Adulteration in food is normally present in its most crude form, prohibited substances are either added or partly or wholly substituted.  In India normally the contamination/adulteration in food is done either for financial gain or due to carelessness and lack in proper hygienic condition of processing, storing, transportation and marketing. This ultimately results that the consumer is either cheated or often become victim of diseases. Such types of adulteration are quite common in developing countries or backward countries. However, adequate precautions taken by the consumer at the time of purchase of such produce can make him alert to avoid procurement of such food. It is equally important for the consumer to know the common adulterants and their effect on health.

Food... the basic necessity of life.

We toil day and night for what? For that two morsel of wholesome nutritive food. And if at the end of the day we are not sure of what we eat, than what are we toiling for? We may be eating a dangerous dye, sawdust, soap stone, industrial starch, Aluminum foil and believe it, even horse-dung! Inviting disease rather than good health. And what are the law enforcing authorities doing? Looking the other way, ignoring, sitting on files and being bought and bribed.

Milk... that ever-enduring milk. For time immemorial it had had been the basic staple food right from our

growing up stage, to when we have grown up. As a child we need it for growth and as a grown up we need it for replenishing our nutrition daily. Tired and bogged down, need something to rejuvenate... take a glass of milk. But even this has not been spared.

Common adulterant, addition of water, flour, or any other starchy material say industrial starch. Addition of water and extraction of fat is very common and not harmful. But what when the milk you drink is not milk at all? Rather combination of urea, liquid detergent, a little sugar, vegetable oil and water... a Synthetic Milk! Remember the case in Delhi, where the racket was busted a few years back and there was a lot of hue and cry in the media regarding the same. Think of all those children who may have had the synthetic milk, what havoc it must have created for their system physically. And how are we sure that even now, we are not being supplied the same milk? Are the authorities doing any thing like random checking of milk and regular intervals?

Turmeric is the basic ingredient of all our Indian cooking. Any Indian dish is not complete without it. But before you buy your next quota of this "masala" be careful of what you are buying. It may be adulterated with, Lead chromate, (which adds color as well as weight to it, being heavier), Metanil Yellow dye Or any starch based items like flour or rice powder or even industrial starch. Except flour or rice powder, all the other adulterants are health hazardous and cause irreparable damage to our system when eaten at regular intervals for a long period of time. Take for instance Lead chromate, it is one of the most toxic salts of lead. It can cause anemia, paralyses, mental retardation and brain damage in children and

abortion in pregnant women. Metanil yellow dye which is another non-permissible toxic colorant, is used mostly to color Besan or gram flour, pulses, miscellaneous prepared foods namely sweetmeats like ladoo, burfi, jelabi, dalmoth, papad, etc. to get that attractive deep yellow color. Food grade colors are available in the market but being more costly, traders take advantage of the lackadaisical approach of the law enforcing authorities and substitute it with the said cheap and non-permissible dyes and colors.

While still on "Masalas" or spices, does one know what are the common adulterants, take for instance, for coriander powder or chili powder- sawdust, rice bran and sand. But wait! One cannot even imagine or fathom- horse-dung and cow-dung! This is not only unethical, from the business point of view, but a sin committed against the society at large. Any trader who is found resorting to such means of adulterations should be taken to task very strongly. People should try as far as possible to buy whole spices and grind them at home or purchase properly packed spices (with proper informative labeling) of standard F.P.O. I.S.I or AGMARK certified companies. 

Has anyone ever given a thought why the puffed rice or any other white colored eatable looks so dazzling white and bright, and attractive on the show windows of a sweetmeat shop? Well they may have been treated by ultra marine blue a chemical dye which is a non-permissible and prohibited. And for that rich deep pink color (Gulaabi) Rhodamin-B is used- again a non-permissible colorant. This colorant has also proven to be carcinogenic.

Argemone seeds that grow as weeds in the mustered fields are mixed with mustered seeds and its oil is mixed with mustered oil. Just a trace amount is all right, but when added deliberately it causes serious health hazards and even death. Dropsy is a straight after effect of consumption of this oil. It may also cause swelling, irregular fever, low pulse rate, enlargement of the liver, respiratory distress which may lead to heart failure. Adulteration of oil has become rampant, with a wide variety of oils available in the market, the consumer is not sure what combination of oils he gets when he buys it loose from the market. It is very harmful and hazardous to health when mixed with crude castor oil, industrial palmolein-oil, mineral oils etc. This is certainly a crime against humanity aimed at earning money at the cost of public health.

