LABORATORY RECORD

FOOD ANALYSIS LABORATORY

SUBMITTED BY

RAJA M

2013304019

FOOD TECHNOLOGY

CENTRE FOR BIOTECHNOLOGY

ANNA UNIVERSITY

CHENNAI-25

ANNA UNIVERSITY

CENTRE FOR BIOTECHNOLOGY

This is to certify that this is the bonafide record work done by the following student in the FOOD ANALYSIS LABORATORY during the academic year 2015-2016.

NAME : RAJA M

ROLL NO. : 2013304019

CLASS : B.Tech FOOD TECHNOLOGY

SEMESTER : V

SIGNATURE OF SIGNATURE OF

LAB-IN-CHARGE THE HOD

Submitted for the Practical Examination held on ____________

INTERNAL EXAMINER

INDEX

S.NO DATE NAME OF THE EXPERIMENT SIGNATURE

1. DETERMINATION OF pH & TOTAL DISSOLVED SOLIDS, SUSPENDED SOLDIS OF POTABLE WATER.

2. DETERMINATION OF TOTAL FAT CONTENT IN BAKED AND DRIED PRODUCTS

3. DETERMINATION OF FREE FATTY ACID AND ACID VALUE OF GIVEN FOOD SAMPLE.

4. DETERMINATION OF MOISTURE CONTENT OF FRUIT JUICES BY OVEN DRYING METHOD.

5. DETERMINATION OF TOTAL SOLIDS IN FRUIT JUICES USING REFRACTOMETER.

6. DETERMINATION OF ADDED SODIUM BENZOATE IN FOODS

7. DETERMINATION OF ALOCOHOLIC ACTIDITY BREAD.

8. DETECTION OF ADULTERANTS IN DIFFERENT FOOD SAMPLES

9. DETERMINATION OF ALCOHOLIC ACIDITY OF WHEAT FLOUR.

10. DETERMINATION OF GLUTEN CONTENT IN WHEAT FLOUR.

11. DETERMINATION OF BLEACH VALUE OF DIFFRENRNT FLOUR SAMPLES (petrol number)

12. DETECTION OF MONO SODIUM GLUTAMATE (FLAVOR enhancer) in foods.

13. ESTIMATION OF IODINE CONTENT IN SALT

14. DETECTION OF SULPHITES IN FOOD SAMPLES.

15. ESTIMATION OF VITAMIN C IN FRUIT JUICES.

16. EXTRACTION AND IDENTIFICATION OF ADDED COLOR FROM CANDIES

17. DETERMINATION OF MELTING POINT OF VANASPATHI

18. ESTIMATION OF PEROXIDE VALUE

DETERMINATION OF pH & TOTAL DISSOLVED SOLIDS, SUSPENDED SOLIDS OF POTABLE WATER.

AIM:

To determine the pH and total dissolved solids, suspended solids of portable water.

PRINCIPLE:

The term pH refers to the measure of hydrogen ion concentration in a solution and is defined as the negative log of hydrogen ion concentration in water. The values of pH range from 0-14 where from 0-7 it is considered as acidic and from 8-14 it is basic. When the concentration of hydrogen and hydronium ions are equal, it is termed as neutral pH.

The pH electrode used I the pH measurement is a combined glass electrode. It consists of sensing half-cell and reference half-cell together form an electrode system. The sensing half-cell is a thin pH sensitive semi permeable membrane separating two solutions namely the outer solution, the sample to be analyzed and the internal solution enclosed inside the glass membrane and has a known pH value.

An electrode potential is developed inside and another electric potential is developed outside, the difference in the potential is measured and is given as the pH of the sample.

The term total dissolved solids refer to the materials that are completely dissolved in water. These solids are filterable in nature. It’s defined as residue upon evaporation of filterable sample. A well-mixed sample is filtered through a mixed sample is filtered through a standard glass fiber filter, and the filtrate is evaporated to dryness in a weighed dish and dried to constant weight at 179-181°C. The increase in dish weight represents the total dissolved solids.

PROCEDURE:

(a)pH determination:The major steps are involved in the experiment. They are

(1)Preparation of reagents.(2)Calibration of instruments.(3)Testing of samples.

PREPARATION OF REAGENTS:

1. Buffer solution of pH 4.0I. Take 100 ml standard measurement flask and place a funnel over it.

II. Using the forceps carefully transfer one buffer tablet of pH 4.0 to the funnel.

III. Add little amount of distilled water crush the tablet and dissolve it. IV. Make up the volume to 100 ml using distilled water.

2. Buffer solution of pH 7.0:I. Take 100 ml standard measurement flask and place a funnel over it.

II. Using the forceps carefully transfer one buffer tablet of pH 7.0 to the funnel.III. Add little amount of distilled water crush the tablet and dissolve it.IV. Make up the volume to 100 ml using distilled water.

3. Buffer solution of pH 9.2:I. Take 100 ml standard measurement flask and place a funnel over it.

II. Using the forceps carefully transfer one buffer tablet of pH 9.2to the funnel.III. Add little amount of distilled water crush the tablet and dissolve it.IV. Make up the volume to 100 ml using distilled water.

