Food Molecules and Experiments

Food Molecules

• Scientific Experiments: Good experiments are repeatable, have controlled variables, testable hypotheses, clear variables (independent and dependent), and large sample sizes.
• Elements vs. Molecules: Elements are single atom types (e.g., O₂, H₂), while molecules are multiple bonded atoms (e.g., H₂O, CO₂).
• Major Food Elements: Key food elements include carbon (C), hydrogen (H), oxygen (O), nitrogen (N), and phosphorus (P).
• Elements vs. Compounds: Elements are single atoms; compounds are bonded different atoms (e.g., H₂O, CO₂).
• Atomic Particles: Atoms have protons (+, nucleus), neutrons (neutral, nucleus), and electrons (-, orbit nucleus).
• Bond Types: Ionic bonds involve electron transfer (e.g., NaCl), covalent bonds involve electron sharing (e.g., H₂O, CO₂). Polar covalent bonds have unequal sharing, while non-polar covalent bonds share electrons equally.
• Bond Type Determination: Ionic bonds form between metals and nonmetals, covalent bonds between nonmetals, and polar covalent bonds result from electronegativity differences between nonmetals.
• Polarity: Polar molecules have an uneven charge distribution, while non-polar molecules are symmetrical.
• Molecular Bonds: Intramolecular bonds occur within molecules (covalent, ionic), while intermolecular bonds exist between molecules (hydrogen, Van der Waals).
• Bond Strength: Covalent bonds are strongest, followed by ionic, then hydrogen, and finally Van der Waals.
• Bond Energy: Breaking bonds requires energy; forming bonds releases energy.
• Cooking & Bonds: Intermolecular bond breaking is a physical change, while intramolecular bond breaking is a chemical change.
• States of Matter: State depends on energy: low energy = solid, medium = liquid, high = gas.
• Physical Changes: Changes like melting or boiling don't create new substances.
• Chemical Changes: Changes like burning or rusting form new substances.
• Organic vs. Inorganic: Organic molecules contain C-H bonds (glucose, proteins), while inorganic molecules lack these (water, salts).
• Abundant Food Molecule: Water is the most abundant food molecule.
• Water Structure: Water in different phases exhibits distinctive structures (solid = crystalline & tightly packed, liquid = close but moving, gas = widely dispersed).
• Water & Solvents: Water dissolves polar/ionic substances (NaCl, sugar) and repels non-polar substances (oils, fats).
• Macromolecules: Large molecules (carbohydrates, proteins, lipids) are built by monomers. Polymers are chains of repeating monomers.
• Food Macromolecules: Carbohydrates (monosaccharides/sugars), proteins (amino acids), and lipids (fatty acids).
• Carbohydrate Types: Monosaccharides (e.g., glucose), disaccharides (e.g., sucrose), and polysaccharides (e.g., starch, cellulose).
• Starch vs. Cellulose: Both glucose polymers, but differing bonds cause structural differences. Starch is digestible, while cellulose isn't.
• Starch Detection: Iodine turns blue-black in the presence of starch.
• Fatty Acids: Long chains of carbon & hydrogen atoms. Saturated have no double bonds (solid), unsaturated have at least one (liquid), and trans are artificially altered.
• Amino Acids: Amino acids have central carbon atoms, an amino group, a carboxyl group, and a side chain (influences polarity).
• Protein Structure: Amino acid sequence affects protein shape and function.
• Protein Denaturation: Process of breaking intermolecular bonds alters protein structure.

Dairy

• Ruminant Digestion: Ruminants (e.g., cows) digest cellulose using bacteria in their stomachs.
• Milk Molecules: Milk contains lipids (milk fat), carbohydrates (lactose), and proteins (casein, whey).
• Lactose: A disaccharide of glucose and galactose.
• Lactose Intolerance: Lack of lactase enzyme causes difficulty digesting lactose.
• Lactose Fermentation: Bacteria ferment lactose, producing gas.
• Lactose-Free Milk: Lactase breaks lactose into simpler sugars, which makes it sweeter.
• Milk Fat: Exists as emulsified fat globules within proteins.
• Milk Proteins: Casein (forms micelles) and whey (liquid portion).
• Milk Mixture: An emulsion.
• Emulsifiers: Hydrophobic tails & hydrophilic heads.
• Emulsifier Micelles: Oil in the middle, water on the outside.
• Milk Fat Globules: Emulsified compounds in milk.
• Casein Emulsification: Stabilizes milk fat.
• Homogenization: Reduces fat globule size for even distribution.
• Foams: Espresso foam is protein-based, while whipped cream is fat-based.
• Butter Formation: Lipids cluster into solid form, like butter.
• Hydrogenation: Adds hydrogen to unsaturated fats, creating a solid fat (e.g., margarine).