Archive for June, 2016

Science Makes Sense-Chemistry and Social Justice-Week40: Fats, salt and sugar: are we eating too much?

June 28, 2016

Two famous Michaels, Michael Pollan and Michael Moss lament the fact that we are cooking less and relying on fast foods.  In their books, ” Omnivore’s Dilemma”,  “Cooked”( Michael Pollan) and “Salt, Sugar, Fat”( Michael Moss), they outline how food is delivered and how home cooking is being sidelined in many houses.(Refs.1,2,3)

I was fortunate to grow up in a home where my parents cooked most of the time.  Even when I started living away in my own home, I did cook almost every day and going out was relegated to once a month or every two months.  These days, I prefer a simple meal at home.  However, most working people eat at odd times and sometimes order in, since they come home tired to plan and prepare a meal.  This has led to more consumption of oily foods, laced with extra salt and desserts/breakfast foods loaded with fat and sugar.  It is also true that the availability of fresh fruits and vegetables at reasonable prices is not as easy in poorer neighborhoods where fast food restaurants are seen more often.  Today we shall look at the prevalence of fast and convenience foods, who tends to buy them and what measures are being taken in certain neighborhoods to encourage healthy eating. We shall look at the additives added in convenience and fast food as well and revisit the saturated, unsaturated as well as trans fats discussion.

First we will look at the term’processed food’.    Processed food is different from home-cooked food in the sense that additives are added to preserve shelf life.  The simplest processed food we see in the supermarket is canned soup.  What does it contain?   A lot of salt is added to preserve it and other additives are also added.  In the inner linings of food cans you find BPA, (Ref.4) which is chemically a bis phenol derivative where two phenol rings are connected via three carbon chains. (Ref.5)  BPA has been known to leach into the soup itself and cause obesity as well as breast and prostate cancers; it has even caused behavioral problems in young girls.  Salt as we know it is sodium chloride, NaCl, and high amounts of sodium ions is known to be responsible for heart attacks and  has lead to strokes (Ref.4)

Besides the additives indicated above let us look at food flavorings and colors, preservatives, chemicals added to change the texture of processed foods.  Among artificial flavoring, butyl alcohol,C4H9OH is one chemical that is added to mimic flavors of naturally occurring foods like butter, fruits.  There are serious health problems caused by too much consumption of this food flavoring.  Artificial sweeteners like aspartame, splenda are used by people with diabetes.  We know that regular sugar causes obesity and heart problems, but the artificial sweeteners consumed continuously causes headaches, seizures and even hallucinations. Benzoic acid(C6H5COOH)  is used  as a preservative in certain pickles, jams and fruit juices and this can cause asthma attacks, hyperactivity in children and neurological disorders.   Artificial colors like Blue 1,2 and some yellows and reds are known to cause certain kinds of cancers.  Vegetable oils that are brominated, ie contain Br, (bromine) a halogen,causes tremors and headaches.  (The Br is added as an emulsifier to prevent the oil from separating out). Carageenan, a  familiar thickener found in ice-creams, jellies has been found to form ulcers and cancers in animal studies.  High fructose corn syrup or HFCS  a fructose polysaccharide from corn, has been known to cause obesity and elevated cholesterol.  We already know the dangers of saturated fats ( less or no double bonds in the fatty acids that produce the oils/fats by esterification) but trans fats are even worse.  This is produced by forcing hydrogen gas over vegetable fats at high pressure and causing -COOH in trans positions hence the name’trans-fats‘.  Many fast food, especially fried foods contain trans-fats and the greater consumption has let to obesity among children and heart diseases.  Nitrates,nitrites of sodium(Na2NO3,Na2NO2) are used extensively in processed meat and is known to be a carcinogen.  And finally, sulfur dioxide, SO2, is added to dried fruits and is responsible for migraine headaches and asthma attacks.(Ref.6)

This list is not exhaustive, there are many more additives, fillers, flavors and colors used in processed foods that are not healthy at all.  But one would imagine that the above chemicals are enough for most of us to start cooking/ eating at home making simple, healthy meals while we know what is going inside our bodies.