CALIBRATING THE INSTRUMENT:

Using the buffer solutions calibrate instrument.

Step-1:

1. In a 100 ml beaker take pH 9.2 buffer solution and place it in a magnetic stirrer, insert the Teflon coated stirring bar and stir well.

2. Now place the electrode in the beaker containing the stirred buffer and check for the reading in the pH meter.

3. If the instrument is not showing the pH value of 9.2, using the calibrating knob adjust the reading to 9.2

4. Take the electrode from the buffer, and wash it with distilled water and then wipe gently with soft tissue.

Step-2:

1. In a 100 ml beaker take pH 7 buffer solution and place it in a magnetic stirrer, insert the Teflon coated stirring bar and stir well.

2. Now place the electrode in the beaker containing the stirred buffer and check for the reading in the pH meter.

3. If the instrument is not showing the pH value of 7, using the calibrating knob adjust the reading to 7

4. Take the electrode from the buffer, and wash it with distilled water and then wipe gently with soft tissue.

Testing the sample:

I. In a clean dry 100 ml beaker take the water sample and place it in a magnetic stirrer bar and stir well.

II. Now place the electrode in the beaker containing the water sample and check for the reading in the pH meter. Wait until you get a stable reading.

III. The pH of the given water sample is 8.84IV. Take the electrode from the water sample, wash it with distilled water and then wipe

gently with soft tissue.(b)TDS and Suspended Solid estimation:

Total Suspended Solids (TSS) is solids in water that can be trapped by a filter. TSS can include a wide variety of materials such as slit, decaying plant and animal matter, industrial wastes and sewage.

Total Dissolved Solids (TDS) are solids in water that can pass through a filter. TDS is a measure of amount of material dissolved in water. This material can include carbonates, bicarbonates, chlorides, sulphates, phosphates, nitrates, calcium, magnesium, sodium, organic ions and other ions.

Total solids:

1. Take a clean dry glass beaker (which was kept at 103°C in an oven for 1 hour) of 150 ml capacity and put appropriate identification mark on it. Weigh the beaker and note the weight.

2. Pour 50 ml of the thoroughly mixed sample, measured by the measuring cylinder in the beaker.

3. Switch on the oven and allowed to reach 105°C. Check and regulate oven and furnace temperature frequently to maintain the desired temperature range.

4. Place it in the hot air oven and care should be taken to prevent splattering of sample during evaporation or boiling.

5. Dry the sample to get constant mass. Drying for long time usually 1-2 hour is done to eliminate necessity of checking for constant mass.

6. Cool the container in desiccators; desiccators are designed to provide an environment of standard dryness. This is maintained by the desiccant found inside. Don’t leave the lid off for prolonged time or the desiccant soon be exhausted. Keep desiccators cover greased with the appropriate type of lubricant in order to seal the desiccators and prevent moisture from entering the desiccators as the test glassware cools.

7. We should weigh the dish as soon as it has cooled to avoid absorption of moisture due to its hygroscopic nature. Samples need to be measured accurately, weighed carefully and dried and cooled completely.

8. Note the weight with residues as w2.

9. Find out the weight of solids in the beaker by subtracting the weight of the clean beaker determined by the following step. Calculation of Total Solids, TS (mg/l) = (mg of solids in the beaker X 1000) /volume of sample

Total Suspended Solids:

1. Same as above (step 1 of total solids).2. Take a 50 ml of sample and filter it through a double layered filter paper.3. Dry the filter paper and weigh it (w₂ )4. Then repeat the same procedure as in step (3) to (7) of the total solids determination and

determine the dissolved solids connects as follows:

Total Dissolved Solids:

1. Same as above (step 1 of total solids).2. Take 50 ml of sample and filter it through a double layered filter paper.3. Collect the filtrate in a beaker.4. Dry in hot air oven and cool it.5. Weigh the beaker.

Calculation of TDS (mg/l) = (mg of solids in the beaker X 1000)/ volume of sample.

Calculation of dissolved solids,TDS (mg/l) = ( TS – TSS )

RESULT:

DETERMINATION OF TOTAL FAT CONTENT IN BAKED AND DRIED PRODUCTS

AIM : To determine total fat content in baked and dried products using soxhlets apparatus.

DESCRIPTION: Lipids are a group of substances that in general are soluble in ether, chloroform & other organic solvents but are relatively insoluble in water. An accurate & precise quantitative analysis of lipids in fees is important not only for nutritional labeling, but also for determining whether the food meets the standards for identifying & uniformly for understanding the effects of fats and oils on the functional and nutritional properties of foods. The validity of the fat analysis of a food depends on many factors, including proper sampling & preservation of sample before the analysis.

Because of commercial regulations, it is important for food products to be able to report fat content in a serving size of a food item. The soxhelt procedure allows for the calculation of total lipid or fat content in the food sample.

