Chapter 25 – Infographic descriptions

25.0a A Guide to Types of Fat and the bonds they contain

Fat is an essential part of our diets, and has a number of important roles in the body. However, there are different types, and there are health concerns surrounding eating too much of some types of fat. Here, we look at what distinguishes different types of fat, and their effects on the body.

Triglycerides and fatty acids: Triglycerides account for around 95% of the fat in our diet, and are formed from the combination of glycerol and three fatty acid molecules. The three fatty acids are often different, and the chemical structures of these fatty acids defines the type of fat. Cholesterol is made in the liver, and transported around the body by low density lipoproteins (LDL) and high density lipoproteins (HDL). Different fats affect LDL and HDL differently. 

Saturated fats: Contain no carbon-carbon double bonds. Saturated fats are solids at room temperature. They increase levels of LDL in the bloodstream. They have previously been associated with heart disease, though more recent studies and reviews have called this association into question.

Monosaturated fats: Contain one carbon-carbon double bond. They are liquids at room temperature, but solidify in while chilled. They reduce levels of LDL in the bloodstream, thereby decreasing the total cholesterol to HDL ratio (HDL helps take cholesterol back to the liver where it can be disposed of).

Polyunsaturated fats: Contain two ore more carbon-carbon bonds. They are liquids at room temperature, but they start to solidify when chilled. They are split into omega-3 and omega-6 fatty acids. Polyunsaturated fats help reduce LDL levels, decreasing the total cholesterol to HDL  ratio.

Trans fats: Contain carbon-carbon double bond in a trans rather then cis configuration. Formed artificially, via a process called hydrogenation; also found naturally in small amounts in meat and dairy products. They raise LDL, and are associated with heart disease. Many countries are phasing them out.

Read more about “A Guide to Types of Fat and the bonds they contain [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND

25.0b Everyday Chemicals: Acetic Acid – Vinegar & Volcanoes

Acetic acid also known as ‘ethanoic acid’ or the acid component of vinegar.

Acetic acid: colourless liquid, CH3COOH.

Acetic acid is best known for its presence in vinegar, produced by fermentation and oxidation of ethanol. Table vinegar is a solution of 4-8% acetic acid in water. Trace molecules contribute colour and nuances of flavour to different types of vinegars. Acetic acid also used in food as an acidity regulator, with the E number E260.

Vinegar often recommended as household cleaner: removing smears/streaks from windows/mirrors and it contains descalers for removing limescale, reacting with the calcium carbonate that limescale is primarily composed of. Studies show acetic acid has antibacterial effect.

Approximately 1/3 of all acetic acids are used in production of vinyl acetate. Polymerisation of vinyl acetate monomer produces polymer polyvinyl acetate (PV), the main component of PVA glue.  Acetic acid also used as solvent and precursor to photographic film, inks and dyes, and synthetic fibres.

Acetic acid in the form of vinegar can be used in household science experiments to create volcano-like effect. Acid reacts with baking soda (sodium bicarbonate) in a neutralization reaction creating carbon dioxide and causing a frothing effect.

Read more about “Everyday Chemicals: Acetic Acid – Vinegar & Volcanoes [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND

25.1a The sour science of vinegar varieties

Vinegar is produced by the two-stage fermentation of raw materials containing sugar or starch. In the first fermentation, yeasts convert sugar to alcohol (ethanol). In the second fermentation (acetification) ethanol is oxidized to acetic acid by acetic acid bacteria.

Acetification: Acetic acid bacteria need oxygen to convert ethanol to acetic acid. In longer, traditional processes, the bacteria grow on teh surface of the fermentation liquid. In industrial methods the bacteria are submerged, with oxygen pumped in.

Distilled vinegar: Distilled vinegar is not itself distilled, but produced from distilled alcohol, made from barley malt or corn. Like other vinegars, the main acid is acetic acid (5-8% by volume). Other compounds are limited compared to other vinegars, but include traces of ethyl acetate.

Apple cider vinegar: Apple cider vinegar is amde from fermented apple juice. Like wine vinegar it contains other acids, such as malic acid from apples, Wine and sider also contain higher alcohols, such as propanol, which react to form additional acids and esters during vinegar production.

Balsamic vinegar: Traditional balsamic vinegar is made by converting sugars in cooked grape must be ethanol, oxidizing to acetic acid, then ageing for at least 12 years. Researchers have identified 5-acetoxymenthyl-2-furaledhyde as important to its long-lasting sweet taste.