But the switch is not easy and between the unhealthy but appetizing messages from the advertising industry, the convenience of ordering take-out and the higher prices of good healthy foods makes it very challenging for consumers to eat a balanced, nutritious meal everyday. (look at Activities and Nuggets)

Activities for Middle School Teachers:

Teachers can encourage students to map out their neighborhoods and actually find out what kind of food stores are available close by.  Then  each student can bring a can of food from home and find out what are the ingredients in them.    What chemicals are there in the additives? Why are they added to the food?  Is it made close by or comes from a far off place?  The teacher can then link geography with that particular can of food and ask students to see why that can of food  had to come from so far away.   The teacher can  introduce words like “locavore”  and”CAFO”and explain the meaning.  What alternatives would make sense? How did their grandparents obtain their daily food?  They could interview each other and find out how often they eat at fast food places, whether their family or friends have a vegetable garden in the summer and where they buy their groceries.  Does culture, where they come from influence what they eat?  Are students willing to try foods from different countries?  What limits them ?  Does having more money make people eat better food?   Does food advertising affect their daily food habits? Why or why not?

Students can also do research on where the food is grown, how it is grown and the difference between organic and regular food, GMO and non-GMO food, and humane or inhumane ways of raising chickens,animals for food consumption and who can afford which kind of food.

Nuggets of Information:

Most artificial flavorings have been banned in the European Union.(Ref.6)

“Food First ” is a book written by Fraces Moore Lappe where she encourages people to understand the politics of food and why growing your own food is the best way to control what one can eat.(Ref.7)  It is also necessary not to be a passive consumer but understand that supermarkets encourage us to consume high fat, high sugar products by simple things like arrangement of cereals / cans/ processed foods in an aisle.(Ref.8)

Morgan Spurlock in the movie”Supersize Me” makes us think twice about eating at fast food places too often.  He actually did an experiment on himself by eating fast food day and night for a month at McDonald’s and noticed how adversely it affected his own health!(Ref.9)

CAFO, or concentrated animal feeding operations or factory farms, keep animals in small confined spaces to feed and take care of them before butchering them for meat.  There have been enough studies done to show that the process is inhumane and unhealthy.(Ref.10)

References:

1. Pollan, Michael, Omnivore’s Dilemma (Penguin Press,2006)

2.Pollan, Michael, Cooked (Penguin Press,2013)

3.Moss, Michael, Salt, Sugar, Fat (Random House,2013)

4.http://www.rodalewellness.com/health/canned-soup

5.http://www.chemspider.com/Chemical-Structure.6371.html

6.http://peopleforethicalliving.com/health-and-fitness/food-choices-nutrition/dangerous-food-additives/

7.Lappe, Frances Moore,Food First (Souvenir Press Ltd.,1980)

8.http://www.regainedwellness.com/supermarket-psychology/

9. Supersize Me! the movie with Morgan Spurlock

10.Foer,Jonathan Safran ,Eating Animals (Little Brown and Co.,2009)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Science Makes Sense- Week 39:Organic Chemistry,Lipids, oils and fats

June 21, 2016

Almost every child in America gets its first taste of fast food with a packet of fries: Mmmm…so good! As children we grew up with occasional treats of fried potatoes that were irresistible. When I first landed in the U.S.,I always bought a bag of potato chips to remind me of fried food in India.
Oil has a unique way of adding flavor to any food. Today let us look at the chemistry of oils. Lipids are biological chemicals that do not dissolve in water.(Ref.1) These are a group of fat soluble compounds found in the tissues of plants and animals. Fats and oils are a sub-set or subgroup of lipids and are basically storehouses of energy. But lipids play an important role in the formation of cellular membranes,cellular signaling, nutrient functions with relationships to vitamins A,D,E,and K as well as being storehouses of energy. Furthermore, lipids are complex molecules with carbon, hydrogen and oxygen as well as nitrogen and sulfur and other small constituents.(Ref.2)
Fats and oils share a common molecular structure; fats are solids at room temperature, oils are liquids. What is the molecular structure?
They are esters of tri-alcohols, i.e., three -OH groups,also called glycerols,hence fats and oils are also commonly known as glycerides.  An ester has the H in the -OH group replaced by  a carbon chain and since there are 3 -OH groups there could be three different carbon chains called R1, R2 and R3 respectively.(Ref.1)  Remember that an ester in organic chemistry is like a salt in inorganic chemistry .  A salt is the neutralization reaction between a base/alkali and an inorganic acid, whereas an ester is a similar kind of neutralization reaction between an alcohol and an organic acid.   The more accurate name would be Triacylglycerols.   Hydrolysis (or reaction with water) of fats leads to glycerols and fatty acids.(Ref.1)

