Humor

You Might Be a Home Chemistry Geek if...

• You're at the market buying Honey, Baking Powder, Vinegar, Kosher Rock Salt, Corn Oil and a sturdy looking glass measuring cup, but don't plan to do any cooking today.
• You've bought a gallon of apple juice for the sealable glass jug it comes in.
• Your water bill is higher than the rest of your utilities combined.
• You go through more paper towels than most families of six.
• You have a case lot of coffee filters, but no coffee maker.
• You catch yourself thinking "Wait, has this been neutralized?!?" before dumping the spaghetti boiling water into the kitchen sink.
• Even though you're a single guy, you spend a lot of time in kitchen stores looking for very specific items.
• You find yourself explaining to the Sur Le Table cashier that "I'm going to use this jerky dehydrator to do low-temperature evaporation of a solution of potash", etc.
• You're irritated at having to explain to the supermarket guy that, no, mineral water is actually the opposite of distilled water, so you really do need the distilled kind.
• You begin to wonder why the government thinks any nonzero value of "Total Dissolved Solids" in drinking water is ok.
• You have a "real, chemical-grade fire extinguisher" in your kitchen
• Your fire extinguisher is the only device in your kitchen for which you have read the instructions.
• Your fire extinguisher is the only thing in your kitchen for which you check the freshness date faithfully
• You're buying a cartload of clear glass rubber gasket canning jars (for storing hygroscopic materials), and are confused when the cashier asks you what kind of preserves you make.

Got more? Send em my way.

Soap 2

In which I make soap but do no damage to my kitchen.

Melting the tallow

I melted the 1kg tallow from Tallow 3 over heat low enough to produce no steam or smoke. I combined 120g of slightly lumpy (not completely anhydrous) sodium hydroxide lye and 325ml of water, let it cool, then added it slowly to the warmed liquid tallow.

Stir, stir, stir

Very little soap floated to the top, but every time I stirred the mixture, more light colored solids accumulated at the bottom of the pot. I had expected that the soap formed would rise to the top, and indeed some fluffy soap-like curds did come to the top, but the more viscous and cohesive mass stayed at the bottom. The more I stirred, the more formed. I kept the heat at the minimum setting throughout. I ended up with something that looked more like applesauce or loose tofu than soap.

Set

When the stirring produced no further solids, I stopped and turned off the heat, and left it overnight. During the night the saponification completed normally. I ended up with a thick cake with rice-crispie-sized pellets on top, and a very thin layer of clear viscous liquid at the bottom. This cannot be the whole of the glycerin, since it's not even 5ml of liquid. A quick swab with some litmus paper shows it as extremely alkaline, so I assume some of the sodium hydroxide went unused and collected here.

I am not shaping the soap at this point, I'm just setting it aside as large cakes for later use.

Tallow 3

In which I overcook the tallow

Another trip back to the market, and the butcher generously provided me with 2.1kg of assorted fat. I added the 600g of tallow from Tallow 2 as a heating medium rather than water, and simmered. This produced approximately 1.5kg of tallow total.

Darker tallow

Unlike Tallow 1, I let the rendering continue at a higher temperature well into the browning stage, so the resultant tallow was significantly darker than my previous efforts.

This could be for several reasons:

• Some fraction of the fat might have reached its smoke point and decomposed, leaving carbon with sufficiently fine grain to pass through the filters.
• Some substance from the meat or connective tissue might have dissolved into the fat, giving it a darker hue.
• It's possible there's some mineral in the tap water that's promoting darker tallow.

Or any number of other things.

Clarifying the tallow

I remelted the tallow at very very low heat, then let it set. The underside of the tallow contained the majority of the darker mass. I scraped it off, then repeated the process. On this second run there was also a dark mass on the underside. I scraped it off and repeated a third time. On the third run, there was no dark mass to scrape off, nor on the fourth. Apparently the tallow had reached its maximum clarity even though it wasn't white. I had removed a total of 429g of tallow and "dark stuff".

Lower yield

The total yield from the preceding experiment and this one was almost exactly 1kg of tallow. That was less than I had expected.