PRINCIPLE: Crude fat content is determined by extracting the fat from the sample using a solvent. Then determining the weight of fat recovered. The sample is contained in a porous thimble that allows the solvent to completely cover the sample; the tumble is contained in an extraction apparatus that enables the solvent and the sample & allows it time to dissolve all of the fat contained in the sample. In order for the solvent to thoroughly penetrate the sample it is necessary for the sample to be as finely as comminuted as possible .

MATERIALS REQUIRED : Soxhlet apparatus Filter paper Petroleum ether

PROCEDURE 1: Pretreatment: Drying - Most samples should be pre dried to optimize the fat extraction .water in the sample can decrease the efficiency of solvent extraction, resulting in low fat recoveries. Conversely water soluble components in the sample such as urea, carbohydrates, salts & glycerol can be extracted, with fat yielding falsely high recoveries.

Samples are weighed into the extraction thimble and are typically dried at 102±2ºc for 1-2 hours.

PROCEDURE 2: Weigh 3gms of the sample & pack it in a filter paper. The sample is placed inside a soxhlet apparatus. The round bottom flask is filled to its three fourth with petroleum ether. The setup is fixed & the temperature is set to 50ºc. After the completion of extraction, the RBF with the solvent containing extracted

fat sample is placed in the hot air oven for evaporation. After the complete evaporation of the solvent the weight is taken. The quantity of fat collected from the sample can be calculated by subtracting the

RBF from the total weight taken.

RESULT:

DETERMINATION OF FREE FATTY ACID AND ACID VALUE OF GIVEN FOOD SAMPLE

AIM: To determine acid value of given oil/fat sample.

PRINCIPLE: The acid value is determined by directly titrating the oil/fat in an alcoholic medium against standard potassium hydroxide/sodium hydroxide solution.

MATERIALS REQUIRED : Samples Apparatus Reagents (A),(B),(C)

(A)ETHYL ALCOHOL: Ninety five percent (95%) alcohol or rectified spirit neutral to phenolphthalein indicator.

(B)PHENOLPHTHAEIN INDICATOR SOLUTION: Dissolve one gram of phenolphthalein in 100ml of ethyl alcohol.

(C)Standard aqueous potassium hydroxide or sodium hydroxide solution 0.1N or 0.5N, the solution should be colorless and stored in a brown glass bottle.

THEORY:

DEFINITION-ACID VALUE: The acid value is defined as the number of milligrams of potassium /sodium hydroxide required to neutralize the free fatty acids present in one gram of fat. It is a relative measure of rancidity as free fatty acids are normally formed during the decomposition of oil glycerides. The value is expressed as percent of fatty acids calculated as oleic acid.

ANALYTICAL IMPORTANCE: The value is a measure of the fatty acids which have been liberated by hydrolysis from the glycerides due to the action of moisture, temperature & lipolytic enzyme lipase.

PROCEDURE: Mix the oil or melted fat thoroughly before weighing, weigh accurately about 5 to 10g of cooled oil in a 250ml conical flask &add 50ml to 100ml freshly neutralized ethyl alcohol and about 1ml of phenolphthalein indicator solution. Boil the mixture for about 5 minutes and titrate against the alkali solution shaking vigorously. The weight of the oil/fat taken for estimation & the strength of alkali used for titration shall be such that the volume of alkali required for the titration, which does not exceed 10 ml.

RESULT:

DETERMINATION OF MOISTURE CONTENT OF FRUIT JUICES BY OVEN DRYING METHOD

AIM:

To determine the moisture content of foods using oven drying method

DESCRIPTION:

The moisture (or total solids) content of foods is important to food manufacturers for a variety of reasons. Moisture is an important factor in food quality, preservation, and resistance to deterioration. Determination of moisture content also is necessary to calculate the content of other food constituents on a uniform basis (i.e., dry weight basis). The dry matter that remains after moisture analysis is commonly referred to as total solids.

PROCEDURE:

Weigh accurately about 5 grams of sample in silica crucible.

Dry in Hot air oven at 100±2°C for 5 to 6 hours.

Cool in a dessicator and weigh. Dry again for 30 minutes, cool in dessicator again and

weigh.

Repeat the process of heating and cooling in a dessicator until the difference in two

successive weighings is less than 1 mg.

Record the lowest weight.

Carry out the determination in duplicate.

RESULT:

DETERMINATION OF TOTAL SOLIDS IN FRUIT JUICES USING REFRACTOMETER

AIM:

To determine the total solids in fruit juices, ketup, jam using refractometer.

MATERIALS REQUIRED:

1. Fruit juices

2. Hand refractometer

PRINCIPLE:

REFRACTIVE INDEX (RI)

When light passes from one medium to another, the speed at which the light travels will change depending on the parameters of the materials. This principle can be seen when looking at a straw in a glass or an oarsman on the river, as shown in the diagram. The ratio or change in the speed of light is called refractive index and instruments that measure this parameter are called refractometers. The refractive index of a liquid is related to its concentration and so a refractometer can display the concentration in suitable units, such as °Brix (% sugar).

