Food Chemistry

Food Chemistry

  • Definition: Study of chemical processes and interactions in foods

  • Forms of Water in Foods:

    • Free Water:

      • Lightly entrapped and easily pressed from food

      • Acts as a dispersing agent and solvent

    • Absorbed Water:

      • Associates through intermolecular hydrogen bonds

      • Held tightly in cell walls or protoplasm

    • Bound Water:

      • Unavailable as a solvent

      • Varies based on protein content in different foods

  • Physical Properties of Water

    • Appearance: Colorless, odorless, tasteless liquid

    • Boiling Point: Temperature at which liquid changes to vapor

    • Freezing Point: Temperature at which liquid changes to solid

    • Density: About 1 gm/cc, varies with temperature

    • Viscosity: Resistance to deformation

    • Surface Tension: Tendency to shrink in minimum surface area

    • Refractive Index: Describes speed of light through material

    • Dielectric Constant: Measure of material's polarization by electric field

    • Compressibility: Effect of temperature and pressure on substance

  • Chemical Properties of Water

    • Amphoteric Nature: Acts as both acid and base

    • Auto-protolysis: Ionization of water forming hydroxide ion OH-

    • Water Hardness:

      • Types:

        • Hard Water: High in dissolved minerals like calcium and magnesium

          • Temporary Hard Water: Contains calcium and bicarbonate ions

        • Soft Water: Contains small amounts of dissolved salts

  • Types of Water

    • Tap Water: Directly from faucet, may not be suited for drinking

    • Mineral Water: Naturally contains minerals

    • Spring/Well Water: Rainwater accumulated underground

    • Purified Water: Undergoes purification treatment

    • Distilled Water: All minerals and salts removed

    • Sparkling Water: Carbonated water

  • Uses of Water in Food Production

    • Food Ingredient: Must be free from undesirable taste, odor, and impurities

    • Agricultural and Primary Production: Used for irrigation

    • Cleaning and Sanitation:

      • Cleaning: Washing equipment, containers, etc.

      • Sanitization: Reducing microorganisms

      • Sterilization: Destruction of all living organisms

  • Processing Operations: Used in heating, refrigeration, etc.


  • Functions of Water in Food

    • Heat Transfer: Transfers and moderates heat effects

    • Universal Solvent: Earth's universal solvent

    • Solution: Solute molecules dissolve completely

    • Colloidal Dispersions:

      • Suspension: Starch grains floating in liquid

      • Emulsion: Water-in-oil or oil-in-water emulsions

  • Moisture Content

    • Moisture content is the total amount of water in food, usually expressed as a percentage of the total weight.

Carbohydrates

  • Carbohydrates are also known as carbs or saccharides, the most abundant biomolecules in nature.

  • They are used as energy fuel, for synthesis of glycoproteins, and as precursors for other organic compounds.

  • Carbohydrates are polyhydroxyaldehydes or polyhydroxyketones and their derivatives.

  • Structure of Carbohydrates

    • Fischer Projection and Haworth Projection are used to represent organic molecules.

    • Conformation refers to the spatial arrangements of atoms in a molecule.

  • Classification of Carbohydrates

    Monosaccharides

    • are simple sugars named based on the number of carbons.

    • Aldose and Ketose are based on the position of the carbonyl group.

    • Triose, Tetrose, Pentose, and Hexose are based on the number of carbon atoms.

    Disaccharides

    • form from two monosaccharides through dehydration synthesis.

    Oligosaccharides

    • These are relatively low molecular weight polymers of monosaccharides that are covalently bonded through glycosidic linkages

    Polysaccharides

    • Polysaccharides are long chains of monosaccharides linked by glycosidic bonds.

    • Starch is a mixture of amylose and amylopectin, stored form of sugars in plants.

    • Cellulose is a major component of plant cell walls, while chitin makes up arthropod exoskeletons.

