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Investigation of Food Content

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Judith L. Gasalatan

Aim: To investigate the food content of different food samples.


Food Sample




Vitamin C

Whole meal bread

There is fat present and became cloudy

There is starch present that the colour changed into dark brown

No protein is present

No vitamin C is present

White bread

There is fat present and became cloudy

There is starch present because the colour changed into dark brown

No protein is present

No Vitamin C is present


There is fat present

No starch is present

No protein is present

No Vitamin C is present


Fat is present

No starch is present

No protein is present

No Vitamin C is present

Apple juice

No fat is present

No starch is present

No protein is present

Vitamin C is present

Orange juice

There is fat present because it became cloudy

No starch is present

No protein is present

Vitamin C is present

Conclusion of the investigation:

During our experiment, we have found out the different contents of different samples that we used. We have gathered different results which gave us the knowledge to identify which samples contain different types of food groups. When we tested for the whole meat bread, we added 2 ml of water to the food sample then added four drops of alcohol afterwards in the test tube. We shook the test tube and recorded the change in colour. The colour became cloudy which signifies that there is fat present in the whole meal bread. When we tested to see if there is starch present, we added 1 ml of water to the sample then added 1-2 drops of iodine solution and shake the test tube. We have found out that there is starch present because the colour changed into dark brown. Moreover, when tested for protein after adding 1 ml of water and 1-2 drops of biuret reagent in the test tube, the colour showed no changes which identifies that there is no protein present in the sample. Then, when we tested if there is Vitamin C present after adding 1ml of distilled water and 1-2 drops of DCPIP solution, again, it showed no changes as well which gave us a result that there is no Vitamin C present in whole meal bread.

When we tested for the white bread, it showed the same results as to the whole bread as well. It contains fats because it became cloudy when we observe the results and contains starch in it because it changed into colour dark brown.

For the third sample which is the butter, when we tested for fats by adding two ml of distilled water then added four drops of alcohol in the test tube, we found out that it contains fats because it turns into cloudy after shaking it off. When testing for starch by adding 1 ml of distilled water to the sample and added 1-2 drops iodine solution, it gave us no changes which means that it doesn’t have starch. When we test it for protein, we added 1 ml of distilled water and 1-2 drops of biuret reagent, it gave us the same result when we test for starch. The same process we did for protein and Vitamin C and no changes occurred during the test.

Next is the milk which the only food group present is fats. When we shook the test tube after adding the 2 ml of water and four drops of alcohol, the colour changed into cloudy form and while testing for the other food groups which are the starch, protein and Vitamin C, no changes were happening.

When we tested for the content of apple juice, we added 2 distilled of water to the food sample the added 4 drops of alcohol. After that, we shook the test tube and observed the result which gave us no changes. When testing for protein, we only added 1 ml distilled water and added 1-2 drops of iodine solution. After shaking it, there was no colour pink or purple occurred. However, when we test it for Vitamin C by adding the 1 ml of distilled water and 2 drops of DCPIP solution, the colour changed into red which signifies that Vitamin C is present.

Lastly, we tested the food group content of orange juice. To test if there is fat present in the food sample, we added 2 ml of distilled water and four drops of alcohol then shake it off. After that, it became cloudy which means that fat is present in the food sample. Testing the starch by adding 1 ml of water and 1 or 2 drops of iodine solution, it gave us no changes in the colour because if there is, it would change into dark brown. Then testing for the protein we added 1 ml of distilled water and 1-2 drops of biuret reagent, still, no changes were happening because it didn’t change into colour pink or purple. Lastly, when we test it for Vitamin C, we added the 1 ml of distilled water into the food sample and few drops of DCPIP solution and the colour changed into red. In addition, the more drops we put in it, the more the colour changed into red and that means that there is more Vitamin C present in the food sample.