REFRACTOMETER:

Refractometers are instruments to measure substances dissolved in water and certain oils. The refractometer works using the principle of light refraction through liquids. As light passes from air into a liquid it slows down. This phenomenon is what gives a "bent" look to objects that are partially submerged in water. To put it simply, the more dissolved solids water contains, the slower light travels through it, and the more pronounced the "bending" effect on light. Refractometer use this principle to determine the amount of dissolved solids in liquids by passing light through a sample and showing the refracted angle on a scale.

The scale most commonly used is referred to as the Brix scale. The Brix scale is defined as: the number of grams of pure cane sugar dissolved in 100 grams of pure water (grams sugar/100 grams H20). Other scales have been developed to measure salt, serum proteins (albumen) and urine specific gravity.

The Brix scale is the most widely used scale and is based on the relationship between pure sucrose in water concentration (weight %) and RI.  The Brix scale is more popular than RI itself.  Brix is used for testing 'liquid food' products.  Even when the food does not just contain sucrose in water, but other dissolved ingredients, the Brix scale is used as a measure of 'nutritional value'.  Thus soft drinks, juices, sauces, preserves etc. are assigned 'a Brix value' as part of the Quality Assurance for the product.  Indeed, in the juice and soft drink industries, the Brix value is arguably the most important parameter in quality control.

PROCEDURE :

Spread the sample on the measuring prism in a uniform manner. The illuminator flap with matted surface is then closed. The shadow boundary and graduation seen through the eye piece and the measure of

brix value is TAKEN. Look through the eye piece while pointing the prism in the direction of light. Focus and take the reading of where the base of the blue colour sits on the scale and

record the % percentage sugar (brix). If the reading is completely blue then it indicates that brix value lies below the

graduation scale prescribed in the refractometer. On the other hand if it is completely white it indicates that brix value lies above the graduation scale prescribed in the refractometer.

RESULT:

DETERMINATION OF ADDED SODIUM BENZOATE

IN FOOD

AIM:

To determine added sodium benzoate in food sample.

REAGENTS REQUIRED:

1. Ethanol

2.Chloroform

3.Phenolphthalein

4.HCl

PRINCIPLE:

Sodium benzoate is a common type of food preservative made by synthesizing NaOH and Benzoic acid. Sodium benzoate preserves food by having anti fungal properties. It works by entering the individual cells in the food and balancing it's pH value, increasing the overall acidity in food. By lowering the intracellular pH of certain foods, Sodium benzoate creates an environment in which fungi and other microbes cannot grow.

Hence, sodium benzoate is heavily used by soft drinks industry and in acidic foods.

PROCEDURE:

Weigh 10 g of sample and add 10 ml of 10% and 12 g NaCl. Add sufficient water to bring volume upto 50 ml and let it stand for 30 mins with

frequent shaking. Add drops of phenolphthalein and drops of HCl until the color change , then add

excess 3ml HCl Transfer into separating funnel. Add 25 ml of chloroform. Let it stand for 30 mins

with frequent shaking. Transfer 12.5 ml of chloroform ( lower layer) into conical flask and evaporate off

chloroform ion stream bath. Add 50 ml of 50% ethanol solution. Titrate with 0.05 M NaOH using phenolphthalein as indicator. Calculate amount of sodium benzoate using the below formula

RESULT:

DETERMINATION OF ALOCOHOLIC ACTIVITY OF BREAD

AIM:

To determine the alcoholic activity in bread sample.

PRINCIPLE:

The acidity figure is a measure of freshness of flour and due to free fatty acids in it, the value increases upon storage. Free acids in the flour are extracted using neutral ethyl alcohol and titrated with standard alkali. The results are calculated in term of NaOH .

REGENTS:

Neutral alcohol 90 % (v/v) Std. NaOH sol. (0.05N) Ph.ph.sol. (1% in ethyl alcohol)

PROCEDURE:

5 gm of sample in 250 ml conical flask. Add 50 ml of 40 % neutral alcohol previously neutralized against phenolphthalein.

Shake well and allow to stand for 24 hrs. Filter the extract and filtrate combined extract against 0.05 NaOH sol. Using ph. Ph as

indicator.

RESULT:

DETECTION OF ADULTERANTS IN DIFFERENT FOOD SAMPLES

AIM:

To detect various adulterants present in food samples.

MATERIALS REQUIRED:

Spices(Black pepper, chilli powder, asafoetida), green peas, honey ,beverages(tea,coffee) , fats and oils(coconut oil, edible oil, ghee) ,milk.

PROCEDURE:

Name of Food

0Adulterant Simple Method for detection of Common Adulterants

Milk Formalin Take 10 ml of milk in a tests tube and add 5 ml of con sulphuric acid from the sides of the wall without shaking. If a violet or blue ring appears at the intersection of two layers then it shows presence of formalin.

Ghee Vanaspathy Take about one tea spoon full of melted sample of Ghee with equal quantity of concentrated Hydrochloric acid in a stoppered test tube and add to it a pinch of sugar. Shake for one minute and let it for five minutes. Appearance of crimson color in lower (acid) of Vanaspati or Margarine.

Coconut oil

Any other oil Place a small bottle of oil in refrigerator. Coconut oil solidifies leaving the adulterant as a Separate layer.

