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Identification of food constituents in milk essay


•To compare and analysis the composition of two various kinds of unknown milk, K1 and K2. •To determine the differences of the body fat content in milk trials, K1 and K2. •To compare the reducing sugar in the equally samples of dairy, K1 and K2. •To compare the protein concentrations in the the two samples of dairy, K1 and K2.


Milk provides a useful dietary source of calcium, which is essential for the expansion and repair of bone and tooth. Dairy is the initially source of nutrients as it played an important function in man nutrition.

The constituents in milk which can be vital in food preparation are enzymes, nutritional vitamins, pigments, salts, sugar, excess fat, and aminoacids. Different milk samples which contain different meals constituents may have a different nutritional value respectively. Sudan (III) can be fat-soluble absorb dyes used for staining of triglycerides (fat). It is used in the experiment to detect to get the presence of fat. It will appear as crimson globules in the event fatty acids exist in the dairy sample.

Benedict’s reagent is used to test for the existence of reducing all kinds of sugar. The solution will certainly form a brick-red medicine when the dairy sample includes reducing sugar (glucose, maltose, lactose. )

Sugar that may form a great aldehyde and ketone in the presence associated with an alkaline option is known as reducing sugars. The Biuret evaluation is used to evaluate for the existence of protein. The biuret evaluation is based on the ability of Cu (II) ions to form a violet-coloured chelate complicated with peptide bonds (-CONH-groups) in alkaline conditions. In Biuret’s evaluation (consist of sodium hydroxide and birdwatcher (II) sulphate solution), the perfect solution is will choose purple if the proteins are present in the milk sample. Healthy proteins are organic compounds essential for growth and repair. Proteins molecules consist primarily of amino acids connected together through peptide provides.


Copper(II) sulphate option, unknown dairy sample (K1, K2), food preparation oil, unadulterated water, salad oil, Sudan(III), full cream milk, Benedict reagent, 10% potassium hydroxide, 0. five per cent copper(II) sulphate


Evaluation tubes, plastic pipettes, natural, water bath


(A) 1 . A clean test out tube full until 1cm of the top with copper (II) sulphate solution. 2 . A small amount of K1 is definitely pipette into a clean plastic-type pipette and a drop is gently released in to the copper (II) sulphate solution as shown in Number 3. Another drop of milk is further introduced. 3. Then the pipette is definitely withdrawn little by little without disturbing the birdwatcher (II) sulphate solution. The movement of K1 is definitely observed cautiously and the observations are known. 4. The process above is usually repeated employing new, new copper (II) sulphate option, new clean glass equipment and the sample of K2. Observations for the movement of K2 are recorded and any differences in the behaviour of the drops of K1 and K2 are mentioned carefully.

(B) 1 . six test pipes are received and figures them from 1-6.

2 . The materials classified by Table 1 are added.

a few. The material of each pipe are blended thoroughly.

4. The colour changed from the tubes items are documented.


1 . 1ml cooking essential oil + 1ml distilled water

2 . 1ml salad petrol + five drops of Sudan 3

3. 1ml full cream milk + 5 drops of Sudan III

5. 1ml distilled water & 5 drops of Sudan III

five. 1ml distilled water & 1ml cooking food oil + 5 drops of Sudan III

six. 1ml food preparation oil + 5 drops of Sudan III

(C) (i) Minimizing sugar evaluation

1 . 2cm3 of K1 obtained is poured to a test tube and added by 2cm3 of Benedict’s reagent. The reagent together with the K1 remedy is mixed thoroughly. 2 . The test conduit is shaken occasionally when ever placed in the bath together with the temperature of 94ᶿc and left intended for 5 minutes. three or more. The colour altered is seen and the observations are documented. 4. Procedures 1-3 happen to be repeated with another test of milk, K2. The observations will be recorded.

(ii) Protein test out

1 . To 2cm3 of K1 acquired in a check tube, 2cm3 of 10% potassium hydroxide solution is usually added with it and the tube is shaken to mix the contents. installment payments on your 0. 5% copper sulphate solution is usually added a drop at a time and the tube is shaken continuously. The drops added did not go beyond 10 drops. 3. Types of procedures 1 and 2 will be repeated employing another sample of milk, K2 instead of rest solution.


