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Fats and PRACTICAL 4 AND OILS

Structure 4.1 Introduction 4.2 Fats and Oils 4.3 Analytical Tests for Fats and Oils 4.4 Assessment of the Quality of Edible Oils/Fats 4.4.1 Moisture Content 4.4.2 Colour 4.4.3 Impurities 4.4.4 Acid Value and Free Fatty Acids 4.4.5 Peroxide Test 4.4.6 Purity Tests Activity 1: Determination of Moisture Content Activity 2: Determination of Impurities Activity 3: Determination of Acid Value and Free Fatty Acids Activity 4: Determination of Peroxide Value Activity 5: Purity Tests of Oils/Fats

4.1 INTRODUCTION

We have already studied about the structure, properties and functional role of fats and oils in the theory Course (MFN-008) in Unit 3. We suggest you look up the unit once again before you start with this practical on fats and oils which focuses on determination and assessment of the quality of fats and oils.

Objectives After undertaking this practical and the activities given herewith, you will be able to: • determine the nature of or or the blends to see whether it is of the type required or specified, and • assess the quality of fat in terms of moisture content, colour, impurities, acid value, purity.

4.2 FATS AND OILS

Oils and fats form an integral part of the dietaries the world over. In the body they are the primary source of energy. As you know, chemically they are complex mixtures of esters of fatty acids and glycerol. Fat in the liquid state is known as oil. There are various types of fatty acids present, which may be saturated or unsaturated in nature. Hence, the composition of different fats/oils depends upon the types of fatty acids present namely, stearic, oleic, palmitic, recinolic etc. Table 4.1 gives you composition of some edible fats and oils. Different forms of oils or fats are available namely, crude oil, refined oil, , hydrogenated fats, , , and . You will note that acidity in oils/fats is frequently expressed as the percentage of free fatty acids present in the sample. The percentage of free fatty acid in most of the oils and fats is calculated on the basis of , although in and it is often calculated in terms of lauric acid, in in terms of ricinoleic acid and in in terms of . However, the overall composition of fatty acids in a given sample of oil/fat is conducted through GLC (Gas Liquid Chromatography technique).

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Principles of Food Table 4.1 Science

The type of oil/fat also depends upon the source of extraction.

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Fats and Oils Animal sources provide us with fish oils and fats, milk fat, lard, fat and . Nut oils and fats, oils and bran oils are obtained from the plant sources. The crude oil is obtained from plant and nuts by expelling or extraction with , whereas, fats from the animal tissue is obtained by the process of rendering. These crude oils/fats contain suspended impurities, moisture and higher percentage of free fatty acids.

The production of edible oils usually involves the process of alkali refining, bleaching and deodorization of the crude oils. These processes are designed to remove suspended impurities and the substances which are responsible for colour, unpleasant flavour and those substances which either act as catalysts or are associated with rancidity.

Hydrogenation involves the catalytic addition of hydrogen to highly unsaturated liquid oils thereby converting them to solid fats. These oils are not susceptible to the process of hydrolytic rancidity.

We have just recapitulated the basic concept of fats and oils, which you may recall studying in Unit 3 in the theory booklet. With this basic understanding, we move on to the study of the analytical tests in fats and oils.

4.3 ANALYTICAL TESTS FOR FATS AND OILS

The analytical tests used in fats and oils are to: • determine the nature of fat or oil or the blends to see whether it is of the type required or specified, and • assess the quality of fat. Many tests are involved to evaluate these two factors involving the physical analysis and chemical analysis. However, due to the complexities and time constraints, only a few tests are being discussed in this unit. Only the tests to determine the quality of fats/oils are being undertaken. Let us first of all become familiar with the quality parameter requirements for fats/oils. It may be necessary to assess the quality of either "crude" oils or "refined and deodorised" oils. For the former (crude oils), the specified criteria are usually moisture, impurities, colour and free fatty acid contents and tests for adulteration are used while for the latter (refined/deodorized oils), flavour, FFA content, moisture, colour, rancidity, adulteration and stability to are the minimum requirements for reliable judgment. In this practical we will be conducting the important tests for purity.