Mal vinegar: Malt vinegar is made from fermented malted barely – essentially unhopped beer. Malt vinegars don’t contain tartaric or malic acids, but do contain small quantities of lactic acid. Branched chain compounds, like 2-methylpropanoic acid, contribute to its flavour and aroma.

Wine vinegar: Wine vinegar are produced by fermenting wine. The main acid is still acetic acid, but other acids from grapes, such as tartaric acid, are present in smaller amounts. Phenolic compounds are also present, both from the wine and from barrel ageing from some varieties.

Rice vinegar: Rice vinegar is made from fermented rice and varies in colour from colourless to black. In some varieties, furfural and pyrazines such as tetramethylpyrazine (TMP) contribute toast-like flavours. Buttery acetoin (3-hydroxy-2-butanone) is also present in many rice vinegars.

Read more about “The sour science of vinegar varieties [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND

25.2a RTC Week 2015 – #4: Deuterating Fatty Acids to Treat Diseases

Maksim Fomich, research at the Institute of Physical Organic Chemistry in Belarus, is looking into deuterated fatty acids.

Polyunsaturated fatty acids (PUFAs) are obtained from diet and can be found in cell membranes. Their oxidation can lead to potential problems.

A deuterated unsaturated fatty acid: 11,11-d2-Linoleic acid

Deuterium is a hydrogen atom with a neutron also added to the nucleus, represented by the symbol D, or 2H, and accounts for a very small proportion of the natural abundance of hydrogen. Deuterated compounds have deuterium atoms in place of some of the hydrogen atoms. By deuterating polyunsaturated fatty acids (PUFAs), reactive parts of the molecule can be protected.

Uses of deuterated PUFAs:

• Tests on yeast show small additions of deuterated PUFAs help prevent cell death dur to oxidation.
• Oxidation of PUFAs is thought to play a role in Parkinson’s disease. D-PUFAs diminished degeneration in mice.
• D-PUFAs are in human clinical trials for the treatment of Friedreich’s ataxia, a nervous system disorder.
• D-PUFAs could be used to treat some retina diseases, as some of these could be due to destruction of retina lipids.

Read more about the “RTC Week 2015 – #4: Deuterating Fatty Acids to Treat Diseases [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND

25.2b Why Shouldn’t You Eat Rhubarb Leaves? – The Chemistry of Rhubarb

Different species of rhubarb contains a wide variety of anthraquinone compounds. Ahthocyanin pigments are the main compounds responsible for rhubarb red colouration, anthraquinone also coloured. Emodin (orange colour), Chrysophanol (yellow colour), Physcion (red-orange colour).

Rhubarb also contains various derivatives of anthraquinone compounds including sennosides. During digestion these are turned into active compounds which have a laxative effect. Chief among these is the metabolite called rheinanthrone. Sennosides are found in senna plants and are on the World Health Organizatio’s (WHO) list of essential medicines.

Rhubarb leaves are high in oxalic acid (0.52g per 100g) and oxalate salt (15-30g lethal dose in humans) content, which can cause nausea and vomiting if ingested. Debate if other poisonous compounds in the leaves may contribute. The stalk is sage to eat as it contains lower oxalic acid content, the dominant acid being malic acid.

Read more about the “Why Shouldn’t You Eat Rhubarb Leaves? – The Chemistry of Rhubarb [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND

25.2c Sourness & Scurvy – The Chemistry of a Lemon

The sour taste of lemons is caused by the presence of organic acids. The major acid in lemons is citric acid, which makes up around 5-6% of the lemon’s juice.  Other acids in lower concentrations then citric acid: malic acid is present around 5% of the concentration of citric acid.

Lemons contain high levels of vitamin C (ascorbic acid): 50mg per 100g, on par with oranges and around double the amount of limes.

Vitamin C deficiency can lead to scurvy, a disease that cause loss of teeth, jaundice, eventually death. In the 1700s, all British ships required to provide lemon juice ration to seamen to guard against the disease.

Read more about the “Sourness & Scurvy – The Chemistry of a Lemon [New tab]” by Andy Brunning / Compound Interest, CC BY-NC-ND

25.5a Table of Esters and Their Smells v2

Read more about the “Table of Esters and Their Smells v2 [New tab]” by James Kennedy, shared with permission under CC BY-ND 4.0.

25.5b RTC Week 2015 – #2: Oil Spill Clean-Ups Using Fruits & Oils

Attribution & References

Compound Interest infographics are created by Andy Brunning and licensed under CC BY-NC-ND

Except where otherwise noted, content on this page has been created as a textual summary of the infographics used within our OER. Please refer to the original website (noted below each description) for further details about the image.