Triglyceride molecules contain carbon and hydrogen molecules and usually six oxygen atoms in every molecule.  This makes them highly reduced or unoxidized.  They resemble the hydrocarbons in petroleum and are good sources of fuel.  In fact the normal human body stores fats as fuel/ energy for several weeks’ survival.  Plants too do the same thing and this allows them to deal with unpredictable sources of food supply.(Ref.1)

A triglyceride is called a fat if it is a solid at 25°C, if it remains a liquid at this temperature, it is termed an oil.  The difference in melting point reflects the difference in the degree of unsaturation and number of carbon atoms in the original fatty acids that resulted in the triglyceride. (Ref.3)

Pure fats and oils are colorless,odorless and tasteless.  They are lighter than water, their densities are usually around 0.8gm/cc. They are poor conductors of heat and electricity and hence are excellent insulators for the body, slowing the loss of heat through the skin.(Ref.3)

The double bonds in fats and oils can undergo hydrogenation as well as oxidation.  The hydrogenation of oils is used commercially to produce margarine.  Most fats are obtained from animal sources whereas most plant sources produce oils.  Saturated fats/oils are derived from saturated fatty acids ( less or no double bonds) while unsaturated fats/oils are derived from unsaturated fatty acids ( more double bonds).  The high consumption of saturated fats, along with high cholesterol leads to increased risks of heart disease..(Ref.3)

The study of lipids, fats and oils indicates how necessary they are in the function and maintenance of our body’s functions.  However, too much of saturated fats and oils consumption today, especially because of the  fast food industry and in the changes in our lives has led to all kinds of medical problems.  We shall look closer at this topic next week.

Here is a small table to illustrate the predominance of saturated fatty acids in fats and more of the unsaturated fatty acids in oils:.(Ref.4)

Animal fats   Saturated acid(%)             Unsaturated Acids(%)

C10 &less     C12     C14     C16    C18        C18(a)C18(b) C18(c)

Butter     15         2          11        13        9            27      4         1

Lard             –        –             1         27     15          48    6          2

Plant oils               Saturated acid(%)           Unsaturated acids(%)

Coconut     –       50           18        8     2             6      1           –

Corn           –        –             1        10      3            50     34        –

Olive           –         –           –          7        2             85       5       –

Safflower   –         –            –         3        3             19     76       7

Activities for Middle School Teachers:

Let students make models of different fatty acids and triglycerides. Students need to research the reasons why unsaturated fats are not solids even though there are more double bonds here and the molecule ( fatty acid or corresponding triglyceride) may be dense and therefore could become a solid.  The Van der Waals weak intermolecular forces are stronger when you have long chain straight molecules; this happens with saturated fat molecules.  On the other hand, the presence of double bonds causes kinks in the structures making them non-planar.  Students will find a relationship between melting points and straight-chain versus non-planar structures. Students can plot a graph and present results.(Ref.5)

Nuggets of Information:

When all three hydroxyl groups (-OH) groups in the glycerol molecule are esterified with the same fatty acid, the resulting glyceride is called a simple glyceride.  In nature, you never see a simple glyceride, since the esterification in nature involves several different fatty acids.  That is because naturally occurring acids are a mixture of several fatty acids.(Ref.3)  No single formula can be written to represent naturally occurring fats and oils.  They may be derived from several different fatty acids.  Palmitic acid is the most abundant saturated fatty acid and oleic acid is the most abundant unsaturated fatty acid.(Ref.3)

Even though most fats are derived from animals, the exception is fish oil; triglycerides from fish are found as oils..(Ref.4)