The physiochemical characteristics of the fats/oils have been covered under paragraph A.10 of Appendix B of PFA Rules. Some of the specifications laid down by PFA/AGMARK for vanaspati and are listed in Table 4.2

Table 4.2: Specifications laid down by PFA/AGMARK for vanaspati and mustard oil Parameters Mustard oil specifications Vanaspati oil specification Moisture content % max 0.25 0.25 Colour by lovibond tintometer in 50 -- 1/4" cell expressed as Y+5R (max) Refractive index at 40 DC 1.4646-1.4662 --- 168-177 -- value 96-112 ---

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Principles of Food Free fatty Acid %max --- 0.25 Science Unsaponifiable matter %max 1.20 2.0 Baudauin test Negative Positive Colour produced by baudauin test ---- 2.0 red (min) BR reading at 40 DC 58-60.5 -- Rancidity test Negative Negative Suspended and foreign matter Nil Nil Test for oil Negative Negative Taste and flavour Characteristic Characteristic Test for Argemone oil Negative Negative Test for Hydrocyanic acid Negative Negative Polybromide test Negative Negative Source: Prevention of Food Adulteration Act, 1954

After learning about the specifications for oils lay down by PFA, let us get to know about the procedures for conducting these tests. We will not be covering the tests for determining the nature of oils/fats like , unsaponifiable matter, since you will be covering these in the Nutritional Biochemistry Practical. The tests, which are required for quality assessment, would be covered here in the subsequent section and in the experiments included herewith.

4.4 ASSESSMENT OF THE QUALITY OF EDIBLE OILS/FATS

Various parameters are used for the assessment of the quality of fats and oils. Some of the important ones include determination of moisture content, colour, impurities, acid value, peroxide value and tests for the presence of adulterants in fats and oils. Let us review these parameters one by one, starting with the moisture content.

4.4.1 Moisture Content

Moisture content of the fats/oils is an important parameter and does not remain the same throughout the period of storage. More the moisture content, more prone is the fat to the process of hydrolytic rancidity. In this process, the reacts with water and for each molecule of water involved, one molecule of fatty acid is released. When a molecule of fat reacts with three molecules of water, glycerol and three fatty acids are formed as shown in Figure 4.1

Figure 4.1: Triglyceride reacts with water to give glycerol and fatty acids

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Thus, it is very important to control the moisture content in the oils/fats which Fats and Oils otherwise would lead to the development of off flavours.

4.4.2 Colour

The colour of the oil is of considerable importance commercially and is an agreed standard of comparison. The colours of oils are usually declared in Lovibond units, and may be measured in an instrument designed for the same.

The instrument includes a standard light source, glass ended cells of accurate length and the series of coloured glasses of yellow, red and colour. The colour of the oil is matched by a suitable combination of them. For an accurate analysis, it is important to keep the following points in mind: • Number of matching glasses should be kept to a minimum. • The oil must be clear and bright, filtration should be done if required. • The oil should not be heated to an extent so that it affects the colour of the oil. The dimensions of the cell used and the mode of expressing the colour readings for different oils as given by BIS in SP:18 (Part XIII) -1984 shall be as indicated in Table 4.3.

Table 4.3: Colour reading for different oils as given by Bureau of Indian Standards

Oil/Fat Size-Designation of Mode of expressing colour reading cell (in) Castor 1 Y+5R Groundnut 1 Y+5R Coconut 1 Y+5R Sesame 1/4 Y+5R Mustard 1/4 Y+5R Mahua 1/4 Y+5R Cottonseed (washed 1/4 Y+10R and refined) 4.4.3 Impurities

The impurities or total dirt in an oil/fat consist of the sum of all mineral matter present together with the organic constituents, exclusive of water and volatile matter, which are not dissolved by a specified applied under specified conditions. The total impurities can be separately estimated for total dirt and organic dirt.

4.4.4 Acid Value and Free Fatty Acids (FFA)

Acid value is a measure of hydrolytic rancidity present in the sample of oil/fat. It reflects the state of freshness or deterioration of the material and also the quantity of glycerols to be released as a result of neutralization of fat/oil. It has a wide implication in the oil refining industry as it gives the fair idea of the state of oil/fat and also the total quantity of alkali required to neutralize a particular batch of oil or fat to make it suitable for the purpose of hydrogenation. Acidity also helps in predicting the quantity of oil or fat, which will pass into soap stock as a compulsive by-product of the refining process.

