"YUCK, this ice cream is all gritty". What's that all about?
Well, I'll tell you. It's the ice crystals. Both the taste and the texture of ice cream is dependent on the size and distribution of these crystals.
The crystals need to be as small as possible and distibuted evenly through the ice cream. When the crystals are large and clumped together the ice cream tastes bland and gritty. This happens when you don't put the ice cream back into the freezer quickly enough after dishing out a serving and the crystals go through a thaw then refreezing cycle.
When the ice cream is first manufactured it is frozen extremely quickly. This fast freezing process results in tiny crystals. If these crystals melt and then refreeze at a much slower rate - as in your freezer - they will grow to be much larger and hence the gritty taste.
The problem for ice cream manufacturers is to limit the impact of the inevitable thaw/refreezing cycle that will happen to some extent in transportation from the factory to your freezer at home, or to the ice cream parlour. Researchers have used Linkam's LTS420 and cryo-CSS450 to study both the initial freezing and distribution of crystals, and the thaw/refreezing cycle, in order to design additives to control crystal growth.
Robyn Sue Fisher, founder of Smitten Ice Cream, isn't concerned with the thawing and refreezing of ice cream. Using her fantastic patented Kelvin machine, she freezes the ingredients on the spot with liquid nitrogen and uses a clever mixing process (see video) to ensure the tiny crystals are evenly distributed in the mix.
The awesome Kelvin machine adds to the excitement and drama at the ice cream parlour - and of course you get delicious fresh ice cream. Hungry yet?
I don't suppose there's any danger Robyn will be coming to us for a cryostage though.
You can watch a great interview with Robyn about how she came up with this process and turned it into an exciting new business here.
By Vince Kamp