Experiments In Food Science
Experiments In Food ScienceLaboratory Manual, Volume 2ContentsIntroduction: What is Food Science?, p.1Experiment 1: Invisible Lipids, p.2Experiment 2: Jelly Making, p.3Experiment 3: Effect of Temperature on Taste, p.4Experiment 4: Super Cooling of Water, p.5Experiment 5: Iron Extraction, p.6Experiment 6: Reverse Spherification, p.6Experiment 7: Pickling, p.7Experiment 8: Emulsions, p.8What is Food Science?This laboratory manual has two purposes. The firstpurpose is to describe what food science is and whatfood scientists do. The second purpose is to describe funlaboratory experiments that that demonstrate practicalapplications of food science.Food science is all of the science involved in takingagricultural food products from the farmer’s gate to thegrocery store, restaurant, or dinner table. Food scientistswork with all sectors of agriculture. Food science includesboth basic and applied biology, microbiology, chemistry,math, business, engineering, physics, and other disciplines.A food scientist’s goal is to make safe, high quality foodproducts that are profitable to all segments of agriculture.Those who earn a bachelor of science in food sciencehave starting salaries of 45,000 to 60,000 per yearand work for some of the largest food manufacturingcompanies in the country. Food science students canalso compete in national competitions dealing with food,such as Dairy Judging, Meats Judging, New ProductDevelopment, and the Research Chef’s Association.These events offer participants networking and learningopportunities for future career growth.Some food science majors pursue careers in veterinarymedicine or other healthcare fields. They complete the foodsafety option in the food science curriculum, which allowsthem to work towards an undergraduate degree whilecompleting the prerequisites for veterinary school. Theveterinary school acceptance rate for food science majorsis very competitive compared to the acceptance rate for allpre-vet disciplines.But food science graduates who do not pursueprofessional degrees in healthcare also have great jobopportunities and often advance rapidly. They canwork for regulatory agencies, ingredient and equipmentmanufacturers, research firms, suppliers, or othercompanies; all offer great opportunities for food sciencegraduates.Laboratory exercises in this manual demonstrateprinciples behind lipid extraction, jelly making,temperature and taste, freezing, iron extraction, foodstates (liquids, gels, etc.), emulsions, and pickling. Theselaboratory experiments demonstrate some simple scientificprinciples that apply to food manufacturing and show thecharacteristics of some common foods.
Experiment 1: Invisible Lipids5.PurposeThis experiment demonstrates the presence of lipids incommon foods.6.Materials 7.5 grams potato chips (broken into small pieces)5 grams semi-sweet chocolate chips (crushedbetween two pieces of foil with a rubber mallet)5 grams sunflower seeds (crushed between twopieces of foil with a rubber mallet)60 milliliters ethanolThree 150 milliliter beakersThree 100-mm petri dishes or weigh boatsBalanceGlovesAluminum foil8.Add 10 more milliliters of ethanol to the beakers,swirl for 1 minute, and decant the ethanol into thepetri dishes as before.Allow ethanol in the petri dish to dry overnight ina well-ventilated area or under a hood. Look in thepetri dish to see the lipid that was extracted.Allow the beakers with the food samples to dryovernight.Weigh the beakers with the dry food samples.Record the weights.NotesLipids are soluble in organic solvents. In thisexperiment, ethanol is used to extract lipids from food.When extraction is complete, the lipids become visible.Two types of lipids should show up in the petri dish:saturated and unsaturated lipids. Saturated fatty acidshave all single bonds, have a maximum number ofhydrogen associated with the carbon atoms, and aresolid at room temperature. In contrast, unsaturatedfatty acids are liquid at room temperature and havedouble bonds between the carbon atoms. Fatty acidsthat have more than one double bond are known aspolyunsaturated fatty acids.Procedure* Please do not consume any of the food products.*1. Label each of three beakers with the three types offood. Weigh and record the weight of each beaker.2. Weigh and transfer each food sample to labeledbeakers. Record the weight of the beakers with thefood samples.3. Add 10 milliliters of ethanol to each beaker andswirl for 1 minute. Be sure to perform this step in awell-ventilated area or under a hood.4. Carefully decant the ethanol from each beaker intoa labeled petri dish or weigh boat. Make sure thefood samples remain in the e-Experiments/ xperiments/TeacherGuideLIPIDS.ashxExtraction of LipidsFoodWeight of beaker(grams)Weight of beakerwith food (grams)Weight of foodsample (grams)Potato chips5Chocolate chips5Sunflower seeds5Weight of beakerwith dried foodovernight (grams)Weight lost fromfood (grams)1(Weight of beaker with food) – (Weight of beaker with dried food) Weight lost from food(Weight lost from food / weight of food) x 100 percent lipid extracted12Description of FatsFoodColorTextureOdorPotato chipsChocolate chipsSunflower seeds2ViscosityPercent lipid extracted2
