A lot of people can't have milk or dairy products in general because they have a problem with lactose. Lactose itself can't be absorbed and it first needs to be broken down into its components: glucose and galactose. For many of us, this conversion is easily carried out by an enzyme called lactase. However, some people don't produce enough or any at all, so unchanged lactose is able to make it to the colon. There are bacteria there that can break it down, but they do it by fermentation. This produces a lot of hydrogen, carbon dioxide, and methane gas, which leads to bloating and a bunch of other abdominal problems. The lactose, as well as other non gaseous fermentation products, will also raise the osmotic pressure in the colon, leading to an influx of water and diarrhea. The severity of these symptoms mostly depends on the level of lactase deficiency, as well as the amount of lactose that was ingested. Over the last few decades, lactose free milk and lactose free dairy products in general have become a lot more common. The question though is how is the lactose removed? It is impossible to use traditional chemistry techniques, because it would ruin the flavor and probably make it unsafe to drink. What's used instead is a more modern enzyme based approach, which can selectively break down the lactose without affecting the rest of the milk. At first this might sound kind of complicated to do, but it's actually surprisingly easy For this video, I wanted to explore a couple ways that this is commonly done in industry; And I'm going to be starting with the simpler method, which is just straight up adding lactase to milk. In my local pharmacy, I found some drops under the brand name "Lacteeze" and in the ingredients you can see it contains lactase. I went out and got a liter of milk and before adding anything, I wanted to test the glucose level. The easiest way to do this is using some diabetic test strips, which are normally meant to test for glucose in urine. The strips are highly specific for glucose and since the only sugar in milk is lactose, it should come out negative. The way it works is: I just dip it in, wait 30 seconds, and then compare it to the reference chart. The result was exactly as I expected and it told me there was no glucose According to the instructions I had to "add 10 to 15 drops for every liter of milk." The amount that's added here isn't super important, but it will affect how long it takes to get rid of all the lactose. I just went with 10 because it was the middle point and I felt it was a good amount. When it was all added I screwed the cap back on and gave it a good mixing. Then a couple minutes later, I tested the glucose level again. At this point it was only about ten minutes since the first drop was added, and I was already starting to detect glucose. So what's going on here is a hydrolysis reaction, where the lactase is splitting the lactose into its two components, glucose and galactose. When a molecule of lactose enters the active site of the enzyme, it gets attacked by an amino acid called glutamate. This breaks the glycosidic bond between the two sugars and the glucose is kicked off. The galactose unit that stayed bound to the enzyme is then attacked by a water molecule, which releases the galactose and regenerates the enzyme. This cycle repeats itself over and over again, until eventually pretty much all the lactose is gone. Anyway, I put it in the fridge for the time being and tested it again at the one hour mark. I don't remember why I didn't test it sooner, but in any case by the five hour mark It was already off the chart so unfortunately from this point on I wasn't really able to test the glucose level. To hydrolyze as much as possible, I ended up just putting it in the fridge for a couple days. What I have now should be virtually lactose free, and it's completely safe to drink. It does taste different than regular milk, though, because both galactose and glucose are significantly sweeter than the original lactose. One thing to mention is, that the presence of the active enzyme that still in the milk is probably going to reduce its shelf life. Most sources of lactase are not 100% pure, and they often contain small amounts of other enzymes that can break down milk proteins. On top of this, if the lactase wasn't perfectly sterilized it could also contain small active amounts of the microorganism that was harvested from. So, to solve both these issues, the milk is usually just Pasteurised which deactivates the enzymes and kills the microorganisms. In general though, this process is still quite easy and many companies seem to use a variation of it. However, there is one major downside, which is cost. The lactase enzyme tends to be quite expensive. So just adding it, and then deactivating it, is kind of wasteful. Slightly different methods have been developed to use as little enzyme is possible, but it still isn't ideal. For some companies, a possible solution to this problem is to just fix the enzyme to a solid support At first this might sound complicated, but it basically just means attaching the enzyme to something solid, so it can be easily recovered and separated from the milk. What's also nice, is that once it's separated, it can be used in a new batch of milk and the process can be repeated. There are a lot of ways to fix an enzyme to a solid support, but I figured the easiest way to do it here was to just entrap it in some calcium alginate jelly. To make the jelly, I actually have to start with sodium alginate, which is an edible polysaccharide that comes from brown algae. I need to make roughly a 2% solution, but doing this manually is often a big pain, and it's much easier to use a blender. So in here, I have about 10 grams of sodium alginate and 500 mL of water, and I mixed it for about a minute. When it was done, I poured it into this smaller container, and you can see it was quite goopy. It's also white because of a whole bunch of air bubbles that were introduced by the blender. Into this I then poured in the entire bottle of Lacteeze. I mix it around as thoroughly as possible, and then I moved on to making a second solution. This one was even easier to make and I just dissolved 5 grams of calcium chloride in 500 mL of distilled water. The most common use of calcium chloride is for de-icing, especially on roads in the winter. I'm not using dirty road salt here though, and I went out and bought some nice and clean food grade stuff. Anyway, when