Believe it or not, there is some real science involved in the making of ice cream. Guinness book of records, p266. To bear the "Meets USDA Ingredient Standard for Ice Cream" stamp, it has to contain at least 10 percent milk fat, and a minimum of six percent non-fat milk solids. However, when the dispersed phase is soluble in the continuous phase, another mecha?nism operates. Post was not sent - check your email addresses! Add 4 cups of ice cubes or crushed ice to a large, gallon-sized baggie. How these ingredients are processed will affect the texture of the product and this comes down to understanding the physical chemistry of ice cream. Cream must be cooled significantly. This breaks the fat globules up into an emulsion of much smaller droplets (<1μm) with a much larger surface area. Making ice cream is a divine way to teach science. How to Make Ice Cream in a Bag Step 1: Mix the Ingredients of Your Ice Cream Prepare all the materials and ingredients needed. Consider this part of the process a great way to work off some calories before you consume the deliciousness waiting in that small bag. I’ve created a set of worksheets to use in making ice cream a fun science experiment. Explore surface tension by making patterns in milk using items from the kitchen cupboard. The best way to store ice cream is in a tightly-sealed, closed container, preferably plastic or in a cardboard carton that has some thin plastic lining so the container doesn’t become soggy. This is known as the Gibbs-Thomson equation. Sorry, your blog cannot share posts by email. T  is the absolute temperature and c is the concentration of surfactant molecules in solution. The local business of lithium mining. Food and science! First, the intrinsic viscosity of the sugar solution decreases as it gets colder. Emulsifiers are surfactant molecules, ie they consist of a hydrophilic (water-loving) head group and a hydrophobic (water-hating) tail. Ice cream mix at ca 4°C is pumped into the barrel. Still needs more shaking but you get the point! The emulsion can reduce its free energy by reducing its interface area, eg by droplets coalescing. Your place or mine? Instead, one of the liquids is dispersed throughout the other. Fig 3(a) Schematic diagram of homgenisation showing the break up of large fat globules into small droplets. ICE CREAM CHEMISTRY. Use the thermometer to measure the temperature of the ice in the gallon Ziploc bag. Learn how your comment data is processed. Then read on. (William Thomson, later Lord Kelvin, is best known for proposing the absolute scale of temperature.). Freezing Point Depression and Colligative Properties Materials 1/2 cup milk 1/2 cup whipping cream (heavy cream) or (substitute 4 Tbsp. The quality of ice cream depends on its microstructure: small ice crystals and air bubbles give the ice cream a smooth, soft texture. She demonstrates how our knowledge of how ice freezes can be applied to ice cream … The size of the ice crystals largely determines how fine, or grainy, the ice cream eventually turns out. Pour a cup of milk into a ziploc bag. Our understanding of solution phenomena such as freezing point depression owes much to François-Marie Raoult (1830-1901), who measured the freezing points and other physical properties of many solutions. If you cool a sucrose solution below its freezing point, ice forms and removes water from the solution; the sucrose concentration therefore increases and the freezing point decreases further. The shaking (or stirring in an ice cream maker) moves the warmer cream mixture from the inside to the outside of the bag so it can freeze evenly. So having created and preserved the microstructure, the ice cream finally reaches the consumer in perfect condition. This book is ideal for undergraduate food science students as well as for people working in the ice cream industry. If your kids are missing school or you’d love to help them with some cool science to keep busy, check out this page, At-Home Resources for Kids (and their grownups). Making Ice Cream at Home or in the Classroom Put all the food ingredients into the small bag. Shaking the small bag of cream within this briny mixture results in heat from the cream being absorbed into the salty water. Mmmmmm, Related Post:   Easy Experiments: Valuable How To Resources for Home and School. The supplies to make it you’ve likely also got in your drawers at home as well. Example: A mixture consisting initially of 3.00 moles NH 3, 2.00 moles of N 2, and 5.00 moles of H 2, in a 5.00 L container was heated to 900 K, and allowed to reach equilibrium. We love it as a treat on a hot summer