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Saturday, September 4, 2010

A Recipe for a Rainy Day - Where did the Oxygen go?

Here is a little bit of kitchen science that will give your little ones a head start on science this year.  Schools usually just draw pictures and tell the kids about oxygen and how much there is of the stuff in the air, but you can give your kids an actual visual representation.  They can watch it happen and see the results.  I always think that doing is better than being told.  So if you have a rainy day and want to smarten up the kids, have a go at this recipe for success and let the kids help. (you will like it too, I promise)

Room air contains about 21% oxygen and an exhaled breath about 16%. This demonstration will provide a visual to support these values in a way that children can understand. Oxygen is a necessary component of any fire. This demonstration also stresses this in a way that small children can understand.

What you need:

1 shallow bowl

1 candle - This can be any type but small birthday candles work best. Attach the candle to the bottom of the bowl using hot wax.

A few drops of food color so we can see the water – blue is the preferred color but any will do.

A clear jar that is tall enough to invert over the candle and has straight sides; you will want make a scale on the side of the jar – I use duct tape. Mark of the jar in tenths

The first experiment will be with room air.

Put some water in the dish (about 1/3 of what the jar can hold) into the dish with the candle and add a few drops of food coloring to make the water more visible. Light the candle and quickly invert the jar over the candle and into the pool of water sealing the air and candle inside the jar. Now watch as the candle flickers and goes out. You will see the water rise inside the jar. It will rise to be near the 2nd mark on the scale or 2 tenths which is 20%. (If you do this over again, make sure to force new room air into the jar as the air from the last burning will be trapped inside and your results will be inconsistent.)

Questions to ask:

Why did the candle go out? . Because there wasn’t enough oxygen in the air in the jar to support a flame any more, and without oxygen you can’t have fire.

How much oxygen was in the air? You should have just about 20% of the jars capacity filled with colored water.

Now do this again with exhaled air.

Refill the dish and light the candle. Have one of the children blow hard into the jar until they run out of breath. Quickly invert the jar over the candle just like you did before. The candle will go out much faster and a water level in the jar will rise to just about 1/10th of the jars capacity or the first mark on your scale.

Questions to ask:

Why did the candle go out so fast? When you exhale air it doesn’t contain very much oxygen because you use it in your body.

How much oxygen was left in the air? About 16% or less.

Have fun with this.

Tuesday, July 13, 2010

Making Yogurt - Anyone can do it!

Love Yogurt? – It’s not that hard and it’s so good for you!
Web Md has an awesome article on the health benefits - Check it out
I have problems with products that are produced in factories with lots of additives. You know, the million cow hamburger. The quality control in my kitchen is much better and guess what - no additives!  I know I have a fresh product that hasn’t been sitting in a warehouse or been left on the loading dock for hours in the heat. If it's going into my body, I what control of what's in it.

This is so simple and cost effective! I make 32 oz at a time (that’s about 5 containers). The cost to me is 60 cents a batch. My daughters, who have young children, make it by the gallon.  Topped with fresh fruit and crunchy cereal is our favorite way to serve it. Yum!
Here are some of the critical rules:

1. It is best to use whole milk (it’s the fat in the milk that make it creamy). The low fat yogurts on the market use pectin or gelatin to make the product "gel" or hold together.

2. Temperature is critical! Use a thermometer to determine the temperature of the milk.

3. You need live culture. Dannon all Natural will do nicely as will any other yogurt with live culture.

4. Do not add anything other than vanilla to the milk, all the flavorings and sugar are added after the yogurt is made. This is because these additives can interfere with the inoculation and growth of the culture that makes the cheese. Honey and other sweeteners can cause the culture to fail, but once incubated and cooled they may be added.
(note: my daughters add sugar before the milk is cultured and the product turns out a little thin but they like it.)

Equipment you will need

A thermometer that will measure up to 200 degrees and as low as 90 degrees. I use the little cooking thermometer but I have used a meat thermometer too.

Glass jars to hold the yogurt. I use canning jars, but you can use any glass container you can put a lid on. You aren't going to need to seal the lid so any covering, even wax paper and a rubber band will do.

Two quart jars with lids to hold boiling water. I use old mayonnaise jars and canning lids because I don't have to worry if they happen to tip over.

A thermal container to be the incubator for the yogurt. I use grocery thermal bag (I think it cost me a dollar) but you can use anything that will hold heat, even bath towels.

How to do it.

1. Heat the milk to 180 degrees and then take it off the heat.
2. Cool the milk to just under 100 degrees. I also get the jars of hot water ready now (microwave each jar on high for 4 minutes with the top off. When done close the jar)

3. Now stir up the starter yogurt so it is creamy and add it to the cooled milk. Stir until completely mixed into the warm milk.

4. Fill your jar with the yogurt milk and cap with lid. Place in the center of the incubator. Place the hot water jars on either side of the yogurt jar. Make sure the hot jars do not touch the yogurt jar.

5. Close up your incubator and cover with a bath towel if you are using a thermal bag. Set it in a warm place for 4 to 8 hours. The longer it incubates the tangier it will be. When you think it is done, take a look. The yogurt in the jars will be thick and not move when the jar is tipped on it’s side. Chill.
When you get near the bottom of the batch, it’s time to make some more. Just use the remaining yogurt as the starter for the next batch.

Want to make a thinker yogurt or a more calcium rich yogurt? For every quart of milk add 1 cup of powdered milk.  This will produce a thick, calcium rich product.   Happy eating and good health.