Experiment 2: Jelly MakingTreatment 2 (low sugar)Purpose1.This experiment demonstrates the importance of pectinin jelly making. It also shows how the amount of sugarused affects the jelly.2.3.4.Materials 5.Commercial pectin (like Sure-Jell)Concentrated apple juiceBalanceSugarGraduated cylinder600 mL beakersStirring rod or wooden spoonHot plateHeavy glovesRepeat steps as in control, but use 39 grams ofsugar instead of 79 grams.Record your results.Treatment 3 (high sugar)Repeat steps as in control, but use 159 grams ofsugar instead of 79 grams.Record your results.Treatment 4 (low pectin)1. Repeat steps as in control, but use 5 grams ofpectin instead of 10.5 grams.2. Record your results.NotesJellies are made from the strained juice of fruits.Jellies should be crystal clear and hold their shape but softenough to spread. The main ingredients to make jelly are pectin, which is a carbohydrate found in fruits(some fruits have more pectin than others, socommercial pectin is available) an acid, like lemon juice or citric acid sugar, and juice (almost any juice will make jelly).To make jelly, pectin and lemon juice are added to fruitjuice. The solution is then heated, making pectin watersoluble. When sugar is added, the pectin precipitates out,forming insoluble fibers. Lemon juice lowers the pH andaids in the gelling process. The insoluble fibers produce amesh-like structure that traps the fruit juice, much like asponge absorbs water. This enables the mixture to form agel. Too little sugar will result in a runny, liquid jelly; toomuch sugar will produce a jelly that has some firmness butwill not hold its shape. Sugar also contributes to flavor andacts as a preservative.ProcedureTreatment 1 (control)1. Place 117 ml apple juice in a 1000 mL beaker.Gradually add 10.5 grams pectin, stirring to mix it.2. Place the beaker on a hot plate and stir constantlyover high heat to a full boil.3. Add 79 grams of sugar. Return the mixture to afull, rolling boil. Boil hard for 1 minute, stirringconstantly. Be sure to adjust the heat source sothat the liquid does not boil up the sides of thebeaker. CAUTION! This mixture can boil over veryquickly if it’s not carefully watched.4. Remove the hot beaker from the heat source. Placethe hot beaker on a heatproof pad and allow the jellyto cool. Use a spoon to skim off the foam on the top.5. If the sample gelled, loosen the pectin from thebeaker with knife and then invert the beaker to slidethe gel onto a paper plate. Observe the consistencyof the gel and its ability to hold a AEPC/IFT/unitone.phpJelly ConsistencyExperimentJellyControlRegular formulaTreatment 1Low sugarTreatment 2High sugarTreatment 3Low pectinConsistency3
Experiment 3: Effect ofTemperature on Taste4.Purpose5.This experiment demonstrates how temperatureinfluences taste.6.Materials7. 15 grams non-iodized salt (sodium chloride, NaCl)15 grams food-grade citric acid15 grams granulated sugarWaterNine 150-mL beakers (three for each chemicalcompound)Weigh boatsHot platesThermometersIce bathScaleNotesFor many years, scientists have observed thattemperature affects perceived taste of foods. The tastebuds in our tongue contain receptors that are sensitive totemperature and specifically recognize sweet, bitter, sourand salty. When warmer food comes in contact with thesereceptors, a stronger electrical signal is generated in ourtongue. This signal is sent to our brains, intensifying theflavor of the food and causing us to recognize the taste.Certain desserts, such as ice cream, are sweeter whenthey are warm. Likewise, beer tastes less bitter when itis chilled. Have you ever noticed that soups taste saltierwhen cold? As the temperature of the food increases, ourability to distinguish sweetness also increases.Procedure1.2.3.Leave the three beakers labeled 20 C at roomtemperature.Place the three beakers labeled 40 C on hot plates.Place thermometers in the beakers.Place the three beakers labeled 4 C in an ice bath.Place thermometers in the beakers.Monitor the temperatures of the solutions. Whenthe desired temperature is reached, carefully tastethe solutions. Record your observations in thetable provided.Label three beakers “NaCl.” Assign a temperatureto each beaker and label them accordingly. Labelone beaker “4 C,” one “20 C,” and one “40 C.”Add 5 grams of NaCl (salt) and 95 grams of waterto each beaker.Repeat steps 1 and 2 for sugar and citric acid.When you finish, there should be three treatments(NaCl, citric acid, and sugar), and each treatmentshould have three assigned vor ObservationsContents of Beaker4 C20 C5 grams NaCl,95 grams water5 grams citric acid,95 grams water5 grams sugar,95 grams water440 C
