• Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

Macromolecules in Food

Extracts from this document...

Introduction

Experiment 7: Title: Macromolecules in Food Objectives: * Detect the presence of carbohydrates, starch, proteins and lipids in food samples provided. * Carry out the tests that are used to detect the macromolecules found in the food samples. * Put into good use the methods that have already been learnt to test samples. Introduction: Everyday materials such as foods are composed of organic molecules such as carbohydrates, starch, proteins and lipids. It will be possible for us to determine if these organic substances are present by using the tests we learned in the last experiment. Various chemicals will be used in this practical to test for the presence of these molecules. Most often, we will be looking for a particular color change. If the change is observed, the test is said to be positive because it indicates that a particular molecule is present. If the color change is not observed, the test is said to be negative because it indicates that a particular molecule is not present. In all of the procedures, we will need to include distilled water as a control. Usually, a control goes through all the steps of the experiment but lacks one essential factor (the experimental variable). The missing factor allows you to observe the difference between a positive result and a negative result. If the control sample tests positive, we know that our test is fail. All of the experiments below, except for the iodine test, require that you use a sample solution. Therefore, if you are using a non-liquid sample, we must first dissolve, mix or mash the sample in water (a few drops) before adding any reagent. A) Reducing sugar Materials: * * Benedict's reagent * Test tube * Beaker * Hot plate * Apple juice, coke, potatoes, onions, and soy beans Methods: 1. A boiling water bath is made by filling a beaker about half full of water and it is heated on a hot plate. This water bath is used in several activities. 2. ...read more.

Middle

It is also one of the most recognizable and widely sold commercial brands. It is generally agree that Coca-Cola can be harmful if consumed to excess, particularly to young children whose soda consumption competes with, rather than complements, a balanced diet. This is because coke contains high sugar and lack of essential nutrient such as protein and vitamin. Hence, it is calories-rich and nutrient-poor beverage. This high sugar soft drink also will cause obesity. Obesity is a condition in which the natural energy reserve of humans or other mammals, which stored in fat tissue, is expanded far beyond usual levels to the point where it impairs health. Results: Sample(1ml) Reducing Sugars Starch Protein Lipids Soft drink Green blue to brick red Precipitate form Present Yellow remain yellow Not present Yellow to light orange Not present Not transparent Not present Discussions: There are several tests we use in this experiment to test the component in the coke. The tests are Benedict test, iodine test, Biuret test and paper test. The red precipitate is formed when Benedict test is performed on the coke. This shows that the coke contains reducing sugars. When the iodine is added to the coke, yellow colour is observed. This means that the coke do not contain starch. There will be dark blue in colour if the coke does not contain starch. The coke also give a negative results for the Biuret test (colour unchanged) and the paper test (no transparent spot). The table below shows the nutrition facts of the coke which we found from the internet: The nutrition facts of the coke also support our results which the coke is free of fat, protein, and starch. The coke also contains sodium as show in the table above. Onions Introduction: Onion in the general sense can e used for any plant in the Genus allium but used without qualifiers usually means Allium cepa L, also called the garden onion. ...read more.

Conclusion

In the presence of starch the Iodine will break the glycosidic bonds to form the precipitate (an iodine-starch complex is formed causing a color change from reddish-brown to violet-black). Supposedly, the test for Iodine reagent with soybeans should produce a positive result. But unfortunately in this experiment, the soybeans do not contain much starch to proof that there's starch present, so the reddish brown color remains unchanged. A reducing sugar is a straight chain sugar with free aldehyde or ketone at the end. A positive test for Benedicts was an orange or brick red precipitate. In Benedict's test, Benedict's reagent (a solution of sodium citrate and CuSO4) will produce an insoluble brick red or orangish Cu2O precipitate in the presence of reducing sugars (aldoses and some ketoses) and heat. In the presence of reducing sugars, he benedict's solution will cause the precipitate because it reacts with the free aldehyde or ketone present at the end of the sugar chain. To detect protein, the Biuret test will be used. In this test, NaOH and CuSO4 are added to test solutions. In the alkali environment, the Cu2+ ions will oxidize. In the process Cu2+ ions reduced to Cu+1 producing a purple color whose intensity directly correlates with the amount of protein present. A positive test for Biuret was lavender to black precipitation, which depends on the amount of protein present. A positive test for the grease spot test was to see if there's a translucent patch on the brown paper when it is dried. In each of these, there were stronger test and some tests provide weaker results. Stronger corresponds to a higher amount of the substance present and weaker correspond with a lower or lowest amount substance present. For example, the potato will have a strong test towards iodine reagent \, whereas the soybean was barely positive. For the Biuret reagent, the soybean was a chunky purple, leading us to believe that it was the strongest result towards protein test. Each of these tests involved a chemical change, except for the grease spot test. In this case the change was a physical one. ...read more.

