I have been camping out in a hotel for a month and a half, and in order to still enjoy my whole leaf tea, I have my Teavana Tea Steeper and a small hot water heater. Local tap water here in Cincinnati is rather foul (my apologies on multiple levels to Cincinnatians), so I have been buying cases of bottled water for me tea brewing.
A couple of weeks ago instead of buying my usual case of spring water (no brand preferences), I went and bought a case of Niagara “purified” water, which appears to be pretty much pure water with nothing in it. I thought that would be better for my tea making, and certainly better for my hot water maker (which was constantly getting crusty with white mineral residue from the spring water I had been using).
However, over the last week I have noticed that the purified water produced much paler and weaker flavored teas (also lacking in aroma). This result applies to all the teas I have tried, but for me has been most apparent with green teas. Increasing the brewing times or steeping temperature makes no difference.
Today I switched back to spring water (Ice Mountain brand, in case that’s of interest), and voila, flavor and color had returned to my brewed teas, at normal brewing times and temperatures.
So, what I take away from this accidental experiment is that apparently a bit of alkalinity and mineral content is necessary for the water to release the full flavor and color of the tea. Interesting thing to learn.
I did some online research about the subject and came across this article (which is experiential, and not really scientific, but interesting nonetheless) – Water for Tea.
In any event, I have learned my lesson, and while the purified water resulted in a much cleaner hot water pot, it’s not something I ever want to voluntarily use to brew tea again. I’ll suffer with mineral residue in the pot in exchange for better tea brewed with spring water.
This morning’s kitchen science experiment was making hazelnut caviar. More specifically, caviar using hazelnut syrup (sugar free, of course). It involves using sodium alginate and calcium chloride, but I will save the details for later.
For now, let me tease you with a photo:
Why, you might ask, is the caviar green? The short story is that we weren’t sure the process was working because our hazelnut syrup, water, and sodium alginate mixture was almost the same color as the aqueous calcium chloride bath, so we wanted to add some color to make the process more visible. Green food coloring was the closest food color at hand.
Suffice to say that the above pictured caviar and pearls release a rich sweet hazelnut flavor when you chew them.
While we normally don’t eat large quantities of bananas because of the high starch and sugar content, we occasionally make exceptions for finger bananas, so on an impulse last week, when I encountered bunches of them at a local market, I bought one bunch (about 20 bananas). Initially they were still a bit green, but as the week progressed they continued to ripen, and we were just not eating them fast enough.
Faced with the prospect of possibly having to throw them out, I remembered that some years ago I bought a dehydrator with the intent of making beef jerky. Intent and reality never collided, and the device sat in our storage room collecting dust. Until now, as I realized this would be a perfect way to save the bananas from premature extinction.
It was a match made in heaven.
What a dehydrator does is blow warm (or hot) air down over trays of food. The warm air evaporates or dehydrates the moisture from the food, effective drying it out. Very simple process. The particular dehydrator I had was made by Open Country, targeted primarily at folks who hike around a lot and want to carry food with them that weighs less than normal (considering I probably bought this at a outdoor sporting store, it makes sense).
After carefully reading the manual, I sliced up all the bananas, placed them on the dehydrator’s trays, set the dehydrator’s temperature to 135°F (the temperature suggested for fruit) and let the device do its thing for the next 8 hours, after which we had dehydrated banana slices.
The dehydrator, as part of the process of forcing moisture out of food, ends up shrinking the food item being dehydrated, which in turn concentrates the flavor. So, the dehydrated banana slices were sweeter and more flavorful than regular moist bananas.
I felt inspired now, having realized how stupidly easy it was to use the dehydrator. So, next I got some lean roast beef (raw), sliced it in quarter inch thick strips against the grain, and then marinated it for half a day in a mixture of ketjap manis, sambal oelek, garlic, vinegar, and water.
I then dehydrated the beef for eight hours at 155°F (recommended for meat), and voila! Beef jerky! After it cooled, we found the beef jerky to be a bit drier than desired. Next time I think we’ll try for 6 hours and see if that makes it a bit moister. But it tasted great, and there was no question that it was fresh beef jerky.
