Fats

• FATS

  • The visible fats and oils or the visible animal fat in a meat carcass
  • Contain C, H, O in glyceride linkage
  • When hydrolyzed, it yields 3 fatty acids and a molecule of glycerol
  • Gen formula: CH3(CH2)N – COOH
  • The longer the carbon chain, the higher the degree of unsaturation, the more liquid the fat or oil becomes
• FAT – solid at room temperature

  OILS – liquid at room temperature
• Fats functions:

  • Serve as a fuel in the body - 9kcal/g
  • Reserve supply of food and energy for the body.
• Fat is stored in the adipose tissue and serve as a protector for the vital organs that is, surrounds the vital organs to keep them in place and also act as shock absorbers

  • subcutaneous – 50%
  • surrounding organs and abdominal cavity – 45%
  • intramuscular tissues – 5%
• OBESITY/ADIPOSITY – excessive fat storage
• 4. Act as heat insulators – helps the body to keep warm during cold weather

  5. Act as electrical insulators and allow rapid propagation of nerve impulses

  6. Constituent of lipoproteins which are found in cell membranes and in the mitochondria
• 7. Means of transporting lipids in the bloodstream
• 8. Supplier of essential fatty acids

  • essential fatty acid – one that cannot be synthesized in the body and should be ingested preformed or ready made from food sources.
  • linoleic acid - maintain normal growth and reproduction
  • arachidonic - prevention of an ezematous skin lesion in infants
• 9. Carrier of fat-soluble vitamins

  • Vitamin ADEK need a fat soluble medium to keep them in solution and to facilitate reactions whether in foods or in the body.
  • fortified margarine, fortified milk, butter and certain plant oils carry fat soluble vitamins
• 10. Sparer of protein, thiamin and niacin

  • adequate supply of energy from fats and CHO, will save protein from its function of tissue building and repairing.
  • thiamin and niacin are not appreciably needed in fat metabolism as compared to CHO metabolism thus they are spared for their other regulatory functions in the body.
• Other Special Functions:

  1. Fat has a high satiety value- has staying quality in the stomach- slowly digested and depresses the hunger sensation
  2. Contributes to flavor and palatability
  3. helps retain moistness in food products
  4. certain lipids are emulsifying agents which help in the transport of fatty substances that cannot easily pass through the cell membrane.
  5. Fatty acid are precursor of PROSTAGLANDINS - participate in the regulation of blood pressure, heart rate and lipolysis
• Physical Properties:

  1. Generally white or yellow solids and liquids
  2. Odorless and tasteless – but can become rancid, develop unpleasant odor and taste
• 3. Insoluble in water but are soluble in organic liquids as benzene, acetone and ether

  4. Do not diffuse through a membrane

  5. Lighter than water and have a greasy feeling
• 6. Form a temporary emulsion when shaken with water

  • EMULSION - a finely divided insoluble solid in a liquid
  • can be permanent by adding an emulsifying agent such as soap
  • in the body, they are emulsified by bile before they can be digested
• Classification of Fats

  
  

  According to the number of bonds between carbon atoms

  1. Saturated

  • bad cholesterol
  • contain only bonds between C atoms.
  • found in dietary products, oils, and meat
• Dietary saturated fats increase the blood levels of low density lipoproteins (LDL), which aid in the deposition of cholesterol on artery walls.
• Vegetable oils have been substituted as a way to lower cholesterol and LDL levels in the blood
• B. Unsaturated

  • good cholesterol
  • contain a few double bonds between C atoms
  • have lower melting points than the saturated fatty acid- the greater the degree of unsaturation, the lower the melting point
• B. Unsaturated

  • Monounsaturated – those that contain only one double bond
  • Polyunsaturated – contain many double bonds
  • Eicosanoids – which include the prostaglandins, leukotrienes, prostacyclins and thromboxanes
• Accdg to complexity of the molecule and chemical composition

  • Simple - a compound that on hydrolysis yield one or more molecules of an acid and one or more molecules of alcohol.
  • if hydrolysis yield 3 fatty acid and glycerol, the simple lipid is a fat or an oil.
  • if hydrolysis yields fatty acid and a high molecular mass monohydric alcohol, the simple lipid is a wax.
• Kinds of Simple Composition

  1. Triglycerides, neutral fats: found in adipose tissue, butterfat, lard, fish oils, olive oil, corn oil etc.

  • esters of three molecules of fatty acids + 1 molecule of glycerol.
• Kinds of Simple Composition

  
  

  b. Waxes: Beeswax, head oil of sperm whale, cerumen, carnauba oil, and lanolin

  • composed of esters of fatty acids with alcohol other than glycerol;
  • of industrial and medicinal importance
• According to the complexity of the molecule and chemical composition.

  • Complex – upon hydrolysis yields one or more fatty acids, an alcohol, to an and some other type of compound.
• B. Complex

  1. B. Complex 1. Phospholipids - contain a phosphoric acid residue in addition to an alcohol and fatty acid. ipids - contain a phosphoric acid residue in addition to an alcohol and fatty acid.

