Chanterelle + Apricot (TGRWT #12)

The "They go really well together" relay rolls on, and it's time for #12 - matching chanterelle and apricot. Host for this round is Tri2Cook. I've been rather reluctant to try on mushrooms in cooking, but there has to be a first time for everything. So, I strayed into the kingdom of fungi.

Since we had bought a lamb earlier this autumn and had planned on a dinner (literally) on parts of this for some time, I thought this might be a good opportunity. At a wedding dinner many years ago, we were served a wonderful creamed chanterelle side dish with some meat that I now have forgotten (but the chanterelles etched into my memory). We were going to be eight at the table, of which two were children.

The meal

• Oven-roasted lamb shoulders (rosemary, thyme, cellery, carrots, onion, salt, pepper)
  
• Creamed chanterelles with apricots
• Mashed potatoes & carrots (mixed)
• Brussels sprouts and green peas
  
  
• Blue cheese (Royal blue, rather mild)
• Sugared ("sweet-pickled") pumpkin
• Lingonberry jam/jelly (Scandinavian replacement for cranberry jelly)
  

Creamed chanterelles with apricot

• canned chanterelles, 3 tins each containing 110 g mushrooms
• 7-8 dried apricots
• 150-200 ml double cream
• 150 ml skimmed milk or water
  
• 1-2 T butter
• thyme, salt, pepper

The day in beforehand, apricots were chopped in small squares and soaked in the double cream. The mixture was warmed in the microwave until lukewarm and then left to infuse in the fridge overnight, resulting in a yellow apricot-flavoured cream, in which time it had almost solidified. Thinned with skimmed milk and some water until fluid.

The chanterelles were drained, rinsed in cold water and dried on a paper towel. The stock was reduced (very salty as the canning stock was salted). The chanterelles were lightly fried in butter, apricot-cream (with the apricot bits) and spice was added and brought to a light boil. Thickened with corn flour and some of the reduced stock was added.

Lamb shoulders
The day in beforehand, two shoulders from a small free-range lamb (12 kg after slaughtering) were rubbed with a mixture of thyme, rosemary and ground black pepper. Slashed and half garlic cloves inserted. Left to marinate overnight. Next day rubbed with salt and placed in cooking bag. Added one onion cut in four, 3-4 coarsly chopped carrots and a one coarsly chopped cellery. Left in 110-120 °C oven for 4.5 hrs. Since the meat was home-slaughtered free-range, I turned down the idea of a sous-vide approach and went for meat cooked to the brink of disintegration (interior temperature was 100 °C for 1.5-2 hrs).

Gravy
The juice from the lamb shoulders was used as base for a standard gravy made with corn flour, adding the rest of the reduced chanterelle stock.

Verdict
The lamb was great, cooked greens and mashed potatoes/carrots don't need further comments. Two shoulders from such a small lamb was sufficient, but not too much for eight people.

The creamed chanterelles/apricots (chanterots, maybe?) were good, but by no means exceptional. I realise that my lack of formal food education might play a role here, combined with my lack of experience with cooking mushrooms in general. The creamed chanterelles were based on a recipe, but felt somewhat insipid and lacked some sort of freshness. It was almost like chanterelles and apricots were too similar (doubly insipid, in a way). Adding blue cheese made a difference, however, cutting through the rather bland, mildly sweet taste. Maybe the "chanterots" lacked acid, or perhaps a little soy sauce? Or was lamb not the perfect match? Pork or turkey might work even better with this one.

A few thoughts on the pairings in this meal
In planning the meal, I browsed through the main ingredients over at the food pairing site. Starting with the main flavour contributors lamb, thyme, rosemary, garlic and apricots. There were no separate scheme for chanterelle, but one might maybe use mushroom, or...? Not surprising, several matches came up, resulting in the inclusion of blue cheese on-the-side as well as choosing carrots as part of the vegetables. I wanted to add chopped almonds as well, but unfortunately I forgot. The resulting food pairing scheme of the ingredients used is shown below (created using the free CmapTools mind map software).

Erik

Non-stick chewing gum

A great article in the last issue of Science in School: "Easily removable chewing gum". Secondly: is there a culinary potential in restaurant/home-made chewing gum?

The article by Halina Stanley in the last issue of the Science in school (free journal) is fun reading, describing why gum sticks and also referring to recent research at Bristol University (UK) on making non-stick chewing gum.

