The Good Oil on Oils [and fats!] - PowerPoint Presentation

1. The Good Oil on Oils [and fats!]John SherwoodU3A November 2022

2. OutlineSome introductory chemistryNature of Fats and oils – saturated and unsaturatedAnimal and Plant fats - Butter and margarine“Good” and “bad” fats - omega numbers, cis/transRancid fatBiodiesel

3. Basics 1 – the atom

4. Basics 2 – the elementsSource: Science Notes

5. Basics 3 - chemical bonds (electron sharing)Source: University of Tasmania“one shared pair”

6. Atoms can share one, two or three electron pairsSource: University of Tasmania..

7. The Amazing Carbon atomIn the nucleus:6 protons6, 7 or 8 neutronsOutside:6 electrons, 4 of which are “active” (can be shared to form 4 bonds)PS Its not black even though we show it that way!

8. The carbon atom:Forms chains (straight and branched) by joining togetherForms rings …dittoCan bond with an amazing number of other elementsMore carbon compounds than all other elements combined!!Large families of compounds – eg alcohols, esters, acids, amines, chlorohydrocarbons, DNA, proteinsThe big divide – inorganic and organic chemistry

9. Hydrocarbon Chainsatomsbonds*

10. Hydrocarbon ringscyclohexane

11. Carbon Dioxide (CO2)

12. Bonded atoms form moleculesSource: SelingerWater (H2O) Ammonia (NH3) Methane (CH4)

13. Chemists use shorthand to represent moleculesSource: The Chemistry Notes

14. Sooooooo……fats and oils

15. An essential chemical familyThey all have the same basic chemical structureFats are solid at room temperature, oils are liquid. Collectively called Lipids or triglyceridesFats derive chiefly from animals; oils from plants although fish lipids are often oilsDon’t dissolve but float on waterColourless when pure. Impurities impart colour (eg carotene in butter)

16. Dietary sourcesButterMargarineVegetable oilsCreamAvocadoCheeseNutsMeatFish

17. ImportanceIn most foods because plants and animals use them as an efficient way to store energy.Promote cell growthInsulate our bodies to maintain body temperatureProtect sensitive organs (eg kidneys)Aid absorption of some nutrientsRaw materials to produce some hormones

18. They are compounds formed from an alcohol (glycerol) and organic acids (fatty acids)glycerolFatty Acid(s)+*plus water

19. Now, showing the fatty acid chainOR:

20. Saturated and unsaturated?Saturated – no double bonds in the fatty acid carbon chainUnsaturated – at least one double bond in the fatty acid carbon chainPolyunsaturated – many double bonds in the carbon chain**Animal fats are usually saturated; plant and fish oils are unsaturated

21. *The 'omega-number' refers to the first carbon atom of the first double bond from the (left-hand) hydrocarbon end of the molecule - note stearic acid is fully saturated and therefore is not assigned an omega number.

22. Making margarineHydrogen is combined with the double bonds in plant oils to make saturated fatsHydrogenation imparts desirable features such as spreadability, texture, "mouth feel" and increased shelf life to naturally liquid vegetable oils.

23. One more detail about double bonds….* The double bond doesn’t allow rotation so these arrangements are fixed

24. Unintended consequences: Hydrogenation introduces some serious health problems. These occur when the cis-double bonds in the fatty acid chains are not completely saturated in the hydrogenation process. Any remaining double bonds are converted to their trans configuration. These unnatural trans-fats appear to be associated with increased heart disease, cancer, diabetes and obesity, as well as immune response and reproductive problems.

25. Source:https://www.chemistrysteps.com/what-is-the-trans-fat-in-food/

26. And cholesterol…

27. Do we need cholesterol?Cholesterol is a fat-like, waxy substance that helps your body make cell membranes, many hormones, and vitamin D. The cholesterol in your blood comes from two sources: the foods you eat and your liver. Your liver makes all the cholesterol your body needs.Cholesterol and other fats are carried in your bloodstream as spherical particles called lipoproteins. The two most commonly known lipoproteins are low-density lipoproteins (LDL) and high-density lipoproteins (HDL).Source: John Hopkins Medicine

28. Trans fats and cholesterol levels in our bloodstream High-density lipoproteins (HDLs) are responsible for transporting cholesterol out of the blood and eventually out of the body. HDLs are usually referred to as 'good' lipoproteins.Low-density lipoproteins (LDLs) also carry a high percentage of the cholesterol in the blood. Unfortunately LDLs can deposit lipids like cholesterol onto the walls of arteries. If the deposits build up, they restrict blood flow causing various heart conditions including high blood pressure leading to heart attacks. LDLs are usually referred to as 'bad' lipoproteins.It is thought that trans fats behave like saturated fats in the body and raise LDL levels increasing the risk of cardiovascular problems. Trans fats also lower HDL levels exacerbating the problem.

29. Plant SterolsSource: Mayo clinicPlant sterols (or phytosterols) are a naturally occurring part of all plants. They are mainly found in vegetable oils but are also present in smaller amounts in nuts, legumes, grains, cereals, wood pulp and leaves. The main sources of plant sterols added to foods in Australia are soybean oil or tall (pine) oil.

