bdevidal

Hey, you're preaching to the choir. I drive a British car, I built my own coffee roaster, cold smoker, greenhouse, etc... I'm with you on the ridiculous project thing, but where you lost me is bitching about the price for an NSF certified product that is designed for restaurant kitchens. ← Ah, gotcha. That prob came across as more gripe'y than I intended. I completely understand why a pro-product would cost as much as they do, what with design requirements, insurance concerns, etc. It was just a personal off the cuff remark reflecting my own finances more than anything; there was a moment of "Man, you know how much gear I could buy for 3800 bucks..." What do you drive, MGB? Sprite? Sunbeam? -B

I would disagree with the "no value" part. There are plenty of things that are hard to come by for any price, regardless of pay grade. If all I need is a blender that does what a blender does, I'll go buy a blender. If I need a blender that does something very specific for which there is limited or no market, then DIY it is going to have to be, short of paying someone else to build it for you. And what's the fun in that? The other thing is that, other than personal or monitary benifits, DIYing things (within reason) often provides insights into and solutions for other problems. Or it may spur some new creative idea that hasn't been conceived of before. Or maybe it's just because taking stuff apart is fun. -B

One other thing: That's pretty much (as far as I know) how freeze drying works. They freeze the material, then put it in a refrigerated vacuum chamber. The material stays below freezing, but the low vacuum drastically increases sublimation. When it's done, you're left with a fine dry powder. It's also similar to how they make dry ice. It's cost prohibitive to either generate a cold enough or high enough pressure environment to make CO2 solid, so they compress the CO2 to a liquid state, let the heat of compression dissipate, then suddenly drop the pressure. A portion of the liquid CO2 boils off rapidly, dropping the temp of the rest of the CO2 and producing little solid flakes of frozen CO2. This is then compressed into blocks of dry ice. It's amazing that that process is even remotely economic enough that you can run down to the local grocery store and buy a block for a couple of bucks. -B

You can build yourself an immersion circulator for a couple of bucks also when the real thing is a grand or more. It's a tiny market, the product works, and the product is targeted at restaurant kitchens where building and maintaining some hacked together solution isn't worth the effort. ← I'm amazed at how often that's the case in many different and divergent circumstances. And in some (most?) cases, the hacked/DIY version is as good or better than the commercial equivalent. There's a great tutorial on doing home pressure bagging of composite laminates (like high quality fiberglass mat or carbon fiber) using a vacuum pump based on an old refridgerator compressor. I've been thinking of making my own electric convection oven with all sorts of custom goodies (lower and higher heat range that commercial, integrated rotisserie, larger capacity, boosted infrared for broiling, PID control, etc) and even with those add-ons it would be still be pretty cheap. Of course, such an oven wouldn't and shouldn't be used installed in a kitchen like a normal, UL-listed oven. But that's why there is the great outdoors... -B

Vapor removal has a couple of options. Most pumps are rated in how many CFMs they can move, so I believe that as long as the vapor volume was less than the pumping volume you could establish any vacuum you want. Also, if the vapor volume exceeded the pumping volume, the vacuum would decrease (pressure would increase), the liquid would stop boiling, less vapor would be produced, and the vacuum would increase; I assume it would naturally tend toward equilibrium. Of course, that doesn't address the issue of actually running that water vapor through the vacuum pump, which I assume is not good for it and would immediately re-condense as it hit atmospheric pressure. You would have to set it up like a still, with a boiling chamber and a condensing chamber (ice water) prior to the pump. In fact, part of what got me thinking about this was a discussion on vacuum distillation as a way of reducing the energy input needed to produce ethanol. In practice, you would prob want a desiccant filter between the condenser and the pump just to make sure you're running as little water vapor through the pump as possible. The cooling issue is interesting. In practice, you would want to have some controllable means of introducing heat so that you could control the process all the way up to boiling @ STP (or at least pressure). Stove would work, a PID controller would prob work better. You could do without external heat if you controlled how hard of a vacuum the pump pulled. The pump would vacuum, the liquid would boil (assuming a boiling point below room temp), the liquid would cool to the point that it stopped boiling, the pump would stop at the preset vacuum, the liquid would absorb heat from the surrounding vessel, which would in turn pull heat from the room temp air, the liquid would warm to the point of boiling again, repeat. Now in this case, without knowing how the temp gradient would be distributed in the vessel or the liquid, I'm unsure if it would reach an equilibrium or would oscillate up and down. Plus it would take forever. Have you seen the new (somewhat) design for self cooling beverage cans? They use a two part lower section separate from the beverage. The upper half of the lower section is in contact with the bottom of the beverage portion and is filled with a water gel. The bottom half of the lower section is a vacuum with a solid desiccant. Somehow (still not sure) when you activate the cooling unit the barrier between the two cooling sections is breached, the vacuum+desiccant causes the water in the gel to boil, drawing heat from the beverage and cooling the drink. Still trying to think of some other uses for the above rig... -B