day. Modern ice cream freezers are less exotic. In a small resealable plastic bag, combine half-and-half, sugar, and vanilla. Crystals that are initially large become smaller, and those that are initially small disappear completely. In ice cream, liquid particles of fat—called fat globules—are spread throughout a mixture of water, sugar, and ice, along with air bubbles (Fig. I am passionate about the weird and unusual. Creating this microstructure is the key to making good ice cream - and to understand how to do this, you need to know some physical chemistry. Challenge your 14–16 students with this chemistry-themed quiz. It’s a long time for shaking and you’ll need patience. What do you need, you’re asking, to make some ice cream for you and your kids? The ice is rapidly scraped off the barrel wall by the rotating scraper blades, and is dispersed into the mix as small crystals. Five to eight minutes should be enough time to allow the mixture to freeze into ice cream. At the factory, the ingredients are first blended in the correct quantities and this mix is pasteurised to kill any harmful microorganisms. Today, colder refrigerants are available. The net effect is that the total number of crystals is reduced, and their mean size increases, while the total amount of ice is unchanged. where γ is the interface tension. If the ice crystals are too large, the ice cream becomes gritty and unpleasant to eat. Thus, after a few minutes, the emulsion will separate into a layer of oil over a layer of water. Add the half-and-half/egg/sugar mixture to a pan and heat, constantly stirring, until … This is known as Ostwald ripening, discovered by Wilhelm Ostwald, who won the 1909 Nobel Prize in chemistry for this work. The emulsion has a very large oil-water interface area (A),  which increases as the droplet radius (r) gets smaller. Home made ice cream is a healthy alternative to store-bought. After making ice cream, students will measure the temperature of the ice cream (if thermometer is sanitized), and the ice/salt mixture. To make homemade ice cream in a can, you will need to empty and clean metal coffee cans, with the lids. What better combination could you ask for? In emulsions this usually occurs by the coalescence of two drops. Much more than this and the product would be too hard; much less it would be like custard and would not cool you down on a hot day. The amount of sugar (sucrose, C12H22O11) determines the amount of ice in the ice cream because this will affect the freezing point. Shake long enough and enough heat is removed from the cream to turn it into a solid. You’ll need good, strong-arm muscles for this. Ice Cream is my weakness. ICE CREAM CHEMISTRY. By using this site, you agree to its use of cookies. Here in my cabinet of science curiosities get your science geek on. Surfactants lower the interfacial tension: the more surfactant molecules per unit area of the interface (Γ), the greater the decrease. Suppose, for example, they want to make 1 kg of ice cream that contains 50 per cent ice by weight at a normal freezer temperature of -18°C. The 12-16 size must be … You want to make some just for you and the kids? Many foods contain toxins such as oxalic acid. Add four cups of ice cubes to one of the large, gallon-sized bags. Science Alcove is a participant in the Amazon Services LLC Associates Program, the MEL Science Program and KiwiCo affiliate advertising programs designed to provide a means for sites to earn advertising fees by advertising and linking to, MEL Science and KiwiCo. The main objective (apart from the freezing itself) is therefore to keep the size of the ice crystals down as much as possible… In fact, the world record for the fastest ice cream ever made used liquid nitrogen at -196°C.1, The Science of Ice Cream, copyright: 2007, Chris Clarke. The first step is to know how much of each ingredient to use. By lowering the temperature at which ice freezes, you were able to create an environment in which the cream mixture could freeze at a temperature below 32℉ (0℃) and become ice cream. There are two types of surfactant in ice cream: milk proteins (eg casein) and emulsifiers (eg  mono-diglycerides or lecithin from egg yolks or soy beans). Therefore increasing the interfacial area costs energy, which means that the emulsion is unstable. Let me know how your experinent turns out!!! Seal both bags well. One will be a 12-16 ounce size and the other will be a 2-3 pound size. Next, combine the heavy cream… Your student(s) create a hypothesis and investigate the concepts of changes of state, freezing in particular and the chemistry of solutions. There are lots of free science activities to keep the kiddos busy. Shake that bag for 10 or 15 minutes. To create a change of state so liquid cream becomes solid ice cream, the temperature of the cream must be dropped below 0º C or 32º F.  