30. Plant Sterols and CholesterolEpidemiological data have shown a continuous linear relationship between low-density lipoprotein cholesterol (LDL-cholesterol) levels and coronary heart disease (CHD) events. Studies indicate that incorporating plant sterols into the diet may be an effective method of lowering total and LDL-cholesterol levels. By consuming plant sterols daily, adults may lower their LDL-cholesterol levels by around 10% depending on the age of the person. A reduced blood cholesterol level is associated with a reduced risk of CHD and stroke.Source: National Heart Foundation of Australia 2017

31. Reading some labelsJohn West Tuna (g per 100g)Total Fat 4.8Saturated 0.7Trans <0.1Poly-unsaturated 2.6Omega-3 0.093Mono-unsaturated 1.4Cobram Olive Oil (g per 100mL)Total Fat 91.5Saturated 13.9Trans 0Poly-unsaturated 9.2Mono-unsaturated 68.4Tablelands Margarine (g per 100g)Total Fat 64.5Saturated 14.7Trans 0.2Poly-unsaturated 12.3Mono-unsaturated 37.3Plant sterols 8.0Bega Cheese (g per 100g)Total Fat 35.3Saturated 21.3Avocado (g per 100g)*Total Fat 15.0Saturated 3.0Trans 0Poly-unsaturated 1.8Mono-unsaturated 10.0* from web

32. Rancid FatHeat and moisture result in fat breaking down to glycerol and fatty acidsThe fatty acids have an unpleasant smell (think BO!)Appearance and texture of the fat changes alsoRate of reaction is slowed by refrigeration

33. Source: Christoff Industries

34. The lipid is broken down

35. The chart shows oils and fats used to produce biodiesel in the U.S. in 2015  (Source EIA Monthly Biodiesel Production Report )

36. ReferencesSelinger B (1989) Chemistry in the Market Place Harcourt Brace Jovanovich, Sydney (4th edn)https://www.chemistrysteps.com/https://www.docbrown.info/https://chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules

37. LipidsThe lipids are a large and diverse group of naturally occurring organic compounds that are related by their solubility in nonpolar organic solvents (e.g. ether, chloroform, acetone & benzene) and general insolubility in water. There is great structural variety among the lipids, as will be demonstrated in the following sections.

38. https://emoha.com/blogs/health/best-cooking-oils-for-seniors

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46. Source: https://slideplayer.com/slide/14528658/

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49. Fats have many important biochemical roles in the bodies of mammals including protecting organs, layers of insulation and an energy store and therefore an important component of a healthy balanced diet.Vegetable oils are also considered another important component in a balanced diet.Therefore, fats and oils (chemically they are triglyceride esters) are very important in the food industry.Animal fats and vegetable oils are examples of triglyceride esters made from the 'triol' alcohol propane-1,2,3-triol (glycerol) and linear long hydrocarbon chain fatty carboxylic acids Source: https://www.docbrown.info/page06/rcoohderivs9.htm

50. The triesters of fatty acids with glycerol (1,2,3-trihydroxypropane) compose the class of lipids known as fats and oils. These triglycerides (or triacylglycerols) are found in both plants and animals, and compose one of the major food groups of our diet. Triglycerides that are solid or semisolid at room temperature are classified as fats, and occur predominantly in animals. Those triglycerides that are liquid are called oils and originate chiefly in plants, although triglycerides from fish are also largely oils. 

51. In partial hydrogenation, a controlled quantity of hydrogen is added to the vegetable oil in the presence of finely divide nickel catalyst (large surface area). This is illustrated in Fig 8 above using skeletal formulae.The hydrogen adds to some of the C=C double bonds, increasing saturation and decreasing unsaturation.In the above case two of the original four C=C double bonds have been hydrogenated in the triglyceride ester of the vegetable oil to make margarine with a higher softening point.The product has is a higher softening/melting point so that the product is a soft solid ('margarine') at room temperature. (Check out the melting point trend in section 6.9.1).The advantage of hydrogenation is that the order of fatty acids on the glycerol is unchanged.There is however, one disadvantage to the hydrogenation process.The C=C bond is weakened when the glyceride molecules are adsorbed onto the nickel catalyst surface.This is necessary for the addition of the hydrogen molecule.Unfortunately stereo-isomerisation can happen and some of the Z C=C linkages (cis) can change to E C=C (trans) linkages. Trans-fats are considered less healthy in our diet than cis-fats.Source: docbrown

52. Source: https://www.docbrown.info/

53. Linolenic acid is a polyunsaturated omega-3 fatty acid with three C=C bonds.The linolenic acid group of molecules, octadecatrienoic acids, are obtained from triglyceride esters of linolenic acids in vegetable oil, but the richest source of omega-3 acids is fish oils.

54. Systematic name is octadec-9-enoic acid and a monounsaturated omega-9 fatty acid - one C=C bond.Oleic acid is obtained from the triglyceride esters in olive oil from the many olive groves in Europe and elsewhere.

55. Fig 3 emphasises the difference between a polyunsaturated vegetable oil triglyceride and a fully saturated one from an animal fat. (source: docbrown)

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59. Source: https://www.youtube.com/watch?v=Io-fovloFxo