Seeds contain a lot of oil/fats; the stored energy helps seedlings during germination.  later, they have solar energy available for photosynthesis.(Ref.3)

Hydrolysis of fats and oils in the presence of a base produces soap and the process is called saponification.(Ref.3)

Lipids can be  further classified as fats, oils, phospholipids, waxes, sterols .(Ref.4) Phospholipids  are a class of lipids similar to triglycerlides , where the fatty acid from which it is derived contains a phosphorus atom; they are present in cell membranes. Sterols are a class of lipids with structure similar to cholesterol.(Ref.6)  Cholesterol comes under the umbrella of steroids which have a carbon backbone with four fused ring-like strucures and a hydoxyl group (-OH).  Waxes are esters of a long-chain fatty alcohol and a fatty acid.  Many plants and fruits have a waxy coating to prevent water loss.(Ref.7)

Ear wax is composed of phospholipids and esters of cholesterol!(Ref.7)

References:

1.http://scifun.chem.wisc.edu/chemweek/pdf/Fats&Oils.pdf

2.http://www.differencebetween.info/difference-between-lipids-and-fats

3.http://chemwiki.ucdavis.edu/Textbook_Maps/General_Chemistry_Textbook_Maps/Map%3A_The_Basics_of_GOB_Chemistry_(Ball_et_al.)/17%3A_Lipids/17.2_Fats_and_Oils

4.http://www2.chemistry.msu.edu/faculty/reusch/VirtTxtJml/lipids.htm

5.http://chemistry.stackexchange.com/questions/4058/saturated-vs-unsaturated-fats-structure-in-relation-to-room-temperature-state

6.https://quizlet.com/94654736/chapter-5-lipids-fats-phospholipids-and-sterols-flash-cards/

7.http://biology.about.com/od/molecularbiology/ss/lipids.htm

 

 

 

 

 

  

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Science Makes Sense Week 38:Noble gases

