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Molecular Gastronomy Elke Scholten Wageningen University Food Physics group Molecular Gastronomy? Gastros (Gr) = stomach Nomos (gr) = knowledge or law Moles (Latin) = small unit of mass Classic: Molecular laws on the stomach Modern: Molecular laws on the pleasure of eating Herve This: Molecular Gastronomy Harold McGee: On food and Cooking Understanding of phenomena in cooking: -Flavor / color (chemistry) -Structure (physics) -Sensation (psycology) Food and art Craft: - Repetition - Tradition - Technical Art - innovation - creativity - expression Presentation versus Interplay between flavor and texture Restaurants El bulli, Barcelona: Ferran Adria Fat Duck, London: Heston Blumenthal Number 1 in the world: Noma, Copenhagen: Rene Redzepi 2011: Dutch restaurants in top 50: Oud Sluis, Sluis: Sergio Herman Librije, Zwolle: Johnny Boer (19) (37) Food! Science in food Physiology and Psychology Technology/Science Creation/art: New Cooking Processes Tools, Innovation, Creativity Science in food Building blocks for food Three main food structures: - Emulsions - Gels - Foams How can you control structures with the available building blocks ? Science in food Building blocks for food Dispersed phase Continuous phase gas liquid solid Gas -- Aerosol (fog) Aerosol (smoke) Liquid Foam (beer) Emulsion (mayonnaise, milk) Suspension / dispersion (starch solution) solid Foam (bread) Emulsion (cheese) -- Food structures - Emulsions Mixture of two immiscible liquids, such as oil and water Droplets of oil in water Not stable: add ingredients to make it stable egg: contains protein Emulsions No stabilizer Can be found in: - Milk - Meat - Fish - Eggs - Gelatin Building blocks : - Proteins - Oil (fat) - Water Mayonnaise Recipe: egg yolk, salt, mustard, pepper, vinegar, olive oil Egg yolk: provides the protein: stabilizer Mustard, pepper: taste Vinegar: pH low Oil: oil droplets in water. The more and smaller the oil droplets, the thicker the mayonnaise (creamier) How to make the mayonaise? - Adding the oil to the water and whisking very rapidly Other ingredients: - proteins: egg yolk, egg white, gelatin - pH: any liquid that has a low pH: coke, orange juice, etc - Oil: other ingredients that have oil in them Mayonnaise variations Yolkless mayonnaise: egg white, oil, vinegar (pH) Eggless mayonnaise: add the oil to a warm gelatin solution. The gelatin will gel upon cooling Chocolate mayonnaise: replacing oil by chocolate fat, egg white Creamy texture Heating in microwave Proteins will glue to each other more Chocolate cake Orange mayonnaise: orange juice, gelatin, oil Protein interaction Positive charges Negative charges Protein is a spherical entity with a certain charge Protein interaction Low pH: more positive charge H3O+ high pH: more negative charge OH- Every protein has a different iso-electric point: Depending on the pH, a protein is negatively or positively charged. + - - + - + + + - - + pH - Protein interaction + + + + Charge density: double layer + + Distance between proteins is determined by the amount of charge and thus by the pH + + - - - + - + + - + pH - Protein interaction Effect of pH: + + + + + + + + + + + + + + + + + + + + + Aggregation of proteins + Unfavorable for stability Effect of salt: + + - + - + - + + + -+ - + + - + - + Aggregation of proteins Baileys + tonic Is it dangerous or is it safe? + ? Baileys + tonic Addition of tonic Cream: fat Stabilized by milk proteins Change in pH aggregation of proteins Creaming and coalescence of oil droplets Baileys + tonic CO2 Oil layer on top of protein solution Oil layer starts to foam Baileys + tonic Is it dangerous or is it safe? Food structures - Foam A substance that is formed by trapping many gas bubbles in a liquid or a solid - Bread (air in solid) Cake Ice cream (air in water / ice) Beer foam Cappucino foam (milk foam) Mousse Meringue No stabilizer Food structures - Foam A substance that is formed by trapping many gas bubbles in a liquid or a solid - Bread (air in solid) Cake Ice cream (air in water / ice) Beer foam Cappucino foam (milk foam) Mousse Meringue Building blocks : - Proteins - Water - Air - Fat Solid fat proteins Foams Cappucino foam: The more protein/fat the milk has, the more stable the foam Meringue: crispy sweet egg white foam Only need proteins to make a foam: Gelatin instead of milk or egg proteins Cucumber foam Other vegetable foams and fruit foams Peanut butter foam, parmesan foam Wine foam Champagne foam ESPUMA Foams Coffee espuma Champagne espuma Mango and forest fruit espuma Coke + Mentos? What happens? Coke + Mentos? What happens? Coke contains CO2 bubbles. Growth of bubbles depends on thermodynamic parameters Need energy to grow 4 G r 3 4r 2 3 Coke + Mentos? What happens? Add mentos? Porous material lots of small cracks and sites. Lowers the energy to let bubbles grow Porous sites and cracks act as nucleation sites for bubble growth. (nucleation and growth) Speed depends on the energy and the amount of nucleation sites Beer and fish? What happens? Beer and fish? Addition of fatty substances: - Lipids are small molecules Competition between components: kinetics: smaller molecules adsorb faster Foam - ice cream Creamy ice cream: - Fat 5% - milk 75% (proteins, water) - Sugar 20% Fat Air 50% proteins Ice crystals : 30% (frozen water) air Sugar molecules: Anti-freeze effect Building blocks : - Water / ice - Air - Fat - Sugar - Proteins Sorbet ice - water / fruit 75% - Sugar 25% - stabilizer (gelatin) Foam - ice cream Recipe: milk, cream, sugar, air Fat and proteins: stabilizers Sugar: anti-freeze substance determines the ratio between solid ice and liquid water Adding sugar: changes chemical potential of water: A L A0 RT ln x A L At a certain temperature, chemical potential of ice is in equilibrium with the chemical potential of the sugar solution A 0S A0 RT ln x A L Amount of sugar determines the freezing point depression (equilibrium between ice and solution – melting /freezing point) TF K K msolute i M solute Foam - ice cream TF K K msolute i M solute Sugar is not the only anti-freeze agent: - alcohol - salt 0 -5 -10 sugar temperature -15 -20 -25 alcohol -30 salt -35 -40 0 20 40 60 Concentration anti-freeze agent (%) 80 100 Foam - ice cream Amount of sugar (or alcohol / salt) determines the percentage of solid ice: % ice T M solute 1000 KK i 100 1000 msolute 1000 T M solute K i K During eating, the amount if ice Decreases 80 ice fraction (wt. %) 70 60 50 200 40 300 400 30 Sensory perception (coldness, smoothness, etc) 20 10 0 -20 -15 -10 temperature (ºC) Freezer temperature -5 0 Different anti-freeze agent: Different ice curve Different sensory perception Foam - ice cream What do you need to make ice cream? - Water - Stabilizer (fat, protein, gelatin) - Anti freeze substance (sugar, gelatin, alcohol, salt) Wine ice-cream / liquor ice cream: - fruit: water, sugar (anti freeze) - Alcohol: water (anti-freeze) - Stabilizer (cream, gelatin) Vegetable/meat ice cream: - vegetable: water - Fish/ meat: proteins, fat - No sugar: other stabilizer (gelatin) Wine ice-cream shrimp ice-cream Caipirinha ice cream Garlic ice-cream Ice cream - new dishes Tomato and basil sorbet ice - 5 tomatoes - 120 ml lemon juice - 1 spoon of salt (anti freeze) - 70 ml water - 70 gram sugar (anti freeze) - tomato puree - chopped basil - gelatin (to stabilize the air) Ice cream - new dishes Egg and bacon ice cream Fat duck, London - 300 gram bacon - 1 liter milk (water, proteins) - 25 gram milk powder (proteins, fat) - 24 egg yolks - 125 gram glucose (anti freeze) Gels Gels are materials that are elastic and they have properties in between a solid and a liquid state - Cheese Gummy bears Cooked egg There are two types of gels: - Protein gels - Polysaccharide gels (eggs, meat) (desserts) Protein gels Gels are materials that are elastic and they have properties in between a solid and a liquid state Scrambled eggs? The temperature has an effect on the structure of an egg Why? Protein gel - Eggs when temperature increases they unfold they form crosslinks results in a gel Protein is folded The strength of the gel depends on the temperature Network Gel Protein gel - Eggs The perfect egg!! The protein in egg white (albumin) unfolds at 65C The protein in egg yolk unfolds at 70C An egg cooked between 65 C and 70 C Protein gel - Meat Meat Meat contains a lot of proteins When heated the proteins will unfold and cluster together 40C: unfolding proteins 50C: muscle contracts 55C: myosin clusters 66C: other proteins cluster 70C: myoglobin looses oxygen: turning pink 79: actin clusters 80C: meat becomes grey 100C: water evaporates 150C: chemical reactions Polysaccharide gel Polysaccharides are multiple sugars which form large chains. Starch: amylopectin amylose Other sugars: Xanthan Agar (seaweed) Pectin: fruit Carrageenan: seaweed Alginate: algae Polysaccharide gel Polysaccharides are multiple sugars which form large chains. Parameters that influence gel strength: - Salt - pH - Specific ions Sugar network Gel - Brittle gels - Elastic gels Polysaccharide gel Effect of: - pH - salt Groups that can become positive pH determines amount of charge determines the distance between the molecules Salt decreases the effect of charge Groups that can become positive Polysaccharide gel Effect of: - Specific ions alginate Negative charges Calcium (positive) interacts with charges on alginate (negative) They form a network which is very strong Polysaccharide gel Gels: - Fruit gels (water – sugar) Foam gels (water – air – sugar) - Juices Alcohol Edible cocktail: Martini-blueberry Science in food Building blocks for food By controlling amount of building blocks one can play with the physical properties of food: - Gel like - Incorporation of air (foams) - incorporation of oil (emulsions) - Controlling amount of ice Defines the structure of food! New ingredients El Bulli: Texturas Spherification line Gelification line Surprise line New dishes Spherification line Liquid pea ravioli Algin: alginate Calcic: calcium alginate with calcium gel Solution of peas, water, mint and algin Dip into water with calcic Outside will turn into a gel New dishes Spherification line Fruit caviar: melon orange lemon New dishes Spherification line Melon caviar in a ham consomme New dishes Gelification line ribs underneath a beet-juice and campari gel Gellan: gelatin agar Kappa/iota: carrageenan They all form networks and therefore a gel Expectation Expectation Egg vanilla ice cream on mango Expectation Mango ravioli on a bed of coconut Mango ravioli made by spherification With alginate and citric Coconut gel is made by adding agar or carrageenan Expectation mustard ice cream with gel of olive oil and a foam of vinegar Expectation can lead to a different flavor sensation questions