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 Professor Paul Blowers of the University of Arizona has taken the art of cooking into the classroom setting, creating a teaching tool that opens the field of chemical engineering to an ever-wider audience. As a creative effort and a propagation of scientific advancement, Professor Blowers’ unique teaching program presents advanced scientific concepts using familiar food preparation techniques, blending science and art in an inspiring teaching initiative.
You have undertaken a teaching initiative to inspire interest in and understanding of chemical engineering. What has been the inspiration behind using cooking as a teaching tool for such a complex subject?
There are a few separate reasons for cooking and food being good access points for introducing chemical engineering concepts. My parents always asked me what I was learning when I was an undergrad. Since neither had much technical training or mathematics backgrounds, I had a hard time explaining esoteric topics such as heat transfer, mass transfer, transport phenomena, and kinetics. I started trying to bridge what they were already familiar with and advanced scientific ideas. Heat transfer became how to predict the length of time it takes to bake a potato, mass transfer became why one does not make Jello shots with alcohol in the pot when heating, transport phenomena became why one grinds coffee beans and then heats the water up to make coffee, kinetics became why it takes a while to make bread from scratch and why it cannot be done quicker (without a bread machine).
The next reason is that everyone eats. Students eat all kinds of things, admittedly often beer, pizza, and ramen noodles, but you can start with descriptions of how one ferments beer to get at so many different ideas in chemical engineering. You can use almost any food to center a discussion on a new topic! Also, every food, other than organic home-grown foods, is going to have been touched by some chemical engineering aspect at some point, from planting seeds through ending up on your table. Bananas are often shipped underripe and then ripened rapidly with ethylene gas close to the point of sale. Seeds are often coated with fungicidal chemicals to prevent their premature destruction. If the foods are processed in any way or shipped, you need chemical engineers to create the process. Discussing all these links reminds students of the importance of our field and how many lives we touch, even for "simple" products such as potato chips.
Finally, I love food and I love to cook. I had a roommate once in grad school that made an observation about an improvisational recipe I was creating, that I should dice the ingredient small for a wide distribution and overall flavor, but dice it larger if I wanted people to say, "Wow! This has XXX in it!" It was such fundamental chemical engineering centered on the basic ideas of how matter behaves, that I just keep thinking about these ideas, even now.
Can the knowledge of chemical processes and the effects of various ingredients improve one’s culinary skills?
There are so many ways to go with this question that I'll again pick a few. I guess if you talk to professors often you find that there are always many answers to the same question :)
Let us think about canning for a minute as an extreme example of improving culinary skills. If you do it wrong, you die. I make homemade ketchup, corn relish, salsa, jelly, and other things somewhat often as I do not like many of the products on the market for either their price or their ingredient list, which has many things I'm not necessarily willing to put into my body. There are combinations of pH (acidity) and temperature that kill and prevent the growth of bacteria, such as that which causes botulism. If you know the food chemistry and acidity and can achieve the right temperatures for the right amount of time, you don't have to worry about killing your parents when you send them a jar of corn relish for Christmas. You know that when they and you eat the product, you will all be safe. Even sterilizing the jars and lids and equipment in the dishwasher involving hot water and steam is all about knowing the physics and how to do things more efficiently. I find using the dishwasher on the hot temperature cycle allows me to begin canning and do everything simultaneously, so that I minimize the amount of time it takes to get everything done.
I am going to step aside for a minute and think about canning in a different way, which is about sustainability and using the least amount of resources possible to accomplish a goal. We tried canning on one burner a few times using a gas stove and it took forever to reach boiling in the massive canner we have. So one time, I thought about using the oven to supply more heat from below to minimize heat losses. This was a chemical engineering inspired trick, since I know heat rises and that turning on the oven would add a new source of heat that would naturally lead to improved heat transfer to the canner and liquid inside. However, if you do that without a purpose, it is a waste. I made a casserole for dinner and made homemade bread to match with another recipe for the week at the same time, also roasting garlic to make garlic bread. The water in the canner boiled earlier and I saved time, even if I used some natural gas in the oven.
The next optimization (again engineers do things stepwise and always try to improve) was to use two burners while using the oven to roast a ton of peppers and tomatoes for a salsa intended for a campus competition (I came in third place!). The water in the canner boiled so fast that I was actually behind using the dishwasher this time. Covering the lid to eliminate water evaporation losses also aided in reducing energy and time needs; this essentially created a system where energy transfer heat losses were reduced and simulated an adiabatic system with heat input only.
