Starch Suspension

[Narelle01]

Hi everyone,
New job, new staff.
Can some one please tell me how to make a starch suspension.

Thanks! Its for Thursday.

[Ocker]

I have always found the best way is to boil some rice and strain the water off this is starch suspension also works best for starch for food testing

[rae]

Morning,
I usually make a 1% solution, which is 1g in 100ml of water. So if I make 1L I will weigh out 10g of starch in a large beaker, measure out 1L of water and add enough water to the starch to make a watery paste, mix this up well. Then add the rest of the water to the beaker heat on a hot plate/magnetic stirrer if you have one, until boiling. Allow to cool and use.

I know other people use water they have cooked or washed rice in but I like this method.

Lorrae

[RosalieM]

We have a jar of potato starch and I usually put a spoon full of it in some water, add some hot water to dissolve and then top it up with cold water to the required amount.

[smiley]

Five of those starch packing beads in 250mL of hot water. Stir a lot and it's done. You can vary proportions according to whether you're just testing for starch, or doing an amylase expt. Use less for the amylase experiments, (i.e. one in 100ml) and whatever if you're just doing starch testing or seeing if starch can go thru dialysis tubing. The joy of those packing beads is that they've already been cooked, so they dissolve really well.

[Narelle01]

arhhhh next time i get a package i will save the packing beans!

"You know you're a labby when...."

thanks for your wonderul suggestions.
10 teachers here - i am run off my feet - just unpacked my animals body parts for various dissections and splashed it all over my white shirt...I am now wearing a lab coat! time

[Ocker]

What do you mean! next time you will save the packing beans.
Every time you save beans for bio capture/recapture prac and all the other uses

[smiley]

Ocker,

What capture/recapture prac can you do with starch packing beans?

[Ocker]

you take 100 beads and throw into photocopy paper box
Reach in and take bead place an x on it
Throw back in and shake
Take another bead and mark with x unless it already has x then mark o
repeat 100 times
then do the Maths

[dime]

What are starch packing beans. Only get polystyrene here. Make sure you use boiling water on potato starch, after making paste with cold water, as the starch grains have to burst (cook) to go thick.

[Narelle01]

i get them around my nutrimetics order, it was supposed to be watered into a garden - less land fill and all that.

But if you want to, you can buy them from Officeworks in a huge bag....bag saving them from mail is prob better way to go!

[RosalieM]

Counting starch beans sure beats counting lentils!!! Or popcorn kernals is another one I've had to do... I get them around my nutimetics orders too, so I'll start collecting Dime - if you want to get some next time you're over you're welcome to take some home!

[smiley]

Dime,

There's lots of them around. They LOOK like the old polystyrene, but they're actually made from starch. Drop some iodine on them and you'll soon know which is which.

[lada]

Narelle,
just a tip.Next time put the lab coat on before you unpack the bloody parts . It works better that way and shirt stays clean...ha ha.
Lada

[Robdean]

I wear my neck to floor chemical resistant vinyl apron - nothing soaks through that!

[sunray18]

as to body parts - the shirt would make a good forensics experiment... waste not want not... {you know you're a labbie...{}
starch - I have one teacher who demands rice starch, one who won't touch it and thinks only a chemical out of a bottle is good enough, another who wants me to use potato starch.... and another who complains if it is too thick - or too thin - or - can you imagine if I introduced another form of starch!

as to the prac you were talking about Ocker - we use coloured toothpicks... have you ever tried that? and sometimes they take them down onto the grass and do it - somehow the green ones never make it back!

[Lyn]

I usually put a teaspoon of soluble starch (flat or rounded it doesn't matter) in a 1litre beaker, add enough cool water to make a runny solution in the bottom of the beaker then add boiling hot water while stirring like mad so it doesn't go lumpy. The solution will go clear nearly every time and then I add water to make up the litre. If the solution is too hot I whack it in the fridge to cool it down as quickly as possible. I don't think I've ever weighed the starch out.
As for the packing beans just stick one on the end of your tongue. You'll know soon enough if it is a starch based packing bean. There were boxes of these packing beans in the senior staff room the other day and I looked at them and said to myself do I have anywhere to keep these? are the kids doing pracs that they might need these? am I going to regret walking away from these? and I left them there. Decisions, decisions.
Lyn.

[Ocker]

Hey Pam the red/green toothpicks is the natural selection prac
The soluble beans usually smell like popcorn
With starch if you add hot water it will go into solid lump always dissolve in cold water then add hot
the original request was for suspension, when you use powdered starch it usually settles out very quickly where the rice water settles very slowly, disadvantage is after a week is after a week it gets a bit wiffy!!!! was looking for smiley with a peg on the nose!

[Lyn]

Does this mean you cannot use the soluble starch (Iodometric indicator) as a starch suspension in cold water?
Lyn.

[Narelle01]

I had an order for 500ml starch solution come in...so i went to my nutriemetics box, got 2 handfuls of packing beans, and mixed them in some hot water.
After this i took a few mls and dropped a drop of iodine onto it - BLACK!!
Hey presto - easiest and most environmentally friendly starch solution EVA!!!

I am just going to take a bow..... or do a dance....