic appearance.
- Chemicals in Foods
- Students build on the knowledge that chemicals are used to prevent the growth of microorganisms in food. They examine labels from various processed foods to determine the food additives present. They first match names of foods to a description of contents on the label. They then consult a master list of additives to determine the main purpose of the added chemicals to change some physical characteristics of the food during processing; to enhance the nutritional content, color, or flavor; or to preserve the food. Students then classify the additives from the labels according to the categories and consider the impact an additive free diet would have on their eating habits.
- Preventing Oxidation
- Students investigate the ability of ascorbic acid, sodium benzoate, sodium carbonate, and vinegar to prevent banana slices from turning brown. Chemicals that retard the browning process are identified as food additives that can be used to improve the appearance of foods.
- Vitamin C Titration
- Students titrate a drink solution containing vitamin C to determine the relative amount of vitamin C in two different solutions. They compare the amount of vitamin C found in a powdered drink that has been freshly made to one that was prepared the previous day. This is used as a model to introduce some of the trade-offs involved in preserving foods with methods that reduce the nutrient value and in using foods that are not fresh. It is intended to help students think about how to preserve the nutritive value of foods.
- Testing for Pesticides
- Students test samples of re-hydrated black-eyed peas for the presence of simulated pesticide residue. The activity introduces the concerns that people have about exposure to pesticide residues. Students discuss limitations in the testing procedures and the interpretation of results, how risk comparisons and analyses are performed, and how knowledge of these factors might influence individual decisions to eat a given food.
- Investigating Food Safety
- Students evaluate techniques used to increase food safety, focusing primarily on preservative techniques. They evaluate evidence and make recommendations about how these technologies should or should not be used.
This module has 8 activities which will require 10 to 15 ~50-minute class periods to complete. SEPUP modules employ the 4-2-1 model: each student is part of a team of 2 and each team partners with another team to form a group of 4 that shares some equipment.