On the ingredient side, it's easier to reformulate recipes when you can estimate some of the properties of the foods. I just made a recipe from an older 1950s cookbook for something called Sicilian Meat Roll. The problem is that my family and I are vegetarians. So, knowing that the beef flavored TVP I was using had a certain moisture content and I needed to prevent the beef from falling apart, I reduced the water suggested, upped the egg content, and adjusted the recipe by adding some fat that would improve flavor. Unfortunately, I did not get it quite right and the roll of meat fell apart as I transferred it. Next time, I'll up the solid contents with the addition of whole wheat flour or more breadcrumbs. I might also replace the egg with flax seed oil if we have someone vegan over, as flax seed oil seems to bind foods like eggs do. All of these modifications are possible because I'm thinking about the chemistry and physical properties.
What is cooking like in your own home? Has your awareness of scientific concepts simplified your home cooking?
I'm about efficiency, taste, and minimization of waste. Every Wednesday, I sit down with several cookbooks and rummage through many to find all the recipes we're going to make for the week. It is rare that we ever throw anything away (minimization of waste). If we have a soup that calls for half a cabbage, we make cole slaw to transform the left over cabbage into a well seasoned salad that matches with vegetarian hot dogs on a different day (minimization of wasted food). If we're having cauliflower in an Indian stew one day, it is simply steamed for a side dish on another day or broken up for additions to salads on many days.
I guess simplifying, now that I think about it more, is also about simplifying your life. In graduate school, I was walking about 9 miles a day, while working 8 hours a day and trying to get in all the social things I wanted to do. I would cook most of my meals on Sunday morning before lunch for the entire week. There are four burners on a stove and two racks in an oven. I could do six recipes simultaneously if they were all hot and more if they weren't. I would then fill all sorts of empty cottage cheese containers with all the food I'd made and then store all the food in the refrigerator and take out what I wanted to eat for lunch and dinner each day throughout the week, sometimes making something fresh that couldn't be stored easily to match with a combination of my "leftovers". By doing this, I invested about 2 hours in cooking and didn't have to plan around a busy life for the rest of the week. This also minimized waste through recycling, because I was making full use of all the empty cottage cheese containers I always seemed to accumulate... also saving me money on buying more Tupperware! If you have a busy life, do all your cooking in one day and store casseroles, salads, etc. in the refrigerator until needed.
In all planning and cooking, you need to be aware of what degrades faster and under what conditions, mostly through experience, to plan well. Bean sprouts don't keep fresh, so use those early in the week or you have a bitter mess of watery greens late in the week. Canned ingredients are good in the last few days before you go shopping. Using raw ingredients and dried beans and unprepared foods saves a ton of money, but may sacrifice time. However, the time you spend cooking can be used to be with your family and to continue to grow together.
On this point of cooking and time, my son often stands on a step stool next to me at our island stove and wants to smell all the spices, peel the carrots, ask about why each ingredient is going in, and I know no better way to fill time while being productive than working with him as a 4-year old to make a meal. As an aside, just today, he was taking a bath and came out into our kitchen to get two measuring cups from the drawer there to take back to my wife in the bathroom. I later sat in with him while he finished his bath and he was talking mostly to himself saying, "I mix the 'banzo beans with the soy juice and then I need a little more..." as he poured water back and forth among the measuring cups and his "food processor" – a metal coffee cup he had also taken from the kitchen. I'm not sure what he is getting from all our interactions, but it's clear he's learning a language and a way of thinking about food at a very basic level.
You have used bread-making as an example of the chemical processes that go on behind common food-making procedures. How do the ingredients used to make bread display the fascinating chemical processes that bring about the final product?
Bread is fascinating and I'm just a practitioner and not an expert or even theoretician on how to do it well... Keep that in mind as I respond to this question.
I was recently told by a medical specialist that I needed to eliminate simple starches from my diet as much as possible, in addition to sugars. However, there are so many foods out there and recipes out there that I want to eat; I needed to replace ingredients with minimal effect on final taste. Chemical engineering led me to many successes.
Many whole wheat bread recipes call for some white flour. This is for a couple of reasons, but if you think about the engineering, you can achieve the same result with a mix of other methods. A pure whole wheat flour bread rises so much more slowly, and is tougher than a mix of flours. So, you can either let it rise longer, but then when you punch it down, the wheat gluten is still very developed and you have a tougher loaf (appropriate for some recipes). Or, you can mix in some soy flour or garbanzo bean flour or something else and let it rise less and then it comes out "lighter" in texture and in less time.