Taking this one step further, it came to me that I've never been served home-made chewing gum at any restaurant. Wouldn't this be an interesting as palate-cleanser, say as an alternative to sorbets, granitas etc.? I googled "make your own chewing gum" and came up with loads of hits. Some of these were ready-made kits (going at $10-20), but even more interesting were some of the more general recipes that allow for leeway in flavour addition. However, I guess a ready-made kit might be a good starting point. It seems that the most commonly available products are based on natural gum (chicle), whereas most commercial brands nowadays use synthetic polymer mixtures to achieve the ideal properties, more on this in the Science in school- article.

Teaching potential
I suppose there are numerous possibilities in teaching polymer chemistry using chewing gum, testing various properties etc. A number of relevant links in the article for experiments and activities.

I'd really like some gum base for Christmas present this year :)

Erik

PS: Science in school is highly recommended reading in general, not only for teachers. On top of all, it's free :)

Green vegetables and chlorophyll revisited

"I am an imbecile! I see only half of the picture!"

...is one of my favourite quotes of Agatha Christie's famous detective, Hercule Poirot. After pondering for months about why the broccoli cooking water turns green when using slightly basic and not when the water is slightly acidic the answer was right beneath my nose all the time, and I felt exactly like beloved Hercule (see the posting "Christmas dinner trimmings - a hot potato? Part two").

The trick to cooking wonderfully green vegetables is using a pinch of baking soda (sodium bicarbonate) in the cooking water. Because the water then is slightly basic, the magnesium ion is retained in the chlorophyll, and the colour is a vivid green, see the above mentioned posting. Deliberately using some acid (vinegar) renders the vegetables dull olive green.

What puzzled me was that the cooking water turns green when the vegetables are the most green, whereas the water is completely colourless when the vegetables are dull. How come? For a long time my hypothesis was that the chlorophyll, or some of its derivatives, is extracted to the water when using baking soda, but not when using vinegar.

Earlier this autumn, during a kitchen lab lesson, it suddenly struck me that the chlorophyll (or a chlorophyll derivative) might be there all the time, but that it's invisible in the acidic water, and that seems indeed to be the case. In fact, it retains it's colour, being green in basic water, and colourless in acidic water (see Martin's comment in the Christmas dinner trimming post).

The ultimate test is to look for chlorophyll colour in the acidic water, and the most straightforward experiment was to add some base to the colourless cooking water, and voila: the water took colour! Rendering the solution acidic again by adding some more vinegar resulted in colourless solution, as seen from the video below.

So, this is an example of chemical reversibility: adding one ingredient (i.e. acid/vinegar) you push the situation one way, adding another (baking soda/ammonium chloride, neutralising the acid), you pull it back to towards the starting point.

What might be learned/taught
In my opinion, this adds some chemistry to the kitchen trick of cooking green vegetables with bicarbonate. Also, it provides a meaningful arena for teaching acid/base equilibria and naturally occurring indicators.

Some details
To be honest, in this case it's slightly more complicated than going straight forward and back, and the colour diminishes in going back and forth. Acid and base is added consecutively, whereas the magnesium ions that are responsible for the colour are constantly diluted. Also, adding acid/base introduces other ingredients (acetate/vinegar and sodium/ammonium ions from the base). Thus it's not an entirely pure back and forth situation. I guess, if I'd added magnesium ions together with the baking soda there should might have been a more distinct colour change . One of these days I'll have to do just that.

Finally, the world is usually more complicated than meets the eye. I might very well have missed a point or two somewhere along the way. But anyway; I'm content with this explanation, and the observation of reversibility adds another dimension to using this experiment with students.

Late addition
When chlorophyll (either structure, a or b) reacts with an acid, pheophytin is formed. This is also coloured, but more olive-green or yellowish , depending on whether it's the a or b form. It might very well be these, or derivatives thereof, that are seen in the water solution. There are loads of scientific publications on chlorophyll, of course. A paper of relevance to science education is found in J. Chem. Ed. (This, Valverde, & Vignolle).

Banana and clove milkshake (TGRWT #11)

Martin at khymos.org has posted another invitation to join in on "They go really well together" (TGRWT). The idea is that foods with one or more flavour compounds in common will taste well in combination; the concept of flavour pairing. This is my first attempt to participate, and the focus is what might be work together with kids (i.e. in a school situation).

My first idea was to keep things very simple, and don't add too many ingredients. That way, the flavour pairing experience might also be easier to perceive and evaluate.

Banana and clove milkshake
200 ml milk
500 ml vanilla ice cream
1 banana
4 or 10 whole cloves, each cut in two (for more efficient extraction)

Simmer milk with cloves for five minutes, cool to room temperature. Remove the cloves, cut banana in pieces. Run milk, banana and ice cream in a blender. Serve.

