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Helen S. Joyner
Assistant Professor
hjoyner@uidaho.edu
School of Food Science
University of Idaho
Better Cheddar: Using Statistical Tools to Monitor Cheese Quality Attributes

In this case study students assume the role of quality assurance personnel at a small artisan cheese company. They are given a flowchart of the cheesemaking process and a set of process data. They must develop control charts to monitor process quality from this data as well as determine if the process is producing product outside of the specification limits. They are asked to make recommendations for general process changes based on their analysis of the process. The case was developed for an upper-level undergraduate statistical food quality management course and is appropriate for any undergraduate or graduate course that covers principles of statistical quality management and quality management tools, such as operations management courses and statistics courses that cover quality management. It is also appropriate for use in quality management seminars and short courses.


Concentrating on Whey: The Use of Statistics in Process Control 

This interrupted case study follows the progress of Kenny, the head operator for a whey protein processing system, as he works with Cheryl, a quality management specialist, to implement control charts to monitor process variables. Students assume the role of Cheryl as she shows Kenny how to create a control chart, explains the different types of out-of-control behaviors seen in control charts, and demonstrates how to calculate process capability and capability index.  Kenny uses this information to determine a probable cause of variation. Originally developed for a senior-level undergraduate statistical quality management course, this case study is also appropriate for courses focusing on quality management in industrial settings, as well as for a general undergraduate statistics course. Although familiarity with HACCP (Hazard Analysis Critical Control Points) principles is assumed, students are not expected to know about whey protein processing fundamentals.


Cool as a Cucumber: Designing a Refrigeration System

In this case study, students are asked to design a new refrigeration system for a company that stores produce. Students will need to consider various aspects of refrigeration system design, such as single- versus multi-stage, size, operating temperatures and pressures, cooling load, compressor efficiency, overall system efficiency, and cost. An Excel spreadsheet is provided for students to design their system (see Supplemental Materials).  All calculations are performed by the spreadsheet; students input their desired values.  After the refrigeration system is designed to the satisfaction of the students, they are asked to discuss why they chose their specific operating parameters. This case study is appropriate for food engineering, food processing, and introductory heat transfer courses.


Farming in Space: Developing a Sustainable Food Supply on Mars

If you were limited to choosing only three crops to sustainably farm in an arid, inhospitable environment, what would they be and how would you decide? This interrupted case study places students in the role of a proposed self-sufficient Martian colony that requires an optimized profile of food crops. After students form small groups, they discuss the factors that affect sustainability of a food supply, determine criteria for selection of crops to grow, and rank crops using these criteria. Lists of criteria and of foodstuffs are provided, but the case can easily be transformed into a problem-based learning (PBL) case by having students research and generate their own lists. The case includes questions that walk students through the selection process and require them to explain why they chose their criteria and how those criteria apply to their chosen foods. The case is designed for undergraduate students at the introductory level in courses in astronomy/astrobiology, food science/nutrition, agricultural engineering, or any discipline where sustainability is a key theme.


Flowing Fine: Moving Fluids on an Industrial Scale 

In this case study, students assume the role of a process engineer for a pilot plant. Students are tasked with selecting a piping arrangement from a list of available options, creating a diagram of the flow system, determining the terms needed in the general energy balance for their system, calculating the amount of energy lost in the system, and determining how much power is needed by the pump for the system. Students are also asked to discuss various aspects of system design and provide suggestions for reducing energy losses. The ability to properly size a pump for a process is an important skill, as improperly sized pumps are at best inefficient; they can also wear faster due to overloading or cavitation, and may also cause product foaming due to cavitation. Properly sized pumps, on the other hand, provide the necessary work to transport fluids efficiently. Originally developed for an upper-level undergraduate food engineering course, this case is also appropriate for food processing, and introductory fluid flow courses.


One Bad Apple: Designing Sampling Plans for Better Food Quality

In this case study, students assume the role of a quality assurance (QA) technician who is working on finding the root cause of customer complaints for apple cider.  Students will critically examine the sampling practices for the apples used for processing, construct acceptance sampling plans based on given guidelines, discuss the appropriateness of the sampling plans for food processing, and evaluate uses of the sampling plans for accuracy. Students will also use Excel to generate operating characteristic (OC) curves. The case was originally developed for a senior-level undergraduate statistical quality management course, but is also appropriate for courses focusing on quality management in industrial settings, as well as for a general undergraduate statistics or experimental design course.


Potato Chip Problems: Using Basic Quality Tools to Solve Food Quality Issues

In this case study, students assume the role of a quality assurance team that is in charge of determining potential causes and solutions for potato chip bags that open during the shipping process. Students will use basic quality control tools to evaluate the process, brainstorm potential causes, determine the most likely cause of the problem, and develop potential solutions for the problem. A couple of the case exercises require students to create fishbone (Ishikawa) diagrams. A summative writing assignment and a set of optional questions for further exploration are included. This case study is appropriate for courses focusing on quality management in industrial settings, as well as a general undergraduate statistics or experimental design course.


Tasty and Safe: Heat Transfer in Orange Juice 

In this case study, students assume the role of process engineers in an orange juice production facility. They determine modes of heat transfer to and from the orange juice, develop equations for the heat transfer scenario they have identified, and design a tubular heat exchanger for the system. They also discuss heat exchanger selection. This case study was developed for an upper-level undergraduate food engineering course. It is appropriate for food engineering, food processing, and introductory heat transfer courses.


The Company‚Äôs Best Yogurt: The Importance of Statistics in Food Product Development

In this case study, students assume the roles of research and development personnel in a dairy company that is developing a low-fat yogurt. Guided by research provided by the company's marketing department, students must select attributes of the yogurt to improve, develop an experimental design for evaluating the effects of ingredients on their selected attribute, analyze the data generated from their design, and determine their most successful formulation. Students should be familiar with ANOVA and basic experimental design and have an understanding of general principles of quality management in food manufacturing. Originally developed for a senior-level undergraduate statistical quality management course, this case is also appropriate for courses focusing on quality management in industrial settings, as well as a general undergraduate statistics or an experimental design course.


What Are the Odds? A Cupcake Mishap 

"Gerri" is the owner of a local bakery that specializes in cupcakes. Her assistant, "Kelsey," is preparing an order for a wedding when she discovers that she has lost her ring and can't find it anywhere in the kitchen. Since the ring had been loose on her finger, she and Gerri conclude that it must have fallen into the cupcake batter while Kelsey was making the batch. Gerri is furious and demands that Kelsey remake the cupcakes. The story leaves off with Kelsey facing unspecified consequences as Gerri leaves to deal with customers. Students will need to apply statistical probability theory as well as food safety regulations to determine the likelihood of finding the ring in a certain group of cupcakes and provide a solution to the case study. Developed for a senior-level undergraduate statistical quality management course, the case is also appropriate for courses focusing on quality management in industrial settings as well as for a general undergraduate statistics course.


Whey Off Balance: Analyzing Processing Issues Using Mass Balances

In this case study, students assume the role of a process engineer on a whey refinement process.  As the process engineer for the line, students must develop a block diagram of the process, perform a mass balance on each step of the process, and determine any discrepancies between the flow rates they have determined in their mass balances and the theoretical flow rates based on clean, fully-functioning equipment.  Students are asked to develop reasons for any flow rate discrepancies found.  This scenario is commonly found in industry, as mass balances are routinely used to determine the presence of leaks, the need for cleaning, or faulty equipment. This case study was developed for an upper-level undergraduate food engineering course. It is appropriate for food engineering, food processing, and introductory mass balance courses.