Edible oil Mineral oil Take 25 ml of Alcoholic KOH in conical flask, add 1ml of oil sample to be tested, Boil on water bath, and Carefully add 25ml of boiling distilled water along the sides of test tube with slight shaking. Turbidity indicates the presence of mineral oil.

Black pepper

Papaya seeds Papaya seeds float in ethyl alcohol along with immature seeds whereas mature seeds of black pepper sinks. Float the sample in ethyl alcohol, separate all the floaters and examine:Cut the seed into two halves and put a drop of iodine solution. The pepper seed gives blue color due to presence of starch while papaya seeds gives pale blue color due to presence of dextrin.

Chilies powder

Water soluble color

Water soluble artificial color can be detected by sprinkling a small quantity of chilies or turmeric powder on the surface of water contained in a glass tumbler. The water soluble color will immediately start descending in color streaks

Asafoetida (Hing)

Starch Add tincture of iodine, appearance of blue colour shows the presence of starch.

Green peas Artificially coloured

Take a little amount of green peas in a 250 ml beaker add water to it and mix well. Let it stand for half an hour. Clear separation of colour in water indicates adulteration.

Tea Used tea Tea leaves sprinkled on wet filter paper. Pink or red spots on paper show colour

Coffee Chicory Gently sprinkle the coffee powder on surface of water in a glass. The coffee floats over the water but chicory begins to sink down within few seconds. Also the falling chicory powder particles leave behind them a trail of colour, due to large

RESULT:

DETERMINATION OF ALCOHOLIC ACIDITY OF WHEAT FLOUR

AIM:

To determine the freshness of wheat flour by estimating the alcolic acidity.

PRINCIPLE:

The acidity figure is a measure of freshness of flour and due to free fatty acid in it, the value increases upon storage. Free fatty acids in the standard alkali. The results are calculated in terms of sulphuric acid or oleic acid.

PROCEDURE:

Weigh 5gm of sample in conical stoppered flask and add 50ml of neutral ethyl alcohol. Stopper shake and keep the flask for 24 hours with occasional shaking. Filter the extract through dry filter paper. Titrate the combined alcoholic-extract with .05 NaOH using phenopthalein as indicator. Calculate alcoholic acidity as sulphuric acid using the relationship.

RESULT:

DETERMINATION OF GLUTEN CONTENT IN WHEAT FLOUR

AIM:

To determine the percentage of gluten in wheat flour.

PRINCIPLE:

Gluten is obtained by kneading and washing the flour dough several times with water, crude gluten is obtained which contains albumin, globulin, glutonin, gliadin and protose.

PROCEDURE:

Weigh 25 grams of wheat flour in a dish. Add 15ml of water and make it into a dough. Keep the dough gently in a beaker filled with water for one hour. Remove the dough gently and place in a piece of muslin cloth and wash it with a gentle

steam of tap water till it is free of starch. Transfer the residue using spatula to a tared silica dish and weigh it. Spread the residue of gluten in thin layer. Place the dish in hot air oven at 100 degree celcius for 2 hours. Cool in a desicator, weigh and calculate percentage of gluten (dry basis). Percentage weight of gluten = 10000(M2-M1)/M(100-M3)

Where M2= weight of residue + dish

M1= weight of empty dish

M = weight of material taken

M3= percentage of moisture in sample

RESULT:

DETERMINATION OF BLEACH VALUE OF DIFFERENT FLOUR SAMPLES (petrol number)

AIM:

To determine the bleach value of different flour samples.

PRINCIPLE:

It is a measure of the degree of bleaching of flour. The creaminess of the flour gets reduced due to the use of bleaching agents. The flour is extracted with petroleum benzene. The optical density of the extract is measured. The OD of yellowish color is due to the unbleached or un-oxidized xanthophylls pigments present.

PROCEDURE:

1. Weigh accurately about 10g of four. Transfer to a reagent bottle.2. Add 100g of petroleum benzene, stopper the bottle and shake well for 3-4 hours.3. Filter the solution. Measure the OD of the solution at 425 nm and 660 nm.(difference

between the two is a measure of bleach value).4. Unbleached flour has value of 0.2 and if heavily bleached then it falls below 0.1. the

value decrease with an increase in the degree of bleaching.

RESULT:

DETERMINATION OF MONO SODIUM GLUTAMATE (Flavor enhancer) in foods.

AIM:

To detect the presence of Mono Sodium Glutamate (MSG) in the given food sample.

PRINCIPLE:

MSG is separated by paper chromatography and this spot is colorless. Since it is a salt of amino acid ninhydrin is used as the detecting reagent as it is specific to the free amino acid group. Color developed on heating for few minutes. Since the rate of ninhydrin color reaction is affected by humidity and temperature. On the whole, this aid in the detection of MSG to the development of purple spots.

MATERIALS REQUIRED:

Beaker 250ml, watch glass, chromatography paper no-1,n- butanol, acetic acid and ninhydrin.

PROCEDURE:

Prepare 1% solution of the given sample with water. Spot it on a whatmann chromatography no-1 paper along with MSG standard.