Result: using 10 cloves gives a milk shake with a marked, but not dominant, clove flavour. Using 3-4 cloves gives a milk shake with just a hint of clove flavour. Hence, the latter left me with the question: "there is something different about this, but I cannot really put my finger on it". Quite fascinating. In my opinion, banana milk shake is on the brink to being insipid. The cloves made a difference, adding another note to the drink. Conclusion: I find the banana-clove combination to be successful.

Chocolate stuffed banana
1 banana
3-4 squares milk chocolate (preferably chopped hazelnut-type)
6-7 whole cloves
optional: ice cream and berries/fruit to serve

Cut each banana lengthways, through the skin, making sure you don't cut all the way through the bottom layer of skin. Distribute the cloves by piercing/inserting them along the length of the banana on both (in)sides. Place chocolate squares in the cut of the banana, wrap in aluminium foil and cook for 15-20 minutes at 225 °C (or on barbecue for ca. 10 min). To serve, unwrap the bananas and place them on serving plates, skin and all.

Result: A typical barbecue or hiking dessert, rather heavy on the sweet side. I thought maybe the cloves would make a difference. The cloves did not cut through the heavy, cloying feeling. However, it added a layer of complexity and variation as the different spoonfuls tasted somewhat differently (one spoon had clove flavour, the other hadn't). Serving together with ice cream and slightly tart berries (i.e. redcurrants) compensates for some of the heaviness.

Finally, adding cloves to banana bread would be an interesting variation of this recipe. I've not tried this, however.

Erik

Primitive food, heat transfer and a day out

What did people do when there were many to feed and ovens weren't though of yet? To start digging a hole in the ground was maybe not a bad idea. At least, that was what we did with 40 twelve-year old kids. This is the Stone age way of cooking, and we ended up feeding 130 persons.

Cooking in a cooking pit (nice animation at steinalder.no) is in fact quite a simple thing as long as you've got enough time. At a school trip for seventh-graders at Bratteberg skule (primary school), this was one of the points during a day of many such activities. Groups of five kids spent ca. 45 minutes working at the pit. We started at 11.30 and dug up the food at 18.00, feeding the kids, teachers, and families for a real feast of lamb's legs, salmon and potatoes. The work was guided by a parent (secondary school teacher) and myself.

Menu for 130 persons (might be scaled down, of course)
six legs of lamb (2.3-2.7 kg each)
seven salmons (ca. 3 kg each)
130 potatoes (preferable baking potatoes)
salt, pepper, garlic, herbs (thyme, oregano, rosemary)

Equipment
2-3 shovels
bar (lever for removing rocks stuck in the ground while digging)
firewood (a couple of 80 litre sacks for each pit)
loads of aluminium foil, good quality
thick, heat-resistant working gloves (at least two pairs, non-plastic)
terracotta pot with lid (optional)
cooking thermometers (optional, but a lot to be learned from using. We used six in parallel)

What to do

The day in beforehand
rub lamb's legs with salt, pepper, herbs and garlic. Pack thoroughly in foil, preferably four layers. Keeping or removing the bone is a matter of taste (and skill), optional. Salmons might be done two different ways. In our case, five were filleted, rubbed with salt, pepper and herbs and packed as single fillets in foil. The other two were gutted and cleaned, but kept as round fish. Rubbed with salt, pepper and herbs, and placed in terracotta pots. Stick in thermometer probes into the food if you've brought them. Potatoes are wrapped singly in two layers of foil, but this might be done on the day as a parallel activity to digging.

On the day, for one pit (we made two)

1. cut out rectangular pieces of the turf, in total approximately the size of a coffee table, ca. one by two metres. Be sure to keep the turf on whole pieces, and turn them over to each side
   
   
2. dig the pit where the turf is removed. Depending on the size of the stones, the pit needs to be 0.4-0.7 metres deep. Round stones require a somewhat deeper pit compared to flat ones. At the same time, collect loads of stones/rocks. Size may vary, but minimum is the size of an open hand. Maximum size is what you can carry, both to the pit and back (we don't want to leave too many marks in the nature). You need enough stones to cover the area of the pit to at least three layers.
   
   
3. line the bottom and sides of the pit with stones.
   
   
4. build and light a fire in the pit. Use plenty of firewood. The fire is burning steadily, add more stones to the fire (you need at least 50% more than you think, so don't be modest with the stones). Let the fire burn down (takes at least 1-1.5 hours)
   
   
5. remove the loose stones and charcoal from the pit with shovel or gloves, leaving the ones lining the pit. Layer the food and hot stones, making sure that all the food is surrounded by hot stones. Turn the turf back over the stones/food, earth side down. Stick one thermometer probe directly into the pit (if you've got one)
   
   
6. leave for at least 2.5 hours (lamb or fish in pot) or one hour (fish fillets in foil). Potatoes are ok after one hour if they're well surrounded by hot stones (in our case, the ones in the middle of the pit were good, the ones out on the sides were not ready).
   