Ghee is adulterated to the extent of 80 to 85 percent with Vanaspati . In actuality it is Vanaspati flavored with 15 or 20 percent of ghee by special process. Even in the year 1935-36 when, six samples of so called pure ghee was collected it was found that they were adulterated with vegetable products made from groundnut, and other oils and the extent of adulteration was up to 80 percent. 

Sand, dirt, earth, gritty matter, soap stone, common salt are added to flour, refined flour (maida), gram flour (besan), spices, sugar, tea-dust and coffee. And washing soda is added to table salt. In tea-dust one can even finds iron filings. And remember that lovely silver leaves used to decorate sweetmeats, burfi, and pan, you may be surprised what it is. It may be aluminum leave or foil,

which is again very bad for health, causing a lot of physical complications.

Dried seeds of volatile oil are added to cloves, while mineral acids to vinegar, papaya seeds to black pepper. Aniseed or 'sauf' that after food tit-bit, is dyed with malachite green dye for that nice green color. In food grains and whole spices extraneous matter like stalks, stems, and foreign seeds are added.

Injurious Adulterants/Contaminants in Foods and their Health Effects

S.No

Adulterant Foods Commonly Involved

Diseases or Health Effects

Adulterants in food

1 Argemone seedsArgemone oil

Mustard seedsEdible oils and fats

Epidemic dropsy,

Glaucoma,

Cardiac arrest2 Artificially

coloured foreign seeds

As a substitute for cumin seed,Poppy seed, black pepper

Injurious to health

3 Foreign leaves or exhausted tea leaves, saw dust artificially coloured

Tea Injurious to health, cancer

4 TCP Oils Paralysis5 Rancid oil Oils Destroys vitamin

A and E6 Sand, marble

chips, stones, filth

Food grains, pulses etc.

Damage digestive tract

7 Lathyrus sativus Khesari dal alone orMixed in other pulses

Lathyrism (crippling spastic paraplegia)

Chemical Contamination

8 Mineral oil (white oil, petroleum fractions)

Edible oils and fats,Black pepper

Cancer

9 Lead  chromate Turmeric whole and powdered, mixed spices

Anemia, abortion, paralysis, brain damage

10 Methanol Alcoholic liquors Blurred vision, blindness, death

11Arsenic

Fruits such as apples sprayed over with lead arsenate

Dizziness, chills, cramps, paralysis, death

12Barium

Foods contaminated by rat poisons (Barium  carbonate)

Violent peristalisis, arterial hypertension, muscular twitching, convulsions, cardiac disturbances

13Cadmium

Fruit juices, soft drinks, etc. in contact with cadmium plated

‘Itai-itai (ouch-ouch) disease,  Increased salivation, acute

vessels or equipment. Cadmium contaminated water and shell-fish

gastritis, liver and kidney damage, prostrate cancer

14Cobalt

Water, liquors Cardiac insufficiency and mycocardial failure

15Lead

Water, natural and processed food

Lead poisoning (foot-drop, insomnia, anemia, constipation, mental retardation, brain damage)

16Copper

Food Vomiting, diarrhoea

17Tin

Food Colic, vomiting

18Zinc

Food Colic, vomiting

19Mercury

Mercury fungicide treated seed grains or mercury contaminated fish

Brain damage, paralysis, death

NOTE : Safe limits have been prescribed for above metals in different food. Continuous use of food contaminated with these metals beyond safe limits may cause these diseases

Bacterial

contamination20

Bacillus cereusCereal products, custards, puddings, sauces

Food infection (nausea, vomiting, abdominal pain, diarrhoea)

21Salmonella spp.

Meat and meat products, raw vegetables, salads, shell-fish, eggs and egg products, warmed-up leftovers

Salmonellosis (food infection usually with fever and chills)

22Shigella sonnei

Milk, potato, beans, poultry, tuna, shrimp, moist mixed foods

Shigellosis (bacillary dysentery)

23 Staphylococcus aureus

Entero-toxins-A,B,C,D or E

Dairy products, baked foods especially custard or cream-filled foods, meat and meat products, low-acid frozen foods, salads, cream sauces, etc.

