FRESHMAN CLINIC I

Chocolate Coated Cookie Processing

ObjectivesIn this experiment you will be exposed to food processing, Good Manufacturing Practices for the food processing and pharmaceutical industries, and some basic statistics. Your group will coat Oreo cookies with chocolate, then recalculate a nutritional label and perform a simple statistical analysis as an introduction to quality control.

IntroductionThe chocolate manufacturing process offers a unique sequence of chemical engineering unit operations. These operations can be isolated to demonstrate different chemical engineering fundamentals. The raw material, cocoa beans, undergoes many diverse processing steps depending on the desired final products. An overview of the chocolate manufacturing process is shown in Figure 1. Briefly, fermentation and drying of the cocoa beans is followed by shelling, roasting, and grinding to obtain a chocolate liquor which is 55% cocoa butter. A series of separation and mixing processes are used to obtain the final product whether it will be cocoa butter, cocoa powder, or other consumer products such as milk or dark chocolate.

Figure 1: Process flow diagram for milk chocolate, chocolate syrup, and cocoa powder [1].

document.doc Page 1 of 65/8/2023

FRESHMAN CLINIC I

The semi-sweet chocolate used in this week’s experiment is a blend of chocolate products such as cocoa powder, chocolate liquor, and cocoa butter that have been separated from the raw material (cocoa beans) then re-mixed in the desired proportions with other ingredients such as sugar, lecithin (an emulsifier), milk solids, and flavorings. These diverse components present many challenges for processing of chocolate in terms of mixing, fluid flow, and temperature control.

One contributor to the unique characteristics of chocolate is cocoa butter, which can comprise as much as 50% of a finished chocolate product. Cocoa butter is a complex fat with interesting properties; it is a mixture of fatty acids and glycerides. As chocolate cools, crystals begin to form—chocolate has up to six crystalline structures, each with a different melting temperature, from 17oC to 35oC. Chocolate must be melted, then cooled, then melted again to achieve satisfactory crystal nucleation and uniform crystallization responsible for the glossy sheen of good quality chocolate. If chocolate is cooled too rapidly or slowly, or not tempered properly, the chocolate may solidify into unacceptable unstable or super stable forms. One example of a super stable form is known as “fat bloom” because the crystalline structures resemble blooms. Care must be taken during processing to keep chocolate at the appropriate conditions to prevent this phenomenon.

Before beginning any food processing or food handling, personnel must be trained in Good Manufacturing Practices (GMPs). GMPs are important in the food and pharmaceutical industries because the quality and safety of products from these industries in particular can have a profound effect on the health of people who consume them. Therefore, care must be taken to ensure that food and pharmaceutical products are free from contaminants that might harm consumers. You will be introduced to some basic GMPs during this experiment.

Chocolate manufacturing requires not only the skills specific to chemical engineering, but all types of engineering expertise. When developing a new product or improving an existing one, engineers can contribute in the following areas:

Chemical Engineering: Making sure products that are developed in test kitchens have the same characteristics when produced on a large scale. As an example of how chemical engineers play a role in chocolate processing, the chocolate liquor or chocolate components and other ingredients must be transported from storage or mixing tanks to other locations, such as enrobing stations. Flow through pipes must meet all GMP requirements and also not change the characteristics of the chocolate. Therefore, variables such as temperature, flowrate, and pressure must be controlled. Chemical engineers also design packaging that retards food spoilage, and may help with safety, GMP compliance, and wastewater treatment and transport. Chemical engineers are often plant managers at food manufacturing facilities.

Mechanical Engineering:Mechanical engineers help design and fabricate the large-scale equipment used in food manufacture, and are also responsible for implementing systems for transporting finished

document.doc Page 2 of 65/8/2023

FRESHMAN CLINIC I

products. Other areas in which mechanical engineers may contribute include packaging design and bulk packaging.

Civil Engineering:Civil engineers are concerned with how the plant interacts with the environment. They design the building, and also work to make sure all discharges from the plant (wastewater, air, etc.) are in compliance with government and local regulations. Civil engineers may design on-site wastewater treatment facilities, or arrange for transport to municipal treatment facilities.

Electrical Engineering:Electrical engineers design systems that ensure each package contains the right amount of candy bars or cookies. These engineers also design control systems for complex processing steps.