On the topic of temperature, when we first moved here, I was thinking about how great it was going to be to let our dough rise outside on our Tucson patio since it was so warm and the rising step would go much faster (most chemical transformations, starches to carbon dioxide that adds all those fluffy bubbles to your bread), are about doubled for every ten degree rise in temperature. I was envisioning making bread that would rise in 20 minutes or less... Two things caused problems with this and they are obvious with our family background... You can't expect a normal bread to rise without a crust if you don’t have a ton of excess water in the towel; wet is needed, not just damp, when you cover the dough for rising. A tough skin forms that isn't very good when you just use a damp towel in the desert. The other problem was that my wife is a veterinarian: you can't expect a bowl full of rising bread with a towel over it on your side patio to remain "dog-free" for long... I came around the corner of the house to bring the dough in and our terrier had her head under the completely dry towel, as she wagged her tail and chowed down on the dry-skinned dough.
The chemistry of bread is complex. If you let the bread rise too long, you end up with ethanol... Yes, that ethanol that you pay lots of money to drink; bread rising due to yeast is just another fermentation experiment. If you want a wonderful thin pancake that is sour and spongy, try finding an injera recipe from Ethiopia and make that since the ethanol content is what makes it sour and spongy at the same time. You intentionally force the chemical reactions to move far to the product of ethanol, ending up with something delightful and perfect for thick stews, or as a scooping media to eat instead of using a spoon.
I guess it's not just the ingredients, but also the processing conditions that matter with all bread processes.
Has the use of cooking as a model for teaching chemical engineering been a success?
I think so, although I've never assessed the "success" formally on the cooking front. Students from two years ago remember exam number three and still curse me for it...I had them estimate the amount of Iranian air (world's largest producer of pistachios) that would be need to dry their entire crop of nuts from 33% moisture content by mass to 7 % used for shipping. This involved the first six chapters of the book we use and had students think about a real problem. My wife's comment after she heard about the problem was, "Can't I just give you a gift for your birthday (pistachios) without you making it into a problem for your students?" Um... No.
To me, success means that students stick with this tough major through all the trials. I'm successful if they can explain some topic to a non-chemical engineer using food or any other real world example. This ties in with your next question.
Instilling an interest in chemical engineering among the public is crucial for the field’s growth and financial support for future projects. Do you see a potential for the teaching initiative in classroom settings for the young generation?
Chemical engineering has many, many issues in attracting students and interest from the public. Most of the companies that produce obvious chemical products like petroleum/gasoline are viewed negatively by the public, even though they provide critical energy needs for the world. So, when people know about our major, they are often negative.
I see potential for teaching initiatives with younger students in the classroom that help them see not just chemical engineering, but engineering as a whole as a way of leading to a better world. I do many recruiting activities with high schools, but also middle schools as well. When you can tell students, "Vaccines to end re-emergent polio are made by chemical engineers," you reach them in a life saving way. If you can tell them, "We are behind the technologies that let you have ice in your lemonade during the summer," they know there is a connection to their lives. If you show them how colored dyes diffuse in Kool-Aid after solubilization of the dyes, you address how color and flavor may not be linked by having them sample with and without sugar and with and without stirring. They get mass transfer and transport phenomena on a visceral (literally! and yummy) level... :)
Here are some recipes that I've created that are somewhat simple and liked by the family:
Four Cupper Tortellini Salad
History:
My wife and I have a delicious dip that we got from a murder mystery dinner game a long time ago. Well, we often have leftovers of the artichokes and roasted red peppers that we don't know what to do with. This recipe addresses that issue.
Ingredients:
12 oz dried tortellini
1T margarine
1 cup diced pimientos
1 cup diced artichoke hearts
4 cloves minced garlic
1 cup sliced packed spinach
1 cup shredded parmesan cheese
How to:
Boil the tortellini until tender, drain, and rinse with water.
Fry the margarine and add the pimientos, artichoke hearts, and garlic.
Cook until garlic starts to brown
Add the spinach and wilt.
Toss in tortellini.
Add the parmesan cheese and some black pepper.
To Serve:
Serve warm with cottage cheese for a complete protein.
Rice Vinegar Cole Slaw
History:
We had just made several cabbage dishes but still have a stubborn 1/4 of a head of cabbage left over. Knowing that Chris likes celery seed, hates creamy (sour cream or mayonnaise) based cole slaws, I whipped this one up and she liked it so much she ate the remaining bit as a snack late the night we had it for dinner.