When you add salt to the ice, salty water results that is much colder than the freezing point. Though it might not solve any of those questions for you or turn you into Einstein, the interior of the place, preparation of the flavored delight , the periodic table of ice cream flavors, and just about everything awakens your inner genius. It is important that the microstructure of the ice cream is preserved during its journey. An understanding of the physical chemistry of ice cream is the route to a smooth, soft, creamy dessert. Fig 2 The freezing point of sucrose solutions as a function of sucrose. Now put the small bag with cream mixture inside the large bag. by Teresa Coppens | Apr 4, 2018 | Lesson Plans | 2 comments. How do we balance the risks and benefits to health? Ice cream is an emulsion—a combination of two liquids that don't normally mix together. First, fill the large, gallon sized bag with the ice you prepared as well as rock salt. © Courtesy of M. Kirkland, Unilever R&D Colworth, Fig 1 A scanning electron micrograph of ice cream. From the curve, the sucrose mole fraction in equilibrium with ice at -18°C is 0.083 or 63 per cent w/w, ie: The total mass is 1 kg, and 50 per cent of this will be ice, so the remainder, must be sucrose and unfrozen water. Aboretum Definition: 18 Valuable Resources to Get you Started, Easy Experiments: Valuable How To Resources for Home and School, What is Fringe Science? Add 1/4 cup sugar, 1/2 cup milk, 1/2 cup whipping cream, and 1/4 teaspoon vanilla to the quart … A lesson presentation with activities for your 11–14 students on polymers and their properties, Use real life examples to help students get to grips with the properties of ceramics, polymers and composites. Weird Ideas That Make You Think, Science Quizzes: Awesome Resources to Make You Smarter. lce cream typically contains ca 60 per cent ice by weight. In fact, the U.S. Department of Agriculture has specific rules that define what can and can't be labeled "ice cream." The manner in which this is accomplished is a result of the chemical properties of molecules in the emulsion. Grab a cup of your favorite brew, get comfortable at Science Alcove and learn to love your inner science geek! Prepare your ice cream mix by adding 1 tablespoon of sugar, ½ cup of half-and-half (or milk or heavy whipping cream), and ¼ teaspoon of vanilla extract to a small sealable baggie. However, in an emulsion, the very small droplets of fat are dispersed through the water, avoiding this separation. There are ice crystals (ca 30 per cent by volume), air bubbles (50 per cent) and fat droplets (5 per cent) from the cream, held together by a viscous sugar solution (15 per cent). EXTRA CREDIT - Once you complete this experiment: research, design, and implement the way in which colligative properties can be used to make ice cream. These adsorb to the surface of the homogenised fat droplets and stabilise the emulsion (Fig 3 (b)). Ice cream is the result. How about a couple of Ziploc bags – one big and one smaller. After hardening, the ice cream is packaged and transported from the factory to the shop. The mix is homogenised by forcing it through a small hole under high pressure (Fig 3 (a)). Ice cream factories typically use liquid ammonia at -30°C and ice cream making is much faster. This site uses cookies from Google and other third parties to deliver its services, to personalise adverts and to analyse traffic. He showed that there was a linear relationship between the freezing point and the alcohol content of drinks. This is described by the Gibbs adsorption isotherm, named after J. Willard Gibbs (1839-1903), one of the founders of modem thermodynamics and statistical mechanics. If you have a password, Enter the Library Here. The freezing point depression deviates from linearity above mole fractions of ca 0.02. Well, if you’re making thousands of gallons to supply endless supermarkets then ya your equipment might be complex and expensive. Zip it up tightly. Multiple hands to do the work will make the job so much easier. 