   
7. Carefully lift of the turf, remove the food, unwrap, and serve.

Experiences
In our case, this was a highly successful activity, and was perfect for a day out with class/school, be it the last day before holiday, school trip, or just a day in the garden with friends (if you've got a garden that allows for digging). With only adults, calculate 5-6 hours from start to serving, add one hour for a school activity. I've done this a number of times with university college students, but this is the first time with primary school kids. No problems, but one needs to be at least two adults.

The temperature in the pit was surprisingly high. We started out with almost 320 °C in the closed pit(!) at 15.00, ending up at 140 °C 3.5 hours later. It was really fun recording the temperatures, seeing how the temperature in the pit fell and the food heated up. I regret not putting a thermometer in one of the potatoes, though. We also recorded the temperature in the fish and soil outside the pit (omitted in the plot). The temperature in the fire was recorded with an IR thermometer, going well above 500 °C.
In our case, this was a highly successful activity, and was perfect for a day out with class/school, be it the last day before holiday, school trip, or just a day in the garden with friends (if you've got a garden that allows for digging). With only adults, calculate 5-6 hours from start to serving, add one hour for a school activity.

The food is extremely tender and flavourful due to the long cooking (we left the lamb 3.5 hrs and fish fillets 1 hr 20 min). However, I wouldn't recommend aiming at medium rare done meat, but rather go all the way to the pulled pork-type texture (where the meat just falls apart). The fish might be somewhat overcooked, but who cares? This is supposed to be primitive cooking!

If you open the pit too early, there is no going back - the heat is gone. In that case, you better have a fire or an oven at hand. That's maybe the drawback with the method, and the best reason to accept somewhat overcooked food.


What might be learned

• Cooking time vs. type of food (lamb takes long, fish fillets short)
• heat transfer (stones and pit cools, the food warms)
  
• heat capacity (the stones store the heat that is used for cooking)
• data logging (temperature vs. time)
  

...and as a bonus comes that this is a nice outdoor activity with lots of physical exercise. Also, the large span of activities allows for a number of personalities to attend. In our case, those with lots of energy to spare dug and carried stones, whereas those with less energy of motivation could deal with the firewood, wrap potatoes or log the temperature.


Other comments
We did the temperature logging manually, recording time and temperature with pen and paper. Automatic dataloggers with computer interface are of course a possibility, but we went for the manual method.

I've not included safety matters here, but heat, open flame, the use of sharp and heavy tools etc. are all matters that carry a certain amount of risk. However, it should not put anyone off as long as the work is well organised and adults are present (this applies to the Norwegian school regime, at least).

The ideal type of ground for a cooking pit is slightly moist, not too sandy, and with a good layer of turf. That way, the pit keeps its shape, and the turf works as a tight lid.

How to afford this with a tight school budget? In our case, the guests that attended the meal in the evening (parents, families) payed an entrance fee. This covered most of, or all, the expenses.

Make sure that you leave as few marks as possible. Keep the turf whole, don't leave hot stones directly on the turf (leave them on the heaps of earth you've dug up), carry most of the stones back to where they were found. And, by all means, ask for permission to dig and light an open fire.

Erik

Deciphering an old preserves recipe

Teaching food preservation methods combined with science often results in the classical why-questions; why does the recipe tell us to do things this way, and why is that so important (...and is it really that important?)

Autumn means ripe fruit, berries and vegetables, and many of us look forward to harvesting for the coming year. Only a few areas of the world have the benefit of continuous supply of fruit and vegetables (especially we up here in the north), and this has lead to loads of ways to preserve food. Nowadays, however, many of these methods are used for culinary purposes rather than survival. Recently, Martin wrote about cherry jam (I have given a few on his post as well). Also, Hervé This has written about culinary proverbs and old wives tales, "culinary precisions" as he terms them, some being sound advice from a scientific viewpoint, some being directly misleading, and others probably not making that a big difference.

So, I thought this might be a good time to take a recipe for sugar-preserved pears and have a closer look at it, step by step. It is in fact a quite fun exercise.

Traditional sugar-preserved pears «the old fashioned way» (generic recipe)

1. Heat jar in oven or water by slowly increasing the temperature to above 100 °C and keeping it at that temperature for a certain amount of time (i.e. 15 minutes). Cool.
   