    • Chitin is a macromolecule that makes up the exoskeleton of arthropods (such as insects and crustaceans)


  • Physical Properties of Carbohydrates

    • Monosaccharides and Disaccharides are crystalline solids, while Polysaccharides are amorphous solids.


  • Types of Carbohydrates

    • Sugars like sucrose, glucose, fructose, maltose, and lactose provide energy and sweetness.

    • Starch is the main carbohydrate in food, found in cereals, vegetables, and fruits.

    • Fiber aids in digestion and blood sugar regulation.

  • Forms of Carbohydrates

    • Simple Carbs are one or two sugar molecules found in refined sugars and natural sources.

    • Complex Carbs contain three or more sugar molecules and are rich in fiber.

    • Whole Carbs are unprocessed and contain the fiber found naturally in the food.

    • Refined Carbs have been processed and had the natural fiber removed or changed.


  • Source of Energy

    • Carbohydrates are the main source of energy for the body, fueling various organs and systems.

  • Biological Recognition Processes

    • Immunoglobulins and peptide hormones contain glycoprotein sequences linking amino acids to carbohydrates.

  • Stores Energy

    • Excess glucose is stored as glycogen in the liver and muscles.

  • Preserve Muscle

    • Muscle can be broken down into amino acids to generate energy when glucose is lacking.

  • Digestive Health

    • Soluble fiber forms a gel-like substance in the body.

    • Insoluble fiber adds bulk to stools, aiding in digestion.

  • Heart Health and Diabetes

    • Soluble fiber delays carb absorption, leading to lower blood sugar levels.

  • Macromolecule Building

    • Glucose is converted to essential building blocks like ribose and deoxyribose.

  • Increase Triglycerides

    • Eating a sugar-rich diet can increase your triglyceride levels, which may elevate your risk of heart disease.

  • Health Risks

    • Sugar-rich diets can increase triglyceride levels and the risk of heart disease.

    • Rapid fluctuations in insulin and blood sugar can lead to diabetes and heart disease.

  • Weight Gain

    • Whole grains with fiber and protein promote appetite control.

  • Nutrient Deficiencies

    • Processed carbohydrates can lead to deficiencies in vitamins and minerals.

    • Deficiencies can cause symptoms like dry skin, weak muscles, and depression.

  • Sugar Addiction

    • Sugar addiction can result in nutrient deficiencies, overweight, and obesity.

Lipids

  • Categories of Lipids

    • Fatty Acids

      • Have a polar and nonpolar end, crucial in lipid structure.

      • Double bonds can lead to geometric isomerism affecting configuration.

    • Glycerolipids

      • Composed of glycerol and fatty acid triesters like triglycerides.

    • Sphingolipids

      • Complex compounds with a sphingoid base backbone.

    • Sterols

      • Important in membrane lipids, including bile acids and cholesterol derivatives.

    • Prenol Lipids

      • Synthesized from isoprene units, used in natural products and vitamins.

    • Saccharolipids, Polyketides, and Triacylglycerols

      • Involved in membrane structures and natural product synthesis.

  • Fats and Oils

    • Fat Molecule Composition

      • Consists of glycerol and fatty acids with ester bonds.

    • Trans Fats and Omega Fatty Acids

      • Trans fats occur naturally and artificially, while omega fatty acids are essential.

    • Types of Omega-3 Fatty Acids

      • Include EPA and DHA, crucial for various bodily functions.

Lipids

  • Alpha-linolenic acid (ALA) Waxes

    • Found in feathers of aquatic birds and leaf surfaces of plants

    • Hydrophobic properties prevent water from sticking

  • Phospholipids

    • Major constituents of the plasma membrane

    • Composed of fatty acid chains attached to a glycerol or sphingosine backbone

    • Amphipathic molecule with hydrophobic and hydrophilic parts

  • Lipid Soluble Vitamins

    • Classified as "water soluble" or "fat soluble"