Experiment 4: Supercooling of WaterProcedurePurpose1.This experiment demonstrates how water can remainliquid below its normal freezing point of 0 C.2.Method 1 Materials 3.4.20 mL bottled distilled waterIce cubes2 Tablespoons saltLarge glass bowlThermometerClear plastic cup5.Cover the top of the beaker or bowl with plasticwrap.Using a pipette, place several drops of distilledwater on the plastic wrap. Make sure the drops arespaced apart from each other.Place the beaker or bowl in a freezer for 5 minutes.Remove the beaker or bowl from the freezer andnote that some drops are opaque, and others aretranslucent. The opaque drops are frozen, whilethe translucent drops are liquid.Touch the translucent drops with an ice cube andwatch them freeze instantaneously.Procedure1.2.3.4.5.6.ReferencePour 20 mL distilled water into a clean, clearplastic cup.Place the cup in the center of the glass bowl. Coverthe cup with plastic wrap.Add ice cubes inside the bowl until the level of theice is above the level of the water in the cup.Sprinkle 2 tablespoons of salt over the ice cubes.Uncover the cup. Insert a thermometer.Monitor the temperature of the water. When thetemperature reaches -1 to -3 C, carefully removethe cup from the ice.Make the water freeze by pouring it over a piece ofice or by dropping a small piece of ice into the ivitydrops.htmlNotesSupercooling is cooling a liquid below its normalfreezing point without crystallization. Water’s normalfreezing point is 0 C (32 F). When water is cooled toits freezing point, ice crystals begin to form and growin the water. Impurities in the water can trigger icecrystal formation, preventing the water from becomingsupercooled. A sample of pure water (free of impurities),cooled slowly, can produce supercooled liquid water.However, when ice touches supercooled water, it catalyzesthe crystallization of the liquid, and the water s.org/science-fair-projects/project ideas/Phys owtoguide/a/how-to-supercool-water.htmExperiment 5: Iron ExtractionPurposeThe purpose of this experiment is to demonstrate thepresence of iron in breakfast cereals.Method 2 (Mini supercooling of water) Materials Bottled distilled waterWide mouth beaker or bowl (glass)Plastic wrapIce cubesPipetteMaterials 5150 grams breakfast cereal (Total cereal worksbest)Plastic bag with zip top or twist tieWarm waterBeakersLarge magnetic stir bar (70 mm)Stir bar retriever rodScaleMagnetic stir plate
Procedure* Please do not consume any of the food products.*1. Place cereal into the plastic bag, close the bag, andcarefully crush cereal into a fine powder. Transfercrushed cereal into a beaker. Place stir bar in beaker.2. Add enough warm water to cover the crushedcereal completely. Stir contents until the mixtureis brown and soupy. Allow mixture to stand for 30minutes.3. Remove stir bar with a stir rod.4. You should notice a fine gray powder of ironattached to the stir rod. Wipe the powder on awhite napkin to see the iron better.Procedure*Please do not eat any of the food products.*1. Combine berries, sugar, and calcium lactate in thebowl of a blender. Puree the mixture.2. In a separate bowl, mix the sodium alginatein 2 cups of water until the sodium alginate iscompletely dissolved. Refrigerate for 15 minutes.3. Remove sodium alginate bath from therefrigerator.4. Using a measuring spoon, carefully transferseveral spoonfuls of the berry puree into thesodium alginate bath. Spherification should occurimmediately. Allow the spheres to sit in sodiumalginate bath 2-3 minutes.5. Pour the remaining water into a clean rinsingbowl. Transfer the spheres to the rinsing bowlusing a slotted spoon.6. Remove spheres carefully from rinsing bowl, asthey are fragile.NotesMany breakfast cereals are fortified with food-gradeiron particles (metallic iron) as a mineral supplement.The body must have iron for to function properly. Ironis digested in the stomach and absorbed in the smallintestine. Iron is present in muscle tissue and someenzymes, and approximately 60 to 70 percent of the humanbody’s iron is found in hemoglobin. If all of the body’s ironwere extracted, there would be enough iron to make onlytwo small /learn-about-foodscience/k12-outreach/ ilsfor-breakfastNotesExperiment 6: Reverse SpherificationSpherification is a cooking technique in which a liquidis dropped into a solution to create spheres with a thingel membrane filled with the original liquid. Reversespherification occurs because of the interaction between acalcium source and sodium alginate. Calcium ions causealginate polymers to become cross-linked, forming a gel.These spheres have a thicker outer membrane, and thejellification stops when the sphere is removed from thealginate bath and rinsed with water. Jellification occursonly on the surface, as alginate fails to penetrate thesphere. Thanks to these characteristics, reverse spheres arelong lasting, can be manipulated more easily and used inmore ways.PurposeThis experiment demonstrates the process used tocreate edible, liquid-filled spheres.Materials 2 grams sodium alginate½ teaspoon calcium lactate (or calcium chloride)6 cups water (distilled or bottled)1 ½ cups fresh or frozen berries2 Tablespoons sugar2 medium bowlsMeasuring spoonSlotted spoonBlenderBalance6