The tallow, being very very soft, was harder to manipulate and transfer from pot to pot, leaving a fraction of itself behind at each stage. I would hazard a wild guess that 10-15% of the total was lost on the sides of pots and pans or poured out with water.

Future attempts

If I have a large enough batch of fat in the future, I shall try as follows: split it up into four batches, and try low-vs-high temperature, and distilled-vs-tap water.

Tallow Notes

So after the misadventure of Tallow 2, which resulted in a mere 600g of rendered tallow in the pot, I shall start over. That will be covered in the next instalment, Tallow 3. In the meantime, I thought I might write down a few lessons learned.

A few notes

Caveat Scisor: If you're doing this with butcher scraps as I am, remember that you're handling a non-sterile bacterial culture medium. It may have been in a butcher's trash can all morning. You should assume that it is practically alive with microbes at this point. Wear gloves. Avoid cross-contamination. If you was these pots in the same dishwasher you use for regular pots and pans, make sure you set it on "sterilize" when you wash these pots. Most dishwashers in the US have a setting that gets the temperature over 200F. Use it. If you have antibacterial soap, use it to wash your hands afterwards. That sort of thing. The last thing you want is to get sick from handling the raw (literally) materials.

This is a perfectly safe operation, provided you take precautions and use common sense.

Safety Tip: I probably should have said this earlier. Remember that this process generates steam directly from the raw materials, since there is water in the meat. This means that the lid on the container will have water on it when it is lifted off the pot. It would be natural to hold the lid over the pot to let the drips fall back into the pot rather than spilling onto your stove or counter. Do not do this. It can cause spatters and burns. Either let it drip on the counter (it's pretty much distilled water at this point) or keep a container nearby to catch the water drops when you lift the lid.


Terminology: Some people may (rightly) complain that I should be using the more generic term lard in place of the term tallow. Lard refers to just about any kind of rendered fat, whereas tallow can refer to a narrower category: rendered hard fat, or the rendered hard fat from around the kidneys of specific animals. Since I am not being at all specific in what kind of fat I'm rendering, it could be more correctly termed lard.

My only counterargument is weak: People searching for this process are far more likely to use "tallow" as the search term, rather than "lard", since lard is still in common usage and will return results for Crisco, Oleo, et al. In the interests of availability rather than accuracy, I will continue to drive the purists mad and use the term tallow. Mea culpa.

Tallow 2

In which I make two rookie mistakes thus creating unwanted excitement in my kitchen.

I decided to do another tallow rendering for two reasons: First I wanted to take a try at making hand sanitizer now that I have ethanol available, and second because the soaps went over pretty well with F&F.

What goes in

I went to a large local supermarket, rang the butcher's bell, and I asked if he had done any trimming today. When he said he had, I asked if I could get "a couple pounds" of the trimmings. He was happy to oblige, presumably because it was a slow Saturday morning.

I came home and measured it out: precisely 1400g of trimmings, but as you can see from the picture, a rather a high percentage was meat so I'm not sure what the end yield will be.

Getting started

I put the fat in a stewpot with a liter or two of water and turned the gas jet up to medium-high.

You can render fat with no water. It is definitely more efficient: the water's going to boil away or be discarded eventually, and there's no reason to waste the energy turning a liter of liquid water into water vapor. Likewise, it's slightly safer since it's impossible to have a bubble of water pop up through a layer of rendered fat and spatter it everywhere.

I use water because it lets me work directly with big chunks of fat without having to cut them up or grind them, and without spending a lot of time tending the pot at the beginning to make sure the fat melts without burning. By the time the water's boiled away, there's enough liquid fat in the pot to conduct heat to the rest of the contents. It's fire-and-forget.

The smell of rendering

Every time I've done this, I get the smells of cooking food: sizzling bacon mixed with a little stewbeef. Despite this I have heard, over and over, that the smell of rendering is bad. This is one of those things that "everyone knows", it seems. I do open the window and turn on the fan, but it's to get rid of the steam. So either what "everyone knows" is dead wrong, or I've been extremely lucky with the materials I've had to render.

Can someone else who does this please relate your experience? I'd really like to know where this belief comes from.

Rendering

By the 30 minute mark, the liquid bubbling in the pot is dark, more viscous, and spits if you drip a drop of water into it.