Interesting. I'm fairly certain a DIY version with greater capacity could be made for under 300 bucks or less (much less if you already have a pressure cooker or a vacuum pump). I have no idea how they can charge 3800 dollars for that unless it's just a really tiny market. -B

As an offshoot of the To cover or not to cover thread, as well as my chicken stock post, I was thinking... When is boiling not boiling? If you are boiling (or simmering) to drive off water or concentrate something, you are really doing two things: you are removing water and applying heat. Normally it would follow that one is a direct result of the other. But what if you separate them? Heat, depending on its degree, does more than boil off the water. It breaks down chemical bonds, creates new compounds and flavors, etc. For example, take Fat Guy's example of simmering an uncovered tomato sauce to reduce it and concentrate the flavor. What if instead of applying heat to boil the water (and all the other things heat necessarily does), we removed the pressure? Air pressure at sea level is a little over 14 psi. If we were to drop that pressure down to a little less than a half a pound per square inch, well within the capability of even most cheap vacuum pumps, the water would boil at room temperature. You could concentrate/reduce the sauce without any of the heat effects. You could also vary up and down the scale by simply controlling the vacuum. I have a large pressure canner that I'm sure would hold that kind of vacuum (with a couple of modifications). I'm trying to imagine what you could do with a technique like this that you can't do right now. Anyone have any ideas? -B

...I'm still trying to figure out if I have the guts to run chicken stock through a still... ← Do it, man!! Do it!! ← I'm certainly thinking about it. If it works like other distillation/concentration processes, in theory you could capture everything before the boiling point of water, then boil of the water to concentrate the remaining flavors. Combine the former with the later and you should have something approaching Ultimate Demi Glace. -B

You're half right. Water takes *less* time to boil (visually) at higher altitudes (i.e. lower atmospheric pressure) but the things being boiled take longer to finish, since the boiling temp of the water is lower at higher altitudes/lower pressures. This link will not only tell you the boiling point of water at your altitude, it also includes a correction for current barometric pressure. -B

Perfectly clear might be hard; what you gain in low agitation you loose somewhat in the lack of "scum" formation, which normally aids clarification. I would say my stock came out to "servicable clarity", with most of the turbidity from fine particulate matter and not from completely emulsified whatnot, and that was just through a corse sieve. Of course, there's nothing preventing one from doing a cold gelatin clarification on the product. -B

