Sugars are carbohydrates

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Sugars are carbohydrates and have three main purposes: to provide the body with energy; to allow the body to store and transport energy and to aid in bodily needs e.g. immune system, fertilization, pathogenesis, blood clotting and development.

Simple sugars may also be broken down into groups: monosaccharides, disaccharides and polysaccharides. Monosaccharides contain single sugar units, for example glucose, fructose, galactose. They are small and soluble nutrient that pass directly in blood stream. Disaccharides contain two sugar units. They are soluble and are to large to pass directly in the blood stream, thus they need to be digested. Polysaccharides are complex carbohydrates and contain many sugar units. They are usually in the form of starch, cellulose and glycogen.

These carbohydrates all gain quick access to bloodstream providing a slow, prolonged release of energy.

Benedict's reagent is a chemical compound which is used to detect the presence of simple sugars. In order to test substances with Benedict's reagent, a small amount is added to the solution and it is then boiled for several minutes. The results will reveal the amount of simple sugars present in that substance and also shows the color changes that can gauge the amounts of the simple sugars. If there is a presence of simple sugars, the Benedict's reagent changes color to green, yellow, and brick-red, depending on the amount of simple sugar.

Aim

The aim of this experiment is to test a variety of food substances for the presence of simple sugars (reducing sugars).

Hypothesis

Based on the information in the introduction above, if the Benedict's reagent causes the solution to turn green, yellow or brick-red, then we can conclude that there is a presence of simple sugars (reducing sugars); however, if there is another change in color other than the ones mentioned above, then there is no presence of simple sugars.

Equipment

  • Test tubes x 3
  • Test tube stand
  • Distilled water
  • Beakers or glass jars
  • Labels for jars and test tubes
  • Benedict's reagent solution
  • Lab thermometer
  • Eyedroppers
  • Stopwatch
  • Hot plate
  • Water
  • Food Samples (apple juice, potato and skimmed milk)

Method

  1. Prepare a hot water bath using a beaker or glass jar half filled with water. Place on a hot plate and by using a lab thermometer, heat the water to 40-50°C.
  2. Mix each of the food substances with distilled water to form a liquid.
  3. Using the following steps, test each of the substances for the presence of reducing sugars:
  1. Label each test tube
  2. Place 40 drops of each liquid food substance into its own individual test tube.
  3. Add 10 drops of Benedict's reagent solution to each test tube.
  4. Place the test tubes into the hot water bath for 5 minutes - timed using stopwatch
  5. Record results and then analyse.

Analysis:

Based on the results shown above, it was found that the skimmed milk and the apple juice contain simple sugars. The potato did not change to the colours therefore there are no sugars present in potato.

Evaluation:

The experiment in testing for the presence of simple sugars using the Benedict's reagent was successful; however the experiment could have been improved by conducting several trials in order to ensure the proper colors were recorded.

Food Test 4 - Starch - Iodine Solution

Introduction

Starch is a complex carbohydrate, or polysaccharide, which is made up of many sugar units joined together by glycosidic bonds. Starch is plant storage substance, digested by amylase enzymes in salvia and pancreatic juice.

Starch is a very large, often branched, macromolecule that is solid and insoluble in water. They do not have a sweet taste. They go through the digestive system where they are broken down and transported to places in need of energy- it gives a steady release of energy over a prolonged period of time.

Iodine solution is used to test for the presence of starch. If there is a presence of starch in the substance being tested then the iodine will react and will produce a deep purple/black color.

Aim

The aim of this experiment is to test a potato using an iodine solution for the presence of starch.

Hypothesis

If the iodine solution causes the substances to turn brown, blue or black, we can conclude that there is a presence of starch; however, if there is another change in color other than the ones presented above, there is no presence of starch.

Equipment

  • Beaker or jar
  • Iodine solution
  • Water
  • Potato
  • Newspaper
  • Eyedropper

Method

  1. Mix the iodine solution with water
  2. Place the potato onto a newspaper
  3. Using the eyedropper, apply a few drops of the iodine solution onto the potato
  4. Record the results and analyse

Analysis

Based on the results shown above, it was found that the potato contained starch.

Evaluation

The experiment for testing starch was successful. The experiment may be taken to the next level by testing other food substances for the presence of starch.

TAQ 3

Food Test 2 - Proteins - Biuret Solution

Introduction

Proteins consist of large compounds made of amino acids and these are structured in linear chains. They have three main purposes, these are: to aid in the body's growth and repair of muscles; to aid in biochemical reactions in the body and to aid in the body's metabolism.

The Biuret solution is a mixture of copper sulphate and potassium hydroxide, which is used to detect the presence of proteins. In order to test solutions with the Biuret solution, a small amount of the substance is added to the solution and is then shaken gently to test the amount of proteins that are present. In the presence of proteins, the Biuret solution changes the solution color from blue to pink-purple, depending on the amount of proteins present.