    • Lipids are absorbed, digested, and metabolized for utilization by the body

  • Digestion and Absorption of Lipids

    • Short-chain fatty acids absorbed directly

    • Emulsification and hydrolysis of dietary fats

    • Fats broken down by pancreatic lipase

  • Fat Metabolism

    • Fatty acids reesterified with glycerol to form triglycerides

    • Degradation through Beta oxidation to generate acetyl-CoA

  • Lipid Peroxidation

    • Causes oxidative deterioration of lipids

    • Products include lipid hydroperoxides, malondialdehyde, and 4-hydroxynonenal


Protein

  • Essential for building muscle mass

  • Composed of amino acids

  • Plant-based Proteins

    • Chia Seeds and Quinoa offer essential amino acids

  • Protein Shakes

    • High in protein, not regulated by FDA

  • Protein Intake

    • Safe level ranges from 0.8 to 2.0 grams per kilogram of body weight

    • FDA recommends 50 grams of protein per day for adults

  • Pros of Protein

    • Boosts metabolism, increases fat burning

    • Lowers blood pressure, reduces cravings

  • Cons of Protein

    • Overeating can lead to weight gain, fatigue, dehydration

    • Protein deficiency can cause malnutrition

  • Amino Acids

    • Monomers of proteins

    • Structure includes alpha carbon, amino group, carboxyl group, hydrogen atom, and R group

  • Classification of Amino Acids

    • Essential, nonessential, and conditional amino acids

  • Protein Types

    • Complete proteins contain all essential amino acids

    • Incomplete proteins lack some essential amino acids

  • Function of Protein

    • Peptides are compounds of amino acids linked by peptide bonds

    • Structural proteins like actin and tubulin form cytoskeleton

    • Movement proteins like actin and myosin provide muscle movement

  • Functions of Proteins

    • Storage: Legume storage proteins and egg white provide nourishment in early embryo development.

    • Transport: Hemoglobin and albumin carry substances in the blood throughout the body.

    • Regulation: Insulin and thyroxine coordinate the activity of different body systems.

    • Catalytic: Enzymes like amylase, lipase, pepsin, and trypsin help in digestion by breaking down nutrients.

    • Protection: Immunoglobulins protect the body from foreign pathogens.

  • Protein Structures

    • Primary Structure: Linear sequence of amino acids in a polypeptide chain.

    • Secondary Structure: Local folded structures within a polypeptide.

    • Tertiary Structure: Three-dimensional structure of a polypeptide.

    • Quaternary Structure: Spatial arrangement of multiple subunits of a protein.

  • Vitamins

    • Water-Soluble Vitamins: Absorbed in water, e.g., Vitamin B complex.

    • Fat-Soluble Vitamins: Absorbed in fats, e.g., Vitamin A, D, E, K.

  • Water-Soluble Vitamins

    • Vitamin B Complex: Includes B1 (thiamine), B2 (riboflavin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin), B9 (folate), B12 (cobalamin).

  • Fat-Soluble Vitamins

    • Vitamin A: Helps in bone formation and organ function.

    • Vitamin D: Essential for strong bones and muscle function.

    • Vitamin E: Acts as an antioxidant and aids in cell functions.

    • Vitamin K: Essential for blood clotting and bone health.

  • Dietary Supplements

    • Pros: Can prevent diseases and correct nutrient deficiencies.

    • Disease Prevention: Folic acid during pregnancy reduces birth defect risks.

    • Nutrient Deficiencies Correction: Helps reverse medical conditions caused by deficiencies.

    • Not A Food Replacement: Supplements lack the complex nutrients found in food, including phytochemicals.

  • Importance of Whole Foods

    • Essential body minerals and nutrients are best obtained from whole foods like fruits, grains, and vegetables.

    • Daily recommended servings of grains, fruits, and vegetables should still be consumed even if taking dietary supplements.

  • Potential Toxicity of Dietary Supplements

    • Overconsumption of fat-soluble vitamins E, D, and A can lead to toxic levels in the body.

    • Precautionary measures should be taken when combining multiple dietary supplements to avoid exceeding daily recommended servings.