2. Peel pears. Cut in half and remove seeds and core
   
3. Make syrup from water and sugar by boiling the syrup until the sugar is dissolved. Leave to cool
   
4. Fill a jar with the pears. Fill up with syrup, cold or lukewarm, but not hot
   
5. Put the lid loosely on, do not tighten
   
6. Place jar in a pot with cold water almost up to the rim of the jar. Heat slowly and keep at boiling point for a certain amount of time (i.e. 8 minutes)
   
7. Remove jar from pot and
   Either: leave to cool for a certain amount of time (i.e. 15 minutes). Then tighten the lid
   Or: Tighten the lid while boiling hot
   
8. Turn jar upside down and
   Either: store upside down
   Or: leave upside down for a certain amount of time (i.e. 15 minutes)

Taking a closer look
Firstly, the main reason for all these operations is to keep the pears edible for a long time, more specific until the next time ripe pears are at hand (a year, usually...). The two main ways that fresh fruit is spoilt are chemical (enzymes and reaction with oxygen from the air) and biological (microorganisms: bacteria, moulds and yeasts). Even though the methods were developed before the discovery of microorganisms and enzymes, the results of these were evidently clear. The source of enzymes is the fruit itself, whereas microorganisms are ubiquitous: the fruit itself, hands, tools, jar and in the air. So a perfectly sterile fruit would over some time be contaminated by just sitting in the air.
Two important facts: microorganisms thrive and multiply at temperatures between 10 and 40 °C, and die at high temperatures. The trick is thus to avoid the 10-40 °C window. Also, microorganisms need water to thrive and multiply.

So, how much of this procedure makes sense from a scientific point of view? I've marked the steps being most «fishy» with a red asterisk:

1. Heat jar and lid in oven or water by slowly increasing the temperature to above 100 °C and keeping it at that temperature for a certain amount of time (i.e. 15 minutes)
   Makes sense, but cooling leaves the jar and lid ready for infection. However, they're dry and not prone to being infested
   
   
2. Peel pears. Cut in half and remove seeds and core
   No effect other than possibly infecting the pears from hands, tools and surrounding air
   
   
3. Make syrup from water and sugar by boiling the syrup until the sugar is dissolved. Leave to cool
   Sugar has a preserving function due to its dehydrating effect on microorganisms (a later post will deal with this). Sugar won't kill microorganisms, but inhibit growth. If the syrup is thoroughly boiled, microorganisms in the water and sugar are killed. Cooling the syrup is not recommended if it can be avoided (10-40 °C window)
   
   
4. Fill a cold jar with the pears. Fill up with cold or lukewarm, but not hot, syrup
   Warning: we are in the 10-40 °C window. From a microbiological view, the best would be to add hot/boiling syrup. However, this might damage the fruit, such as turning the surface mushy (in the case of plums, the skin would most likely break).
   
   
5. Put the lid loosely on, do not tighten
   Makes sense. During heating, the contents expand and trapped and dissolved air is expelled (gas solubility is lower at higher temperature). The air above the fruit expands when heated and needs to go somewhere
   
   
6. * Place jar in a pot with cold water almost up to the rim of the jar. Heat slowly and keep at boiling point for a certain amount of time (i.e. 8 minutes)
   We are in the 10-40 °C window for quite some time during slow heating. The historic reason is most likely that old glass types had tensions/stress that would result in the jar cracking from shock heating or cooling. Modern glass production methods solve this by i.e. annealing. My experiences with ordinary jam jars is that they manage shock heating and cooling quite well. If the fruit survives, rapid heating is preferable.
   
   
7. * Remove jar from pot and either leave to cool for a certain amount of time (i.e. 15 minutes). Then tighten the lid, or tighten the lid while boiling hot Leaving the jar open at this point is certainly not a good idea. Cooling results in the air above the fruit contracting, sucking in air from the surroundings (see note). Even though microorganisms might die when entering, thermally stable spores might enter which might develop at a later point. Tightening the lid right away is by far preferable. If you use modern jars with aluminium lids that pop down due to reduced pressure inside the jar, this should happen when the jar cools (if you buy a jar of jam and the lid doesn't pop when you open it, return it and get another). If the lid pops up before or during storage, consume immediately («oh, what a disappointment» ;)).
   
   
8. Turn jar upside down and either store upside down or leave upside down for a certain amount of time (i.e. 15 minutes)
   Makes sense. Getting the lid sterile is always a difficult task. Turning the jar lets the hot contents come in contact with the lid, sterilising it getting rid of a majority of the microorganisms present. One might speculate whether keeping the lid seals moist might also be a reason (why wine is stored lying), but a biologist friend of mine meant that the atmosphere above the fruit would result in a moist enough atmosphere for that purpose, and that the sterilising effect of killing microorganisms is the point here. If that is true, it should not make a difference which way the jars are stored.

