Category Archives: Winter

Ice Clarification of Stock

This time last year I started thinking about preparations that take advantage of the frigid outdoor temperatures.  I made candy in the fresh snow and tried the “apple jack” method of concentrating alcohol by freezing.  I’ve just tried another sub-zero preparation, gleaned from the pages of The Fat Duck Cook Book.  It’s a fascinating technique called gelatin-clarification of stock.

In culinary school one of the cool-but-antiquated dishes you learn to make is consommé.  Consommé is flavourful stock that is strikingly, brilliantly clear.

The classical method for clarifying stock uses something called clear meat.  Clear meat contains albumen-rich ingredients like egg whites and certain cuts of meat like shank.  When albumen coagulates, it forms a delicate network that traps the tiny particles that cloud stock.  Unfortunately, in doing this it also removes a lot of the flavour of the stock, so we need to add taste-fortifying ingredients to the clear meat.  The shank-meat will accomplish this to a certain extent, but we also add vegetables.

Once the clear meat is assembled it is added to the cold stock.  The pot is placed over low heat, gently stirred and very gradually brought to a simmer.  As the stock heats up, the eggs and meat start to cook, and the albumen network moves through the stock collecting impurities.  Once the eggs and meat are completely cooked, they form a thick mat on the surface of the stock, called the raft.  To release the pressure created by the simmering stock below, the raft should have a hole poked into it.  The stock-and-raft is simmered gently for about an hour, to extract the flavour of the meat and vegetables.

Heston Blumenthal’s technique for clarifying stock is completely different and absolutely foolproof, though it takes a while longer than the classical method.

Here’s the theory behind the ice clarification of stock.  A properly made stock will be rich in gelatin.  When chilled, gelatin forms a network similar to that of the coagulated albumen in cooked meat and eggs.

For a stock with a typical gelatin concentration, the network forms at any temperature below roughly 10°C.  If the stock is heated above this, the network melts.

Imagine freezing a stock to -18°C.  The gelatin sets up its network, and the water freezes.  Now imagine putting that frozen stock in a 4°C fridge.  The water content will melt, but the gelatin network will stay in tact.  As the water melts it will run through the gelatin network, which acts like a filter and catches the particles that cloud the stock.  Once all the water has melted you are left with a cloudy clump of gelatin, and a pool of crystal-clear stock.

To really test the clarifying-power of this technique, I made the an extra-cloudy pheasant stock by cooking bones and mirepoix at a rolling boil instead of a simmer.  Then I put the stock in a stainless steel bowl, covered it with plastic wrap, and set it outside overnight.  It froze into a solid hemisphere.

To remove the ice, I inverted the bowl and heated the underside with a blowtorch.  Once the curved surface of the hemisphere had melted slightly, the ice slid out of the bowl.  I rested that ice in a colander lined with a clean dish towel, then set the whole contraption in a large glass bowl in the fridge.

It takes quite a while for ice to melt in the fridge.  Mine took about two days.  Freezing the stock in a large, thin sheet would accelerate melting.

The results are surreal.  This is far and away the most dazzling stock I’ve ever seen.  In the photo below you can see how murky the original stock was.

There are two problems with this method, both stemming from the fact that you have removed all the gelatin from the stock.  First, the consommé has a very watery mouthfeel.  To restore the rich texture the diner expects from clarified stock, Blumenthal typically back-adds pure gelatin, which is a bit ridiculous to me.

Second, the process has a very low yield.  The classical method also results in waste, but not to this extent.  I think that my yield was particularly low because of the muddiness of my original stock.  I started with 545 g of pheasant stock, and ended with 305 g of crystal consommé, a yield of only 56%.

Obviously this is not a process I will do very often.  Like, possibly never again.  If you take the time to make a stock properly, it will be clear enough to serve as a soup to all but the most pretentious guests.

Still.  An interesting experiment.

Applejack – Concentration by Freezing

A glass of homemade applejackWhile reading the maple syrup section of On Food and Cooking, I came across a shocking bit of information.

Even though North American Indians didn’t have metal pots until the Europeans came, they had an ingenious method for reducing maple sap to make syrup. They would leave the sap in the cold air overnight. In the morning there would be ice on top. That ice would be mostly (but not exclusively) water, so in discarding the ice they were left with a higher concentration of sugar in the sap.

After reading this, I immediately turned to the section of the book on distilled spirits, to see if there was any mention of whether this method works to concentrate alcoholic solutions. Sure enough, there was a boxed sidenote titled, “Concentration by Freezing,” with references to all kinds of liquors that are made in the frosty outdoors and never see the inside of a still.

On the internet, notably Wikipedia, this process goes by the name “freeze distillation.” My dad, a process engineer, takes exception to the term, as distillation separates solutes based on their different boiling points. There is a process called freeze crystallization that separates solutes based on their different freezing points, but that doesn’t apply here, either. The large difference between the freezing points of water (0°C) and ethanol (-114°C) is not what makes this process work, as evidenced by the fact that the process can concentrate maple syrup, which has no ethanol. I’m going to use the accurate though somewhat anemic word “concentration.”

Process

Put your drink in a bowl and put it in a freezing environment like, say, your freezer. Or maybe your backyard.

When I first read about freeze-concentration, I imagined that there would be a clear, easily separated layer of pure ice on top, and a liquor beneath. This is not what happens. Instead you end up with a strange, delicate-but-solid crystalline block.

Freezing cider: the first step in making applejack

If you turn this block of ice into another container, you can easily mash it up into a slushy mixture.

