Addind Salt to Ice?
Hi All
This question is addressed more to Lapis but please anyone who can answer I'll be ever so grateful.
Tonight I just saw one of the Fat Ladies program adding some salt to ice for her old fashion 1920's ice-cream machine.
I know I've heard of adding salt to ice before but can not remember why or in what context? Does salt keep ice as ice for longer?
Also this is something I've wondered from years ago, does hot water freeze faster than cold water?
it's called freezing point depression, and is the reason people get depressed when it is freezing outside. LOL
Adding salt (or many things (all are types of salt)) to ice will lower the freezing point, just as adding salt to boiling water will raise the boiling point, but only by a couple of degrees. I believe adding table salt to water, one can get to -16?C, or there abouts, near to freezer temps.
Yes, Indian Ice-cream called Kulfi was traditionally made in earthenware containers filled with crushed ice and salt mix. My parents had an ice-cream/Kulfi maker like this one; http://www.ehow.com/list_7512517_ice-makers-use-rock-salt.html and I remember my father using it. It used to be fun for us kids, taking turns to turn the handle. It works by lowering the temperature to well below freezing, as Lapis says.
I have an electric version of this that I bought in India, which I rarely use! It has an outer tube/compartment for ice and salt mix and electric blades to churn the ice-cream. I should dig it out and take some pictures and use it as well. It does make a nice kulfi.
Yes hot water does seem to freeze faster than cold water (I experimented in the freezer with icecubes as a child)... Not sure of the science behind it but would guess something like the atoms are more willing to give away their (heat) energy and so lose it faster ?
Steve
thank you so much for all your answers...interesting Mamta that your dad had a hand turning ice-cream machine..you were very lucky as no such luxuries when I was a kid ;-) !
Yes I've noticed the rolling boil you get when adding salt to a pan of simmering/boiling water.
There is a statement somewhere I read but forget where that water boils faster if you add salt at the beginning of it...say when boiling water for pasta.
interesting stuff isn't it? never stop learning do you?
Yes, it is interesting that you never stop learning, not until your brain goes that is!
The hand turning ice-cream machine was not such a luxury, it was hard work, but we loved it as kids and couldn't wait for it to be ready. The contraption was used regularly in summer months. I am quite ancient azelia. If you were to ask your mum's generation here, they may have seen one! You are probably too young!
You know something, my dad used to have a huge Servel fridge/freezer that ran on kerosene oil, something like this; http://www.servelrefrigerators.com/images/servelLarge3.jpg, but bigger and with rounder edges. He also had a huge selection of food flavourings and colourings. He was a sugar chemist and had been involved in making sweets in one of the factories where he worked. So, all summer through, we used to make various pink, blue, green, purple milk shakes and ice-creams with goodness knows what weird mix and match flavours, good memories :-). That fridge is still there in my brother's house, used as a storing cupboard, he can't bear to discard it. I bet it will work, if one could locate the wick that 'fired' it.
Mamta what a lovely story and a wonderful picture you portray of your summers as a kid!
Yes a possession can become too sentimental to throw away...
...we should remember to pass on the stories that go along with that item so they carry on containing the magic.
Mamta I'm the same age as Kavey so I know you can not possibly be ancient ;-)
Don't forget we were very poor back home and very backwards with regards to technology after so many years of devastating dictatorship.
The Kerosene fridge that Mamta mentions used to be with me for a very long time. It was simply huge and very heavy. It worked quite well. Kerosene oil is a rationed comodity in India even now so running it was quite cumbersome.
I have disposed it off now as it was occupying a lot of our space and we use modern fridges now.
I too have that electric version of icecream maker but I rarely use it as it needs lots of ice,but the outcome is always very good.
I have a suspicion the reason that sort of ice-cream maker is very good is because of the slow action of cooling down the cream. The churning is in order to breakdown the ice-particles as they're created to make them small so the texture of the ice-cream is nice and smooth with no big lumps of ice in them.
I think the slow turning of that sort of machine will give a better texture.
According to Heston the ultimate way to cooling down cream for ice-cream giving perfect smoothness is his favourite ingredient: liquid nitrogen.