Increased salivation, vomiting, abdominal cramp, diarrhoea, severe thirst, cold sweats, prostration

24 Clostridium botulinus toxins

A,B,E or F

Defectively canned low or medium-acid foods; meats, sausages, smoked vacuum-packed fish, fermented food etc.

Botulism (double vision, muscular paralysis, death due to respiratory failure)

25 Clostridium.perfringens

Milk improperly processed or canned meats,

Nausea, abdominal pains, diarrhoea, gas

(Welchii) type A fish and gravy stocks

formation

26Diethyl stilbestrol (additive in animal feed)

Meat Sterlites, fibroid tumors etc.

273,4 Benzopyrene

Skoked food Cancer

28Excessive solvent residue

Solvent extracted oil, oil cake etc.

Carcinogenic effect

29Non-food grade or contaminated packing material

Food Blood clot, angiosarcoma, cancer etc.

30Non-permitted colour or permitted food colour beyond safe limit

Coloured food Mental retardation, cancer and other toxic effect.

31BHA and BHT beyond safe limit

Oils and fats Allergy, liver damage, increase in serum chloresterol etc.

32Monosodium glutamate(flour) (beyond safe limit)

Chinese food, meat and meat products

Brain damage, mental retardation in infants

33Coumarin and dihydro coumarin

Flavoured food Blood anticoagulant

34Food flavours beyond safe limit

Flavoured food Chances of liver cancer

35Brominated vegetable oils

Cold drinks Anemia, enlargement of heart

36Sulphur dioxide and sulphite beyond safe limit

In variety of food as preservative

Acute irritation of the gastro-intestinal tracts etc.

37Artificial sweetners beyond safe limit

Sweet foods Chances of cancer

Fungal contamination

38Aflatoxins

Aspergillus flavus-contaminated foods such as groundnuts, cottonseed, etc.

Liver damage and cancer

39Ergot alkaloids from Claviceps purpurea Toxic alkaloids, ergotamine, ergotoxin and ergometrine groups

Ergot-infested bajra, rye meal or bread

Ergotism (St.Anthony’s fire-burning sensation in extremities, itching of skin, peripheral gangrene)

40 Toxins from

Fusarium sporotrichioides

Grains (millet, wheat, oats, rye,etc)

Alimentary toxic aleukia(ATA) (epidemic panmyelotoxicosis)

41Toxins from Fusarium sporotrichiella

Moist grains Urov disease (Kaschin-Beck disease)

42 Toxins from

Penicillium inslandicum

Penicillium

Yellow rice Toxic mouldy rice disease

atricum,

Penicillium citreovirede,

Fusarium, Rhizopus,

Aspergillus43 Sterigmatocystin

from

Aspergillus versicolour

Aspergillus nidulans and bipolaris

Foodgrains Hepatitis

44Ascaris lumbricoides

Any  raw food or water contaminated by human faces containing eggs of the parasite

Ascariasis

45 Entamoeba histolytica

Viral

Raw vegetables and fruits

Amoebic dysentery

46 Virus of infectious

Hepatitis (virus A)

Shell-fish, milk, unheated foods contaminated with faeces, urine and blood of infected human

Infectious hepatitis

47Machupo virus

Foods contaminated with rodents urine,

Bolivian haemorrhagic fever

such as cereals

Natural Contamination

48Flouride

Drinking water, sea foods, tea, etc.

Excess fluoride causes fluorosis (mottling of teeth, skeletal  and neurological disorders)

49Oxalic acid

Spinach, amaranth, etc.

Renal calculi, cramps, failure of blood to clot

50Gossypol

Cottonseed flour and cake

Cancer

51Cyanogenetic compounds

Bitter almonds, apple seeds, cassava, some beans etc.