spherification/6.Experiment 7: PicklingPurposeThis experiment demonstrates the effect of pickling onpreservation of food.7.WarningsNever alter the amounts of vinegar, food, or waterin a pickling recipe. Do not use vinegars withunknown acidity. Use only well-tested recipes.Do not prepare any part of this experiment usingcopper, brass, iron, or galvanized cookware orutensils; doing so can result in toxic compoundsand undesirable colors or flavors.8.Materials 4 lbs pickling cucumbers (preferably no longerthan 4-5 inches) 1.42 L vinegar, 5% acidity 2.72 lbs sugar 38.2 g pickling/canning salt 7.6 g pickling spice (may be bound in cheesecloth) Knife Cutting board 2 large saucepots 7-8 pint jars with lids and rings Large canner with rack and lid Jar lifter or oven mitts Scale Weigh boats Ladle or measuring cup Tongs Thermometer9. NotesPickling is an ancient form of preservation that consistsof using an acidic medium, such as vinegar, to lower thepH of a food. Pickled foods should have a pH of 4.6 orbelow to prevent the growth of microorganisms such asClostridium botulinum, a deadly spore-forming bacterium.Heat processing, such as canning, also helps destroy anymicroorganisms capable of growing at a pH lower than 4.6.Procedure1.2.3.4.In a saucepot, combine vinegar, sugar, picklingsalt, and pickling spice. Heat over medium heatand bring to a boil.When pickling solution begins to boil, quicklyladle hot solution over cucumbers, leaving ¼ inchof headspace. If pickling spice has been tied incheesecloth, remove spice pouch before addingsolution to jars.Wipe the rim of each jar with a clean, damp cloth.Center heated lid on jar and screw ring downevenly and firmly until you feel resistance.After all jars have been filled and capped, placejars in canner. Water level should be one to twoinches above the top of the jars. Place lid on cannerand bring water to a steady boil. Boil according toyour elevation. If you are at an elevation of 1,000ft. or below, jars should process for 15 minutes; ifyou are at 1,001 ft. to 6,000 ft., jars should processfor 20 minutes.After processing, remove jars with jar lifter andallow them to cool. When jars are cool, test eachjar by pressing the center of the lid. The lid shouldremain firm and not spring back. (If it does,immediately refrigerate or reprocess with a newlid for the full length of time).Wash jars, lids, and rings. Rinse thoroughly toremove detergent residue. Put jars in canner andboil. Remove jars and set them on a towel.Keep lids and rings in simmering water (180 F)until needed.Wash cucumbers and remove the ends. Slicecucumbers into ¼ inch rounds.Pack sliced cucumbers into jars, leaving enoughspace for pickling solution.7
Heat-treating pickles deactivates enzymes in thecucumbers, helping them retain good color, flavor, andtexture. The pickles produced in this experiment areconsidered fresh-pack or quick-process pickles becausethey have not been brined like traditional pickles. Pickleswill last up to a year if properly processed and stored.Procedure1.ReferenceRecommended processing times in a water bathcanner and recipe have been adapted from MakingPickled Products, 2011 by Julie Garden-Robinson, Ph. D.,North Dakota State University Extension Service (NDSU)in cooperation with Joan Hegerfield-Baker, M.S., SouthDakota Cooperative Extension Service.2.3.Experiment 8: EmulsionsPurposeThis experiment demonstrates how to makemayonnaise, a common food emulsion.Combine water,sugar, salt, cornsyrup, mustard,garlic powder, andvinegars in a foodprocessor bowl.Blend well.Blend egg yolksinto mixture untilit becomes frothy.While theprocessor is blending, add soybean oil a little at atime, making sure to incorporate all of the oil intothe mixture each time. Do not stop blending, oryour emulsion could fail! Blend until all the oil hasbeen incorporated and the mixture is smooth andcreamy.NotesMaterials*For best results, all ingredients should be at 50 F.* 32
applications of food science. Food science is all of the science involved in taking . agricultural food products from the farmer’s gate to the grocery store, restaurant, or dinner table. Food scientists work with all sectors of agriculture. Food science includes both basic and applied biology, microbiology, chemistry,
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