High acidity oils or fats produce excess smoke during heating. Moisture content, temperature of heating, duration of heating, type of metal container are parameters which act as catalysts to the process of hydrolysis in fats or oils. Acidity is expressed as FFA% on oleic acid basis like in ghee. However, in certain oils and fats it is expressed on the basis of the fatty acids which are predominant. For example, castor oil which has 86-94% recinoleic acid, coconut oil having its fatty

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Principles of Food acid composition as lauric acid- 44-51%, palmitic acid 7-11%, capric 5-9% and palm Science oil which contains 35-50% palmitic acid. In India, we have the Agmark specifications, the PFA Act specifications, as well as, BIS specifications to denote acidity of fats and oils. 4.4.5 Peroxide Value Autoxidation leads to the development of off-flavours and objectionable taste in fats. The initial oxidation products that are formed are hydroperoxides and are measured by iodimetric methods. The peroxide value of the freshly deodorized fat should be nil and a fat received directly from a processor should seldom exceed a peroxide value of 1.0. Most fats are deemed rancid when their peroxide values are between 10 and 20. 4.4.6 Purity Tests Purity tests for oils/fats would include analyzing the samples for the presence of , , linseed oil, argemone oil, hydrocyanic acid, , mobile oil, groundnut oil, kusum oil or the presence of animal fats in vegetable oils. However, we will be covering only a few considering their feasibility in the laboratories. A) Test for the presence of sesame oil The development of pink colour with furfural solution in the presence of hydrochloric acid (HCl) indicates the presence of sesame oil. This test is also known as BAUDOUIN Test. Generally this test is also used to check adulteration in the sample of ghee. The test results should be positive for vanaspati and negative for all other samples of ghee, oils and fats. B) Test for the presence of linseed oil (HEXABROMIDE TEST) Hexabromide test is done to know the extent of presence of linolenic acid. In presence of fish oils, which are rich in linolenic acid, the test gives precipitates where as if other oils like oil are present, the test gives a clear solution. Animal fats may give turbidity when tested in this way. Thus, this test is carried out to test the presence of linolenic acids in the samples. C) Test for the presence of argemone oil This test helps to detect the presence of argemone oil. Argemone mexicana is the plant, which yields seeds of this oil. The seeds are very small similar to black mustard seeds but has striations and pointed end. Oil extracted from these seeds is toxic in nature and results in epidemic dropsy. These toxic substances are soluble in HCl and with Ferric Chloride (FeCl3) they are precipitated out. These precipitates contain needle-shaped crystals and can be observed microscopically. D) Test for hydrocyanic acid Hydrocyanic acid is present as an impurity in synthetic ethyl isothiocyanate, which is employed to make the flavour of mustard oil more pungent. The method is based on the reaction of hydrocyanic acid on the picric acid paper, which acquires a red colour in the presence of that acid.

After learning about the different tests for assessment of the quality of fats and oils, let us now apply this knowledge in assessing the quality of a given sample of fats and oils in experiments 1-5.

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Fats and Oils ACTIVITY 1 DETERMINATION OF MOISTURE CONTENT Aim: To determine the moisture content in the given sample of oil/fat. Date: …………. Objectives After undertaking this activity, you will be able to: • assess the moisture content in the given sample of oil/fat, and • check the given sample for conformance to the standard for moisture content. Principle Moisture is determined by drying the weighed test material in an air oven. The loss in weight due to evaporation is accepted as the moisture content. However, it has been observed that materials in the air oven method shall also entail loss of volatile and thermo-sensitive constituents, as well as, moisture. Also in case of oils, it is seen that highly unsaturated oils such as fish oils or linseed oil may oxidize under the test condition and an increase in weight rather than a weight loss may be recorded.

Lauric acids and other short chain fatty acids slowly volatilizes under the test condition as their chains are short. Spattering also produces errors as it leads to the loss of sample during drying.