Judith L. Gasalatan


Task 2- Digestive Systems

The digestive system is the group of organs that work together to convert the food to energy and nutrients in order to feed our whole body and helps perform its functions. Digestion is the breakdown of large molecules into smaller molecules that’ll be absorbed in the body.

Food when eaten begins to digest into the mouth but different types of food are digested in different parts of the digestive system. Protein while grinding in the mouth is primarily digested in the stomach and fats is primarily digested in the small intestine.


The process of carbohydrates digestion begins in the mouth with the release of amylase enzyme. The teeth are used to crush, grind and chew the food into smaller pieces that is mix with the saliva and also with the help of the tongue. In the mouth, salivary gland respond to the thought and existence of food by manufacturing a fluid which contains mucous and the enzymes amylase and maltase. In the mouth, amylase enzymes begin to break apart of the bonds holding the carbohydrate polysaccharides sugar together. As chewing and partially digested food reaches the upper stomach through the oesophagus, the lower stomach begins to fill with hydrochloric acid. This acid kills harmful microorganisms that may be present from the food. The oesophagus has band of tight muscle at the lowest part in order to stop the food from getting it back into the mouth. Additional carbohydrate digestion continues from the mouth in the upper stomach. Protein is primarily digested in the stomach. Protein digesting enzymes break apart the bonds holding the amino acids of proteins. Digestive protein partially digestive carbohydrates and undigested fats travel into the small intestine for the digestive process to be completed. In the small intestine, amylase completes the digestion of carbohydrates. Fats are digested into the small intestine by the lipase enzymes. Digested protein, carbohydrates and fats are then absorbed through the villi of the small intestine into the bloodstream. Blood take sugars and amino acids to the liver by the portal vein. The pancreas just like the small intestine excretes enzyme in an alkaline juice to digest protein, carbohydrates and fats. It produces hormones as well which manage the level of blood sugar. From the small intestine, the macerated food is received by the liver in which produces bile for the gallbladder. The gallbladder stock and discard the bile that helps to break down the fats. The food that is undigested from the small intestine is then proceeding into the large intestine. In there, the blood vessels which provides the large intestine discharges water extracted from the waste that is undigested. The undigested food is then removed from the system through the anus.

Different types of nutrients are very important because each has different purpose in our body. We need protein because it helps in growth and tissue repair in our body. It also makes essential enzymes and hormones and provide energy when carbohydrates is not available. According to the DTI (Dietary Reference Intakes) published by the USDA, the number of calories that we should consume that comes from protein is 10%-35%. Protein is found mostly in animals’ sources such as meats, fish poultry and many more. If we eat these kinds of foods, it all contains the essential amino acids that we need.

Carbohydrates are the most needed nutrient that we should have because it is the source of energy and all of the tissues and cells in our body can use glucose in order to have energy. It is also needed in central nervous system, the brain, the kidneys and muscles in order for it to function properly. Carbohydrates are found in starchy foods such as milk, yoghurt and fruits. These carbohydrates pass through the intestinal tract which helps to move the waste out of our body and also help digest the food. They also regulate the quantity of sugar circulating in the blood in order for the cells to get the energy that they need. They may regulate blood pressure and help lower the levels of cholesterol (effects benefits of dietary fibre).

Even though fats have taken bad reputation about causing gain weight, there are some fat that is important for survival. The body uses the fat from the food we eat to provide the energy for our life-functions. Cholesterol, triglycerides and other fatty acids are the fats that can’t make on their own in the body, insulate us, store energy and protect the vital organs. They help proteins do their job and act as messengers.

They also start chemical reactions that help immune function, reproduction, control growth, and other aspects of basic metabolism. The cycle of making and storing fats is at the core of how all the animals and above all, how humans manage their energy. An imbalance can result in diseases such as diabetes and heart disease.

Moreover, the fats also help the body supply certain nutrients as well. The “fat soluble” vitamins in A, D, E and K are stored in fatty tissues and in the liver too.





