Food Science

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Food Science
Chemistry & Lab Event
Forum Threads 2013 2012
2011 Trial
Tests 2013 2012
There are no images available for this event
There are no question marathons for this event
Division B Champion Daniel Wright Junior High School
This event was not held last year in Division C

Food Science focuses on testing the chemical and physical knowledge of baking ingredients. Food Science was originally a trial event in states including Texas and North Carolina. When it was run in Texas as a Trial, it differed from many other states.

Contents

The Event

This event consists of taking a written test and performing some amount of laboratory work along the way, often times in stations. The rules require a viscosity station or section plus at least seven other stations relating to topics listed in the rules.

To be allowed to participate, you must bring:

  • ANSI Z87 goggles (eye protection #4)
  • Lab coats or lab aprons that reach the knees. If you are using lab aprons, your sleeves must reach your wrists.
  • Closed-toe shoes (no sandals)
  • Pants or skirts that cover the legs to the ankles
  • Homemade viscosity testing device (calibrated and with a matching standard curve graph)

You may (and should) bring: (these things are optional, but almost essential)

  • Chemical gloves
  • 1 3-ring binder of any size, containing notes in any form from any source

Macromolecules

Macromolecules are very large molecules. There are conventionally four different biopolymers: lipids, carbohydrates, proteins, and nucleic acids. The last does not apply to Food Science; therefore, we only need to pay attention to the first three. In each of these categories of macromolecules, some subcategories exist.

Lipids

Lipids have many subcategories including fats, waxes, and sterols. The main ones you need to worry about are the triglycerides: fats and oils.

Fats

Fats are a good source of energy, giving 9 kcal/g of fat.

    • The daily recommended amount of fat intake is limited to 65g. These contribute to a large amount of the obesity problem in the U.S.

Fats are most commonly found as triglycerides. Triglycerides are made up of a glycerol "backbone" with three fatty acids attached. Fatty acids are long chains of carbon molecules with an ester group on the end.

A triglyceride

The fatty acids may be saturated, unsaturated, or trans. Triglycerides can use any combination of these different fatty acids.

Saturated Fatty Acids

Saturated fatty acids are one long chain of carbon atoms meaning no double bonds and no fancy stuff. Saturated fats are generally bad for you since they clog your arteries, increasing the risk of heart attack and stroke. Since the carbon atoms in a saturated fatty acid are packed closely together, saturated fats are usually solid at room temperature. Saturated fats are generally found in animals.

Unsaturated Fatty Acids

Unsaturated fatty acids are also a long chain of carbon atoms, this time with one or more double bonds. Unsaturated fatty acids with one double bond are monounsaturated, and those with two or more double bonds are polyunsaturated. Unsaturated fats are generally better for you when not overeaten because they may help lower blood cholesterol level. Since double bonds exist, these fatty acids are much more wobbly and, therefore, are usually liquid at room temperature. Unsaturated fats are generally found in plants such as nuts and seeds. They are also found in fish as omega-3 unsaturated fatty acids.

Omega-3 Essential Fatty Acids

Omega-3 essential fatty acids are found in fish and plants. The name means there exists a double bond three carbon atoms from the non-ester end of the chain. Omega is the last letter in the Greek alphabet (lowercase omega is used). These fatty acids are "essential" because your body cannot produce them on its own, and they are vital for normal metabolism.

Trans Fats

Trans fats are not found in nature, although recent studies suggest that there may be small amounts. Trans fats are unsaturated fatty acids heated up then made so "dizzy" that it changes from cis to trans configuration.

CisvsTrans.jpg

Trans fats are unhealthy for you since they lower high-density lipoproteins (HDLs or "good" cholesterol) and raise low-density lipoproteins (LDLs or "bad" cholesterol). The recommended daily intake should be limited to 2g per day.

Esters

Esters are found on the end of all fatty acids.

Esters are a group of organic molecules that contain -C=O-O- as part of the molecule. More specifically, esters are only one part of the molecules in this group, but any molecule that contains an ester is classified as an "ester".

Esters are derived from carboxylic acids. When a carboxylic acid reacts with alcohol, an ester will form. For example, acetic acid will react with ethanol to make ethyl acetate.

Common esters include ethyl acetate and ethyl ethanoate.

Sterols

The one sterol you'll want to know about is cholesterol. Cholesterol, like all sterols, come in this form:

Sterol.png (picture credit Wikipedia)

Cholesterol comes in high-density lipoproteins (HDLs or "good" cholesterol) and low-density lipoproteins (LDLs or "bad" cholesterol. HDLs are made by your liver, while LDLs are generally consumed. Some types of foods, such as trans fats, are thought to raise LDL levels and lower HDL ones.

If you have too much LDL, your arteries will clog and, as a result, you will get a heart attack. This is cardiovascular disease, the leading cause of death in America.

Carbohydrates

Carbohydrates are, as suggested by the name, hydrates of carbon. They consist of carbon, oxygen, and hydrogen atoms. The formula for a carbohydrate can be expressed as C_m(H_2 O)_n, where, most commonly, m and n are the same.

Carbohydrates include simple sugars, monosaccharides and disaccharides, complex sugars, and polysaccharides.

Simple Sugars

Simple sugars consist of single sugar units (monosaccharides) and disaccharides (which are made up of two monosaccharides). The names of sugars often end in the suffix -ose. Common monosaccharides include:

  • Glucose (also dextrose)
  • Fructose (also levulose)
  • Galactose
  • Mannose

Common disaccharides include:

  • Sucrose (glucose+fructose)
  • Lactose (glucose+galactose)
  • Maltose (only found as a byproduct of hydrolysis of starch; glucose+glucose)

Simple sugars are small, easy to break down, and, therefore, give you energy quite soon after you consume simple sugars. However, they run out quickly, leaving you tired. Think about crashing after a sugar high.

The "Sugars" on food labels consist of mono- and di-saccharides. That's why you see sugar in milk; that's lactose, not added by the manufacturer.

Complex Sugars

Complex sugars are mainly polysaccharides. Polysaccharides are chains of many monosaccharides, most commonly glucose.

Polysaccharides are divided into two main groups, storage polysaccharides and structure polysaccharides.

Storage Polysaccharides

Storage polysaccharides are our main source of energy. There are two main storage polysaccharides: glycogen and starch.

Glycogen is the storage polysaccharide found in animals.

Starch is the storage polysaccharide found in plants. We humans consume a lot of it from foods like pasta or potatoes.

Starch comes in two forms: amylose and amylopectin. Amylose is a straight chain of glucose molecules which coils up. Amylopectin is branched. Since there are more ends to be broken down in amylopectin, it is more quickly digested.

When you look at a food label, the Dietary Fiber and Sugars don't quite add up to the Total Carbohydrate; the remainder is starch.

Structure Polysaccharides

Structure polysaccharides are polysaccharides meant to give structure. Two common structure polysaccharides are celluose and chitin.

Celluose is better known as (dietary) fiber. It is insoluble.

  • What is insolubility?
     *indigestible by our bodies, so it cleans out our insides and comes out as feces.

Proteins

Proteins are polymers of amino acids. Proteins are essential to human life because they carry out orders from the genes in cells.

Proteins can be converted to energy by the liver when there is a lack of carbohydrate or fat; therefore, they provide 4 kcal/g.

Protein Denaturation and Coagulation

Protein denaturation is the undoing of natural structure by chemical or physical means. Denaturation doesn’t change the composition of the protein, only the structure. Protein denaturation can happen because of heat (140-180 degrees Fahrenheit/ 60-80 degrees Celsius), high acidity, air bubbles, or any combination of the three. Since denaturation changes the folds of the proteins, there are more open bonds, so they form new bonds. This creates a thickness or density. Coagulation is the process when these new bonds are formed.

Enzymes

Enzymes are a type of special proteins that catalyze chemical reactions. The names of enzymes often end in the suffix -ase. Examples are maltase (breaks down maltose), amylase (breaks down amylose and amylopectin), and lactase (breaks down lactose).

Some enzymes cause disease due to the fact that some people do not contain them or possess distorted, non-functional forms. The most common disease is phenylketonuria (PKU), which is a lack of functional phenylalanine hydroxylase, an enzyme. When functional, phenylalanine hydroxylase is supposed to break down phenylalanine, an amino acid found in the artificial sugar aspartame.

Amino Acids

Amino acids are the building blocks of proteins. Amino acids consist of 10-40 atoms each, mainly carbon, hydrogen, sometimes sulfur, and at least one nitrogen in the amino group, -NH2. Proteins are formed by linking the amine nitrogen with a carbon atom on another amino acid, forming a peptide bond.

Complete and Incomplete Proteins

You need all of the amino acids to live. There are 9 essential amino acids and 11 non-essential ones. Your body does not make the essential ones, therefore you need to eat them. The other 12 your body makes itself, therefore it is not essential to eat them. For a person with a normal diet, all 9 essential amino acids are normally found in most meats.

This poses a problem for vegetarians, who cannot eat proteins with all the essential amino acids. So they must eat complementary proteins, or two different food ingredients, when, eaten together, make complete protein sets that contain all the proteins that you need to eat. An example of a pair of complementary proteins is rice and beans.

Food Testing

At the competition, you are expected to be prepared to perform certain experiments on the Approved List of Ingredients. Most tests will instruct you on use, though.

Viscosity

Viscosity is the required testing subject of Food Science. You will need to make your own homemade viscosity testing device and prepare one or more standard curves.

Vocabulary

Viscosity-the resistance of fluid to flow

Centipoise-a measure of viscosity. Often abbreviated cP. \frac{1}{100}^\text{th} of a poise.

Making a Viscosity Testing Device

To make a viscosity testing device, there is a set of possible instructions in the rule book.

You probably will need to use the same amount of liquid or, if using the method above, do not change the lines. If you do not use the same amount each time, your graph will be wrong and you will not be able to accurately predict centipoise.

