1 Food Experiments in the Unit Operations Lab Mohammad Biswas, Laura Kelley, William Josephson & David Mills Chemical Engineering Dept. Auburn University 2007 AIChE Annual Meeting Salt Lake City, Utah

2 The Lab CHEN 3820 – Chemical Engineering Laboratory I  Jr Level Course  2,3 or 4 person groups  Texts by Geankoplis & Taylor  Objectives include Reinforcement of fundamentals Tech writing Data analysis  Experiments go for 2 x 3 hour sessions & include Pump Piping Fluidized Bed

3 FALL ’06 - The Challenge “Design an experiment that teaches something about food” My motivation – lack of knowledge, desire for variety, importance of the topic My expectations – chemistry heavy approach

4 The Relevant Literature

5 Available Tools

6

7 Group Alpha’s Proposal Investigate relationship between boiling time & spaghetti stickiness

8 from Group Alpha Objectives o Generally, you are to determine the relationship between boiling time and stickiness of spaghetti noodles. o You should also consult other sources while investigating why spaghetti will stick to a ceiling or wall when it is “done.”

9 from Group Alpha Operation – Normal o Remove a few spaghetti noodles from boiling water at regular time intervals o be sure to use caution when removing the spaghetti noodles from boiling water o Throw noodles at a nearby wall to check for ‘al dente’ o Record visual observations on firmness, color, and stickiness

10 from Group Alpha Background Students should be able to utilize resources from outside of the classroom such as the internet to explore what is changing in the noodles with respect to cooking time. Students should understand that it is the starch in the noodles that gives the stickiness to them. As the noodles cook longer the starch is leached from the noodles into the surrounding water. Some of the starch breaks down into the sugar dextrin, coats the noodles and makes them sticky when removed from the water. Maltose and glucose are also products of the starch degradation and contribute to the pasta’s stickiness. Students should examine what would happen if the noodles were cooked in a very large amount of water, or a very small amount of water? The starch concentration would vary as would the stickiness of the noodles.

11 from Group Alpha Discussion Students should understand and state that as the length of cooking time is increasing the concentration of starch in the surrounding water is increasing. This means that as cooking time increases the spaghetti noodles should be growing stickier and stick better to a wall. It should also be understood that as cooking time increases more water is impregnating the noodles themselves, moving closer toward being fully saturated. This causes the noodle to lose rigidity and become more pliable.

12 Group Bravo’s Proposal The Fat-O-Meter (aka “Hot Fat”) Substance Heat Capacity (kJ/kg) Water4.184 Whole Milk3.85 Oil2.01

13 Group Bravo’s Proposal Q = m C P ΔT Use the Easy Bake to determine fat content? Procedure – standard sample size, standard heating time, monitor ΔT

14 Group Bravo Results SubstanceFat Content in Sample (g)Temperature Change from Heating Coffee027.4 Tea033.9 Orange Starburst Smoothie /50 Mixture of Smoothie and Water Whole Milk143.7 Chocolate Milk Olive Oil2895.6

15 Group Bravo Results

16 Group Bravo Results

17 Group Charlie’s Proposal Generate Drying Curves

18 Group Charlie’s Proposal Bake Cookies Vary initial water content, shape Monitor water content via weighing

19 Group Charlie Results

20 Group Charlie Results

21 SPRING ’06 No food experiment But….

22 SUMMER ’07 & beyond… Butter Experiment has been part of CHEN 3820 Base Case is w/ KitchenAid mixer & whipping cream Parameters include Heavy vs Regular Whipping Cream Salt amount KitchenAid vs Manual Agitation My Expectations

23 Butter Results

24 Butter Results

25 Butter Results

26 Butter Results

27 Butter Results Background & Understanding Fat in milk exist as droplets covered in a membrane. The churning process breaks this membrane exposing the fat globules. Additional churning results in the globules coalescing into a separate fat phase 3. All fats, including milk fat, are triesters of glycerol. These molecules contain three carboxyl groups and have three long organic tails as can be seen in the saturated fat molecule seen in Fig.2. Figure 2: Saturated fat molecule As was previously stated, adding salt to milk or whipped cream can reduce churning time. This phenomenon could be the result of the electrostatic interactions between the long organic chains of the fat and the ions introduced into the milk emulsion.

28 The Future of Food Experiments in CHEN 3820 Butter – will continue, will tweak (e.g., yield) Mixing Experiment? Corn Starch? May repeat student designed experiment

29 A Sincere Thank You To the students in CHEN 3820 Chemical Engineering Laboratory I