At the 0:45 mark, there is clearly no water left in the bottom of the pot. There is a large amount of liquid fat, with the larger pieces floating in it. I checked to make sure nothing was stuck to the bottom, and that the floating bits still included fat that had not liquified. Then I turned the gas down to just over "low": enough to keep the fat bubbling and continue the process.

At the 1:10 mark, it was done. There were huge clumps of solids still floating, but when I fished a couple out and cut them in half, they were all protein. I took the pot off the stove and turned off the gas jet. Later measurement showed 220g of deep-friend protein. Too bad I don't have a dog.

Tip #1: If you have just strained 220g of protein solids out of a pool of hot oil, when setting them aside, do not set them on a styrofoam butcher's tray. Melted styrofoam is neither an attractive nor pleasantly fragrant addition to your kitchen space. -Ed

The liquid tallow

I poured the whole lot through a spaghetti strainer to remove the chunks and got the (relatively) pure fat into a different pot. I waited until water dripped in did NOT spit, then tossed in enough warm water to form a short layer underneath the tallow. Then I stirred the pot to bring the water into contact with the oil and its contents.

The layer of water gives the carbonized bits and chunks still in the tallow somewhere else to be. Most of them are heavier than water, so they fall out of the tallow and into the water. Likewise curing salts or other material from the meat tend to prefer the water to the fat.

I set it aside and let it cool down on the cooktop, then put it in the fridge.

The initial results

Once the tallow had hardened in the fridge, I weighed it. I had 780g of very soft tallow. I'm not kidding, the results tallied exactly 1kg to the gram. The tallow was so soft because the source had included a lot of soft, low melting point beef fat. It was also somewhat brownish, apparently from stuff that had made it through the strainer or that hadn't left the fat for the water.

A little math, for the sake of science: 1400g in, 1000g out, 400g LOI. I assume it's almost all in water lost as steam, because the amount that could have been lost as fryer smoke would be fractional grams at most.

I elected to try and get it to a pure white before proceeding, so I decided to reboil it and filter it more completely through a finer seive, and then through a paper filter.

Second boil

You know, I knew there was a reason I hadn't used water in the second boil the first time I made tallow. I ended up with a mini-BLEVE that blew the lid off the boiler and covered a substantial fraction of my kitchen counters and floor in a fine coating of liquid tallow. Eeew.

I *do* have a chemical rated fire extinguisher, but happily it was not needed.

Tip #2: If you are going to boil water under oil, do it at a rolling boil, like when you make spaghetti and put a little oil on the top. Or don't boil water under oil at all. Or if you do, be prepared to handle surprises. -Ed

After-incident report

In retrospect, the problem was obvious, and the payoff is some practical experience with some fairly cool physics:

The water is essentially in a sealed container: the bottom and sides are the pot, and the "lid" is a coating of oil. The oil "lid" acts something like a blanket: absorbing some heat while reflecting another fraction back into the water. Since the water is in direct contact with the bottom, which is in direct contact with the flame, the water gets hotter much faster than the oil.

There is also a slight pressure exerted on the water due to the weight of the oil. This means that when a substantial bubble of water vapor finally forms and rises through the oil, the oil is pushed away from the part where the bubble comes through, removing the weight of the oil and suddenly creating an area of low pressure in the water. The lower pressure lowers the boiling point of the water underneath, which causes more of the water to suddenly convert to vapor, causing more holes in the oil, causing lower pressure, and each cycle speeds the next. This is not a true BLEVE, because nothing is exploding, but the forces at work are pretty much the same.

In short, it tends to go from a quiet pot to a fountain of oil blowing the lid off your pot in a very small fraction of a second, probably leading to excitement and cleanup projects you might wish you didn't have.

As always, Caveat Scisor.

Things I learned

1. When doing a purifying boil on tallow, skip the water
2. The screen on a Samsung Galaxy Note 3 is liquid-tallow-proof
3. Even though it wasn't used, I'm really glad I have a good fire extinguisher

Conclusion

After the cleanup, I came to the conclusion that there wasn't enough tallow to continue the experiment, so I disposed of the remainder of the tallow and started again at the top.

If the weather continues bad tomorrow, I'll probably go back to the market and begin Tallow #3.