Aim

The aim of this experiment is to test a variety of food substances for the presence of proteins.

Hypothesis

If the Biuret solution causes the solution to turn pink or purple, then we can conclude that there is a presence of proteins; however, if there is another change in color other than the ones presented above, there is no presence of proteins.

Equipment

  • Biuret solution
  • Test tubes
  • Test tube stand
  • Eyedropper
  • Food samples (egg white, apple, cheese)
  • Distilled water
  • Labels for test tubes

Method

  1. Mix each of the food substances with distilled water to form a liquid solution.
  2. Using the following steps, test each of the substances for the presence of proteins:
  1. Label each test tube
  2. Place 40 drops of each liquid food substance into its own individual test tube.
  3. Add 3 drops of Biuret solution to each test tube.
  4. Cover and shake each test tube gently to mix solutions together.
  5. Record results and then analyse.

Analysis

Based on the results shown above, it was found that the skim milk and the egg white contains proteins. The potato does not contain proteins because it did not change to a colour which would result if there was a presence of protein.

Evaluation

Our experiment in testing for the presence of proteins using the Biuret solution was generally successful; however, there were several weaknesses with this method of testing the presence of proteins using the Biuret solution. Sometimes the differentiation between the colors blue and purple were difficult to tell apart. Suggestions to improve this experiment would be to use more of the Biuret solution, as that might help with the distinguishing of different colors. Another suggestion would be to conduct several trials in order to ensure the validity of the colors recorded.

TAQ 4

Food Test 3 - Fats - Brown Paper Test

Introduction

Fats have three main purposes in the body, these are: to provide the body with warmth; to help in biological functions such as energy storage; and to provide vitamins A, D, E, K.

There are several different types of fats with different structure: monounsaturated, polyunsaturated fats, Omega-3 and saturated fats.

The translucence test, which uses unglazed brown paper, is used to test for fats (lipids). If lipids are present, the lipid is absorbed into the paper and causes it to appear translucent which means that light is able to pass through it and it looks like a greasy spot. This is because the paper in a brown paper bag or any other paper under microscopic examination is made from thousands of fibres that are separated by gaps of air. When oil or any liquid absorbs into the paper, it acts like a fibre optic cable, it transmits the light from one side to the other, it fills the gaps and makes light shine through the paper by acting like a light pipe. The gaps are filled with oil, so the light can pass through the paper from one side to the other.

Aim

The aim of this experiment is to test a variety of substances for the presence of fats.

Hypothesis

If the solutions cause translucent spots on the brown paper, there are lipids present. Any other result from these tests will show no presence of lipids.

Equipment

  • Vegetable Oil
  • Water
  • Brown Paper x 2 pieces
  • Eyedropper
  • Stopwatch

Method

  1. Label the two brown pieces of paper
  2. Place a small sample of the substance to be tested on a piece of unglazed paper.
    1. Spread it as thinly as possible over a small area. Solid foods should be ground on the surface of the paper
    2. Discard excess solids
    3. After 10 minutes (timed using stopwatch), hold the paper up to the light to look for translucent spots
  3. Record results

Analysis

Based on the results shown above, it was found that the vegetable oil contains lipids. This is based on its translucency with the paper. Conversely, the water had results that indicated no presence of lipids.

Evaluation

The experiment in testing for the presence of lipids was successful. Whether or not the solutions caused translucent spots on the pieces of paper were easy to see.

TAQ 5

Carbohydrates

Carbohydrates have three main purposes:

  • To provide the body with energy
  • To allow the body to store and transport energy
  • To aid in bodily needs e.g. immune system, fertilization, pathogenesis, blood clotting and development.

Carbohydrates contain three elements:

  • Carbon
  • Hydrogen
  • Oxygen.

Carbohydrates can be broken down into two groups:

  • Simple carbohydrates
  • Complex carbohydrates.

Simple Carbohydrates (also known as simple sugars) include:

Sucrose http://www.coursework.info/document/7/5/7/757781/757781_files/image001.gif glucose + fructose

Lactose http://www.coursework.info/document/7/5/7/757781/757781_files/image002.gif glucose + galactose

Maltose http://www.coursework.info/document/7/5/7/757781/757781_files/image001.gifglucose + glucose

Simple sugars may also be broken down into the amount of bonds they have:

Monosaccharide

  • Single sugar unit e.g. glucose, fructose, galactose
  • Soluble
  • Small (not digested, pass directly in blood stream)

Disaccharides

  • Two sugar units e.g. sucrose, lactose, maltose
  • Soluble
  • Too large (needs to be digested)

Polysaccharides

  • Many sugar units:
  • Starch - plant storage substance, digested by amylase enzymes in salvia and pancreatic juice
  • Cellulose - found in plant cell walls (cannot be digested by mammals as do not have cellulase) helps stimulate muscles in gut (peristalsis)
  • Glycogen- animal storage substance

These carbohydrates all gain quick access to bloodstream providing a slow, prolonged release of energy.