Several methods such as Dean and Stark method, Karl Fisher method are available for estimating the moisture content of an oil. However, for our estimation in laboratories, using the basic infrastructure, we will be conducting the moisture content with the air oven method. Materials Required Sample of oil/fat Moisture dish-made of porcelain, silica, glass or aluminium Oven-electric, maintained at 105 ± 1°C. Desiccator Weighing balance Procedure Carry out the experiment following the procedure enumerated herewith:

1) Weigh accurately about 10 to 15 g of the sample in the moisture dish, previously dried in the oven and weighed. 2) Place the dish in the oven maintained at 105 ± 1°C for 1 hour. 3) Cool in the dessicator and weigh. 4) Repeat the process of drying, cooling and weighing at 30 minutes intervals until the difference between two consecutive weighings is less than one milligram. 5) Record the lowest weight. 6) Calculate the moisture content using the formula given herewith. Calculations 100(W1− W2) Moisture percent by weight = W1− W

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Principles of Food Science where, W1 = weight in g of the dish with the material before drying W2 = weight in g of the dish with the material after drying to constant weight, and W = weight in g of the empty dish. Precautions

1) The oven-dried sample should not be kept in open but in the dessicator before weighing. 2) The process of drying should be repeated till the difference in the weighings should be less than 1 mg. 3) The oven temperature should be regulated throughout the process of drying. Findings

Record your findings in the format given herewith:

W = ………………. g

W1 = ………………. g

W2 = ………………. g

Now calculate the moisture content using the formula given above.

Calculations

Moisture % by weight =

Inference The given sample of oil has ………………… % moisture by weight. The maximum limit for the moisture content according to PFA, is ………………. % by weight.

Conclusions (Comment on % moisture content of given sample with respect to PFA) …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………….

Submit the activity for evaluation.

………………………………. Counsellor Signature

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Fats and Oils

ACTIVITY 1 DETERMINATION OF IMPURITIES

Aim: To determine the impurities in the given sample of oil. Date: …………. Objectives After conducting this activity, you will be able to: • determine impurities such as total dirt and organic dirt in the given sample of oil, • differentiate between total dirt and organic dirt, and • check whether any given samples of oils/fats conforms to the standard. Principle As discussed in sub-section 4.4.3, total impurities can be regarded as total dirt and organic dirt. The materials required and the procedure for determination of total dirt and organic dirt is presented separately next.

A) For Determination of Total Dirt Materials Required Sample of Oil/fat Oven-electric, maintained at 100 ± 1°C. Dessicator Weighing balance Filter paper Procedure Carry out the experiment following the procedure enumerated herewith: 1) Take 30-50 g of oil or fat at a temperature below 60ºC. 2) Filter through a filter paper previously dried in the oven at 105ºC and weighed. 3) Extract the filter paper containing the impurities with light petroleum ether of grade (boiling pt. 40ºC – 60ºC). In this step, basically pour the ether onto the filter paper. 4) After complete extraction, dry the filter paper and its contents in the oven at 98º C-100ºC till a constant weight. 5) Calculate the percentage of total dirt as:

100(W2− W) Total dirt, percent by weight = g where, W2 = weight in g of the filter paper with dirt. W = weight in g of the filter paper g = weight in g of the oil/fat taken for analysis B) For Determination of Organic Dirt Materials Required Sample of oil/fat Oven – electric, maintained at 100 ± 1°C. Flat-bottom dish – of stainless steel, porcelain, silica or platinum Muffle Furnace maintained at 550 ± 10°C

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Principles of Food Desiccator Science Weighing balance Filter paper Whatman filter paper no. 42 or its equivalent

Procedure Carry out the experiment following the procedure enumerated herewith:

1) Take 30-50 g of oil or fat at a temperature below 60°C. 2) Filter through the whatman filter paper previously dried in the oven at 105°C. 3) Extract the filter paper containing the impurities with light petroleum ether. 4) After complete extraction, dry the filter paper and contents in the oven at 98°C-100°C. 5) Keep the filter paper in a tared/previously weighed dish. 6) Ignite in a muffle furnace at 550 ± 10°C for one hour. 7) Cool in the desiccator and weigh. 8) Heat the dish again at 550 ± 10°C for 30 minutes, cool in the dessicator and weigh. 9) Repeat this process of heating for 30 minutes, cooling and weighing until the difference between two successive weighing is less than one milligram. Record the lowest weight. 10) Calculate the total organic dirt using the formula given herewith.

