Fat lecture

Overview of Lipids

• Lipids include fats, oils, and waxes; focus on fats and oils in food.

Types of Fats

• Animal Fats: Butter (milk), lard (pork), suet (beef).

• Plant Oils: Olive oil, palm oil, coconut oil, corn oil, soybean oil, peanut oil.

Functions of Fats in Food

• Flavor: Unique taste; enhances overall flavor by carrying soluble compounds.

• Texture: Important for emulsions; contributes to creamy textures.

• Cooking: Heat transfer medium in frying; allows higher cooking temperatures than water.

• Tenderization: Softens baked goods (cakes, biscuits).

• Aeration and Anti-foam: Incorporates air into batters; acts against foam formation.

Structure of Fats

• Composed of glycerol and fatty acids.

  • Glycerol: 3 carbon atoms with hydroxyl groups.

  • Fatty Acids: Carboxyl group + carbon chain; can be saturated (no double bonds) or unsaturated (with double bonds).

  • Triglycerides: Main form in foods; composed of glycerol and three fatty acids.

Physical Properties of Fats

• Solubility: Fats are fat-soluble; less affinity for water.

• Melting Point: Influenced by chain length and degree of saturation.

  • Shorter chains = lower melting points.

  • More unsaturation = lower melting points.

Deterioration of Fats

• Hydrolytic Rancidity: Fatty acids are released from glycerol due to heat or enzymes (lipases); leads to off-flavors like butyric acid.

• Oxidative Rancidity: Occurs in unsaturated fats; produces off-flavors and losses of nutrients. Catalyzed by metals, light, and increased temperatures.

Fat Substitutes

• Sucrose Polyester (Olestra): Fat-like but indigestible; calorie-free alternative.

• Salatrim: Short-chain fatty acids, lower in calories; resembles fat in properties.

• Simplesse: Derived from proteins; provides creamy texture without calories.

• Oatrim: Derived from oat fiber; mimics fat texture, used in frozen products.