Develop in the mobile phase containing n-butanol : acetic acid : water(12:3:5) . remove the paper and air dry it.

Spray it with 0.2% ninhydrin in acetone. Heat the paper in the oven for 2 minutes. A bluish purple spot corresponding to the

standard spot shows the presence of MSG. Natural glutamates do not give spot under such low concentration.

SAMPLES USED:

1. Knorr taste maker2. Aginomoto

3. Chings4. Dominos taste maker

RESULT:

ESTIMATION OF IODINE CONTENT IN SALT

AIM:

To estimate the iodine content present in the given sample of iodised salt.

PRINCIPLE:

The potassium iodate liberate iodine from potassium iodide which is titrated against standard sodium thio sulphate.

REAGENTS:

Iodine flask – 250ml

Burette

Potassium iodide solution (15%)

Sulphuric acid 2N

Sodium thiosulphate (0.005 N)

Starch indicator (1%)

PROCEDURE:

Take 10g of the given sample of iodised salt in an iodine flask, add 50ml of distilled water and dissolve the salt completely.

Add 10ml of 15% potassium iodide and 2ml of 2N sulphuric acid. Immediately insert the stopper moistened with potassium iodide solution . Mix by gentle

rotation and keep the flask in dark for 15 min. Carry out a blank simultaneously exactly similar way but without the sample. At the end of the specified time rinse the stopper with water and titrate the liberated

iodine with 0.005N sodium thio sulphate with continuous swirling until a faint straw color remains.

Add 1ml of 1% starch solution and resume titration until the blue color just discharges.

Titrate the blank also similarly. At the end of the titration rigorous shaking is essential for precise.

RESULT:

DETECTION OF SULPHITES IN FOOD SAMPLE

AIM:

To detect the presence of sulphites in the given food sample.

PRINCIPLE:

Sulphur dioxide is a widely accepted preservative for many food products such as beverages, squashes, grape resins, dehydrated food products , caramel ,etc.

PROCEDURE:

Add small amount of sulphur free zinc in a beaker. Weigh 10gms of food sample and add 10ml of water and dilute it to the ratio 1:1. Then take 10ml from the diluted sample and add it to the beaker which contains the zinc. Add 20 ml of dilute Hcl(1:3) ratio to the sample. Shake well and dip the lead acetate paper. The H2S generated turns exposed portion of lead acetate paper black.

RESULT:

ESTIMATION OF VITAMIN C IN FRUIT JUICES

AIM:

To estimate vitamin C content in the given sample of fruit juices.

THEORY:

Ascorbic acid is a water soluble vitamin. Vitamin C is easily oxidized, majority of its function in vivo only on this property. It plays a key role in the body’s synthesis of collagen or norepinephrine by keeping the enzymes responsible for these processes in their active reduced form. Vitamin C may also play a role in the detoxifying by products of respiration. Ocassionally during respiration oxygen is incompletely reduced to superoxide ion instead of being reduced completely to its -2 oxidation state. Normally an enzyme called superoxide dismutase converts o2- to h2o2 and o2, but in the presence of fe2+ the hydrogen peroxide may be converted into the highly reactive hydroxyl radical(oH). The hydroxyl radical can initiate unwanted and deterious chemistry within a cell when it removes a hydrogen atom(H) from potential move reactive free radical. Ascorbic acid can denote a hydrogen atom to a free radical and thus stop these reactions from occurring.

The human body cannot produce ascorbic acid and so it must be obtained entirely through one’s diet. A vitamin C deficiency in human results in the disease called scurvy, whose symptoms include hemorrhaging(in gums), joint and exhaustion. In its final stages, scurvy is characterized by a profound exhaustion diarrhea, pulmonary and kidney failure which results in death. A very small daily intake of vitamin C(10-15 mg/day) is required to avoid deficiency and steve off slurry.

The federal Food and Drug Administration has adopted a recommended dietary allowance (RDA) of 60mg/day for adults, less for children and more for pregnant and lactating women.

Fruits ,vegetables and organ meats are generally the best source of ascorbic acid, muscle meats and most seeds do not contain significant amounts of ascorbic acid in plants varies depending on such factors as the variety, weather and maturity. But the most significant determinant of vitamin C content in foods is how the food is stored and prepared since vitamin C is easily oxidized, storage and the cooking in air leads to the eventual oxidation of vitamin C

by oxygen in the atmosphere. In addition, ascorbic acids water solubility means that a significant amount of vitamin C present in a food can be lost by boiling it and then discarding the cooking water.

PRINCIPLE:

The amount of vit C in a sample until be determined by redox titration using the reaction between ascorbic acid and 2,6-dichlororoindophenol(DCIP).DCIP is used as the titrant because it should

1.Only oxidize ascorbic acid and no other substances that might be present

2.Because it will act as a self indicator in the titration. To be a self indicator a substance must be one color in the presence of excess analyte has all reacted.

In acidic solutions DCIP is red, but if ascorbic acid is present, it will be reduced to a colorless substance. The solution will remain colorless as more DCIP is added until all of the ascorbic acid has reacted. As soon as the next drop off DCIP solution is added at the solution will be light red, due to the excess DCIP and the end point of the titration has been reacted.