The six liquids, standards, suggested by the rules to calibrate your device are:

  • Water-1 cP
  • Milk-5 cP
  • Crisco Canola Oil-40 cP
  • Castor Oil-900 cP
  • Hershey's Chocolate Syrup-1500 cP
  • Meadow Gold or Eagle Brand Sweetened Condensed Milk-5000 cP
  • Pure Honey-7000 cP

These are not the standards as they appear in the 2013 rules exactly, but there has been a Rules Clarification. This is how the new list should appear.

Be sure these liquids are all fresh and at room temperature when you start testing. Every control possible should be made so that the only dependent variable should be the fluid's viscosity. Things like the person doing the test , the room temperature, the amount of liquid, the device used, are all important controls.

You can create your standard curve graph with Excel or another spreadsheet program. You should be able to now predict the mystery liquid's viscosity at the competition!

Do not forget to hand a copy of your standard curve(s) to the supervisor with your test.

Molecule Detection Tests

There are certain tests used to detect macromolecules and other molecules in food. You may have to perform some of these at the competition. The most common tests that you are expected to perform are Benedict's, Biuret's, Iodine, and the Brown Bag test. You may also need to know about Sudan III/IV and Vitamin C Reagent(dichlorophenolindophenol).

Benedict's

Benedict's solution is also known as Fehling's solution. It tests for reducing sugars, or a sugar with a free aldehyde. The reaction between a reducing sugar and Benedict's is between the reducing sugar's aldehyde and the copper sulfate in Benedict's.

To use Benedict's:

  1. Put a small sample of the food into a test tube.
  2. Liquify the food by adding enough water to make it a liquid, if the food is not already a liquid.
  3. Add 5-10 drops of Benedict's Solution.
  4. Carefully heat the test tubes in a hot water bath at 40-50^\circ Celsius for five minutes.

To deduce the results:
The liquid will turn green, yellow, or brick red depending on the amount of sugar present. Green is the least sugar, yellow is more, and red is the most.

Note that Benedict's will only work with reducing sugars.
Reducing sugars are sugars with free aldehydes. (An aldehyde group is of the form R-CH=O where R is something organic.)
Here's a rule of thumb: all monosaccharides are reducing sugars but not all reducing sugars are monosaccharides. Lactose, for example, is reducing; however, sucrose is not. Make sure you know your reducing sugars, because trick questions often arise on tests on this subject.

Remember that Benedict's needs heating to work when answering test questions about it!

Biuret's

Biuret's Reagent is for detecting the presence of proteins. The active agent in Biuret's is also copper sulfate. The reaction is due to the formation of complex between the cupric ions in copper sulfate and the lone pair of electrons present on the nitrogen and oxygen atoms of peptide bonds of proteins.

To use Biuret's:

  1. Put a small sample of the food into a test tube.
  2. Liquify the food by adding enough water to make it a liquid, if the food is not already a liquid.
  3. Add 2-5 drops of Biuret's Solution.
  4. Swirl gently to mix.
  5. Let sit for five minutes.

To deduce the results:
Biuret's will turn a pink/purple in the presence of proteins.

Iodine

Iodine solution, also Lugol's Iodine, is used to detect starch. It is a mix of the element iodine and potassium iodide. The reaction is the result of formation of polyiodide chains from the reactive starch and iodine.

To use Iodine:

  1. Put a small sample of the food into a test tube.
  2. Liquidify the food by adding enough water to make it a liquid, if the food is not already a liquid.
  3. Add 2-5 drops of Iodine.
  4. Swirl gently to mix.

To deduce results:
The solution will turn dark blue, almost black, in the presence of starch.

Note that amylose (straight chain form of starch) will stain less than amylopectin (branched form of starch).

Brown Bag

The brown bag is the easiest and least formal test. It tests for lipids (fats).

To perform this test, spread, rub, or pour some of the food on a brown bag. Wipe away the excess, and hold the bag to the light. Foods containing more lipids will stain the bag more transparently than ones that have less lipids.

This test can also be done with plain paper, though the paper has to dry before it can be analyzed.

Density

You may have to find the density of certain baked foods made from ingredients on the Approved List of Ingredients such as bread. To do this, you will have to first cut it into a uniform cuboid (a 3-D rectangle). Next, use a ruler to measure the height, length, and breadth of the object. Record these measurements. Now, weigh the object. The event supervisor must provide a scale. Use the density formula to find the density of the food. Make sure to give your answer in the units wanted. The most common units wanted is \frac{g}{cm^3}.

The density formula is \text{Density}=\frac{\text{weight}}{\text{height}\cdot\text{length}\cdot \text{breadth}}

Standard Curve

The standard curve is a graph used to help determine the viscosity of an unknown liquid. Make sure your standard curve matches your viscometer! (Eg. If you have used 2 different viscometers before, make sure you bring the right curve with the right viscometer to the competition.) The event supervisor may require you to turn in a copy of your standard curve, so make sure you have another copy!

Competition Tips

  1. Study a lot. This event is one of heaviest in terms of what you need to know, so learn a lot and keep it in your brain!
  2. Ask the event supervisor if you can unstaple and then later re-staple your test. This event will be a crunch on time, so this strategy may help so you can split the work with your partner.
  3. Get a lot of rest before the competition! Self-explanatory.