Calculations 100(W2− W) Total organic dirt, percent by weight = g where, W2 = weight in g of the dish with filter paper with dirt W = weight in g of the empty dish g = weight in g of the oil/fat taken for analysis

Findings Record your findings in the format given herewith:

Total Dirt Organic dirt

W2 (weight in g of the dish with filter paper with dirt)

W (weight in g of the empty dish)

g (weight in g of the oil/fat taken for analysis)

Calculations

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Now using the formula given above calculate the following: Fats and Oils Total dirt, percent by weight =

Total organic dirt, percent by weight =

Inference

The total dirt percent, present in the given sample is…………………… .

Total organic dirt, percent by weight present in the given sample is ………………. .

Conclusions

(Comment on the total dirt and organic dirt % in the given sample with respect to the standard). …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. …………………………………………………………………………………………. ………………………………………………………………………………………….

Submit the activity for evaluation.

……………………………. Counsellor Signature

VITY 3 73

Principles of Food DETERMINATION OF ACID VALUE AND FREE FATTY Science ACIDS

Date: …………. Aim: To determine the acid value and free fatty acids in the given sample of oil/fat. Objectives This activity will help you to: • know the acidity in given sample of fat/oil, and • determine the free fatty acid composition in the sample provided for analysis. Principle The acid value is determined by directly titrating the material in an alcoholic medium with aqueous or hydroxide solution. Free fatty acid is calculated as oleic, lauric, ricinoleic or palmitic acids (refer to section 4.2 of this practical). The materials required and the procedure for the determination of acid value and free fatty acid is given herewith. A) For Acid Value Materials Required Sample of oil/fats namely any refined oil or hydrogenated fat. Reagents - ethyl alcohol (95%), phenolphthalein indicator solution, standard aqueous sodium or potassium hydroxide solution (0.1 N or 0.5 N) Pipette (10 ml) Conical flask

Procedure Carry out the experiment following the procedure given herewith:

1) Mix the oil or melted fat thoroughly before weighing. 2) Weigh accurately a suitable quantity of the cooled oil/fat in a 200 ml conical flask. 3) Add 50-100 ml of the freshly neutralized hot ethyl alcohol (i.e ethyl alcohol with pH 7). 4) Boil the mixture for about 5 minutes and titrate while as hot as possible with the standard aqueous alkali solution shaking the solution vigorously during titration. Continue the titration till the solution turns pink, which is the end point. 5) Calculate the acid value as per the formula given herewith.

56.1VN Acid value = W where, V = volume in ml of the standard solution used for titration N = normality of the standard solution used W = weight in g of the material taken for the test

B) Free Fatty Acids

The acidity is frequently expressed as the percentage of free fatty acids present in the sample.

Materials Required

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Materials required are the same as above. List down the materials you would require Fats and Oils here.

Procedure Procedure for carrying out the free fatty acids in the given sample is same as that for acid value determination. Write down the procedure as you conduct the experiment in the space given herewith.

Calculations

The calculations in terms of different fatty acids are as follows: Free fatty acids, in terms of 28.2 VN Oleic acid, percent by weight = W

Free fatty acids, in terms of 20.0 VN Lauric acid, percent by weight = W

Free fatty acids, in terms of 29.8 VN Ricinoleic acid, percent by weight = W

Free fatty acids, in terms of 25.6 VN palmitic acid, percent by weight = W where, V = volume in ml of the standard solution used for titration N = normality of the standard solution used W = weight in g of the material taken for the test Results and Observations Now record your findings for the acid value and the free fatty acid test in the format given herewith

S. No. Initial reading Final reading Difference

Pilot

1

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Principles of Food Science 2

3

Titre value = ……………(V)

Volume of standard solution used (V) = …………… ml

Weight of the oil taken for analysis = …………… g

Normality of standard NaOH|KOH used = ……………

Now write the formula and calculate the following:

a) Acid Value =

b) Free fatty acids, in terms of Oleic acid, percent by weight =

c) Free fatty acids, in terms of Lauric acid, percent by weight =

d) Free fatty acids, in terms of Ricinoleic acid, percent by weight =

e) Free fatty acids, in terms of Palmitic acid, percent by weight =

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Inference Fats and Oils Acid value, percent by weight calculated in the given sample of oil is………………..