Gastro-intestinal disturbances

52 Polycyclic Aromatic

Hydrocarbons(PAH)

Smoked fish, meat, mineral oil-contaminated water, oils, fats and fish, especially shell-fish

Cancer

53Phalloidine (Alkaloid)

Toxic mushrooms Mushroom poisoning (Hypoglycemia, convulsions, profuse watery stools, severe necrosis of liver leading to hepatic failure and death)

54Solanine

Potatoes Solanine poisoning (vomiting,

abdominal pain, diarrhoea)

55Nitrates and Nitrites

Drinking water, spinach rhubarb, asparagus, etc. and meat products

Methaemoglobinaemia especially in infants, cancer and tumours in the liver, kidney, trachea oesophagus and lungs. The liver is the initial site but afterwards tumours appear in other organs.

56Asbestos (may be present  in talc, Kaolin, etc. and in processed foods)

Polished rice, pulses, processed foods containing anti-caking agents, etc.

Absorption in particulate form by the body may produce cancer

57Pesticide residues (beyond safe limit)

All types of food Acute or chronic poisoning with damage to nerves and vital organs like liver, kidney, etc.

58Antibiotics (beyond safe limit)

Meats from antibiotic-fed animals

Multiple drug resistance hardening of arteries, heart disease

TESTS TO DETECT ADULTERATION IN MILK

There are many methods known for detection of adulteration in milk but the methods discussed below are simple but rapid and sensitive methods to detect adulteration.

I. Detection of Neutralizers in milk

1) Rosalic acid test (Soda Test)

In milk neutralizers like hydrated lime, sodium hydroxide, sodium carbonate or sodium bicarbonate are added which are generally prohibited.

How to detect?

Take 5 ml of milk in a test tube and add 5 ml alcohol followed by 4-5 drops of rosalic acid. If the colour of milk changes to pinkish red, then it is inferred that the milk is adulterated with sodium carbonate / sodium bicarbonate and hence unfit for human consumption.

This test will be effective only if the neutralizers are present in milk. If the added neutralizers are nullified by the developed acidity, then this test will be negative. In that case, the alkaline condition of the milk for the presence of soda ash has to be estimated.

How to proceed?

2) Take 20 ml of milk in a silica crucible and then the water is evaporated and the contents are burnt in a muffle furnace. The ash is dispersed in 10 ml distilled water and it is titrated against decinormal (N/10) hydrochloric acid using phenolphthalein as an indicator. If the titre value exceeds 1.2 ml, then it is construed that the milk is adulterated with neutralizers.

II. Test for detection of hydrogen peroxide

Take 5 ml milk in a test tube and then add 5 drops of paraphenylene diamine and shake it well. Change of the colour of milk to blue confirms that the milk is added with hydrogen peroxide.

III. Test for detection of formalin

Formalin (40%) is poisonous though it can preserve milk for a long time.

How to detect?

Take 10 ml of milk in test tube and 5 ml of conc. sulphuric acid is added on the sides of the test tube with out shaking. If a violet or blue ring appears at the intersection of the two layers, then it shows the presence of formalin.

IV. Test for detection of sugar in milk

Generally sugar is mixed in the milk to increase the solids not fat content of milk i.e. to increase the lactometer reading of milk, which was already diluted with water.

How to detect?

Take 10 ml of milk in a test tube and add 5 ml of hydrochloric acid along with 0.1 g of resorcinol. Then shake the test tube well and place the test tube in a boiling water bath for 5 min. Appearance of red colour indicates the presence of added sugar in milk.

V. Test for detection of starch

Addition of starch also increases the SNF content of milk. Apart from the starch, wheat flour, arrowroot, rice flour are also added.

How to detect?

Take 3 ml milk in a test tube and boil it thoroughly. Then milk is cooled to room temperature and added with 2 to 3 drops of 1% iodine solution. Change of colour to blue indicates that the milk is adulterated with starch.

VI. Test for detection of glucose

Usually poor quality glucose is added to milk to increase the lactometer reading. There are two tests available to detect the adulteration of milk with glucose.

How to proceed?

1. Phosphomolybdic or Barford Test

Take 3 ml of milk in a test tube and add 3 ml Barford’s reagent and mix it thoroughly. Then keep it in a boiling water bath for 3 min and then cool it for 2 min by immersing in tap water with out disturbance. Then add 1 ml of phosphomolybdic acid and shake. If blue colour is visible, then glucose is present in the milk sample.