Remember that operations conducted in a kitchen are far from sterile procedures. For this reason, many such recipes rightfully ask for two and sometimes three actions with apparently the same purpose.

Finally, while hard cheeses with unwanted mould often are safe to eat if the mould is removed by cutting away a layer of the cheese, stored preserves such as jams, sugar preserved fruit and syrups should be discarded if the seals are broken or visible mould is seen. In the cheese, the microorganisms cannot travel due to the dry and solid structure, whereas diffusion is jams etc. occurs rather easily and the whole jar might very well be contaminated even though the visible mould is removed.

What might be learned/taught
Loads of microbiology. However, since I'm primarily a chemist, I won't venture too far into this. To me, taken that microorganisms are everywhere and that they die when they are heated, the most important things to teach would be (again, from the top of my head):

• temperature-volume relationships of gases and gas-liquid relationships (popping lids, see note below)
• critical thinking, don't always believe what you read
  
• working systematically, always questioning why should I do this? (see Five cardinal rules in cooking)

In fact, this experiment/recipe might be among the few cases where one can test and predict something rather complicated based on a very limited amount of knowledge, but are often stated as among the most important treats in enquiry based science teaching (quite a paradox, really). Such situations are scarce, and I'm thrilled every time I stumble upon one.

Erik


Note: Heat expanding air is easily illustrated by putting a blown-up balloon into the freezer; it contracts. Take it out, and it expands back to (almost, at least) original size. However, when the jar contents are boiling, the headspace will in fact be filled by mostly steam from the preserves. When this water condenses (in the closed jar), the volume of the steam (now liquid water) is reduced by a factor of ca. 1300(!), resulting in a considerably lowered pressure.

Addendum (6. August)
some statements about sterilisation are modified as common canning does not result in sterile product (hence the need for preservatives such as sugar, salt, acid/vinegar etc.). This way of canning/preserving more resembles high pasteurization which is common in some milk products.

Can dry ice be food?

During our summer holiday in the United States this summer, I found over-the-counter dry ice in the supermarket. A truly marvelous thing! This opens up a host of possibilities, both in the home kitchen and as a science teacher.

Dry ice is in fact frozen, solid carbon dioxide (CO₂), the «carbonated» part of carbonated drinks. One fascinating thing about CO₂ is that it sublimes rather than melts – solid CO₂ does not melt to give liquid CO₂, but goes directly over to become gas. Hence, the argument of the producer that dry ice can be used as coolant without getting everything wet. Further, the freezing point of CO₂ is -78 °C (-108 °F), and since this is far colder than that of water/ice the cooling power is larger, but you might get frost burns, so be careful (see precautions below).

Uses
The producer gives a number of suggestions for how to use dry ice, such as:

• Cooling: no wet ice – no water, but note that the low temperature results in water condensing on the outside of the container, especially in humid weather. Stays cold longer than water-based ice
• Freezing: ordinary freezing or flash-freezing (very low temperature gives rapid freezing. Stays frozen longer than water-based ice
• Make carbonated beverages: add dry ice into still beverages to get a fizzy drink (they have a recipe for home made root beer on their web site)
• Special effects – fog or witches brew-like effects
  

The product
The dry ice from this producer comes in solid blocks packed in plain plastic bags. You need to bring some insulated box or bag. Size will obviously vary since the dry ice is stored in insulated containers (using freezer is not of any great help since the ice is far colder than the freezer). Hence, the bag is weighed upon purchase, and the older the dry ice, the greater loss from the bag. This is no problem, as expiry date is no question (as long as it is kept pure and away from other products). As it is meant for use in carbonated drinks, it must obviously be pure enough to ingest (not in solid form however, see below).

My experiences

• Dry ice in blocks is quite hard, but brittle. Use a short and hard knife (I used an oyster knife), a screwdriver or similar to chop off pieces. It should also be possible to shave off to get a more powdery dry ice.
• Dry ice curling: chop off a flat piece and leave it on a table or the floor. After a short while it will start floating with almost no friction against the surface, and you can play around with it. Use gloves or touch is only very briefly

Carbonated drinks (the dry ice must be completely dissolved before drinking)