LIMITATIONS:

Presence of particles ( as in fruit juices) can interfere with your ability to see the end point and so cloudy juices will need to be filtered first. Second, when analyzing solid substances you will need to dissolve the vitC before you can perform the titration. This may require blending or crushing the material and it may also require the addition of known amount of water to the material. And finally, red materials cannot be analyzed by this method because it is impossible to see the end point.

REAGENTS:

1.4% Oxalic acid

2.Dye solution:

42 mg of sodium bicarbonate into 10 ml of distilled water. Dissolve 52 mg of 2,6 dicholoriphenol indophenol and make upto 100 ml with distilled water

3.Stock solution:

100 mg ascorbic acid in 100 ml of 4% Oxalic acid solution in std flask(1 mg/ml)

4.Working standard:

Dilute 1ml of stock solution to 100 ml with 4% Oxalic acid . Concentration of this solution is 100µg/ml.

PROCEDURE:

Pipette 5 ml of working standard into 100 ml flask. Add 10 ml of 4% Oxalic acid and Titrate against dye(V1).End point is appearance of pink

color which persists for few minutes. The amount of dye consumed is equivalent to the amount of ascorbic acid

Extract the sample in 4% Oxalic acid and make up to a known volume (100 ml)with Oxalic acid and centrifuge (2000 rpm for 5 min)

Pipette out 5 ml of this supernatant and add 10 ml of 4% Oxalic acid and Titrate against dye (V2).

RESULT:

DETERMINATION OF MELTING POINT OF VANASPATHI

AIM:

To determine the melting point of vanaspathi .

PRINCIPLE:

Melting point is the temperature at which a solid becomes a liquid at standard atmospheric pressure; at this point, solid and its liquid are in equilibrium at certain pressure.

Melting point is one of the physical properties of a compound by which it is identified. This property is intrinsic to a compound when it is pure. A pure crystalline compound has a sharp melting point. When a sample melts at a lower than expected temperature over an extended range. This indicates that the sample is impure. Therefore, melting point of a compound can give the indication of compound’s purity and for identification.

PROCEDURE:

Determination of melting temperature:

1. To load a sample into a capillary of melting point must be dry, powdered form, homogenous until it gives the accurate result in the determination of melting point.

2. Set the melting temperature to the lowest range.

k3. Load the sample into the capillary tube without touching the sides of the tube. (height of sample = 2mm )

4. Switch ON for the heating block of the melting point apparatus.

5. Insert the capillary tube into slot of the heating block.

6. Look through the eyepiece to show the melting of solid sample.

7. Note down the temperature at which the sample gets completely melts.

RESULT:

EXTRACTION AND IDENTIFICATION OF ADDED COLOR FROM CANDIES

AIM:

To separate and identify the added color from candies.

PRINCIPLE:

Paper chromatography is a method of separation to see what dye is added to colored product. Artificial food colors are added to products in order to enhance their visual appeal. Here, the colored material to be identified is dissolved in a solvent and then spotted on a paper and eluted. Due to different solubilities of the colored chemicals in the solvent and due to different strength of molecular adhesion to the paper, some colors move more than others up the paper, thereby resulting in the separation of the different colored molecules. And this effectiveness of the separation depends on how soluble the chemical is in the solvent and how strongly the chemical is attracted to the paper. Each solute dye is distributed between the paper and the solvent and there is constant movement of molecules between the two phases. However, if one dye is more strongly held by the paper, it progress up the paper by dissolving in the solvent is slowed down, hence the separation of the colors. The final result is the vertical separation of the spots up the paper which is then referred to as the chromatogram.

APPARATUS REQUIRED:

10ml graduated cylinder , 3-4 small evaporating dish, 100 ml graduated cylinder, 400 or 600 ml beaker, 20 or 50 ml beaker, glass stirring rod, ruler, wool yarn, chromatography paper (whatmann no.1 or equivalent), 10cm x 20cm capillary tubes , watch glass to cover beaker.

REAGENTS REQUIRED :

Food color standard solutions: 0.1% solutions of current, F D & C colors ( currently , the approved colors are Red #3 (Erythrosine), Red #4(Carmine), Red #18 (Ponceau 4R), Blue #1 (Brilliant blue), Yellow #6 (Sunset yellow), 5% acetic acid solution – HC2H3O2, ammonia – NH3.

PROCEDURE:

a. Extraction of synthetic colors from food :

1. Use 3 or 4 colors of candy coated gum (gems), juice (maaza), jam (kissan).2. Place 4-6 pieces of candy, all the same color and the same brand, and a small

proportion of juice and jam into a small crucible. Add enough acetic acid to cover the candy.

3. Place the small crucible in the water bath and heat it until the colored coating has just dissolved.

4. Remove the small crucible from the water bath and carefully pour the colored liquid into a second, clean crucible leaving the solid candy pieces behind. In case of juice and jam, leave it as such. This solution contains the food dyes, some sugar, some emulsifier and the acetic acid.

