Lipidy - jednoduché

Lipids

Simple Lipids

  • Simple lipids primarily include acylglycerols and waxes.

Acylglycerols

Structure

  • Comprised of a glycerol backbone.

  • Can be esterified by fatty acids (VMK) up to three times, known as Fischer esterification.

  • Commonly consist of mixed TAGs (triacylglycerols) with three different fatty acids.

Functions

  • They are the most common lipids in food.

  • Serve as a reserve of energy.

  • Provide protective layers for some organs.

  • Are involved in thermoregulation.

  • Play a structural role in the formation of biomembranes.

Properties

  • Saturated fatty acids (e.g., palmitic, stearic) are solid, yielding greasy fats, while unsaturated fatty acids (e.g., oleic) are liquid oils.

  • They possess low melting points (Tt).

  • Insoluble in water but soluble in non-polar solvents.

  • Required as essential nutrients for organisms.

  • Pure fats and oils are colorless, tasteless, and odorless.

  • Extraction methods include pressing or using suitable solvents.

Reactions

  • Fat breakdown: Acidic hydrolysis resulting in glycerol and fatty acids.

  • Saponification: Alkaline hydrolysis of TAGs, producing soap (sodium-based with NaOH or potassium-based with KOH) and glycerol.

  • Hydrogenation: Partial hydrogenation of polyunsaturated fatty acids to control melting points; fully saturated fats lead to shelf-stable products.

  • Oxidative rancidity: Type of autooxidation under warm and humid conditions, breaking double bonds in unsaturated fatty acids, leading to aldehyde formation and undesirable tastes.

  • Ketonic rancidity: Caused by microorganisms degrading fatty acid chains to methyl ketones.

  • Drying of fats: A process involving radical oxidative polymerization, converting unsaturated fatty acids into rubbery substances through direct carbon bonding facilitated by oxidants.

Waxes (Cerides)

Structure

  • Comprised of esters formed from higher fatty acids and monohydric alcohols.

Properties

  • Solid at room temperature, highly hydrophobic, insoluble in water, and soluble in non-polar solvents.

  • They are resistant to oxidation and hydrolysis and have a flash point.

Occurrence and Utilization

  • Found in animals for protective layers (e.g., sperm whale's ambergris, lanolin in sheep's wool) and in plants as protective coatings on fruits and leaves.

  • Utilized in cosmetics, pharmaceuticals, healthcare, candle production, and polishing pastes.

Specific Waxes

  • Beeswax: Contains up to 284 components, consisting of esters and fatty acids formed through metabolic conversions of honey and pollen in bees.

  • Lanolin: A viscous substance secreted by sheep’s sebaceous glands, containing many types of esters, utilized in cosmetics and textiles.

  • Spermaceti: From sperm whale cranial cavities, useful for making ointments.

  • Carnauba wax: Used for gloss enhancement in shoe creams, candies, and chewing gum.

Sphingolipids

Structure

  • Built around the unsaturated amino alcohol, sphingosine (C18).

Types of Sphingolipids

  1. Simple Sphingolipids: Ceramides

  2. Complex Sphingolipids:

    • Phosphosphingolipids (sphingomyelins)

    • Glycosphingolipids (cerebrosides and gangliosides)

Ceramides

  • Type of N-acylsphingosine found in brain tissues, with a role in skin barrier functions and involved in sphingolipid metabolism in the cosmetic industry.