04-Lipids

Introduction

  • Food Chemistry

  • Prepared by: Asst. Prof. Carol M. Encarnado, Department of Chemical Engineering.

Lesson Overview

  • Accreditation Details:

    • Accredited Certified Center of Excellence

    • Full Accreditation Level III

  • Intended Learning Outcomes:

    • Familiarize with lipids, their classification, structures, properties, and changes during processing.

Major Food Components

  • Main Components of Food:

    • Water

    • Carbohydrates

    • Lipids

    • Proteins

    • Enzymes

Nutritive Classifications of Nutrients

  • Micronutrients: Required in small amounts.

  • Macronutrients: Required in larger amounts; provide energy and support growth and repair.

Lipids Overview

  • Definition: Chemically diverse compounds soluble in non-polar organic solvents with low water solubility.

  • Types of Lipids:

    • Fats: Solid at room temperature

    • Oils: Liquid at room temperature

    • Triglycerides, Phospholipids, Sterols.

  • Functions of Lipids:

    • Energy storage (9 kcal/g)

    • Transport of fat-soluble nutrients

    • Flavor and texture in foods.

    • Structural components of cell membranes

    • Signaling molecules.

Classification of Lipids

  • Based on Composition:

    • Simple Lipids: Fats, Waxes

    • Complex Lipids: Phospholipids, Lipoproteins, Sulfolipids

    • Derived Lipids: Isoprenoids, Fat-soluble vitamins, Steroids, Ketone bodies.

  • Based on Function:

    • Structural Lipids: Phospholipids

    • Storage Lipids: Fats, Oils.

    • Functional Lipids: Signals, Cofactors, Pigments.

Fatty Acids

  • Major Components of Lipids:

  • Structure:

    • Methyl group

    • Carboxyl group

  • Chain Lengths:

    • Short-chain (2-4 Carbons)

    • Medium-chain (6-10 Carbons)

    • Long-chain (12 or more Carbons).

  • Types of Fatty Acids:

    • Saturated

    • Unsaturated (Monounsaturated, Polyunsaturated).

Saturation of Fatty Acids

  • Differences in solid and liquid states based on saturation:

    • Saturated: all single bonds, solid at room temperature

    • Monounsaturated: one double bond, liquid

    • Polyunsaturated: two or more double bonds, liquid.

Essential and Non-Essential Fatty Acids

  • Essential Fatty Acids: Cannot be synthesized by the body; must be obtained from diet.

  • Non-Essential Fatty Acids: Can be synthesized by the body.

Sources of Fats and Oils

  • Saturated Fats: Coconut oil, Butter.

  • Monounsaturated Oils: Olive oil, Canola oil.

  • Polyunsaturated Oils: Sunflower oil, Corn oil, Soybean oil.

Triglycerides

  • Composed of three fatty acids and one glycerol.

  • Integral for high-calorie energy source and insulation.

Phospholipids

  • Structure: Glycerol backbone, two fatty acids, and phosphate group.

  • Functions: Form cell membranes, stable in water, create emulsions.

Emulsification Process

  • Emulsifiers (e.g., lecithin) decrease surface tension, allowing the mixing of fat and water.

  • Key methods: whisking, blending to create a stable emulsion.

Steroids and Sterols

  • Steroids: Biological compounds with four fused carbon rings; alter fluidity of cell membranes.

  • Sterols: A subgroup of steroids including cholesterol; crucial for cell membranes and signaling.

Lipid Oxidation

  • Major cause of food spoilage, can generate off-flavors.

  • Process involves auto-oxidation, photooxidation (with light), and enzymatic oxidation.

Strategies to Improve Lipid Stability

  • Use of antioxidants (synthetic and natural) to enhance oxidation stability in foods.

  • Key antioxidants include tocopherols and phenolic compounds from plants.

Conclusion

  • Understanding food chemistry, specifically lipids, is crucial for food preservation, nutrition, and culinary applications.