The above preview is unformatted text

This student written piece of work is one of many that can be found in our University Degree Microbiology section.

Found what you're looking for?

  • Start learning 29% faster today
  • 150,000+ documents available
  • Just £6.99 a month

Not the one? Search for your essay title...
  • Join over 1.2 million students every month
  • Accelerate your learning by 29%
  • Unlimited access from just £6.99 per month

See related essaysSee related essays

Related University Degree Microbiology essays

  1. The aim of this investigation is to make a series of dilutions using the ...

    The dilution with the lowest mean result was the 1:100 dilution. This is a positive sign that the reproducibility of the pipetting was accurate since the tables from 2-5 shows that the volumes went from high to low. Thus showing that the more diluted the neat food dye was the

  2. Identification of an Unknown Enterobacteriaceae. The purpose of the experimental determination of an unknown ...

    Bacteria that metabolize citrate into alkaline end products grow while those lacking the enzymes do not grow. A royal blue color change is observed for a positive test; the plate remains green if the microbe is negative for citrate utilization.

  1. Folic acid. In 1993 the Food and Drug Administration (FDA), in the USA suggested ...

    WHERE IT IS FOUND Folic acids are found in many products. Good sources of folic acid are fruits vegetables, liver, green leafy vegetables, lima beans, legumes, bananas, and orange juice. There are some foods which contain trace amounts of the vitamin but however there is not enough present to be effective.

  2. In this essay I am going to explore the functions of carbohydrates within the ...

    The main common ones, which are found, are the ones, which contain three, five, or three carbon atoms. Trioses, pentoses and hexoses. Named examples of these are glucose and fructose, they are both isomers of C6H12O6. Glucose and fructose are both respiratory substrates, in both plants and animals.

  1. Write an essay in up to 2000 words on the following topics, describing the ...

    Fractionates of the various cellular components are produced, fractions include soluble proteins, membrane proteins, nucleic acids and cellular organelles. The proteins from the lysate can be concentrated using precipitation. There are many Different types of chromatography for protein isolation. Protein separation methods make use of difference in molecular weight, chemical properties (such as net charge)

  2. Nucleic acid hybridization

    Has similar effects on hybridisation rates for DNA and RNA hybrids, except that the maximal rate of hybridisation is obtained at 10-15�C below the Tm. Salt conditions 1. At low salt concentrations, DNA hybridises at very slow rates. 2.

  1. Free essay

    How had research over the past 25 years led us to think that microbes ...

    soon find life elsewhere in the solar system, as predicted long ago by our ancient predecessors. References: Adams, M.W.W., Perler, F.B. & Kelly, R.M. (1995) Extremozymes: Expanding the Limits of Biocatalysis. Nature Biotechnology, 13, 662 - 668. Anderson, A.W., Nordon, H.C., Cain, R.F., Parrish, G.

  2. A review of positive and negative impacts of microbes on the environment

    These principles involve the exploitation of the chemistry of microbes to produce a certain product or desired effect. DNA within individual microbes can be manipulated to produce maximum desired effects, and this process is called genetic engineering. Genes from certain microbes can also be transferred to another type of microbe, which is known as DNA expression.

  • Over 160,000 pieces
    of student written work
  • Annotated by
    experienced teachers
  • Ideas and feedback to
    improve your own work