A. (i)

Type of unidentified milkObservation

K1Milk droplets sank inside the CuSO4.


Type of unidentified milkObservation

K2Milk droplets floated topping CuSO4.


TubeTube solutionDescription of reaction


11mL cooking oil +

1mL distilled water2 layers answer formed, olive oil floated2 layers solution created, oil floated 21mL greens oil &

your five drops of Sudan III2 layers of oil and Sudan 3 droplets formed2 layers remedy formed (slightly red), Sudan III floated 31mL total cream dairy +

5 drops of Sudan III2 layers of milk and Sudan III droplets formedSlightly lilac milky solution formed 41mL distilled normal water +

5 drops of Sudan IIITransparent somewhat red remedy formedTransparent

slightly reddish solution, little black precipitate formed 51mLdistilled water &

1mL cooking petrol +

5 drops of Sudan III3 layers solution shaped, Sudan III at the top when oil with the middle2 layers solution shaped (slightly red), oil sailed 61mL food preparation oil + 5 drops of Sudan III2 layers of essential oil and Sudan III tiny droplets formedSlightly orange solution created Table 1


1 ) What is the rational of Sudan III is used in this experiment? Sudan III from this experiment is used for staining lipids or perhaps fats. Sudan dyes really are a group of lipid soluble solvent dyes named lysochromes. Sudan III also used to color the proteins bound fats in paraffin sections.

installment payments on your Which test tube can be

my spouse and i. Positive control?

Check tube one particular, 2, 3, 5, and 6 happen to be positive control.

ii. Negative control?

Test tube four was adverse control.

3. Describe the biochemistry of liquefied test applying Sudan 3.

Sudan III is used to determine the presence of lipids. It will stain the fat cells crimson. Sudan 3 is usually applying in lipid test. Initially, the liquid being test and water are filled to a check tube about 50 % full. three or more drops of Sudan 3 are included with test tube and staying shaken gently. There will type a red-stained oil layer separate away and drift on the water area due to the presence of body fat.

C. (i) Reducing sugar test

Types of unknown milkObservation

K1Orange precipitate is.

K2Yellow-orange solution is created.

(ii) Protein test

Types of unidentified milkObservation

K12 levels solution of darker a little bit purple milky solution and white colour milk is formed. K2Slightly violet milky answer is formed.


In the part A try things out, milk tiny droplets of K1 and K2 are produced into the water piping (II) sulphate solution carefully. After introduced, both of the droplets are certainly not dissolved in it. The K1 droplet slowly sank in the copper mineral (II) sulphate solution whilst K2 droplet slowly floated on the top of copper mineral (II) sulphate solution as a result of different denseness. The thickness of K1 was greater than the density of K2 and water piping (II) sulphate solution although K2 was lower thickness than CuSO4 solution. This experiment can be used to determine the excess fat contained in different types of milk by the movement of milk droplets in CuSO4 solution. The greater the density of milk, the lower the fat contained. The results confirmed that K1 contained much less fat compared to K2. Consequently , K1 was low-fat dairy while K2 was total cream milk. In the portion B research, cooking olive oil, salad olive oil, full cream milk, and distilled water were combined with Sudan 3 in different check tubes to get determining the lipid. Fats are absurde in polar solvents one example is water and can dissolve in non-polar solvent. Lipids are less dense than water and will float within the surface of solution.

Sudan III in this experiment was used to shade the fats. It tarnished the fat skin cells to become reddish colour. If perhaps lipid was presented, Sudan III is going to stain that and contact form red-stained petrol. In evaluation tube one particular, cooking oil floated boating surface after being shaken. In test out tube a couple of, slightly crimson solution getting observed after shaken showed that salad oil include lipids. In test conduit 3, the white color full cream milk became slightly lilac milky solution after added with Sudan III because of the fat shown in that. In test tube four, distilled drinking water formed a transparent somewhat red remedy after Sudan III was added to that. Sudan 3 was blended in distilled water but water is often negative control because there are simply H2O substances in this. In check tube five, 3 layers solution became 2 layers solution that cooking petrol at the surface. Oil became slightly reddish colored and Sudan III dissolved in olive oil. Sudan III is much more soluble in essential oil than in distilled water, hence the distilled drinking water still clear after research because of Sudan III was absorbed by oil. The past test tube which is test out tube 6th, the declaration was comparable to test conduit 2 but it really formed slightly orange option which also contained fats.