    • Botanicals and herbs can also accumulate to toxic levels, especially for individuals with underlying health conditions.

  • Side Effects of Dietary Supplements

    • Some supplements can cause adverse side effects and interact with prescription medications.

    • It is crucial to use supplements prescribed by a doctor or from reputable manufacturers to avoid dangerous side effects and interactions.

  • Benefits of Obtaining Nutrients from Food

    • Consuming nutrients directly from food is more beneficial than relying solely on supplements.

    • Nutrients from food are absorbed more efficiently compared to those from supplements.

  • Cons of Multivitamins

    • Vitamin Overdose

      • Overdosing on vitamins A, D, E, or K can lead to various health issues.

    • Safety Concerns

      • Multivitamins are not fully regulated by the FDA, potentially containing unsafe chemicals or additives.

      • Allergic reactions, ranging from mild symptoms like itchiness to severe reactions like chest pain, can occur.

  • Nutritional Supplements Pros and Cons

    • Benefits for General Health

      • Some supplements like folic acid can be beneficial without side effects, aiding in preventing anemias and birth defects.

      • Certain supplements can help prevent specific diseases and conditions, such as iron for anemia prevention.

    • Side Effects and Interactions

      • Supplements can have side effects when taken excessively, like zinc causing vomiting and nausea.

      • Negative interactions with medications can occur, reducing the effectiveness of the medicine.

      • Poor-quality supplements may not be effective and should be used under medical supervision.

      • Some vitamins can be toxic in high doses, especially fat-soluble vitamins that accumulate in the body.


Minerals

  • Elements on earth and in foods necessary for body development and function

  • Act as catalysts for biological reactions

  • Make up about 4% of the body

  • Essential for bone and teeth formation, body fluids, enzyme systems

  • Major Minerals

    • Needed in larger amounts, over 100mg/day

    • Vital for health

  • Trace Minerals

    • Required in smaller amounts than major minerals

    • Vital for health, present in the body in <15mg

  • Essential Minerals from Foods

    • Calcium

      • Essential for bones, teeth, blood coagulation, nerve, and muscle function

    • Potassium

      • Aids nerve function, muscle contraction, heartbeat regulation, nutrient transport

    • Iron

      • Oxygen carrier, energy release, cell growth regulation

    • Zinc

      • Functions in taste, wound healing, growth, fetal development, sperm production, immune system

    • Other Essential Minerals

      • Phosphorus, Iodine, Magnesium, Fluoride, Sodium, Selenium

  • Multivitamins/Mineral Supplements

    • Provide necessary vitamins and minerals when not obtained from food

  • Analysis of Ash and Minerals

    • Ash Content

      • Total mineral measure in food

    • Mineral Content

      • Specific inorganic components like Ca, Na, K, Cl

  • Determination of Ash Content

    • Types of Ashing Analyses

      • Dry Ashing

        • Safe, specific mineral analysis, time-consuming

      • Wet Ashing

        • Rapid, less volatile mineral loss, labor-intensive

      • Low Temperature Plasma Dry Ashing

        • Expensive, less trace element loss

    • Other Ash Measurements

      • Water Soluble and Insoluble Ash, Insoluble Ash in Acid, Alkalinity of Ash

  • Atomic Spectroscopy

    • Atomic Absorption Spectroscopy (AAS)

      • Determines mineral concentration effectively

    • Atomic Emission Spectroscopy (AES)

      • Utilizes radiation emission by samples

  • Traditional Methods

    • Gravimetric Analysis

      • Suitable for large food samples with high mineral concentrations

    • Colorimetric Methods

      • Detect mineral presence through color change

    • Titrations

      • Used for calcium content determination in foods

    • Redox Reactions

      • Based on coupled oxidation-reduction reactions

    • Precipitation Titrations

      • Involves insoluble precipitates in titration reactions

    • Ion-Selective Electrodes

      • Sensitive to specific types of ion