Experiment

Your group will be provided with the following materials and equipment: Microwave oven (shared) Glass bowls Kitchen utensils Trays and wax paper Refrigerator (shared) Balance Stopwatch Temperature probe Cookies (9) Chocolate (5 squares) Plastic Rubbermaid container

Procedure:1. Wash hands thoroughly.

2. Don hair net (and beard net if you have facial hair)

3. Assign the following tasks to group members: record keeping, measurements (cookie weight), cookie coating, time keeping.

4. Obtain all necessary equipment and materials.

5. Open a package and place 9 cookies in plastic container.

6. Weigh all cookies, keeping cookies in sequence.

7. Melt 5 squares of Baker’s semi-sweet chocolate or 140 g of chocolate chips for 2 periods of 1 min, stirring after the first minute. Chocolate may not be completely melted—stir until small chunks disappear.

8. Coat cookies in the same order as they were weighed. Coating should be performed by the same person for consistency. The cookie coater should dip each

document.doc Page 3 of 65/8/2023

FRESHMAN CLINIC I

cookie for the same amount of time, and allow cookie to drip until excess chocolate stops flowing from cookie. “Dip” and “drip” time should be the same for each cookie. Excess chocolate should be removed from the bottom of the cookie by scraping a knife along the bottom of the fork holding the cookie.

9. After each cookie is coated, place on a cookie sheet covered with wax paper. Once all cookies are coated, place cookies in refrigerator to cool for ~20 minutes.

10. Remove cookies from refrigerator, and weigh each coated cookie.

Data analysis1. Use the AVERAGE and STDEV function in Excel to calculate an average uncoated

and coated cookie mass in Table 1:

Table 1: Data and calculations for coated and uncoated cookiesCookie # Mass uncoated cookie (g) Mass coated cookie (g)

123456789

Average cookie mass

Standard deviation

Share your individual cookie weights with another group. Recalculate the standard deviation. How does your standard deviation change?

2. Using your average value for the coated cookie and the information in Figures 2 and 3, recalculate a nutritional label for a serving size of 2 cookies. Your label should include grams and percent daily values of total fat, saturated fat, cholesterol, sodium, total carbohydrates, dietary

document.doc Page 4 of 65/8/2023

FRESHMAN CLINIC I

fiber, sugars, and proteins, as well as percent daily values of vitamin A, vitamin C, iron, and calcium.

Hint: first check calculation of total calories based on the knowledge that each gram of fat contains 9 calories, each gram of protein contains 4 calories, and each gram of carbohydrate contains 4 calories.

Figure 2: Nutritional label for oreo cookies Figure 2: Nutritional label for oreo cookiesYou may find some discrepancies between total reported calories and calculated calories. Where might the error lie?

Your nutritional label should follow a format similar to the one shown in Figures 2 and 3, reporting percent daily values, and serving size (2 cookies).

Figure 3: Nutritional label for semisweet chocolate

ReportYour report must contain the following elements:1. An introduction explaining the objectives of the experiment and some

background on chocolate.2. A brief materials and methods, including some commentary on GMPs3. A results and data analysis section in which a recalculated nutritional label

and statistical analysis is presented. A brief explanation of your method for recalculating your nutritional label, as well as some commentary on possible reasons for any trends observed should be included in this section. Do not present a table of all cookie weights. Instead, compare your group’s results (average weight and standard deviation) with your combined results (yours and another group’s weights and standard deviations). Does your standard deviation change? Why or why not?

4. In your results and data analysis section, also compare your average coated weight and nutritional information for 2 cookies to the nutritional information for commercially available “fudge covered oreo” cookies. Note that the serving size is 1 cookie—multiply their values by 2 to compare with your cookies.

5. A conclusions and recommendations section that includes some discussion on how to make your chocolate coating process more consistent.

6. An appendix with raw data and sample calculations.

document.doc Page 5 of 65/8/2023

FRESHMAN CLINIC I

In your report, remember to: Label figures Use headings for different sections Number pages Cite any references used

Reference[1] B. L. Zoumas and J. F. Smullen, "Chocolate and Cocoa," in Encyclopedia of

Chemical Technology, vol. 6, K. Othmer, Ed., 3rd ed. NY: John Wiley & Sons, 1979, pp. 177-199.

document.doc Page 6 of 65/8/2023