The frozen apple cider is broken up to make this slushy mixtureNext you can strain the liquid off the ice crystals.

Straining the liquid off the slushAnd to maximize extract, you can transfer the remaining ice to a salad spinner to squeeze out a bit more applejack.

Spinning the remaining ice to extract more liquid

Results

I started with 10 L of cider, and finished with between 2.25 and 2.50 L of applejack for a volume yield of about 23%.

  • Appearance -The applejack is slightly darker than the cider, with a bronze hue compared to the cider’s gold (image below).
  • Nose –
  • Taste – The difference in taste is pretty substantial. Sharply acidic, with warming alcohol.
  • Mouthfeel – The applejack had a subtly richer mouthfeel.  I was using still cider, but note that if you use bubbly stuff the apple jack will not be carbonated…

A glass of applejack beside a glass of cider: note the darker, bronze colour of the applejack

I also tried this concentration method with beer. I had never heard of beer being freeze-concentrated, but I thought I should try it, since the AGLC has banned strong beer from stores. [Editor’s Note:  There is a classic German beer that is freeze-concentrated: it’s called an Eisbock.]  I used Big Rock Traditional Ale, which is based on (ahem) traditional English ales. It has a dark caramel colour with a hint of red, and is very clear. It has a slightly fruity nose and tastes of caramel and roasted malt. It’s one of my favourite Albertan beers.

I froze 700 g of beer and pressed 215 g of liquor from the ice, meaning roughly two thirds of the beer was wasted.

  • Appearance -The liquor was ever so slightly darker than the original beer.
  • Taste – The difference in taste was noticeable, but subtle. The sweetness and the roasted, caramel notes were definitely enhanced, though it didn’t taste any more boozy than the original.
  • Mouthfeel – The beer lost its carbonation.
  • Overall assessment – The results were pleasing, but not nearly good enough to justify wasting two thirds of a beer.

Future Experiments

In terms of percent of alcohol captured from the original drink, freeze-concentrating is not as effective as distillation, but it definitely has its advantages. It preserves the flavour of the original drink much, much better than distillation, which doesn’t capture any sugars or acidity.

Freeze-concentrating also has advantages over heat-concentrating (ie. reducing over heat). Aggressive concentration by heat introduces dark caramel flavours to the liquid. If you had a chance to taste Indian Head birch syrup when the River Valley Syrup Company was selling at the Old Strathcona market, you know that it is a lot darker in colour and taste than most maple syrup. I think this was because birch sap has a lower sugar concentration than maple, and was therefore reduced more in order to produce a comparably sweet product. The prolonged reduction resulted in lots of deeply caramelized sugars. That darkness of flavour was certainly one of the appeals of the product, but it would be interesting to try freeze-concentrating sap.

Maple Taffy – Tire d’Erable

Winter Food

Throughout late summer I found myself craving winter food. When I was filling my rumpot with fruit and canning my sauerkraut it was twenty degrees outside, but I was thinking of the dead of winter, and the rich, warming, comforting food I would enjoy.

Preservation of food has become central to my idea of local cuisine. I’ve always included meat in my concept of preserving for the impending winter, but I recently realized that this doesn’t make much sense.

Before refrigeration, fresh meat could only be kept in the winter. Of course you could kill a chicken in the summer and eat it for dinner, but what if you were to kill a cow and not have a freezer? My great grandparents associated summertime with pickled meat. Butchering was largely done in the colder months, so they were much more likely to enjoy fresh meat in the winter than the summer.

I’m oversimplifying, but you could say that they ate fresh vegetables and pickled meat in the summer, and pickled vegetables and fresh meat in the winter.

This realization turned my idea of winter food on its head, and I started thinking of ways to use the cold weather in cooking. Now and again I’ll cool large pots of stock in a snowbank, but there are some preparations that have a more significant dependence on the cold. For instance…

Maple Taffy

Pouring maple syrup onto fresh snowUsing snow to make candy has been done for centuries in Canada.  Toffee, for instance, was invented in Quebec.  According to Larousse, a sixteenth century nun set molasses in the snow to attract young natives to her school.

Rapidly cooling sugar syrups helps prevent the growth of crystals, and results in a clear, glassy appearance.

Making maple taffy is simple enough. Start with maple syrup in a pot over medium heat. The higher the concentration of sugar in a syrup, the higher the temperature at which it boils. The maple syrup will start to boil just above water’s boiling point of 212°F. As moisture evaporates and the sugar becomes more concentrated, the temperature of the syrup will rise. The relationship between sugar content and boiling point is direct and predictable: a syrup of 85% sugar will boil at 235°F, a syrup of 90% sugar will boil at 270°F. Candy thermometers are your friends.

Resist the temptation to stir the pot, especially in the later stages of boiling, as you might induce crystallization.

Heating the syrup to 235°F will yield a sticky, slightly runny though still manageable maple taffy. I like this stage because it is a little messy. Higher temperatures yield firmer taffies.

As soon as you reach your desired temperature, pour the syrup over clean snow. Wait maybe ten seconds for the syrup to cool, then pick up the taffy by winding it around a popsicle stick or wooden spoon.

Sugar shacks do this in early spring, during the sap run, so that visitors can taste the first syrup of the season. With few hard maples being tapped around Edmonton, this is as much a celebration of the snow as it is the maple. Maybe a good tradition for the first snow fall, rather than the spring.

Maple taffy wrapped around a stick