1). Click To Tweet. Make the Ice Cream Whip the heavy cream to form stiff peaks. The freezing point depression (ΔT) depends on the concentration of solute molecules, but not their type, and is given by: where Tw is the freezing point of pure water (273 K), Ts is the freezing point of the solution, R is the gas constant, ΔHf  is the latent heat of fusion of water (6.01 kJ mol-I) and x  is the mole fraction of solute. Make sure the bag is properly sealed. The lab includes materials and a clear procedure to follow. Making solutions of salt water and sugar water and determining how the boiling point has changed Determining the freezing point of the salt water and sugar water solutions from part 2. When you put the ice cream in your freezer at home, it is cooled down again, and the ice that had melted freezes again (Fig  4). However, the ice cannot form on the crystals that have disap?peared. Secondly, as Einstein originally pointed out, the viscosity of a suspension of solid particles increases as the volume fraction of solid (. Ice cream scientists use the freezing point curve when formulating ice cream recipes. However, even at temperatures below its melting point, the quality can deteriorate, owing to changes in the microstructure (see Fig 4). Check out MEL Science Program and get super interactive kits mailed right to your door! Have you ever wondered how that cold, sweet goodness is made from a simple cup of cream? Pure water freezes at 0°C, but when a solute (eg sugar) is added, the freezing point of the solution is lowered ('depressed'), because the presence of solute molecules makes it harder for water molecules to order onto a crystal lattice, ie to freeze. In a separate bowl, mix together the sweetened condensed milk, cocoa powder, salt, and vanilla. Ainissa Ramirez, associate professor of mechanical engineering, describes the science behind a tasty bit of chemistry — ice cream. • iCe. Figure 2 shows the freezing point of sucrose solutions as a function of concentration. Not just any frozen treat can be called ice cream. The only way to satisfy both parts of the molecule simultaneously is for the emulsifier to be located at an oil-water interface. The process of making ice cream interested me and once I found out that rock salt was a main component, I decided to not only look up how ice cream is made but why rock salt is used as well. She shows how to make ice cream using liquid nitrogen, which is as cold as the surface of Neptune, and describes why these cold temperatures make ice cream … Check out Great Courses Plus for Homeschool Resources – Click the link below to discover what’s available! Then prepare and start mixing your ice cream ingredients Step 2: Fill the Bigger Bag Here is where we begin mixing our supplies together. Wrap the bag in the towel or put your gloves on, and shake and massage the bag, making sure the ice surrounds the creamy mixture. Dr Chris Clarke  is a research scientist at Unilever R  & D Colworth, Sharnbrook, Bed?ford MK44 lLQ. Now put the small bag with cream mixture inside the large bag. To make ice cream, the ingredients—typically milk (or half and half), sugar and vanilla extract—need to be cooled down. The mix is then cooled to ca 5°C, below the melting point of the fat, which begins to crystallise. Initially, the fat is present as coarse globules. This site uses Akismet to reduce spam. The next time you eat ice cream, think of Raoult, Gibbs, Newton, Kelvin and Ostwald - and all the physical chemistry that has gone into making it! The fat droplets and milk proteins adsorb onto the surface of the air bubbles and stabilise them, in the same way that the milk protein and emulsifiers stabilise the fat droplets. The first step is to know how much of each ingredient to use. (The related observation that the vapour pressure of a solvent above a solution is proportional to the mole fraction of the solvent in solution is Raoult's Law.) Hi, I'm Teresa Coppens, science geek, book nerd, educator, coffee lovin' mom with a coconut aversion. I agree ! The purpose of this experiment is to use this process to make homemade ice cream in a bag. Legend has it that making ice cream by simultaneously freezing and aerating cream originated when Mongolian horsemen took animal intestines filled with cream to eat on journeys across the Gobi desert in winter. Push out excess air and seal. How much sucrose should they use? Check out KiwiCo and get super interactive kits mailed right to your door! One way to do this is by using … Grab the password by filling in the form below. Ready to Find Loads of Printables in the Free Resource Library? An inside view of shaken cream. The hydrophilic part of the molecule is attracted to the water and the hydrophobic part is attracted to the oil. Thus, the ice or snow melts even when the temperature is well below zero. Since the fat droplets are partially crystalline, they form a strong, rigid coating, which prevents collapse of