5. Measure 15cm of wool yarn and add it to the small crucible with the dye solution. Add an additional 3ml of vinegar to the small crucible.

6. Place the small crucible into the water bath and heat the solution for about 5mins, stirring occasionally.

7. After heating, remove the yarn from the small crucible. Rinse it with a little deionized water. The yarn should be colored from the dye.

8. Place the yarn into a clean small crucible and add 1ml of concentrated ammonia solution. Use the stirring rod to make sure the yarn is submerged in the ammonia. If necessary, add up to an additional 1ml of ammonia solution. Heat the small crucible in the water bath for about 5 mins, stirring occasionally.

9. In this stage, the color moves from the wool to the solution.

10.Remove the small crucible from the water bath and allow it to cool. Save this for part B of the experiment.

b. Chromatographic separation of the unknown color mixtures:

1. Obtain a sheet of chromatography paper. Draw a light pencil line across the paper about 1 cm from the bottom of the sheet.

2. Using a capillary tube, apply a small spot on the unknown color mixture (obtained in part A of the experiment) on the pencil line near the center of the paper. ( the color spot should not exceed 0.4 cm in diameter.)

3. Mark the paper, in pencil at the top, above the spot with an X to signify the unknown color mixture. If the spot seems to be too small or too light in color , you can make it darker by applying a second spot of color directly on top of the dry first spot. (It is necessary to allow the spot to dry between applications of color in order to keep it small in size. )

4. Spot the paper with each of the available F D & C colors allowing about 2 cm minimum between 2 different spot. Using a pencil note the identity of each color in the paper below each spot. Add N-butanol, water, glacial acetic acid 20:12:5 solution to a clean 600 ml beaker to a depth of about 0.5 cm.

5. Bend the spotted chromatography paper and place the chromatography paper into the beaker making sure that the spots of the dye are not below the solvent level and the paper is not touching the sides of the beaker and cover the beaker.

6. Measure and record the average distance from the origin to the solvent front. Measure and record the distance each spot moved from the origin.

7. Determine the RF values for the components in the unknown mixture and for each of the F D & C colors that you used. The RF values for the components in the unknown mixture will be the same for the same component in the F D & C known colors. By matching both the color and the RF value of each of the spots, you can determine the identity of the colors you extracted from the food.

RESULT:

The RF value is calculated as

distance travelled by the sample / distance travelled by solvent

Thus, the artificial colors added to the samples were identified using paper chromatography and the results are tabulated as follows

ESTIMATION OF PEROXIDE VALUE

AIM:

To determine the peroxide value of the extracted oil from potato chips.

PRINCIPLE:

Peroxide value is defined as the multi equivalent of peroxide per kilogram of fat. It is a measure of the formation of peroxide or hydro peroxide groups that are initial products of liquid oxidation. The fat or oil in acetic acid chloroform medium is treated with an aqueous solution of potassium iodide. The liberated iodine is titrated with sodium thiosulphate solution.

REAGENTS:

1.) STARCH SOLUTIONTitrate 5g of starch and 0.01g of mercury iodine with 3 ml of cold water and slowly pour it with 30 ml of cold water and slowly pour it with stirring into 100ml of boiling water, boil for 3 mins, allow cooling and decanting off the supernatant clear liquid.

2.) STANDARD SODIUM THIOSULPAHTE SOLUTION(0.1N)Dissolve approximately 24gm of sodium thiosulfate crystals in distilled water which has been well boiled to free from CO2, make up to 1 litre. Store the solution in air cool place in a dark cooled bottle.

3.) STANDARDIZATION OF SODIUM THIOSULPHATE SOLUTIONWeigh accurately about 5g of finely ground potassium dichromate which has been previously dried to constant weight at 100 into a clean 1 litre volumetric flask, shake thoroughly and store in cool dark place. Pipette out 25ml of this solution into a clean glass stoppered 250ml conical flask or bottle, add 5ml of concentrated HCL and 15 ml of 10% potassium iodide solution. Allow to stand in the dark for 3 mins, titrate the mixture with sodium thiosulfate solution using starch as an indicator towards the end. End point is taken when the blue color changes to green. Calculate normality of sodium thiosulphate. N (sodium thiosulphate)W is weight of potassium dichromateV is the volume of sodium thiosulphate solution

ROOH + K+I- H+, HEAT ROH + K+OH- +I2

PROCEDURE:

Weigh accurately 5g of fat or oil in a 250ml glass stoppered conical flask. Add 30ml of glacial acetic acid. Chloroform mixture (3:2v/v) id dissolved. Add 0.5ml of standard potassium iodide, allow to stand for 1 min with occasional shaking wash the stopper and add 30ml of distilled water. Mix well by stirring. Titrate the content with standard sodium thiosulphate solution with constant and vigorous shaking until the yellow color disappears. Add 0.5ml of 1% starch solution. Mix well & continue titration till the blue color just appears.

If the value of oil/fat is less than 0.5ml, repeat the determination using 0.01N sodium thiosulfate solution. Conduct a blank determination of reagent in same way. The titrate value should not exceed 0.1ml.

RESULT: