nathanm

Just about any gel can be made into a fluid gel, although some are better than others. Most gels are "thixiotropic" - also called "shear thinning" or "shear dependent viscosity" or "non Newtonian" - because their viscosity (thickness of the fluid) depends on shear, and typically "lets go' and at some threshold value. Here is background on this http://bizarrelabs.com/slime.htm Making a fluid gel involves either applying shear while the the gel sets (and thus preventing it from setting normally), or letting it set and then applying shear. You also need the right gel strength, and that depends on gel concentration, solid percentage, pH, ion concentration..... Here are some references on fluid gels. http://www.foodproductdesign.com/archive/1995/0195CS.html http://www.foodproductdesign.com/archive/2005/0505CON.html http://www.findarticles.com/p/articles/mi_...164/ai_17551651 Here is a good overview of hydrocolloids http://www.foodproductdesign.com/archive/2002/0602AP.html http://www.foodproductdesign.com/archive/1999/1299ap.html Here is a discussion of the Orbitz drink previously mentioned http://www.chemistry.org/portal/a/c/s/1/ac...rp1_orbitz.html Gellan is one example of a hydrocolloid that has this property, but agar, xanthan and others do too. Most of them do, and under the right conditions you can make a fluid gel from any of them. However, some are better than others. You typically do need a bamix or very high speed mixer to make a fluid gel, although that depends on the gel. I suppose that a weak enough gel could be converted with an ordinary stand mixer, but not in my experience. Even if you don't need one to make the fluid gel you need a high speed mixer to hydrate the gel in the first place. These hydrocolloids are usually not easy to dissolve and hydrate smoothly without a lot of shear. Immersion blenders like Bamix are great for this. Laboratory style homogenizers, or colloid mills are better yet. Certainly that is true with gellan and agar - both of them, as well as many other gelling agents can be turned into a fluid gel. This requires control both of the gel concentration and amount of shear. Most hydrocolloids (including gellan, agar, xanthan, caregeenan) are polysaccharides - i.e. long polymer molecules related to sugars. Note that many of them are metabolized by the body as fiber rather than as a carbohydrate. Here is a description that I excerpted from a Unilever patent (patents are public domain documents so excerpting this is allowed). This covers the issue pretty well: ====================== However, it has been discovered that when a sufficient amount polysaccharides or their derivative gelling agents such as Carrageenan or agar were dissolublized in the surfactant solution and hot solution is allowed to cool to room temperature, the surfactant solution will set to form a range of gel textures. These gels are stable at room temperature but can be remelted by heating above the gel temperature. On cooling the system will re-gel. The formation of gels by natural polysaccharides arises from the physical interaction between the polymer molecules. Hydrogen bonding is usually the major cause of the interaction. For a detailed description on the formation of gels in these types of polysaccharides see R. L. Whistler and J. N. BeMiller, Industrial Gum: Polysaccharides and their Derivatives, Academic Press, 1993. The gel will possess a strength dependent on the strength of intermolecular bonding. If the bonding is weak, it may be broken and the total gel structure disrupted by mild stirring. In this case, the weak gel is said to be thixotropic. When the intermolecular bonding is strong enough, a more identifiable gel forms that may not be easily broken by stirring. Once the gel is formed it may be strong enough that when under applied stress, the gel will separate or cleave as seen with gelatin gels. In some polymeric systems, once a gel is formed, the polymer molecules can further rearrange themselves by sliding over each other or simply moving together to strengthen the overall physical network structure which will cause a decrease in the water-filled spaces between the molecules. Hence water is exuded from the gel to produce a phenomena which is commonly know as syneresis. During the cooling process if the polysaccharide surfactant solutions are subjected to shear either during or after the gelation process, the application of shear will disrupt normal gelation and result in a "fluid gel" that is pourable and cannot hold a shape (see G. O. Phillips and P. A. Williams, Handbook of hydrocolloids, CRC Press, Woodhead Publishing Limited, Cambridge, England, 2000). (the patent is on a kid's shampoo made with a fluid gel http://appft1.uspto.gov/netacgi/nph-Parser...=DN/20040097385 ) ================ The hydrocolloid handbook mentioned above is a good book on the topic, available from CHIPS books. Most of these gels will NOT whip or retain bubbles when they are in the proper state to be turned into a fluid gel. So that is not really a concern. I am doubtful that it could be a concern, frankly, but I suppose it is possible. Note that very high speed shear rips the gel apart and will not allow bubble formation. Gellan has a lot of properties other than being able to be made into a fluid gel. Thermoreversability is different than just melting - to be thermoreversable the gel needs to be able to set AGAIN (as per the passage above). Gellan can do this, but not always -it depends on whether you have high acyl or low acyl gellan, and also on the ion concentration. High acyl gellan is fully thermoreversable, under the right conditions (concentration, pH etc). Low acyl usually isn't. Wylie uses low acyl in his fried mayonnaise - it is NOT a fluid gel, and is not thermoreversible. Note that it is typical that the temperature for gelling is often different than the melting temperature (typically 35C gelling for agar, 85C to melt). Other issues include gel texture (rubbery and "soft", brittle or "hard"), syneresis, flavor release etc. Gelatin is a protein polymer that can cross link in a manner very similar to the polysacchride hydrocolloids. WHen I said "jello in a blender" I was clearly speaking very loosely. However, you CAN make a fluid gel from gelatin - you just have to keep it below melting temperature, and have a weak gel to begin with. The degree of shear-thinning and the thixotropic threshold is not as strong as it is with others, so it is less interesting. You can also make fluid gels from other cross linked protein gels, such as the egg custard case that I mentioned in a previous post.

Fluid gels are made by taking a gelling agent or gum (gellan, agar, or other hydrocolloids), hydrating it, letting it set, then shearing it to break the gel structure. You can do it with many gelling agents - I've even made fluid gels with egg custards - you heat the egg custard until it JUST starts to set then you shear it. Shear means mix with a device that produces high shear (side to side) forces - i.e. an immersion blender. In food labs or commercial production you would use a colloid mill which can generate far higher shear forces than an ordinary kitchen blender or immersion blender. However, the kitchen version will do. Many gels have the property that their viscosity (thickness) depends on shear forces. Which means you can have something that seems set like a gel, until you shake (or otherwise produce shear forces) at which point it instantly thins and pours like a gel. Fluid gels have this property to a high degree. There is a bottled beverage called Orbitz that has small colored "beads" of one gel, that are suspended in a clear liquid fluid gel. The beads stay put while the bottle is on the shelf, but when you go to drink it, it pours. Orbitz is made mainly of gellan, but I think there is some carrageenan (another hydrocolloid gum) in it too. This is all a high tech way to say that fluid gels are basically Jello put in a blender.

Nitrate generally acts as a preservative - both sodium and potassium varieties are used in meat products. It generally is food safe in the small quantities and concentrations you are using. You could probably order some from elsewhere - or send a sample of yours out for analysis to check quality. I agree with your chef de cuisine that exposing the fois gras to the air can't help matters. Whether it is the cause or not is another matter. Have you tried brining with water instead of milk?

Wow, I have wanted to get a freeze dryer for years, but I don't have one. I looked on ebay but never found that looked right. Presumably you have one of the medium sized units that is used for dried flowers, taxidermy etc - those are most common on the market. Lab supply places have very small ones for scientific samples. Food oriented freeze dryers tend to be factory sized. You should try: - Anything that you would put into a conventional dehydrator. It will taste and look different. - Reduce flavored liquids to powder (like in freeze dried camping food). - Strange things like freeze dry some ice cream... - As with a conventional dehydrator, the thinner it is, the faster it will dry. - Anything with too high a fat content may give some problems because the oils or fat will not evaporate, only the water will. - Some things will get too hard to eat. So, for example, taxidermists these days use a freeze dryer to dry whole animals (squirrels, and even larger) instead of skinning and stuffing them. They come out as dry and hard as lumber. So, if you try to freeze dry a steak or roast, expect to break a tooth eating it.

This is the Lauda website http://www.lauda.de/hosting/lauda/website_...iebsanleitungen It is in English, and it has various manuals you can download. Even if it does not have the exact model, you can probably find a similar one.

Induction is great - I have used it for years. As per other posts, there is no radiation issue to worry about. In fact it is safer than gas due to lack of explosion risk, burning risk and combustion products from gas. One point that hasn't been made is that the kitchen stays cool - you are not pumping hot air from the flame around the room. Only the pan gets hot. This dramatically reduces kitchen heat, and reduces the amount of air your hood has to draw away. The 10 step control that FG mentioned is much more accurate and repeatable than a continuous adjustment on a gas flame, so I don't see it as a disadvantage. The simple test as to whether a pan will work on induction is to see if a magnet will stick to it. If it does, then induction should work. This includes a lot of older pans, but certainly not all. However,

I have had it served to me in restaurants, but I don't have the time/temperature for it. I would start at 45C / 113F Nathan

Flatiron steak is called "paleron" in French. Works very well sous vide. I do 131F / 55C for 24 hours

I have a general rule - whenever somebody talks about "impurities" or "toxins", I am highly skeptical. Both terms are used as a catch all for unknown things presumed to be bad, often without any evidence. Just what is is "impure" about stock scum? It comes from the chicken or other meat, just the same as the other components do. It is mostly various coagulated proteins, along with some fats. It is no different in principle from other proteins and fits in the meat. Skimming scum is purely aesthetic as far as I can see - there is no flavor problem. Scum can be removed later by filtering the stock through a coffee filter, or even a very fine tamis.

Smokers like Doc-G are using use small wood chips which are burned on a hot plate smoke generator. Generally they smolder at fairly low temperature (under 600F) and do not produce enough nitric oxide to create a smoke ring. In order to get a smoke ring you need to burn at a higher temperature - either with solid wood, or pellets or another source which is really burning (600F to 750F usually). Note that I am talking about the temperature of the actual combustion, not the temperature of the air around the meat! Air temperature in smokers is usually below 225F. The high combustion temperature produces nitrogen dioxide gas that penetrates the meat and creates the smoke ring. It works best if the meat surface is moist, and as a result happens early in the cooking process. Here is an explanation by a meat scientist at Iowa State University. There are two points of view you can take on the lack of the smoke ring. On one hand, the smoke ring is traditionally used to judge the quality of the smoking in barbeque contests and the like. So from that standpoint a smoker that does not produce a smoke ring may seem inferior. On the other hand it is not clear to me that it is really necessary for flavor - I am not sure you could tell the difference if you tasted blindfolded. It would be interesting to find out in a carefully controlled test. It is possible that you can taste the smoke ring in the final product, but I think it is equally possible that the smoke ring is more of a by-product that is diagnostic of good barbeque technique rather than something you can taste. Unfortunately one aspect of the barbeque world is that peolpe often seem to have strong opinions about what is true and false, but don't always have strong evidence to back it up. This site by the "Dr of BBQ" claims that it is purely aesthetic. Propane or gas fired grills can produce a smoke ring without any wood whatsoever, because nitrogen dioxide can be formed in propane combustion. This tends to argue that it is not as important as people think. Note that I have both kinds of smokers - one that produces a smoke ring, and one that does not. I have cooked on competition barbeque teams, and I am very familiar with what barbeque is supposed to taste like. The red smoke ring in the meat is similar chemically to the red color in meat cured with sodium nitrite or sodium nitrate (also known as prague powder, tender quick, curing salt, pink salt). These curing salts do produce a pronounced taste in fully cured meat - the taste of cured meat (i.e. ham versus pork, summer sausage versus fresh sausage). However is not clear to me from what I have read whether the cured taste of curing salts is related to color change - i.e. nitrogen dioxide gas and curing salt both create the color, but the cured meat taste has more to do with the concentration of the curing salt itself and its interaction with the meat proteins, not the chemical reaction that causes color change. You can use curing salts to create a smoke-ring like effect, and many people do that for barbeque. Purists regard this as a "fake smoke ring".

I don't have any concerns about propane per se. Obviously, one can worry about nearly anything with respect to health because there may be some subtle effect. However the dominant effect here is that high temperature browning of meat REGARDLESS of the method (griddle, grill, gas, electric) can create compounds that are known carcinogens. Note that this is not the malliard reaction per se, but rather if you get it very brown/charred. Singling out propane is a bit weird when there is no proof that propane is a problem, and plenty that over-browning IS a problem. Personally, I don't worry about that either. But if I did worry, then I wouldn't be doing any sort of high temp browning.

Evaporation is a real concern, especially at higher temperatures. I usually cook at low temp, but something like duck confit or carnitas won't have the right texture unless it is at 180F or so. The best answer to water bath evaporation is to have a lid - that basically solves the problem. I suppose one could set up a system with a water hose and a float valve (like in a toilet tank ) but I don't know anybody who does that.

Most information on food safety is just flat wrong, first because it focuses only on temperature (what matters is both time and temperature), and second because it is insanely conservative. "Authorities" tend to worry that people will get sick so they add huge safety factors making the temperatures excessive. The place to look is at the US FDA (Food and Drug Administration) technical memo on cooking regulations for poultry products. FDA is the primary agency responsible for acutally regulating things like food saftey. Other agencies, like USDA (department of agriculture) wil make recommendations, but they have neither extensive technical expertise nor do they set standards enforced by law. The FDA does. So, the FDA is the US Gov't expert in this are and here is the relevant FDA document. What it says is that you can go as low as 136F for Turkey - but you have to hold the turkey at that temperature for a minimum time, given by tables in the document. Note that even this is very conservative becaues it is for products that are stored under refridgeration for weeks after cooking (i.e. sliced turkey cold cuts). Food for immediate service is far safer than this.