Free fatty acid, percent by weight : As lauric acid ……………….

As palmitic acid…………….

As ricinoleic acid………….

As oleic acid…………….

Conclusion

(Comment on the acid value and free fatty acids of the given sample of oil/fat) ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… ………………………………………………………………………………………… …………………………………………………………………………………………

Submit the activity for evaluation.

……………………………… Counsellor Signature

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Principles of Food Science ACTIVITY

4 DETERMINATION OF PEROXIDE VALUE

Date: …………. Aim: To determine the peroxide value in the given sample of fat or oil. Objectives After undertaking this activity, you will be able to: • determine the peroxide value in a given sample of fats/oils, and • check whether any given samples of oils/fats conforms to the standard.

Principle The peroxide value is a measure of the peroxides contained in a sample of fat expressed as milli-equivalents of peroxide per 1000 grams of the material. The material in an acetic acid-chloroform medium, is treated with an aqueous solution of potassium iodide. The liberated iodine is titrated with the standard sodium thiosulphate solution. Materials Required Reagents Acetic acid-chloroform solution - Mix three parts by volume of glacial acetic acid with 2 parts by volume of chloroform Saturated potassium iodide solution Sodium thiosulphate solution- 0.1 N Starch solution (1%) Apparatus Pipette 1ml capacity Conical flask Procedure Carry out the experiment following the procedure given herewith: 1) Weigh approximately 5 g of the sample of fat in a 250 ml conical flask. 2) Add 30 ml of the acetic acid-chloroform solution. 3) Swirl flask until the sample is dissolved. 4) Add 0.5 ml of the saturated potassium iodide solution. 5) Allow the flask to stand exactly one minute with occasional shaking and then add 30 ml distilled water. 6) Titrate with 0.1 N sodium thiosulphate solution with constant and vigorous shaking. 7) Continue the titration until the yellow colour almost disappears. 8) Add 0.5 ml of the starch solution and continue the titration until the blue colour just disappears. 9) Conduct a blank determination of the process in the same manner as described in steps 2-8. Here, we start with acetic acid- chloroform solution only. No fat sample is added. 10) Calculate the peroxide value based on the formula given herewith: Calculations (S−×× B) N 1000 Peroxide value as milli-equivalents per 1000 g of sample = g where, 78

S = volume in ml of sodium thiosulphate solution used up by the sample. Fats and Oils B = volume in ml of the sodium thiosulphate used up in blank determination. N = normality of sodium thiosulphate solution. and g is the weight in gram of the sample.

Results and Observations Weight of the sample taken for the test = ………………….. Volume of acetic acid-chloroform solution added = ………………….. Addition of saturated KI solution = ………………….. Record your observations of the titration performed in the table given herewith.

Titre value Blank (B) Sample (S) 1. 2. 3. Final reading

S= ………………….. B= ………………….. N= ………………….. Weight of the sample = ………………….. Now calculate the peroxide value putting in the values you have written above. But first write the formulae.

Inference Peroxide value in the given sample is ………………….. The sample of oil/fat is …………… (conforming/non-conforming) to the specifications for peroxide value.

Conclusion (Comment on the peroxide value of the given sample with respect to specifications)

Submit the activity for evaluation.

………………………………. Counsellor Signature

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Principles of Food Science ACTIVITY 5 PURITY TESTS OF OILS/FATS

Date: …………. Aim: To detect the presence for sesame oil, linseed oil, argemone oil, mineral oil and hydrocyanic acid. Objectives After undertaking this activity, you will be able to: • discuss the various adulterants in oils/fats, and • qualitatively determine their presence in the given samples. Principle You are already aware of the principles involved in the detection of adulterants. Refer to sub-section 4.4.6. Write the principle involved for each oil in the space provided.