the air bubbles. From authentic glass test tubes, to laboratory grade graduated cylinders, a scientific thermometer, and a highly accurate gram scale, this kit contains all the specialty equipment needed to tackle our Chemistry of Ice-Cream Making: Lowering the Freezing Point of Water project. The solubility of a particle of radius r, s(r)  is given by: where V  is the molar volume and s (∞) is the solubility of an infinitely large particle. A = n  x 4πr2 = (Voil/[4π/3]r3)4πr2 = 3Voil/r. Ice Cream Chemistry In this segment of Science Xplained, Dr. Ainissa Ramirez describes the science behind a tasty bit of chemistry—ice cream. The more ice cream thaws and then freezes again, the larger the ice crystals become which can give the ice cream an icy/course feel and a freezer-burn taste. To make liquid nitrogen ice cream, decide how much ice cream you want to make and multiply that amount by 5 to figure out how much liquid nitrogen you need to buy. There are two reasons for this increase in viscosity. (Salt is put on roads in winter to remove ice.) If the temperature fluctuation is too big, the ice crystals become very large (> ~100 μm),  producing an icy, gritty texture. Click through the slideshow to see how to make your own ice cream. Zip the large bag tightly and start shaking that large bag. @import url(''); If you’re a classroom teacher, making ice cream is super simple and uses the same supplies and instructions. Into a large resealable plastic bag, combine ice and salt. Simply mixing cream, sugar and egg yolks, with a flavour such as fruit or chocolate, and putting them in the freezer won't give you ice cream. They consist of a refrigerated barrel, with a rotating dasher inside, which is equipped with scraper blades. Read our policy. Thus one component of the microstructure - the fat droplets - has been created. Information about your use of this site is shared with Google. Enter François-Marie Raoult Pure water freez… To keep the fat droplets small the emulsion must be stabilised with a surfactant (see Box 1). Fig 3(b) Schematic diagram of homogenisation showing proteins and emulsifiers adsorbed to the small fat droplets. In the next stage the mix is converted into ice cream by aerating and freezing it. • one tablespoon sugar. Add the sugar and vanilla essence ( or just use flavoured milk ). We have already seen that dispersions of one phase in another are unstable and have a tendency to lower their energy by forming fewer, larger particles. Zip the large bag tightly and start shaking that large bag. When you are all done carefully open the bags and extract your ice cream… The barrel wall is cooled to ca -30°C, so that when the mix touches it, ice forms instantly, and heat is rapidly extracted from the ice cream mix (see Box 2). Crush the dry ice. Making ice cream is a divine way to teach science. Put the ice and salt in the large bag. Air is injected, forming large bubbles, which are broken down into many smaller ones by the beating of the dasher. It is a fan favorite with my own kids. • other Flavors/add-ins(optional) • six tablespoons salt. Ice Cream or Frozen Dessert? Got young kids you want to encourage to be passionate about science? Make Ice Cream in a Baggie From Anne Marie Helmenstine, Ph.D., Your Guide to Chemistry. Ice cream making in the 19th century was a slow process. The following is a "how to" make an ICE chart using the example to illustrate the process. Why is this done? As the temperature is reduced, more ice forms, and the solution concentration follows the curve. Solving these two equations gives Msucrose = 320 g. In practice, they also have to allow for other solutes, eg  from milk, when formulating ice cream recipes. The amount of sugar (sucrose, C12H22O11) determines the amount of ice in the ice cream because this will affect the freezing point. Do you need a lot of advanced equipment? London: Guinness World Records, 2002. Want to give your kiddos or classroom students a true lab experience then download my lab worksheet for making ice cream. Come to think of it, you’ll likely need your kids to take over for you. Ice cream is temperature sensitive: if it warms up too much, it melts. You can find it my free resource library. When you take ice cream out of a supermarket freezer its temperature may rise by a few degrees during your journey home, so that some of the ice melts. As the ice cream passes through the freezer, its temperature drops, more ice is formed, and the viscosity of the ice cream increases. Half fill a bigger ziploc bag with ice and add a good amount of salt. Lithium-ion batteries will power the next generation