What is Milk made of?

milk is nutritionally complete food that contains almost everything that's needed for survival and growth whole milk contains six major components vitamins proteins minerals fats sugars and water in terms of vitamins there were two major types water soluble and fat soluble the water soluble ones are pretty constant but the level of fat soluble vitamins depends on the fat content when fat is removed from milk to produce things like skim milk some of the fat soluble vitamins are taken out with it because of this vitamins like vitamin A and vitamin D are usually added after the fat is removed there are many different proteins in milk but the two main types are casein and whey the proportion of each will vary depending on the milk source for example most of the protein in cow's milk is casein but most of the protein in human milk is way I'm going to go into more detail about the proteins later in the video milk is a good source of minerals and I've listed the major ones here many of them are present assault compounds for example calcium phosphate which is a combination of calcium and phosphorus a large portion of the minerals are associated with the casein proteins and the rest are dissolved in the water the fat in milk is a mixture of triglycerides triglycerides don't mix with water and in milk they're present as an extremely fine suspension of small droplets if we take a look at the structure we can see that it's a bunch of long molecules attached to a small backbone the backbone is made from glycerin and the tails come from a group of molecules known as fatty acids a lot of fatty acids are quite stinky but not when they're incorporated into a triglyceride when milk goes bad the triglycerides start to break down which releases the stinky fatty acid in terms of sugar the main one is lactose lactose is known as a disaccharide because it's a combination of two smaller sugars glucose and galactose people who are lactose intolerant lack an enzyme called lactase which normally breaks the bond between these two sugars so for this video I'm going to be separating some milk into the different components that I just mentioned milk is routinely processed into many different things like cheese and protein supplements and I thought it might be interesting to show you guys where this comes from so to separate the milk I just need a few things sodium carbonate acetic acid and ethanol the only component that I won't be separating out here is the fat and that's because it's done using a centrifuge I really don't have the proper setup to do that so I'm starting with skim milk if you decide to repeat the process that I'm doing here it's really important that you use skim milk because any fat will mess things up a magnetic stir bar is added to a beaker and I pour in about 200 milliliters of skim milk the stirring in the heat and then I add a thermometer the goal now is to heat the milk to about 40 to 50 C and to keep it there for 15 minutes from this angle it might be hard to tell but it is in fact stirring anyway after 15 minutes the thermometer is removed and I start to add acetic acid the acetic acid is added in small portions and awaits several seconds between each addition after the second addition a lot of solid stuff starts to form the solid stuff is casein protein that's precipitating out of solution in milk casein exists as its calcium salt called calcium caseinate the structure of the salt is complex and it's composed of three forms of casein alpha beta and Kappa together they form a stable structure called a micelle part of the Kappa casein has a lot of polar residues which can favorably interact with water so on its polar side it interacts with water and on its nonpolar side it's in contact with the alpha and beta casings here's an artistic structure of the casein micelle each circle is a sub micelle which is a mixture of all three types of caseins the outside layer is enriched with Kappa casings and internally the sub micelles are held together by calcium phosphate interactions the micelles are not technically dissolved in the milk and they exist as a colloidal suspension the stability of the micelle is heavily dependent on its interaction with calcium the pH of milk is around 6.6 and at this pH the casein has a net negative charge that can interact with calcium when acid is added the net negative charge is neutralized and this interaction is lost because of this the stable suspension of casein is compromised and it starts to agregate the same process occurs when milk starts to sour bacteria in the milk ferment lactose to lactic acid which drops the pH and causes the casein to clot this process of separating casein is how cheese and casein supplements are made the characteristics of the cheese that is produced depends on many factors like the origin of the milk its fat content the bacteria that's used to ferment it how long it's aged etc the last little bit of acetic acid is added but it doesn't really do too much because at this point pretty much all of the casein has already precipitated I continue to stir things for a little bit and you can see that most of it has clumped up into this large ball to separate it from the liquid I filter it through a little bit of cotton you once everything is filtered through I wash the casein and the filter with a little bit of hot water the funnel is then removed and the solution is placed back on the hot plate the stir bar is removed from the beaker with the casein and it's quickly cleaned using a paper towel for the time being the casein is placed on the side and I cover the beaker with some plastic wrap okay so at this point I've separated off one thing but I still have the albumen the minerals and the lactose to get out in the next step I need to heat things but lactose is sensitive to hot acidic solutions so before proceeding on I need to neutralize any acetic acid that might remain and to do this I use a little bit of calcium carbonate calcium carbonate is insoluble in water so if it doesn't react here it's pretty easy to filter off the calcium carbonate added and the stirring turned on I cranked up the heat the goal now is to heat the solution to about 90 C and to hold it there for 10 minutes so what we're doing here is separating out the whey proteins whey proteins are the proteins that are still dissolved in solution after the casein has been removed the two major whey proteins in milk are albumins and lacto globulin when the solution is heated to boiling the structure of the proteins are compromised and they become denatured they're no longer able to dissolve in the water and they precipitate out when acetic acid and calcium carbonate react they form co2 gas which can cause some foaming here as a solution heats up the foaming might get more intense and it's possible for it to bubble over in my case I didn't really have any problems but it's something to be aware of if you decide to do this yourself just keep an eye on it and have a container sitting around to catch anything if it does end up overflowing after boiling it for 10 minutes I take it off the hot plate I let the beaker sit undisturbed for about 30 seconds and things quickly settle at the bottom the solid at the bottom is a mixture of unreacted calcium carbonate and precipitated proteins now that most of the solids have settled I move on to filtering the solution is passed through two coffee filters which I've put inside the glass funnel it's a good idea to try to filter off just the liquid portion first and then to add the solids after if everything is added all at once the filter will quickly