Sesame oil

Linseed oil

Argemone oil

Mineral oil

Hydrocyanic acid

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Materials Required Fats and Oils 1) One sample of oil (sample 1) and one sample of fat (sample 2) 2) Hydrochloric acid - fuming, relative density 1.19 3) Furfural solution - 2 % solution of furfural distilled not earlier than 24 hours. The reagent is stable up to 3 months if kept in the refrigerator 4) Chloroform 5) Liquid bromine 6) Rectified spirit 7) Ether

8) FeCl3 solution - 10% 9) Alcoholic caustic potash solution- 0.5 N 10) Picric acid paper – soak a filter paper (Whatman no. 1 or equivalent) in a saturated aqueous solution of picric acid, draining excess liquid and drying the dyed paper in air. The paper should be prepared freshly before use. 11) Tartaric acid solution - 10 % (m/v) 12) Sodium carbonate solution - 5% (m/v) Procedure Now, let us start with the procedure for the detection of the aforesaid adulterants in the given sample of oils/fats. Carry out the experiment following the procedure given herewith:

Sesame oil Linseed oil Argemone oil Mineral oil Hydrocyanic acid

1. Take 5 ml of 1. Take 1 ml of oil 1. Take 5 ml of oil 1. Take 0.1 ml of 1. Pour about 30 ml sample in a in a dry test tube. and heat it with oil in a wide of oil in a conical stoppered test tube. 5 ml conc. HCl on test tube and flask. 2. Add 5 ml of a water bath add 2.2 ml of 2. Add 5 ml HCl and chloroform. alcoholic 2. Add 15 ml of 0.4 ml furfural 3. Add 1 ml of 2. Add 5 ml of FeCl3 KOH. tartaric acid solution. bromine solution slowly. solution and mix. dropwise till the 2. Heat it on 3. Shake vigorously mixture is deep 3. Orange red boiling water 3. Stopper the flask red in colour. precipitates in the bath for 5 min with a cork from 4. Allow the mixture 4. Add 1.5 ml of acid layer indicates and add 25 ml which hangs the to separate. rectified spirit the presence of of hot distilled picric acid paper shaking the argemone oil. water and mix. wetted with a 5. Pink or red colour mixture till drop of sodium in the acid layer precipitate 4. For confirmation 3. The presence carbonate indicates the formed gets the precipitate of mineral oil solution. presence of dissolved. should be observed is indicated by sesame oil. microscopically for the immediate 4. Place the flask 5. Add 10 ml of the presence of turbidity in the on a hot water ether and place needle shaped solution. bath for 30-40 the tube in ice crystals. minutes. water bath for 30 minutes. 5. The picric acid 6. Appearance of paper acquires precipitate red colour in the indicates the presence of presence of hydrocyanic linseed oil. acid.

Now, as you have finished with the procedure let us again go through the confirmatory tests. (Fill in the blanks)

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Principles of Food Sesame oil - detection of …………… colour in the acid layer. However, if the colour Science disappears after a few seconds it is absent.

Linseed oil - appearance of …………… in the tube containing oil, chloroform, rectified spirit, liquid bromine and ether.

Argemone oil - presence of …………… ppt. on addition of FeCl3. The ppt. are having …………… crystals when observed microscopically.

Mineral oil - …………… in the solution of alcoholic KOH and oil indicates the presence of mineral oil.

Hydrocyanic acid- …………… coloured spot on the picric acid solution indicates the presence of hydrocyanic acid.

Observations Write the observations in the format given herewith.

Presence of adulterants Sample 1- observations Sample 2 - observations

Sesame oil

Linseed oil

Argemone oil

Mineral oil

Hydrocyanic acid

Inference

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The given samples of oil/fats contains the following adulterants. Fats and Oils

Conclusion (Comment on the quality of oil/fat according to the presence/absence of any adulterant). ………………………………………………………………………………………….. ………………………………………………………………………………………….. ………………………………………………………………………………………….. ………………………………………………………………………………………….. ………………………………………………………………………………………….. …………………………………………………………………………………………..

Submit the activity for evaluation.

…………………………… Counsellor Signature

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