everything had dissolved, I was ready to make the jelly. So I headed back to the sodium alginate mixture, which had cleared up quite a bit in the meantime. I pulled out a small amount using an eyedropper, and then I slowly added it to the calcium chloride solution. It might be hard to see, but it's actually separating out as these little jelly balls. It's very important that it's added drop-wise, because if it's all poured in at once it would just become one solid chunk. Adding it all like this, though, would kind of be a pain. So to make things easier, I added everything to a separatory funnel. Then I open the stopcock, and I adjusted it to a decent rate. What's happening here is a reaction between the sodium alginate and the calcium chloride. This leads to the formation of sodium chloride, as well as calcium alginate which is insoluble in water. Initially, this only occurs on the surface of the drop. But as it sits longer in the calcium chloride, most of it gets converted to calcium alginate. This is why at first the drops are almost completely transparent. But they slowly become more and more opaque. In any case, the final result is a porous network of calcium alginate, with lactase enzyme trapped in it. The lactose in the milk that I'll be treating will be able to interact with the lactase at the surface of the beads, And it'll also be able to diffuse inside and get hydrolyzed there. When all the sodium alginate was eventually added, I then had to separate off the beads to do this, I just used this thing which, I made out of a water bottle. I kept the valve at the bottom open and I poured everything in. Almost all the water quickly passed through and I was just left with the beads. They were still covered with calcium chloride solution though, so I had to wash them a couple times with water. The process that I did was quite simple: I just added distilled water, let it soak for several seconds, and then drained it out the bottom. When I felt like I had washed them enough, I moved on to processing about 200 mL of milk. The general procedure here was to add the milk, let it sit for about 2 minutes, drain it out into a beaker and then test the glucose content. In the first and second run it still tests negative, but by the third one it starts detecting glucose. Then with each subsequent run the concentration slowly increased, until by the tenth one it was off the chart. In the actual industrial process this is usually done in two ways: either in batches, or continuously. In the batch method the milk's just added and stirred for a certain period of time, and then drained away leaving behind the beads. In the continuous method, a column similar to this is used, but it's a lot longer. Fresh milk is added continuously from the top, and it's trickled out from the bottom at a steady rate. This causes the milk to move slowly over the beads, and by the time it reaches the bottom, nearly all of the lactose has been hydrolyzed. In any case, in total I did about 13 runs, just to try to hydrolyze as much as possible. Then everything was drained into a beaker and temporarily put in the fridge. The beads that are left over in the filter thing can then be used to process more milk if I wanted to... ...but I don't. Although this method appears to be better because it saves and recycles the enzyme, and the milk doesn't have to be heated afterwards, there are still some major problems with it. Proteins in milk tend to adhere to the surface, and the pores of the solid support and block the action of the lactase. On top of this, because the solid support is used for an extended period of time, microbial growth in it starts to become a problem. To deal with these issues, it needs to be routinely washed to get rid of the proteins, and re-Pasteurized to kill the microbes. There's also a price to making or buying the solid supported enzyme itself, and it d oesn't last forever, so it's still a recurring cost. So is this method truly better than the other one? I'm not really sure, and to me it seems that it just replaces the old problems with some new ones. As far as I know, the first method I showed is still the dominant one, but maybe as technology progresses this one might take over. When I went and tasted the milk from this run, I had an unpleasant surprise to say the least. *coughing* "That was not good." I apparently didn't clean the beads as well as I thought, so the final milk had a decently high concentration of calcium chloride in it. I think to really get rid of it, I have to soak the beads and do an actual proper washing and not just a couple rinses. Anyway, both these methods so far still have one major issue which I kind of mentioned in my first taste test. Lactose isn't very sweet, but it's being split into glucose and galactose, which are. So the resulting milk has an oddly sweet taste, which a lot of people find off-putting. Because of this new processes were developed, most notably ultra filtration. I'm not actually able to do this myself, but I'm just gonna cover the basic idea here. Under high pressure, milk is pushed against a thin and porous membrane, which allows the smaller components to pass, like water, lactose, and minerals. What's left behind is a concentrated mixture of proteins and fats which can be used to make cheese or re-diluted to make milk. The reformed stuff is pretty much lactose free, but it's still treated with enzyme to get rid of any that might remain. Since the lactose level is so low, though, the amount of glucose and galactose that's made is really small, and doesn't affect the flavor. I've never tried it myself, but it allegedly tastes pretty close to regular milk. Currently on the market there are lactose free products that are made using all the methods that I talked about, and from what I can tell, it seems like the first method is the one that's by far the most commonly done. If you're at all curious, though, I'm sure you could do a little bit of research or read into the fine print, and find exactly how the brand you like is made. As usual a big. Thanks goes out to all my supporters on Patreon. Everyone who supports me can see my videos at least 24 hours before I post them to YouTube. Also everyone on Patreon can directly message me, and if you support me with $5 or more, you'll get your name at the end like you see here
I drink only fairife because it is so similar to real milk. Can't even stand the other stuff anymore, and it used to be all I drank before I knew better.