Complex Carbohydrates come from starch and they are polymers made up of many monosaccharide's' joined together by glycosidic bonds.

They are:

  • Very large, often branched, macromolecules
  • Solid and insoluble in water
  • Have no sweet taste

They go through the digestive system where they are broken down and transported to places in need of energy- it gives a steady release of energy over a prolonged period of time.

Some of the sources for simple carbohydrates are:

  • Sweets
  • Cakes
  • Chocolate
  • Biscuits
  • Jam

Here are some examples of complex carbohydrates

  • Potatoes
  • Pasta
  • Spaghetti
  • Fruit
  • Whole Grain cereals e.g. Weetabix

Proteins

Proteins have three main purposes, these are:

  • To aid in the body's growth and repair of muscles
  • To aid in biochemical reactions in the body
  • To aid in the body's metabolism

Contain: carbon, hydrogen, oxygen, nitrogen

Proteins consist of large compounds made of amino acids and these are structured in linear chains.

Sources of Protein include:

  • Meats
  • Fish
  • Beans
  • Eggs
  • Nuts
  • Dairy Products e.g. cheese, yoghurt

Deficiency causes disease - Kwashiorkor

Fats

Fats have three main purposes, these are:

  • To provide the body with warmth
  • To help in biological functions such as energy storage
  • To provide vitamins A, D, E, K
  • Contain: carbon, hydrogen, oxygen
  • Excess is stored under the skin and around body organs

There are several different types of fats with different structure:

  • Monounsaturated -do not raise blood cholesterol and encourages heart health
  • Polyunsaturated Fats - lowers blood cholesterol and encourages heart health
  • Omega-3 - type of polyunsaturated fat found mainly in oily fish
  • Saturated Fats - raise blood cholesterol and promote heart disease

There are several different sources for each structure:

Monounsaturated Fats

Sources include:

  • Avocados, peanuts, peanut oil and peanut butter
  • Olive oil, olives and olive oil-based margarines
  • Canola oil and monounsaturated table spread
  • Almond and hazelnuts

Polyunsaturated Fats

Sources include:

  • Vegetable oils such as soy bean, sunflower, corn
  • Wheat germ, wholegrain cereals and breads
  • Polyunsaturated margarines
  • Fish oils (naturally present in fish)
  • Seeds and most nuts

Saturated Fats

Sources include:

  • Dairy fats such as butter, clarified butter, cultured butter, butter/margarine mix
  • Milk homogenised or full cream
  • Hard cheeses, cream cheese, sour cream, ice cream and cream
  • Meat fats such as lard, dripping, suet, beef tallow and chefade
  • White visible fat on beef, mutton, lamb, pork, poultry
  • Processed meat, e.g. luncheon, salami, most sausages, tinned corned beef, fatty mince pies and pates
  • Tropical oils such as coconut, coconut cream, palm oil and kremelta

Vitamins

Vitamins are essential substances that cannot be manufactured by the body. We need small amounts of vitamins for growth and development. Without vitamins the body cannot survive.

Fibre

Fibre has three main purposes, these are:

  • Fibre helps your digestive system in processing food and absorbing nutrients.
  • Fibre lowers blood cholesterol.
  • Fibre helps to control blood sugar levels, which in turn controls appetite. This may lead to weight loss or weight gain.

However, there are two different types of fibre; these are Insoluble Fibre and Soluble Fibre. Insoluble fibre helps your bowel to pass food by making stools soft and bulky, this type of fibre helps prevent constipation. Soluble Fibre lowers cholesterol levels and controls blood sugar

Sources of Insoluble Fibre include:

  • beans
  • brown rice
  • fruits with edible seeds
  • lentils
  • maize
  • oats
  • wheat bran, wholegrain breads, wholegrain cereals, wholemeal breads, wholemeal cereals, wholemeal pasta, wholewheat flour

Sources of Soluble Fibre include:

  • apples
  • barley
  • citrus
  • guar gum
  • legumes
  • oats
  • pears
  • strawberries

UNIT 8

TAQ 6

Using hand drawn diagrams of the digestive tract and the histology of its lining:

  1. Analyse the needs for digestion of food did a diagram of the overall digestive system
  2. The digestive system is made up of a series of organs which are primarily concerned with the breaking down, or digestion, of the food we eat. The food we eat is made up of large, complex molecules. The digestive system breaks these large molecules down into smaller, simpler molecules which are then absorbed into the bloodstream and travel throughout all the different parts of the body. These molecules are necessary for growth, repair, and energy. All living organisms need energy to survive therefore, the digestive system is required for survival, as it plays a vital part in the process of creating this energy.