My next effort was to make low-carb chips using daikon radish and eggplant slices, using the dehydrator to eliminate most of moisture so I could more easily fry the slices in my fryer. That worked moderately well, but the four hours they spent in the dehydrator were again a touch too long. What was interesting was that the daikon radish also got bitter after being flash fried, but was incredibly “radishy” tasting out of the dehydrator.
Yesterday we found fresh strawberries at our local market (not a common occurrence here on Bonaire – we’re usually stuck with frozen berries), as well as fresh blueberries (an even rarer happening), so we sliced up one box of strawberries, put them on the dehydrator trays, and dried them out. Krystyana added a handful of blueberries to one of the trays too.
Again, four hours was too long for the strawberry slices – they were completely dry, but powerfully flavored. I plan to take advantage of that dryness to make a potent and flavorful strawberry powder in my blender. The powder can then be used in cooking, as an additive to yogurt or cream, or anything else a strawberry-loving heart desires.
The blueberries were in for 13 hours, and were still overly moist and kind of bland – no doubt due to the fact the skins have not been punctured to assist the escape moisture. I don’t think we’ll try whole berries again. Cutting them in half might have been better.
The kids devoured the original batch of beef jerky, so last night we worked together to marinate two batches of beef – one in a chipotle, brown sugar, chili powder, garlic, and vinegar marinade, and the other in a lemon grass, cumin, soy, brown sugar, and fish sauce marinade. They went in the dehydrator this morning, and four hours later the thinnest slices were ready, and all the meat was properly dried (not overly so) after six hours. Both were delicious.
The kids are already talking about what flavors of jerky they want to make next. And in the process both have been learning about better knife use as well as selecting appropriate cuts of beef (for jerky it should be quite lean).
The manual for the dehydrator also suggests that you can dehydrate sauces like spaghetti sauce for later hydration, or something like apple sauce in order to make a fruit leather that can be rolled up in wax paper and eaten later as a snack. We might try something like that soon.
If you don’t have a dedicated dehydrator, you may be able to simulate the results using a convection oven which can be run at lower temperatures.
As mentioned in my previous postings about sous vide cooking, my own adventures and exploration of sous vide started with the noble egg. Eggs are a wonderful natural food, and for those of you interested in the specifics of an egg’s composition, characteristics, and cooking, I again have to recommend Harold McGee’s “On Food and Cooking, 2nd Edition“, pages 68-117.
I still recall my first encounter with a sous vide cooked egged in a restaurant a couple of years ago, and after trying it I was in gastronomic heaven – the whites were like a soft, delicate custard, while the yolk was thick, rich, and gooey. I could not believe that I had simply settled for chewy, poorly textured, and mediocre eggs all my life. But if you don’t know about alternatives, you never know what you might be missing.
I personally am a huge fan of liquid yolks, and prefer my traditional eggs over easy or poached, and so my first sous vide cooking foray was to make the perfect soft-boiled egg.
McGee explains that egg whites and the yolk are composed of a variety of different proteins, all of which coagulate (solidify) at different temperatures, with the proteins in the egg whites thickening at higher temperatures than the egg yolks. He indicates that egg yolks tend to thicken at around 150°F / 65°C, and the various proteins in egg whites thicken at temperatures ranging from 145°F / 63°C to 180°F / 80°C.
Experiment #1 – Eggs au Naturel @ 64°C – Failed
My first attempt involved just putting the eggs in a water-bath at 64°C to get still runny but nearly solid yolks. Turns out it was a bad idea to put the eggs in the water directly, as they cracked slightly from both the temperature and from bouncing around as a result of the current caused by the immersion circulator, gumming the immersion circulator up with wisps of egg white as a result. I managed to get it clean, but it provided a great first lesson about cooking in a water bath – make sure that your ingredients are sealed away from the water to ensure the water remains clean and pure.
Experiment #2 – Eggs Sous Vide @ 64°C – Better
For the next experiment in cooking eggs sous vide, I actually used sous vide – I vacuum sealed the eggs to prevent them from cracking into the water bath and gumming up the works.
Here too I learned something. Normal sized eggs are less likely to crack when you vacuum seal them into a bag than bigger eggs. I assume that’s because big eggs are likelier to have thinner shells. I learned my lesson quickly, and only cracked one egg out of the dozen or so I used during my experiments.