Ingredients:
1/4 head of cabbage
1/2 c. scallions
1 med. carrot
1 t celery seed
1 T sugar
2 T oil
6 T rice vinegar (unseasoned)
salt
pepper
How to:
Finely shred the cabbage.
Finely slice the scallions.
Peel and shred the carrot finely.
Mix all together and chill.
To Serve:
We had this with veggie hot dogs and some chips on the side.
Roasted Red Salsa
History:
This recipe took third place in a University of Arizona Salsa competition to foster professional development of women in the sciences. It has a mellow flavor that is picked up by two forms of garlic, roasted and fresh.
Ingredients:
1 red pepper
1 yellow pepper
2 jalapeno peppers
1 head garlic plus 2 cloves
3/4 t cumin
1/2 t salt
3/4 t sugar
juice of 1 lemon
dash cayenne
2 t cider vinegar
How to:
In a broiler, roast the four peppers while turning until blackened on all sides. While the peppers are roasting, place the head of garlic whole, wrapped in tin foil, into the oven and let roast. Remove peppers to a covered pot and let steam until cool to loosen the skin (I find using a paper or plastic bag to steam the peppers to be wasteful as you can't reuse the bag after roasting.) When you remove the peppers from the broiler, lower the temperature of the oven to 300 oF and let the garlic roast until soft, about an additional 20 minutes. Remove the garlic from the oven and let cool.
After the peppers and garlic are cool to the touch, peel and finely chop, keeping the liquid from the peppers and pouring that into a mixing bowl with the chopped vegetables. Mince the two cloves of raw garlic before adding the rest of the ingredients to the peppers and roasted garlic. Allow the flavors to mix overnight in the refrigerator.
To Serve:
Serve with chips or in other Mexican recipes where a strong garlic hint accents the other flavors.
German Potato Salad
History:
I like German potato salad, but Chris does not. This is a vegetarian version of the classic potato salad that can be served hot or cold. Max liked it both ways.
Ingredients:
5 medium red potatoes
1/2 cup sliced green pepper
1 small onion, thinly sliced
1 T butter
1/2 cup bacon bits
3/4 cup vinegar
black pepper
1.5 - 2 t sugar replacer
How to:
Bring the potatoes to a boil and simmer for 8 minutes. Turn off the heat and let them sit in the water for 10-30 minutes before draining. Thinly slice.
Heat the butter over medium heat in a skillet and add the green pepper and onion. Saute until soft, but before the onions start to turn brown.
Add everything to the skillet and stir until the vinegar is mostly evaporated.
To Serve:
We had this with veggie hot dogs one day and then I had the leftovers with tofu tuna fish sandwiches the next.
Vodka Cream Sauce Risotto
History:
Chris really likes to make risotto... There's something about stirring in a wine/broth combo while drinking wine that she likes. I don't really like the wine based ones but I do like the idea of risotto and the creaminess, even without cheese added. This recipe melds part of a vodka cream sauce Chris found online with what I like about risotto.
Ingredients:
1 c. Arborio rice
2 c. water
1 vegetarian bouillon cube for 2 c. water
Sauce:
14 oz can diced tomatoes
1 clove garlic
1/4 t red pepper flakes
1.5 T olive oil
1.5 T dried basil
1/4 t sugar substitute
1/4 c. vodka
1/2 c. cream
How to:
Heat the broth and bouillon until boiling.
Meanwhile heat up the Arborio rice in a warm saucepan until heated, but not browning. While you do this, peel and mince the garlic and organize everything else you need.
Add 1/2 c. boiling broth to the rice and stir continuously as you heat it. If you are too warm on the rice, the water will flash vaporize and you'll need to add more almost immediately. You want to be at the point where you add some and it absorbs slowly into the rice as you stir. Add the broth in 1/4 c. increments as you keep stirring. Start to check the rice when you have about 1/2 c. broth left that you haven't added and see if it is al dente. If it is not, add more broth. Keep going until you either run out of broth or it is al dente. If you run out of broth, switch to water heated last minute in the microwave.
When you are done with the risotto, get another pot to make the sauce in. This recipe used the empty broth pot with a remaining 1T broth in it plus the oil.
Add the garlic to the pot and stir until fragrant, but not brown.
Add the red pepper flakes before adding the tomatoes.
Simmer 5 minutes.
Add vodka and simmer 5 minutes.
Add the rest of the basil and sugar and heat through for 5 minutes.
Puree everything with the cream in a food processor. To Serve:
Place the rice in warmed bowl (or not if you don't have time) and pour sauce over each bowl. Yummy!
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