Test pipe 1, 2, 3, 5, and 6th stained red showed the existence of fat when test tube 4 was the only sample liquid that did not stained by Sudan III which will fat missing. In reducing sugar evaluation, Benedict’s reagent was used. Samples of milk, K1 and K2 became orange colored colour solution when tested with Benedict’s solution and heated. The observation showed that there was reducing glucose presented in both two milks. The perfect solution is added with Benedict’s reagent will change color from green to reddish colored depend on the concentration of sugar offered. Before heat, K1 and K2 were bluish milky solution since added with blue colour Benedict’s solution. The colour from the milk altered during heating system in the normal water bath. Throughout the heating section, both of K1 and K2 were converted to green coloring and finally orange colour alternatives were created. K1 created darker color of lemon than K2 and medications formed in K1 showed that the sugars concentration of K1 was higher than K2.

The biuret test is dependent on the ability of Cu (II) ions to create pink or perhaps purple colour when fastened with peptide bonds in alkaline conditions. This was used to test protein in milk K1 and K2. In protein test, both of two samples of milk formed slightly purple milky solution resulting from reacting with potassium hydroxide and copper mineral (II) sulphate solution in Biuret’s test. The solution switched purple eventually of try things out indicated that milk contained protein. After 0. 5% copper sulphate solution put into K1, it probably is 2 layers solution of slightly crimson milky answer at best and light colour milk at the bottom. The several concentration of protein can show by observing the different standard of purple coloring formed. The slightly purple coloring formed in K1 was darker than K2 showed that larger protein attentiveness presented in K1.


1 . Introduced the drop of dairy inside plastic-type material pipette in the middle of CuSO4 solution to prevent affection of motion of milk droplets simply A. installment payments on your Shook the mixtures with Sudan 3 by using stopper as it is contaminant. 3. Carried out the Biuret test pertaining to proteins at room temperatures as it will cause negative benefits. 4. Added 0. five per cent copper sulphate solutions not really exceed twelve drops since it will cause adverse results. your five. Handled potassium hydroxide thoroughly as it is caustic. Washed influenced area right away if it approached with the pores and skin.


The experiment recognized the major food components in several sample of milk. The part A try things out indicated that K2 dairy sample comprised more fat compare to K1 milk test. K1 was low-fat dairy while K2 was total cream milk. The part B experiment was conducted to determine the presence of lipid by adding Sudan (III) into several test pipes. Sudan III will discoloration it and form red-stained oil. The result showed that Test pipe 1, 2, 3, 5 and 6 contains body fat while check tube 5 did not include fat. The moment tested with Benedict’s reagent, K1 milk sample created darker shade of lemon than K2 milk test and the medications formed in K1 confirmed that the glucose concentration of K1 was slightly above K2. K1 milk sample formed more slightly darker purple remedy than K2 when executed in Biuret’s test. Therefore , it can deduce that K1 contained more protein out-do K2.



•The chemical constituents of living subject. 2009. Gathered October twenty seven, 2012 coming from: http://voices.yahoo.com/the-chemical-constituents-living-matter-3856864.html

•Analysis of the Chemical Components of Milk. 2000. Gathered October twenty seven, 2012 from: http://uncw.edu/chem/Courses/Reeves/OnLineLabs/NonScience/9-milk%20lab.pdf

•Experiment 3: Id Of Food Constituents In Milk. 2012. Retrieved Oct 27, 2012 from: http://www.markedbyteachers.com/as-and-a-level/science/experiment-3-identification-of-food-constituents-in-milk.html

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