You can seal them on the "seal only" setting. Just don't try to suck the air out... ← Actually you can't (at least the turkey roasting bags). The turkey roasting bags are made of BoPET (aka Mylar). The property that makes it perfect for a roasting bag (stability at high heat) also make it very hard to heat seal. When used in commercial food packaging, it's actually combined with polyethylene to make it sealable. Of course, you can use the same process with actual sealable vacuum bags, should work the same way. If necessary, you can freeze the contents with the water, then vacu-seal it. But this does have a couple of problems: -Vacuum bags are boiling rated but not oven rated, so you would have to be very careful about oven temp -Since you have to seal it, you can't use the pre-boiled water method. This means you have to bring it up to temp in some other way, preferably a large boiling water bath. The contents have to be hot before you put it in the oven because a low oven would take forever to bring it up to temp (danger zone), a higher temp will compromise the bag either through melting (vacu-bag) or through gas expansion/steam pressure if you overshoot (both bags). If you do it in a water bath, you have to make sure that the bag is suspended off the bottom of the pot or the bag will melt (from contact with the metal w/o the water). Then once at temp, you would either have to put the entire water bath vessel + bag in the oven, or pull a now boiling multiple gallon bag out of the bath and into another container. Don't forget, vacu-bags are boiling rated but they also lose most of their structural integrity around that point (become "stretchy"). -For a fair amount of stock, it would get pretty expensive. As far as the roasting bags go, I double bagged it, but I didn't notice any leaks. There were a couple of tablespoons of liquid in the stockpot when I pulled out the bags (did I mention how easy the cleanup was?), but it did not smell like stock and may have just been condensation of some sort. When emptying the stock, you just fold the bags over the rim of the stock pot and either ladle or pour out the stock; the bag is just the seal with the stockpot doing all the support. The only two things I can think of to be especially careful with are to make sure the oven doesn't go much over 200F (check with actual thermometer, not dial; >212F+water=steam, steam=pressure, pressure=bag that goes pop) and to be careful about sharp bones from the chicken or whatnot. -B (EDIT: It appears I may be mistaken on the makeup of the bag material. It looks like there may be both BoPET and Nylon roasting bags, but I don't know enough about polymer material sciences to say if BoPET may be a subset of Nylon and/or if they are using the word "Nylon" in a non-standard way. I'm still pretty sure, given their heat resistance, roasting bags of either sort won't be heat-sealable with a consumer sealer.)

It's important to remember, though, that "uncovered to concentrate" will only work with things that have have a higher boiling point/vapor pressure than water, assuming water is the main liquid. So generally yes to solids, no to some liquids and most volatiles. For example, boiling salted water will concentrate the salt, but no amount of boiling of an alcohol+water mixture like beer would concentrate the alcohol. I'm still trying to figure out if I have the guts to run chicken stock through a still... As far as cloudiness, absent bone taint, that seems to be normally a function of turbulence rather than a direct effect of covering. Uncovered pots have a greater heat gradient (hot bottom, cool top) than covered pots, which makes it much easier to tune the rangetop to a bare simmer. I can do it with a big enough pot, but it is right at the flare-out point on my gas range. That's one reason I really like the oven method. Bring pot up to temp or fill with boiling water, then put in low oven (180-200F). Even heat, low turbulence, unable to boil as the heat never goes over 212F, and dead easy to set. No skimming, no futzing, easy overnight stock -B

I actually haven't found a reference sample yet, but the corned beef layoff helped. For most of the experiments, I did smaller samples (say, a six pound semi-trimmed flat cut into 6-8 pieces); I only did larger pieces when I already knew I was happy with the results or I was trying to track down a cure penetration issue (grey stripe in the middle = not enough cure penetration; harmless but unsightly). But yeah, it was a lot of corned beef -B

I think that there is no "right" right answer; it will all depend on application and context. A mostly bone stock will be different from a mostly meat stock, a stock intended as mostly a moistening ingredient (or "water++") will need different characteristics than one intended for a consumee, and the requirements for a small stock at home will differ from a universal stock in a restaurant kitchen's steam kettle. You're right, not everything that calls for chicken stock needs to taste formost like chicken, but it's a lot easier to start with the flavor and then pull back than it is to start without the flavor and then try to add it later (I suspect you could dilute this stock if necessary, or if you needed to retain the mouthfeel, you could simmer it for a little while before adding it, but intentionally driving off the Essence of Chicken makes the baby Jesus cry ). -B

After a bit of a layoff, I've started a new round of corned beef trials. My new version is the best yet, and the secret winning spice that I couldn't figure out last time is......dill seeds! I added ~3Tb of whole dill seeds to the 2.0 recipe and it made a world of difference. As soon as the cold weather starts rolling in, I may try a few more variations (next up on the list is juniper berries) -B