• Using dry ice for carbonating drinks results in a quite different effect from using SodaStream-type carbonated drinks. One tablespoon of dry ice in a large glass gave a slight tingling sensation on the tongue. Using too much, results in a somewhat bitter taste. Using shavings is better than large chunks, as the latter take a long time to dissolve. The dry ice was either added and stirred with a spoon (i.e. juice) or added after the liquids in the blender for icy drinks, smoothies etc.
• I tried making icy drinks (slush) using larger amounts of dry ice, but did not succeed. My approach was to crush dry ice together with ordinary ice. This resulted in a layer of rock-hard ice in the bottom of the blender. In addition, I guess this might damage the plastic container of the blender due to over-cooling.
• Dry ice might very well be combined with ordinary ice. In crushed-ice drinks, add the dry ice after the liquid contents. When using whole ice cubes, mix dry ice with the liquid and add ice cubes. In all cases, stir or blend well after adding the dry ice.
• Previously, I've tried using a CO₂-charged dessert whip for making carbonated apple juice. Squirting the juice out of the nozzle gave a carbonated juice quite similar to the dry ice version (much of the CO₂ bubbles out in the process). Martin’s carbonated fruit seem to be quite different, but that may simply be due to the longer waiting time. Obviously, the dessert whip is not meant to make carbonated drinks as there are dedicated soda siphons on the market. Note that Martin also have a few posts that mention the use of dry ice.
  
• The cooling effect of dry ice is low, slow and very local when added to a liquid. In fact, water ice seems much more effective for cooling drinks. This is probably due to the escaping CO₂ gas whereas water ice adds cold water to the mixture as it melts.

Tested recipes:

• Dry iced ice tea: works ok, but the bitterness in the tea might be enhanced by the dry ice
• Carbonated juices (pina colada mix, cherry mix): works ok
• Smoothies: I tried a strawberry/banana/coconut drink («Coconut Dream») below and it was good with a slight tingling sensation on the tongue

What might be learned (or rather, taught)
There are lots and lots that might be learned in connection with dry ice. A few topics from the top of my head:

• Gases, liquids and solids
  
• Freezing, melting and evaporation/boiling
• Friction and force (dry ice curling)
  
• Acid-base equilibria (see also "naked egg"-resource which is relevant, CO₂ is produced)
  
• Solubility of gases in liquids
  
• Questions about CO₂ itself

See also the Q/A section below.

Precautions
Main point: dry ice is harmless if you avoid ingesting it in frozen state and if you’re careful with skin/eye contact.

Ingestion of solid dry ice may result in severe frost damage due to the low temperature of the dry ice. The same might happen from direct skin contact, but it may be handled if small pieces are thrown back and forth between the hands, minimising the contact time. Textile gloves work well. Upon sublimation the CO₂ increases its volume by 540 times. Ingesting a tea spoon of dry ice would then produce 2.7 l gas in the stomach, which might result in internal injury. Dry ice might damage certain plastic items, varnished material etc., due to the low temperature.

Conclusion
In my vocabulary dry ice might very well fall into the category of food, but this depends on how it is used. Use it as a cooland or reagent in a lab, and it is a chemical. Use it for a somewhat more tingling smoothie, and it’s food.

Finally, I have only explored a few possibilities. I expect that many others are more proficient in finding even more tempting culinary applications than these simple icy drinks and smoothies (as have already been suggested in Martin's and other blogs, follow links and comments at his relevant entries mentioned above).

Erik



A few questions and answers
Q: What is the «smoke» coming from dry ice, either pure or in drinks?
A: The fog is not dry ice, but condensed or frozen water from the air (or the drink). The air above the dry ice is cooled to an extent that water in the air condenses or freezes; miniature snow crystals.

Q: Why is expiry date not a relevant issue?
A: CO₂ is among the most stable compounds around. Hence, it will not deteriorate apart from sublime («disappear»). However, if other products that might give off odour etc. are in the vicinity, these might condense on the surface and the dry ice is increasingly contaminated.

Q: Why do pieces of dry ice float freely on hard surfaces?
A: In contact with a warmer surface, gaseous CO₂ is liberated creating a «gas cushion» between the table and dry ice. The same effect being used in hydrofoil boats and what you see if you spill drops of water onto a hot cooking range. As long as gas is produced in the interface, this «gas cushion» results in almost no friction.

Q: Does dry ice float or sink?
A: In water (or other beverages), dry ice will float due to the porous, and thus gas-filled, structure. CO₂, however, is more dense than air and sinks in air (the CO₂ will escape only slowly in a glass filled with CO₂ gas if it is not stirred)

Q: Is it possible for private persons to get dry ice in Norway?
A: Yes, from producers AGA (retailers, choose «industry dealer» when prompted) and Yara Praxair (retailers) through their network of retailers. However, it seems to be quite expensive, at least compared to the $0.99/lb in US supermarkets.