2. Diacetic test

Take a strip of diacetic strip and dip it in the milk for 30 sec to 1 min. If the strip changes colour, then it shows that the sample of milk contains glucose. If there is no change in the colour of the strip, then glucose is absent. In this method the presence of glucose in milk can be quantified by comparing the colour developed with the chart strip.

VII. Test for detection of urea

1. Urea is generally added in the preparation of synthetic milk to raise the SNF value.

Five ml of milk is mixed well with 5 ml paradimethyl amino benzaldehyde (16%). If the solution turns yellow in colour, then the given sample of milk is added with urea.

2. Take 5 ml of milk in a test tube and add 0.2 ml of urease (20 mg / ml). Shake well at room temperature and then add 0.1 ml of bromothymol blue solution (0.5%). Appearance of blue colour after 10-15 min indicates the adulteration milk with urea.

VIII. Test for detection of ammonium sulphate

The presence of sulphate in milk increases the lactometer reading.

How to proceed?

5 ml of hot milk is taken in a test tube and added with a suitable acid for e.g. citric acid and the whey thus separated is filtered. Collect the whey in another test tube and add 0.5 ml of 5% barium chloride. Appearance of precipitate indicates the presence of ammonium sulphate in milk.

IX. Test for detection of salt

Addition of salt in milk is mainly resorted to with the aim of increasing the corrected lactometer reading.

How to detect?

Five ml of silver nitrate (0.8%) is taken in a test tube and added with 2 to 3 drops of 1% potassium dichromate and 1 ml of milk and thoroughly mixed. If the contents of the test tube turn yellow in colour, then milk contains salt in it. If it is chocolate coloured, then the milk is free from salt.

X. Test for detection of pulverized soap

Take 10 ml of milk in a test tube and dilute it with equal quantity of hot water and then add 1 – 2 drops of phenolphthalein indicator. Development of pink colour indicates that the milk is adulterated with soap.

XI. Detection of detergents in milk

Take 5 ml of milk in a test tube and add 0.1 ml of bromocresol purple solution. Appearance of violet colour indicates the presence of detergent in milk. Unadulterated milk samples show a faint violet colour.

XII. Detection of water in milk

Though the adulteration of milk with water can be checked by lactometer reading, other adulterations too affect the lactometer reading. Hence freezing point depression, recognized by AOAC, is usually adopted.

Percentage of water added = Normal freezing point – Observed freezing point X 100                                                                        Normal freezing point

Normal freezing point of milk is taken as –0.55°C. A tolerance level of 3% is given which is equivalent to specifying a minimum freezing point depression for authentic milk of –0.55°C.

XIII. Detection of skim milk powder in milk

If the addition of nitric acid drop by drop in to the test milk sample results in the development of orange colour, it indicates the milk is adulterated with skim milk powder. Samples with out skim milk powder shows yellow colour.

XIV. Detection of vegetable fat in milk

The characteristic feature of milk is its fatty acid composition, which mainly consists of short chain fatty acids such as butyric, caproic, caprylic acid; whereas the vegetable fats consist mainly of long chain fatty acids and hence adulteration of vegetable fat in milk can be easily found out by analyzing the fatty acid profile by gas chromatography.

XV. Detection of buffalo milk in cow milk

The presence of buffalo milk in cow milk is tested by Hansa test. It is based on immunological assay. One ml of milk is diluted with 4 ml of water and then it is treated with 1 ml of antiserum. The characteristic precipitation reaction indicates the presence of buffalo milk in the sample taken. (The antiserum is developed by injecting buffalo milk proteins into rabbits).

XVI. Detection of benzoic and salicylic acid in milk

Five ml of milk is taken in a test tube and acidified with concentrated sulphuric acid. 0.5% ferric chloride solution is added drop by drop and mixed well. Development of buff colour indicates presence of benzoic acid and violet colour indicates salicylic acid.

XVII. Detection of borax and boric acid in milk

Five ml of milk is taken in a test tube to which 1 ml of concentrated hydrochloric acid is added and mixed well. Tip of a turmeric paper is dipped into the acidified milk and it is dried in a watch glass at 100°C or over a small flame. If the turmeric paper turns red, it indicates the presence of borax or boric acid.

Confirmation can be made by adding a drop of ammonia solution on the turmeric paper and if the red colour changes to green, it shows the presence of boric acid.