get clogged and it will just take a long time once everything is passed through I use a little bit of warm distilled water to wash both the beaker and the filter filter is then removed and I squish out some of the excess water the filter paper was then spread out and allowed to dry it was really hard to see against the white background but there was actually some white solid that still remained so to get rid of it I just quickly filtered it again the solution that passes through is still a little bit opaque but there's no white solid the beaker is then transferred to the hot plate and I need to boil away a lot of the water a stir bar is added and I crank up the temperature on the hot plate to speed up the evaporation I also set up a small fan with this setup the evaporation was actually pretty quick when I got down to around 125 milliliters the solution became opaque I continue to evaporate the water until the volume was around 40 milliliters when the stirrings on some of the liquid is pushed up the sides and we also get some foaming so the volume reading isn't super accurate so I turned off the stirring and let things settle to try to get a better reading because I was filming this I tried to do it all in the same shot but I really should have taken the beaker off the hot plate it bumped pretty violently and shot a small amount out of the beaker actually kind of scared me when it happened and I quickly turn the stirring back on in the beaker I now have a concentrated mixture of lactose and minerals and I need to separate them to do this I add 150 milliliters of 95% ethanol this mixture is then brought to a boil and it's boiled for five minutes the lactose is soluble in this hot ethanol solution but the minerals aren't so they should remain undissolved like when I filtered off the albumen I let the beaker stand for something like 30 seconds and most of the solid sank to the bottom this hog ethanol solution was then filtered through a couple coffee filters the beaker in the filter funnel were washed with a little bit of warm ethanol by the time the filtration is done the solution below has cooled a little and lactose starts to precipitate out I get the beaker back on the hot plate and already a lot of lactose has fallen out of solution anyway I turn the stirring in the heating and with the help of the fan I evaporate the ethanol down to around 70 milliliters by the time I get to 70 milliliters a whole bunch of lactose has precipitated the beaker is removed from the hot plate and put somewhere to cool down it's covered with some plastic wrap to prevent the hot ethanol from evaporating once it cooled to room temperature I put it in a fridge for about a week lactose is really not soluble in ethanol but the crystallization can be pretty slow in the meantime I went and got the casein from earlier and I added it to a blender I also added about 200 milliliters of distilled water I put on the lid and then I blended it for about 30 seconds on a low setting the goal here is to break up the casein and to just give it a good washing once I felt like I had mulched it up enough I moved on to filtering it everything was transferred to the filter and the blender was washed with a small amount of distilled water once all the water had passed through I was left with this goopy stuff to further wash the casein and to dry it up I added some 99% isopropyl alcohol once everything had passed through I washed it again with the alcohol then once all of this alcohol had filtered through the casein was transferred somewhere to dry a few days later all of the filter papers were very dry the solid from each was then scraped off and weighed about four days later the lactose ethanol mixture was removed from the fridge and filtered off everything was transferred to the filter and the beaker was washed with a little bit of cold ethanol once everything had passed through I add a bit more cold ethanol to wash the lactose the filter is then removed and the lactose is allowed to dry over the course of a day the ethanol evaporated and I was left with a nice fluffy powder the lactose was weighed and added to a piece of paper and this was grouped with the other solids that I collected the number at the top left corner of each paper just represents the order that they were isolated in with everything isolated I can compare my results with the average composition of skim cow milk casein is associated with a lot of lactose and minerals so it makes sense that the mass I recovered is higher than expected the ratio of casein - whey protein in cow's milk is about 80 to 20 but what I got was closer to a 70/30 split the mass of the whey protein is buffed up a little bit due to unreacted calcium carbonate the lactose that was recovered was about 2.6 grams less than expected I imagine that most was lost in the casein and some probably stayed dissolved in the ethanol the minerals were also less than expected but again most of the missing stuff is probably stuck in the casein just for fun I try to remake the milk from the powders that I got I wanted to make 100 milliliters so I put in about half of everything that I recovered it was quite chunky and would definitely have a hard time dissolving so I quickly put it through a coffee grinder I transferred it back to the beaker and then I added a hundred milliliters of warm water I stirred it around for a few minutes but no matter what I couldn't get everything to dissolve milk is a careful balance of proteins interacting with minerals and sugars to get everything suspended or dissolved all of my proteins are denatured so the casein is not going to go back into suspension and the albumin is not going to dissolve the difference between what I have here and powdered milk is that in powdered milk the proteins are still functional in either case just for fun I tried to taste the milk to see what it was like and it tasted horrible it was especially horrible because some of the bittering agent used in the ethanol was passed on to the lactose anyway that's about it I hope this video was able to teach you guys a little bit about milk so before I let you guys go I just want to mention one last thing a good friend of mine is part of a new nonprofit organization here in Montreal that's called Project pinpoint project pinpoint is a community initiative working to raise funds which will be used to promote safety and security of Quebec youth the goal is to raise $15,000 through fundraising and various other community events all proceeds will be donated directly to the Montreal based Missing Children's Network I think this is a really good cause I've already donated $100 and I'm going to be involved in a few of the events so if you guys have time you should check out their website at project pinpoint CA or drop a like on their Facebook page links to everything will be in the description so as usual I'd like to thank everyone who's supporting me on patreon everyone who supports me will see my videos 24 hours before I release them to YouTube on top of this all of my supporters can directly message me on patreon with any questions or comments that they have and I do my best to respond within about a day or so to all of my patreon messages if you support me with five dollars or more you'll get your name at the end of the video like you see here you

Channel: NileRed

Views: 655,462

Rating: 4.9315805 out of 5

Keywords: nile, red, chemistry, lactose, protein, fat, vitamin, milk, separate, isolate, science, nilered

Id: BV8aFRII1M4

Length: 18min 9sec (1089 seconds)

Published: Mon Mar 27 2017

Reddit Comments

[u/liquidzwords]

[REDACTED]