of electric cars, but how can we mine lithium with minimal impact on the environment? As they galloped the cream was vigorously shaken, while at the same time the sub-zero temperatures froze it, creating ice cream. In this chemistry experiment you will be lowering the freezing point of water by adding salt to ice. Looking more solid! Zip it up tightly. The solubility of a particle in?creases as the particle gets smaller, ie  small particles are more likely to dissolve than large ones. As well as discovering the laws of motion and gravity, Isaac Newton gave his name to the law which states that the rate of change of temperature of an object, eg ice cream, is proportional to the difference be?tween its temperature (T ice cream) and the temperature of the refrigerant, (T r), Thus the colder the refrigerant, the faster the ice cream is cooled down. If you’re getting your kids to help you might need to take over the bag shaking for a while. Grab a copy of this worksheet plus get access to all my printables by filling out the form below. In this segment, Dr. Ainissa Ramirez describes the science behind a tasty bit of chemistry—ice cream. Look at ice cream magnified several hundred times in a scanning electron microscope and you will see that it has a complex structure on length scales of 1 μm to 1 mm (Fig 1). She shows how to make ice cream using liquid nitrogen, which is as cold as the surface of Neptune, and describes why these cold temperatures makes ice cream, creamier. Much more than this and the product would be too hard; much less it would be like custard and would not cool you down on a hot day. Make sure to have spoons on hand so everyone can taste their experiment once all observations are made and recorded! Making ice cream looks at the following concepts of science: For those of us who live in a climate having frigid winters, we’ve seen salt put on the roads during snow or ice storms. lce cream typically contains ca 60 per cent ice by weight. a half cup or full cup of half-half cream, or full cream if you’re not worried about the calories; enough ice to fill the large bag about 3/4 full; Science of Making Ice Cream Lab Worksheet – you find it in my. Then add ½ cup of salt to the bag. If oil and an aqueous solution are vigorously mixed together (eg  to make a salad dressing), the oil is dispersed to form an emulsion of a large number (n) of small droplets with a total volume Voil. At any temperature below the freezing point, there is a given amount of ice in equilibrium with the freeze-concentrated sucrose solution. Well, the salt mixes with the ice or snow and reduces the freezing point of water. In each small sealable bag, place one tablespoon of sugar, ½ cup of half-and-half (or milk or heavy whipping cream), and ¼ teaspoon of vanilla extract. Cream Chemistry. Students will observe and describe the changes in the physical properties of the ingredients. You heard that right – only three and you’ve likely got those ingredients on hand. The Chemistry of Making Ice Cream Introduction I chose to figure out the chemistry of ice cream because it’s a sweet, fun treat that everyone can enjoy. • ¼ teaspoon vanilla extraCt. Put all the food ingredients into the small bag. Check out this page KiwiCo is making available to parents during the Covid 19 pandemic. Thanks for posting. Its only got three ingredients. Most solutions obey this equation when the solute concentration is low, but may diverge from it at high concentrations. At-Home Resources for Kids (and their grownups). Take a look at the picture below. Put the milk bag into the ice bag and give it a good shake. half-n-half) 1/4 cup sugar 1/4 teaspoon vanilla or vanilla flavoring (vanillin) The best refrigerant available was a eutectic mixture of ice and salt (sodium chloride), which has a minimum temperature of -21.1°C. Make sure to record this number so you can record Making ice cream is a divine way to teach science. Looking for something fun to wrap up the term? The same principle is used in making ice cream. I’m going to try this with my boys his weekend. Heck, I love its cool sweetness even on a frigid winter day – snug and warm on my sofa though. Ice cream thus contains all three states of matter simultaneously and is both a foam and an oil-in-water emulsion. Ice cream is a type of emulsion, a combination of fat and water that usually wouldn’t mix together without separating. Most ice creams consist of a successful frozen emulsion of five basic components: – Ice crystals Created when the water-content in the base starts to freeze; they put the “ice” in “ice cream”, giving solidity and body.