One of the interesting things about cooking in a low-temperature water bath is that for most things, as long as your temperature is within a proper range for the thing you’re cooking and you have reached the point where the food has reached the target temperature throughout, you can cook the item for a wide range of time and still achieve the same result. Thus, the result of cooking an egg at 64°C for an hour is not hugely different from cooking it for three hours or five hours. The same applies to many meats in my experience.
With that in mind, I cooked my sous vide eggs at 64°C for around two hours. When I took them out of the bath and cracked them open, I found the yolks were unfortunately a bit more solid than I would like, but the whites had that wonderful light custard texture. The rest of the family agreed the yolk was too firm, and found the whites a bit runny.
Experiment #3 – Eggs Sous Vide @ 63°C – Perfect Yolks
Undeterred, I sealed up some more eggs and cooked them for a couple of hours at a slightly lower temperature – 63°C. The result was the whites were a wee bit runnier, but still like a delicate custard, and the egg yolks were perfectly cooked – gooey and rich but fully cooked. However, the rest of the family was still not wild about the consistency of the egg whites.
Experiment #4 – Long-cooked Eggs @ 70°C
As I was curious about the effect of long cooking of eggs to see whether time really doesn’t make a difference, I also cooked some eggs at 70°C for about 10 hours while I was experimenting with cooking pork ribs in the water bath at the same time.
The yolk was firm, but creamy, and the whites less runny but still delicate. This inspired the next and final (for now) experiment.
Experiment #5 – Separately cooking the whites and yolks
For the final egg sous vide experiment, I took eight eggs and separated the whites and yolks into two cooking-safe bowls. While I am certainly capable of separating whites and yolks using just the egg shell itself, I find I am more productive with a dedicated separating device as pictured below. Plus, it’s cute. Trick to using it properly is to slide the egg innards into the device instead of dropping the egg insides onto the device, as the drop creates enough force that the egg yolk membrane might burst.
Once I was done with separating the eggs, I vacuum sealed each bowl. Another two lessons learned here: First, use bowls or jars that leave about one-third of the top empty – do not fill them to the rim; and second, don’t seal to maximum vacuum – 85-90% vacuum (or 150-100 millibar or so) should be sufficient. Not having known these things, I found my whites and yolks sucked a bit out of the containers during the vacuum sealing process, which in turn burst a couple of the yolks. Fortunately burst yolks still taste good.
Both were cooked for about an hour at 63°C (to cook the yolks just right). The yolks were then removed along with enough water to keep them warm while the whites got cooked for another hour at 70°C.
Result? The yolks were great, of course, and the whites far less runny – just like when I long-cooked the whole eggs, but still custard-like, and most importantly, more to my family’s liking.
However, when we are next up for another egg sous vide experiment, we may try the whites at somewhat higher temperatures to see if that makes a difference, since coagulation of some of the egg white proteins is not complete until around 80°C.
I spent a couple of weeks last month performing experiments in my kitchen using a cooking technique known as “sous vide” (means “under vacuum” in French).
In sous vide cooking you generally vacuum seal (or use inert gases to supplant oxygen) foods and then cook them for a long time at low and consistent temperatures (typically in the range of 50-72 degrees Celsius / 122-158 degrees Fahrenheit).
Sous vide cooking is quite equipment intensive, as it requires, at a minimum, a decent vacuum sealing device, and a way to cook at specific temperatures with a high degree of accuracy (.1 degrees Celsius accuracy is desirable). While there probably are some passable low-priced solutions, if you’re serious about doing a wide range of sous vide cooking at home, I would strongly suggest budgeting about $5,000 for the two key components you will need – the vacuum sealer being one, and the other discussed below.
The common way to achieve the accurate temperature needed is via a device known as an thermal immersion circulator, placed in a water bath. The immersion circulator sucks in water, and then jets it out, heating the water in the process. A highly accurate thermometer built into the immersion circulator is used by the device to ensure the water is not over-heated, but instead kept at the exact temperature programmed into the device. Thermal immersion circulators originated as a piece of laboratory equipment for chemical and biological work, and the original idea to use such a device stems from the “bain marie“.
For my kitchen, I had invested in a C-100 vacuum sealer from Multivac, based on a recommendation and contact information provided by Wiley Dufresne, chef at wd-50, New York’s landmark molecular gastronomy restaurant (although they call it “New American” cuisine on the web site).