  • Phosphoglycerides - the alcohol is glycerol.
  • Phosphophingosides - in which the alcohol is sphingosine, is also called sphingolipids.
• SPHINGOMYELIN – a type of sphingolipids present in large amounts in the brain and nerve tissue
• NIEMANN- PICK DISEASE – a disease of infancy or early childhood

  • sphingomyelin accumulate in the brain, liver and spleen
  • caused by lack of enzyme sphingomyelinaise
• MULTIPLE SCLEROSIS – Demyelinating process where there is a loss of phospholipids and sphingolipids

  • an increased phosphate level occurs in the cerebrospinal fluid.
  • found chiefly in animal tissues
  • composed of glycerol, fatty acids, and phosphoric acid bound in ester linkage to a nitrogenous base
• B. Complex

  
  

  2. Lecithin – called phosphatidyl choline – compound that is important in the metabolism of fats by the liver

  • insoluble in water but are good emulsifying agents in dairy products and in the manufacture of mayonnaise
  • good source of phosphoric acid which is needed for the synthesis of new tissue
  • abundant in egg yolk and soybeans
  • widely distributed in all cells and have both metabolic and structural functions in membranes
• Dipalmitoyl lecithin

  • good surface active agent
  • prevents adherence of the inner surfaces of the lungs
  • causes respiratory distress syndrome
  • absence of dipalmitoyl lecithin in the lungs
  • removal of 1 molecule of fatty acid produce lysolecithin
  • found in venom of poisonous snakes
  • causes hemolysis
  • destruction of the RBC
• B. Complex

  
  

  3. Cephalin

  • occcurs predominantly in nervous tissue
  • plays a role in blood clotting

  4. Plasmalogen

  • found in brain, heart, and muscle

  5. Lipositol

  • found in brain, heart, kidneys, and plant tissues together with phytic acid
  • rapid synthesis and degradation in brain
  • evidence for role in cell transport processes

  6. Sphingomyelin

  • found in nervous tissue, brain, and RBC
  • source of phosphoric acid in body tissue

  7. Glycolipids

  • contain a carbohydrate in addition to sphingosine and fatty acid
• Types of Glycolipids

  1. Cerobroside

  • myeline sheaths of nerves, brain and other tissues
  • yields on hydrolysis of fatty acids, sphingosine, galactose or glucose, but not fatty acids
  • includes kerasin and phrenosin

  2. Ganglioside

  • brain, nerve tissue, and other selected tissues notably spleen
  • Contains a ceramide linked to hexose, neuramin acid, sphingosine, and fatty acid
• Types of Glycolipids

  
  

  3. Sulfolipid

  • white matter of the brain, liver, and testicle, also plant chloroplast
  • sulfur containing glycolipid
  • sulfate present in ester linkage to galactose

  4. Proteolipids

  • brain and nerve tissue
  • complexes of protein and lipids having solubility properties of lipids
• GAUCHER’S DISEASE

  • glycolipids accumulate in the brain and cause severe mental retardation and death by age 3
  • juvenile and adult forms of this disease are characterized by enlarged spleen and kidneys, hemorrhaging, mild anemia and fragile bones
  • this disease is caused by lack of beta-glucosidase
• TAY SACHS DISEASE

  • usually fatal to infants before they reach age 2
  • glycolipids accumulate in the tissues of the brain and eyes due to absence of the enzyme hexosaminidase A
• c. Precursor or Derived

  • compounds produced when simple and complex lipids undergo hydrolysis
  • they include substances such as fatty acids, glycerol, sphingosine and other alcohols
  • formed by metabolic transformation of fatty acid:

  1. Steroids
  2. Fatty aldehydes
  3. Protaglandins
  4. Lipid - soluble vitamins
  5. Ketone bodies
• PROSTAGLANDINS

  • have been isolated from most mammalian tissues, including the male and female reproductive systems, liver, kidneys, pancreas, heart, lungs, brain and intestines
  • richest source is the human seminal fluid
• PROSTAGLANDINS

  Physiological Effects:

  1. Involved in the body’s natural defenses against all forms of change including those induced by chemical, mechanical, physiologic, and pathologic stimuli

  • aspirin and other anti-inflammatory drugs appear to partially operate by inhibiting prostaglandin synthesis
• PROSTAGLANDINS

  
  

  Physiological Effects:

  
  

  2. Involved at the cellular level in regulating many body functions including gastric acid secretion, contraction and relaxation of smooth muscles, inflammation and vascular permeability, body temperature and blood platelet aggregation
• PROSTAGLANDINS

  Physiological Effect:

  
  

  3. stimulate steroid production by the adrenal gland

  4. stimulate release of insulin from the pancreas

  5. stimulate the movement of calcium ions from bone- excessive production of prostaglandins by malignant tissue may provide a partial answer for the hypercalcemia and osteolysis observed in patients afflicted with such a condition.
• PROSTAGLANDIN

  Physiological Effects:

  
  

  6. used clinically to induce abortion or to induce labor in a term pregnancy, to treat hypertension, to relieve bronchial asthma, and heal peptic ulcer

  7. increase cyclic adenosine monophosphate in blood platelets, thyroid, corpus luteum, adenohypophysis, and lungs but decrease CAMP in adipose tissues.

  8. Prostaglandin E1 is now used to strengthen babies born with cyanotic congenital heart disease (blue babies) to prepare them for corrective surgery