Wednesday, April 20, 2011

Protein Power

A few weeks ago, I made a guest appearance at a local high school to teach a food science course. This particular high school had some budget issues previously, and their food science course had its budget slashed. As a result, the teacher had to ask for some outside help from the community. She takes guest lectures on any food-related topic, and as long as the supplies are cheap or you're willing to bring your own supplies, you can come in and work with the students. I came in a couple years ago and did a unit on sugar and how the body uses different sugars. This time I came in and did a unit on protein.

I couldn't take any pictures in the classroom, but we did a quick experiment as well as some meal planning. I thought I'd do a recap and also mock up the experiment for you all to 'participate' in. The students had a lot of fun, so maybe you will enjoy it too!

We talked about:

What foods are high in protein?
How 'big' is protein? 
Why do you need to consume protein?
What is perfect protein? 
How much protein do you need? 

What foods are high in protein? 
I had students shout out their ideas. They had a lot of really good ones, and I had written down some basic information on foods that were high in protein and what their protein content was. Here are some examples. 
Beef - 21g/serving
Chicken - 18g/serving
Tofu - 6g/serving

Milk - 8g/cup
Fish - 12-15g/serving
Beans - 6g/serving 

Those aren't surprising, right? Well, these ones are a little surprising...and the students really liked to find out about them.
Spinach - 6g/cup cooked

Wheat bread - 3g/slice (oz)
Noodles - 8g/serving (c)
Broccoli - 2g/cup

You'll notice that these foods vary a lot in size...and even foods that contain similar amounts of protein (i.e. 2 slices of bread and 1/2 c of beans) take up very different volumes. That is one of the more interesting things about protein...protein can be a variety of shapes and sizes! This is why we measure protein by mass - in grams. One of the students pointed out that 1g is approximately the weight of a paperclip. This is a good unit of measure, but you can't picture a paperclip when you're thinking about grams of protein because protein takes up so much more space - or in other words, it has greater volume. So what can we picture?

How big is protein?

 If you want to follow along in this little experiment demonstration, you'll need the following:

1/2 c milk
2 tbsp lemon juice
1 coffee filter
1 rubber band (or emergency hair binder...heh)
1 cup
1 bowl

Bind your coffee filter to your cup. 
In bowl, add milk + lemon and stir until clumpy. What is happening? The milk proteins react with the acid in the lemon juice and clump. 
Spoon/pour mixture into your filter. Allow to drip. Don't overpour! 
The liquid will drip through the filter and leave the protein attached to the filter. 
I think you'll be surprised at how much volume 4g of protein takes up! 

Why do you need to consume protein? 
Our bodies are made up of proteins. Proteins form tissues and organs. They allow us to see, taste, touch, feel and move! Our bodies have the capacity to make those proteins from other components, like sugar and fat, but a great deal of our tissues are recycled from protein we eat.

Proteins are made up of smaller units called amino acids. These are like puzzle pieces. They have different shapes and sizes, and they give proteins a variety of different characteristics. These amino acids make our skin elastic, they make our eyes jell-ey, and they make chicken taste like chicken and beef taste like beef.
There are 20 regular amino acids. Your body can usually make about 11 of these, but 9 ALWAYS have to be obtained from your diet. If you have a varied diet, this can be no problem. However, some diets are not varied enough can lead to side effects like weak nails, sores in your mouth, hair falling out, and in extreme cases, muscle degradation. 

What is perfect protein?
This is where you hear about combining foods to make 'perfect protein'. Many people know that beans + rice are a perfect protein together.

Another one is corn + peas.

How about peanut butter and toast?
In fact, if you pair (beans, peas, and nuts) with (grains), you almost always get a perfect protein. Just a tip for you veggie types out there!

 How much protein do you need? 
So, we've covered what protein is, what it's made of, how to make it perfect, even how much space it takes up. much of it do we need?

The general rule I've always heard is 1g/kg of body weight per day. There are some people who say that the average woman only needs 25-30g of protein per day, but I really feel that is low. However, if you  have a digestive disorder, or are really, really sedentary, it might be an appropriate amount.

Personally, when I am most active (in the spring, summer, and fall), I try to get 1-1.5g/kg of body weight per day. That works out to be about 75-100 g of protein per day. For me, it works. But, before you go out on any crazy diet plan, you should consult someone schooled in such matters...aka not me.

Hope this was helpful and that you learned something about protein and your body.

What other questions do you have about protein? If I don't know the answer, I'll look it up!

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