Interesting side note: Unbeknownst to us, Wiley sat behind us at a presentation on cooking with liquid nitrogen in New York City about 16 months ago, and by coincidence recognized us from that class when we dined at his restaurant the following night. Wiley invited us into the kitchen for a tour after dinner to show us his modern kitchen and equipment, including containers with all of his “ingredients”, and described some of the cooking techniques he uses. All I can say, other than “Thank you Wiley!”, is that you should not miss an opportunity to try wd-50 the next time you’re in New York City!
A web site on sous vide pointed us to some sources for immersion circulators. We ended up going to the Cole-Parmer web site, which offered a number of options for immersion circulators. I opted for the TechneTE-10D (pictured further above), which features a digital display (and settings), and also a screw clamp which can be used to mount the immersion circulator onto a large pot which holds your cooking medium (water), and which is turn is used to cook your vacuum sealed bags of edible goodness.
Sous vide, as a form of culinary artistry, is still evolving. Its origin in food preparation came from a desire to seal food away from the things that cause it to go bad, such as oxygen and the bacteria that need oxygen to multiply (although there are anaerobic bacteria that could cause problems). At some point someone tried cooking vacuum sealed food while still in the plastic bag and found it could make a dramatic improvement in juiciness, as well as retention of flavor and nutrients. Part of that is because the food is not exposed to air while it cooks. Air will oxidize meats and change their color (brown, typically) and flavor, and similarly, vegetables will lose flavor when cooked in water, steam, or in a pan with fats of any sort.
However, in a vacuum, that’s not an issue – the meat cooks in whatever marinade you have it stored in, as well as its own juices, which would otherwise evaporate. Further, by being able to cook meat and other foods at exact temperatures, you can select the proper level of done-ness throughout instead of the temperature variations that oven-based cooking produces – namely higher heat and thus dryness on the outside going into the meat, and cooler temperatures and less done-ness inside at the center.
What I find fascinating about this process is that it combines science with food, as you need to learn and know at what temperature various foods change states. For example, the proteins in egg yolks firm up at just around 65 degrees Celsius (149 degrees Fahrenheit), but the several different parts of egg whites coagulate at different temperatures, both higher and lower than the egg yolk. And beef is a perfect medium rare (as far as I’m concerned anyhow) at 54.5 degrees Celsius (130.1 degrees Fahrenheit).
One of the cautions with sous vide cooking is that the same low temperatures at which you cook meats are the same temperatures at which bacteria thrive, so if your food source or preparation are not properly hygienic, you could be breeding organisms which lead to food poisoning. There are a number of ways to minimize or remove the risk, including thoroughly cleaning and washing foods before sealing them, searing the outside of meats at high heat in a broiler or pan to quickly kill off any unwanted guests, or using alcohol in your sauces or marinades. More details on this subject can be found here.
A book I am reading about Sous Vide right now which promises to be excellent (and some say it’s the “Bible of Sous Vide”) is the difficult to obtain and unfortunately expensive ($160 and up) “Sous-Vide Cuisine” by Joan Roca and Salvador Brugués. I bought mine here. Thomas Keller of French Laundry and Per Se fame also has a book out on sous vide cooking, “Under Pressure: Cooking Sous Vide” which has some fascinating recipes but does not really address basic sous vide experimentation. And finally, no discussion of food science would be complete without a recommendation of Harold McGee’s most excellent “On Food and Cooking, 2nd Edition“.
In order to not make my posts novella-length, I’ll address actual sous vide cooking experiences in another entry to be posted early next week. For now, let me leave you with a photo of a sous vide cooked egg – creamy, custardy whites with a thick gooey full-flavored yolk. Trust me. It was delicious.
Nice article over at the Boston Globe on how Jell-O works, explaining the science of food.
This same sort of food science is what is a core component in the fascinating field of molecular gastronomy, but that will be a subject of other posts in the future.
One thing I found interesting in the Boston Globe article, however, is that if you put certain fresh fruits, such as papaya, in gelatin, the gelatin won’t set. That’s because papaya and pineapple, among other fruits, contain enzymes which break down protein. Which is also why papain, a papaya enzyme, is helpful in reducing the sting of jellyfish and related stinging organisms – the papain breaks down the proteins of the stinging toxins, rendering them inert. Food as a type of medicine. Cool!