Judith L. Gasalatan


Task 3- Chemical Digestion

Proteins make up our body mass at about 15%. They are the largest amount of ‘solid’ substances in our body. Each protein has its own capacity under the control of its own gene. Its shapes are of key importance and these are regulated by the series of amino acids that make them up.

Proteins are naturally appearing polypeptides because they contribute to mechanical structure of humans and also animals such as the keratin in hair, fibrous proteins such as collagen in tendons and also the fingernails. They enable the animals to move because of the myosin in muscle and also facilitate the transport of smaller molecules around the bodies of animals like the haemoglobin.

As we all know, the enzymes plays an important role in digestion because they help break down large molecules into smaller molecules that can be absorbed easily. They work best on their optimum pH. Like for example, if the stomach doesn’t produce an adequate amount of hydrochloric acid, the pepsin, an enzyme, wouldn’t work properly. The job of the protease enzymes that’s secreted by the stomach, pancreas and the small intestine is to digest the proteins. Proteins are long chains of amino acids and these protease (enzymes) break them into smaller chains of molecules of amino acids which is called peptides. And then eventually, into distinctive amino acids which are small and is then easily absorbed in the small intestine.

http://www.passmyexams.co.uk/GCSE/biology/images/enzymes_digestion.jpgProteinshttp://www.passmyexams.co.uk/GCSE/biology/images/protease_arrow.gifamino acids

In the mouth, amylase from the salivary glands begin carbohydrates digestion. Salivary amylase breaks starch down into smaller polysaccharides and sugars like maltose. However, only a few starch molecules are completely digested into maltose before they enter the small intestine because the acidic pH of the stomach destroys the salivary amylase. The pancreas secreted amylase into the duodenum. In the small intestine, bicarbonate ions from pancreatic juice neutralize gastric juice. Amylase continues the breakdown of starches into maltose. Starch is broken down into monosaccharide, disaccharides and short chains of sugar units called oligosaccharides. Then, the enzymes break down oligosaccharides and disaccharides into monosaccharide which enter into the bloodstream. As maltose is still a disaccharides which breaks starch down into two-glucose units, it needs more additional digestion before it can be absorbed completely. So, the enzyme maltase will break it down into glucose. All end products of carbohydrate digestion such as fructose, glucose and galactose are absorbed as monosaccharides.

In the pictures below showed the breakdown of carbohydrate molecules into monosaccharide which is sugar molecules after going through digestion from the mouth into small intestine and the entire part of the body.



Fats or lipids are absorbed and digested in the small intestine. Foods such as dairy products, meats nuts and seeds contain dietary fat. Lipids are described as fat like molecule that doesn’t have the capacity to dissolve in water. And this failure to dissolve in water adds difficulty to fat digestion. Since fat doesn’t dissolve in water, it moves through the digestive system forming large droplets clumped together. Then, when it reaches in the small intestine, it hasn’t been digested. Bile helped break the fat into smaller droplets that’s made in the liver. The bile contains salts that acts as an emulsifier of lipids. The bile salts disrupt the fat and coat it to form finer droplets. Then, it’ll have more surface area which helps digestion because the pancreatic lipase (fat digesting enzyme) can only function on the exterior part of the fat droplet. The pancreatic lipase breaks down the fat which will result in monoglycerides and free fatty acids which are two products of lipids. Then, it’ll become easier for the small intestine to control these products because there’s only little problem being absorbed out of the digestive tract.

The mucosal lining of the small intestine is where the absorption takes place and when the two products pass through it, they now enter the epithelial cells. Then, they are resynthesized into triglycerides which is a major form of fat stored by the body. Before it leaves the epithelial cells, they will result in the form of chylomicrons that’s composed of lipids and proteins. Then, the water soluble from the coating that the glyceride gives will allow it travel outside the cell.

http://www.bbc.co.uk/staticarchive/c8315e7102bb259642b45de464e710897b069e8f.gifIn the picture shown below is the lipase broken down into fatty acid molecules and glycerol molecules.





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