June 13, 2016

I remember when I was young, I liked stretching on a black sofa almost upside-down and reading a book. My mother would come and implore me to go out and I would be oblivious to her presence. “Why aren’t you reacting? It is as if you are in another world!”, she would remark in dismay.
Sometimes, when I look at the last group in the Periodic Table, the Noble Gases, I wonder if they too belong in another world. Helium,He, neon, Ne, argon, Ar, krypton,Kr, xenon, Xe and radon, Rn are the six common noble gases. All these are obviously gases and the outer electronic structure is a stable octet, which is really a ns2 np6 configuration, where n=2 through 6. The exception is helium, which has a stable duplet or 1s2 structure.
One has already seen that the alkali and alkaline- earth elements try to lose one or two electrons to achieve the stable noble gas structure. In addition we have seen that the halogens gain an electron to have the outer stable electronic structure of noble gases. In fact, almost all elements in the periodic table gain or lose electrons during a chemical reaction to get to the stable electronic structure of these noble or inert gases. This also implies that the last group elements are not reactive. Now is that really a fact?
Till the early 60’s, scientists were talking about the stable octet/duplet rule to justify the non-reactive nature of these gases. Initially it was called Group 0 for this reason. In 1962 and 1963,scientists observed that some of the noble gases,like radon, krypton and xenon form different flourides. In addition, in 2006, scientists in Dubna, Russia, announced that the element 118, the next noble gas, was synthesized in 2002 and 2005 in a cyclotron.(Ref.1) A cyclotron is a high particle accelerator where subatomic particles like protons and electrons are in a magnetic and electrical field and can collide at high speeds with each other.(Ref.2)
Hence there are really 7 noble gases present and since some of them are not completely non-reactive, the noble gases group is now called Group 18 and not Group 0.(Ref.1)
The noble gases are all colorless, odorless, tasteless, non-flammable gases. They also happen to be mono-atomic gases, ie, they exist as individual atoms rather than di- or poly- atomic molecules.(Ref.3) They were originally called inert or rare gases. They are neither inert(since we know some of them react with flourine to form compounds) nor rare, because several of them are found in abundance on earth.(Ref.1) Yet the word’noble’ is appropriate, since certain elements like gold or platinum are also considered ‘noble metals’ because of their reluctance to undergo chemical reactions easily.(Ref.1)
How abundant are these noble gases? It is noted that their abundance decreases with increase in atomic weight, with He being the most abundant while there are only three molecules of element 118! Most of the noble gases are present in the earth’s atmosphere, except for helium, radon and are recovered from the air by obtaining them as liquids and conducting fractional distillation to separate them.(Ref.1) (Fractional distillation is a technique whereby different liquids can be distilled/condensed using differences in their boiling points, to collect each substance separately.)
Actually both radon and even helium are by-products of radioactive decay. After the discovery of radium by the Curies, German physicist became fascinated with radium and discovered a gas that it emitted and he called it ‘radium emitting; he discovered the new element, radon. The breakdown of radium as well as uranium can lead to the production of helium ions as well.(Ref.3)
The noble gases are used in many daily and specialized applications. Helium as we already know has been used in the filling of balloons, for large airships and for children. Helium is also used by divers not for buoyancy but to prevent “the bends” a condition when nitrogen bubbles in the blood as a diver comes up to the surface. Helium is extensively used in the field of cryogenics which is low-temperature science. Neon is best known for its use in neon signs, neon glow lamps are used to indicate on/off signs in electronic instrument panels and in early televisions. Even though radon is considered a hazard it has its uses in earthquake detection, leaks, measuring flow rates. Paleontologists, who study the distant past as well as geologists use argon dating to study volcanic layers, fossils etc. Krypton is mixed with argon in the manufacture of windows with high thermal efficiency, used in lasers as well as halogen headlights. Along with xenon, especially because of its lower cost, krypton has been used as a fuel in space.
(Ref.3)
As one can see, these noble gases are not so quiet and inert as they seem.
Activities for Middle School Teachers:
Have a discussion with students about how certain words like ‘inert’, ‘rare’ to describe the Group 18 gases is really not accurate. Look at the history of the ‘phlogiston’ theory and how the burning/oxidation theory was modified with further experiments in science. Look at the history of the atomic models and see how those models evolved with time and more knowledge. How did the invention of new instruments in the laboratory aid these developments? Compare the evolution of ideas in chemistry, physics with say, social sciences and psychology.
Nuggets of Information:
In 1868, a French astronomer named Pierre Janssen (1824-1907)came to India to observe a total solar eclipse. Using a spectroscope, an instrument for analyzing the spectrum of light emitted by an object, Janssen was able to show a yellow line in the spectrum, never seen before, which seemed to indicate the presence of a previously undiscovered element. He called it “helium” after the Greek god Helios, or Apollo, whom the ancients associated with the Sun.(Ref.3)
Helium is remarkable since it only liquefies close to absolute zero(-272 degrees celcius); that makes it very difficult to liquefy from air.(Ref.3)
Almost all the noble gases have derived their names from the Greek language. Neon comes from the word ‘neos’ which means new,argon from ‘argos'(inactive), krypton from kryptos,(hidden) and xenon from the word ‘stranger’.(Ref.3)
Superman’s kryptonite is an imaginary substance and has no relationship with the noble gas krypton.(Ref.3)
The discovery of radon starting with the element radium was the first clear proof of one element being transformed to another element through radioactive decay. (Ref.3)
Within the atmosphere,, argon is considered the most ‘abundant’ of these gases, about 0.93%.(Ref.3)
Until 1988, most Americans had no knowledge of the existence of radon, when the EPA(Environmental Protection Agency) released a report indicating the harmful effects of radon in homes. From the 80s through the 90s radon detector sales boomed; even today when a house is sold, radon levels need to be checked. This is especially needed if a house has been weather-sealed to improve heating and cooling.(Ref.3)
Chinese scientists made an interesting discovery in the 1960s. Radon levels in groundwater increased significantly before an earthquake. These scientists monitor radon levels to predict earthquakes.(Ref.3)
References:
1.http://www.britannica.com
2.http://www.thefreedictionary.com/cyclotron
3.encyclopedia.com/topic/Noble_gases.aspx

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