For rare duck breast I would go between 124F/51C and 130F/54.4C

Collagen and connective tissue is in joints and bone, but you don't want to eat those things! They are useful if you want to turn collagen into gelatin for a rich stock or aspic. Collagen is also found in tougher cuts of meat - and that's why they are tough.

The best cuts of meat to improve with long sous vide cooking are cuts which have lots of flavor, but normally are tough due to having too much collagen. Short ribs are an example; flat iron steak is another. These cuts tend to be served braised well done via normal cooking in order to tenderize by converting collagen into gelatin. With sous vide you can in effect "braise" them at much lower temperature so they can be medium rare. Other tough but flavorful cuts are the ones to look at for doing this. The problem with eye of round is that it doesn't have much going for it in flavor (or fat content). It does not have a lot of collagen either. Sous vide can improve it to some degree, but can't overcome the inherent limitations.

My Synesso Cyncra was installed yesterday - 1 group, 220V. So far it is working great and I am getting used to the machine - tweaking things to get it the way I want it. I happened to notice an ongoing review of the machine on home-barista.com.

I wound up getting two La Cimbali Junior grinders - they are working very well indeed...

Yes, but there are other cheap cuts of beef that I think are better - flat iron steak, for example.

Salt can generally be used in the same concentration or amount as you would normally use it. Herbs and other seasonings are the ones you need to use in lower concentrations. The reason is simple. Salt does not evaporate or disperse. Herbs, on the other hand, often rely on volitile flavor compounds. In normal cooking these tend to disperse into the air and evaporate (which is why the kitchen smells of garlic if you are cooking garlic in an open pan). These volitiles cannot escape in sous vide, so they tend to have a stronger effect on the food. I have tried eye of round - it works fine. It is not my favorite cut of beef. When I was doing the experiments to calibrate the temperature & time tables I used eye of round because it is a very uniform piece of meat.

Great pictures!

I agree that it is less likely to get a really mediocre shot in Italy - the "average" or typical espresso drink is better than typical US. But as per previous posts I think the best in the US is probably the best in the world. Furthermore the innovation all seems to be in the US. I'd love to be wrong and hear about fantastic espresso places in Italy, or anywhere else in the world, but as far as I know that just isn't the case...

So, the question is, what is the best practice for dealing with pathogens? The main place to worry would be with food that is going to be served raw (sushi) or rare (i.e. outsied the FDA time-temperature relations for 5 or 6 D reductions in pathogen count). Selecting food from a good, reputable source is clearly #1. Washing in a conventional way, and paying attention to hygene generally is #2. In most cases the thing to care about washing isn't the food - it's your hands since the chef often touches dirty stuff (like produce) and then touches food. The question stands as to whether #3 is rinsing in a disinfectant/antibiotic? If so which one would you use? An ideal antiseptic would be easy to remove, would leave no trace, and would thus be tasteless and safe. It would also have to be effective in killing pathogens with a fairly short contact time. Ethyl alcohol would seem to be one choice. A 40% to 50% solution (high proof vodka) is the easiest to get. It has the advantage that it is common, and it evaporates pretty easily so allowing the food to dry should pretty much take care of eliminating it. GSE is apparently another choice - I have not used it, so I don't know much about it.

Keeping it overnight in the bag should not be a problem, and should not make it mushy unless you put something acidic on an enzyme in the bag. I have not tried keeping raw lobster overnight in a bag however, so maybe this is it. The cooking time seems a bit long. Lobster once out of its shell is not that thick. Going by the time / temperature tables I would expect about 20 to 35 minutes cooking time. When I cook lobster I start by pouring hot water over them, then drain immediately and take the meat out of the shell. The hot water makes it easy to pull the meat out. I then bag it with butter, and put it in the water bath at 45C/113F. Since the temperature is already above the temp for the tables (5C/41F) the cooking time will be shorter than the tables say. So generally 15-20 minutes is enough. [Moderator's note: the conversation continues in Sous Vide: Recipes, Techniques & Equipment (Part 2) ]

I stand corrected. The rules on sous vide hygene are hereby amended. Never put any of the following in your sous vide bag: seawater from near deep sea vents, water from hot pools at Yellowstone, and absouletly no hot decomposing compost! I don't think that will be too limiting . Good hygene is a great idea for all cooking, especially sous vide. The first order of priority is to be as clean as you can about evertyhing. That certainly includes fresh herbs which are far more likely to harbor germs than the interior of the meat. Exterior of meat surfaces, particularly poultry are another area to watch. This is somewhat off topic, but I have wondered why is isn't standard practice to dunk food in a disinfectant / antiseptic solution. A salt brine is one option - typically you do this for a long period of time to brine the meat, but even a very brief dunk would kill a lot of the potential pathogens. Another option would be ethyl alcohol - i.e. vodka.