  3. Show importance of both physical and chemical digestion did smaller diagrams showing physical & chemical digestion
  4. Digestion is divided into two parts: a mechanical part and a chemical part. In the mechanical part, teeth physically break down large pieces of food into smaller pieces. In the chemical part, digestive chemicals called enzymes break apart individual molecules of food into smaller molecules, which are absorbed and distributed throughout the body.

  5. Evaluate the role of enzymes and investigate how ph affects the action of enzymes drew a diagram of enzymes and how the bond to substances and did a couple of graphs to show how ph affects the enzymes.
  6. Enzymes are chemicals that dissolve food and help speed up the rate of which food can be digested. The salivary glands and the pancreas produce and secrete their enzymes through tubes into the digestive canal. Food would take forever to digest without enzymes, however with enzymes it only takes a few hours. Enzymes can either join together or divide two molecules and are not fully used up in the chemical reaction, in other words, one enzyme can be used time and time again.

    Enzymes are affected by changes in acidity and alkaline conditions for example, stomach enzymes work best in an acidic situation; this is provided by the hydrochloric acid which is located in the stomach.

    Hydrochloric acid causes the acidity of gastric juice to be in the range of pH 1 to pH 3. This practically guarantees that any bacterium, which enters with food, is destroyed. Hydrochloric acid combines with pepsinogen to form the enzyme called pepsin. Mucin is a secretion which protects the stomach from being dissolved by hydrochloric acid.

  7. Investigate the processes of digestion and absorption of the food we ingest did a diagram of absorption.
  8. The process of digestion starts in the mouth, where the mouth swiftly coverts the food into a soft, moist mass, by secreting saliva from the glands in the cheek linings. This saliva lubricates the food making it easier to chew and swallow, while the tongue moves the food around inside the mouth and pushes the mass between the teeth to grind it.

As soon as the food has been turned into a soft mass, it is then ready to be swallowed. The tongue then pushes this mass, called a bolus, to the back of the mouth and into the pharynx. The pharynx is a cavity which lies between the mouth and windpipe and acts as a pathway leading the down into the digestive system canal.

The presence of the food in the pharynx stimulates the action of swallowing. Food passes through the digestive system by means of rhythmic muscle contractions, known as peristalsis. During this process, the food is squeezed down the oesophagus towards the stomach, while the circular muscles in the oesophagus wall contract and relax.

Separating the stomach and the oesophagus is a circular muscle, called the cardiac sphincter. As food is swallowed, this muscle relaxes, forming an opening through which food can pass into the stomach. The muscle then contracts closing the opening to prevent food from moving back into the oesophagus.

The stomach is a hollow, sac-shaped muscular organ that is able to expand in order to store the food that has been consumed. The stomach churns the food, while combining it with water, hydrochloric acid, pepsin and mucin, known as the gastric juices. Pepsin requires an acidic environment to be able to break down proteins, which the hydrochloric acid provides.

Hydrochloric acid also inhibits the growth of and destroys any bacterium that may have entered the stomach. Mucin lines the stomach, shielding it from the acid and pepsin. Once the food, now called chyme, has been processed by the stomach, it starts moving slowly into the small part of the intestine, known as the duodenum, via the pyloric sphincter.

Most of the digestion, including the absorption of digested food, occurs within the small intestine. Food is pushed through the small intestine by a process of muscular-wavelike contractions called peristalsis. It is in the small intestine where chemical digestion takes place. Enzymes enter the small intestine which breaks nutrients down into smaller molecules ready for absorption. Sugars and starches are broken down into simple sugars, fats are broken down into fatty acids and glycerol, and proteins are broken down into amino acids.

The small intestine is lined with microscopic, single cell layered, fingerlike projections, called villi, which help with the process of absorption. Microvilli are tiny finger-like projections that cover each individual cell. the function of the villi and microvilli is to provide a larger surface area for absorption.

Each villus has a network of capillaries and fine lymphatic vessels, which are responsible for allowing the nutrients, which were produced by digestion, to travel via the blood stream, to the cells of the body. This process is known as diffusion. The simple sugars and amino acids enter the bloodstream via the capillaries and the fatty acids and glycerol enter the lymphatic system via the fine lymphatic vessels.

Once this process of absorption has completed the excess food and digestive juices that were not absorbed, leave the small intestine and moves by peristalsis into the large intestine. The large intestine has many important functions which include the absorption of vitamins that are created by the bacteria inhabiting the colon, the absorption of water and compacting faeces, waste material that consists largely of undigested food, digestive juices, bacteria, and mucus, which is stored in the rectum until it is eliminated out of the body.

Resources

(FSA, 2009)

(BBC Good food Guide, 2010)

(Weight Loss Resources, 2010)

(Tesco, 2010)

Sasha TaylorPage 10

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