Freeware for calculation of food ingredients, nutrients, energy etc.

If you can live with reading some Norwegian, this freeware program will calculate whatever you like in terms of nutrient content, energy etc.

Albeit not among the most recent news (at year and a half old), it might be appropriate to comment on Mat på data 5.0 v2 ("Food on computer") which was last year taken over by the public Food Safety Authorities (Mattilsynet) and rendered free. A great step forward for those who teach food&healt in the Norwegian (Scandinavian) countries, and of course others with interest in having a closer look at food and diet.

Study up to three foodstuffs/dishes simultaneously in detail
Just plug in the ingredients and amounts. It even allows for a large number of ready-made/processed dishes and semi-processed foods, and with an impressive detail in varieties of various foodstuffs (i.e. 15 different varieties of potatoes or potato dishes). Whenever you choose a food or dish, you can choose the amount by grams, number (i.e. no. of tomatoes), volume, or portions (i.e. two slices of pumpernickel bread, one glass of milk). The output is energy content and all the different nutrients, both in numbers and graphically (a couple of varieties). A copy-function for exporting to word processing software etc. in included. The screenshots below show information on the following small meal:

• One egg fried in butter
• Two slices of pumpernickel (black) bread
• Five cherry tomatoes
  

Create your own dish and/or meal
If you have a recipe of your own its no problem regiserking this in the database, and you can then compare your own chocolate cake recipe with the one you buy in the supermarket, or compare your modified version with grandma's. Also, it is possible to register a whole meal as one single entity (i.e. your regular breakfast of cereals, milk and cup of coffee).

Analyse/create a week's diet
If you have registered meals (see above), these might be put together to set up a week's complete diet.

Finally, it also includes some general recommendations for nutrient and energy intake based on a person's age, sex, activity level etc.

It may be downloaded for free from http://matportalen.no/Emner/matpadata. English translation (of the download page, not the software unfortunately).

Truly, a gift.

Erik

Back, ...at last

after a long break in order to finish my doctoral thesis, this summer I plan to start blogging again. Lots of energy and creativity to spare now, so hopefully there'll be some contributions before end of summer.

Erik

The first(?) example of molecular gastronomy in music

More music than science lately, but this one is inevitable:
Recently, the improvisational electroacoustic jazz band Food released their fifth record named "molecular gastronomy"!

Furthermore, seeing the track list, I was baffled by the rather specific concepts taken directly from molecular gastronomy (MG), such as khymos (Martin Lersch's blog), spherification and texturas (ref. the Texturas series by Ferran Adrià at el Bulli) and heston (Blumenthal, at The Fat Duck).

At first, I wondered whether this was a joke, serious, or somewhere in between. Qualitywise, this is by no means a joke. Both from previous recordings and this one, Iain Ballamy (sax) and Thomas Strønen (drums/perc) prove that they are among the foremost in their field, no doubt. Other band constellations they are engaged in confirms this as well.

So, is it possible to hear the gastronomy in the music? (ref. previous posts on food and chemistry/food vs. music). That's a difficult question, and I'm not sure whether I should look for it either. My experience with using other senses than my ears as impulse to improvisation is that things become rather banal if one lets the impulses become too evident in the music. One example when we (Quest) played together with the Norwegian poet and author Lars Amund Vaage reading his poems about sheep farmers from the book "Det andre rommet". The one percussion instrument to be extremely careful about in that context, at least in my opinion, was the (cow) bell.

Anyway, I guess taste, aroma etc. are such unfamiliar impulses to use in music compared to visual (i.e. pictures) and text, that the effect of these may be difficult to discern (I'd really love to have a chat with the Food-guys about this).

I'll surely spend time listening to this, food/gastronomy references or not. Strønen is no doubt a favourite in terms of combining energy, cool-factor and elegance. Coupled with the long mellow saxophone lines of Ballamy and keyboards/effects, the result is simply great music.

Erik

Post-comment after more listening, 16. December 2007:
----------------------------------------------------------
After running the album a few more times, the question of hearing the food in the music is still a long shot to me. What is pretty clear, however, is that the music is closely connected to many of the track names; it's easy to relate/associate the music to the words. Examples are the machine like percussion (especially the bells) in "apparatus", the less rythmic and soft lines of "texturas", and the last track "alchemy" which is a synthesis (or maybe a distillate) of several of the other tracks. So, the search for food/gastronomy in music goes on, or maybe it's already there, the fault being in my mind or expectations?


Track list:
----------
khymos
apparatus
red algae
lota
spherification
texturas
nature's recipe
heston
the larder chef
alchemy