Common Adulterants/Contaminants

in food and Simple screening tests for their detection

 

          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.

 

Injurious Adulterants/Contaminants in Foods and their Health Effects

 

S.No

Adulterant

Foods Commonly Involved

Diseases or Health Effects

 

Adulterants in food

 

 

1

Argemone seeds

Argemone oil

Mustard seeds

Edible oils and fats

Epidemic dropsy,

Glaucoma,

Cardiac arrest

2

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

Paralysis

5

Rancid oil

Oils

Destroys vitamin A and E

6

Sand, marble chips, stones, filth

Food grains, pulses etc.

Damage digestive tract

7

Lathyrus sativus

Khesari dal alone or

Mixed 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

11

Arsenic

Fruits such as apples sprayed over with lead arsenate

Dizziness, chills, cramps, paralysis, death

12

Barium

Foods contaminated by rat poisons (Barium  carbonate)

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

13

Cadmium

Fruit juices, soft drinks, etc. in contact with cadmium plated vessels or equipment. Cadmium contaminated water and shell-fish

‘Itai-itai (ouch-ouch) disease,  Increased salivation, acute gastritis, liver and kidney damage, prostrate cancer

14

Cobalt

Water, liquors

Cardiac insufficiency and mycocardial failure

15

Lead

Water, natural and processed food

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

 

 

16

Copper

Food

Vomiting, diarrhoea

17

Tin

Food

Colic, vomiting

18

Zinc

Food

Colic, vomiting

19

Mercury

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 contamination

 

 

20

Bacillus cereus

Cereal products, custards, puddings, sauces

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

21

Salmonella 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)

22

Shigella 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

(Welchii) type A

Milk improperly processed or canned meats, fish and gravy stocks

Nausea, abdominal pains, diarrhoea, gas formation

26

Diethyl stilbestrol (additive in animal feed)

Meat

Sterlites, fibroid tumors etc.

27

3,4 Benzopyrene

Skoked food

Cancer

28

Excessive solvent residue

Solvent extracted oil, oil cake etc.

Carcinogenic effect

29

Non-food grade or contaminated packing material

Food

Blood clot, angiosarcoma, cancer etc.

30

Non-permitted colour or permitted food colour beyond safe limit

Coloured food

Mental retardation, cancer and other toxic effect.

31

BHA and BHT beyond safe limit

Oils and fats

Allergy, liver damage, increase in serum chloresterol etc.

32

Monosodium glutamate(flour) (beyond safe limit)

Chinese food, meat and meat products

Brain damage, mental retardation in infants

33

Coumarin and dihydro coumarin

Flavoured food

Blood anticoagulant

34

Food flavours beyond safe limit

Flavoured food

Chances of liver cancer

35

Brominated vegetable oils

Cold drinks

Anemia, enlargement of heart

36

Sulphur dioxide and sulphite beyond safe limit

In variety of food as preservative

Acute irritation of the gastro-intestinal tracts etc.

37

Artificial sweetners beyond safe limit

Sweet foods

Chances of cancer

 

Fungal contamination

 

 

38

Aflatoxins

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

Liver damage and cancer

39

Ergot 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)

41

Toxins from Fusarium sporotrichiella

Moist grains

Urov disease (Kaschin-Beck disease)

42

Toxins from

Penicillium inslandicum

Penicillium atricum,

Penicillium citreovirede,

Fusarium, Rhizopus,

Aspergillus

Yellow rice

Toxic mouldy rice disease

43

Sterigmatocystin from

Aspergillus versicolour

Aspergillus nidulans and bipolaris

Foodgrains

Hepatitis

44

Ascaris 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

47

Machupo virus

Foods contaminated with rodents urine, such as cereals

Bolivian haemorrhagic fever

 

Natural Contamination

 

 

48

Flouride

Drinking water, sea foods, tea, etc.

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

49

Oxalic acid

Spinach, amaranth, etc.

Renal calculi, cramps, failure of blood to clot

50

Gossypol

Cottonseed flour and cake

Cancer

51

Cyanogenetic 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

53

Phalloidine (Alkaloid)

Toxic mushrooms

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

54

Solanine

Potatoes

Solanine poisoning (vomiting, abdominal pain, diarrhoea)

55

Nitrates 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.

56

Asbestos (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

57

Pesticide residues (beyond safe limit)

All types of food

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

58

Antibiotics (beyond safe limit)

Meats from antibiotic-fed animals

Multiple drug resistance hardening of arteries, heart disease

 

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In the following table simple screening tests for detection of adulteration in common foods have been prescribed. These tests give idea of presence of adulteration. However, conformation for these adulterations is normally made through laboratory tests.

Detection Kit

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Text Box: Detection Kit
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Simple Screening test for Detecting Adulteration in Common Food

 

S.No

Food article

Adulteration

Test

1

Vegetable oil

Castor oil

Take 1 ml. of oil in a clean dry test tube. Add 10 ml. Of acidified petroleum ether. Shake vigorously for 2 minutes. Add 1 drop of Ammonium Molybdate reagent. The formation of turbidity indicates presence of Castor oil in the sample.

 

 

Argemone oil

Add 5 ml, conc. HNO3 ­­to 5 ml.sample. Shake carefully. Allow to separate yellow, orange yellow, crimson colour in the lower acid layer indicates adulteration.

2

Ghee

Mashed Potato

Sweet Potato, etc.

Boil 5 ml. Of the sample in a test tube. Cool and a drop of iodine solution. Blue colour indicates presence of Starch.  colour disappears on boiling &  reappears on cooling.

 

 

Vanaspati

Take 5 ml. Of the sample in a test tube. Add 5 ml. Of Hydrochloric acid and 0.4 ml of 2% furfural solution or sugar crystals. Insert the glass stopper and shake for 2 minutes. Development of a pink or red colour indicates presence of Vanaspati in Ghee.

 

 

Rancid stuff (old ghee)

Take one teaspoon of melted sample and 5 ml. Of HCl in a stoppered glass tube. Shake vigorously for 30 seconds. Add 5 ml. Of 0.1% of ether solution of Phloroglucinol. Restopper & shake for 30 seconds and allow to stand for 10 minutes. A pink or red colour in the lower(acid layer) indicates rancidity.

 

 

Synthetic Colouring Matter

Pour 2 gms. Of filtered fat dissolved in ether. Divide into 2 portions. Add 1 ml. Of HCl to one tube. Add 1 ml. Of 10% NaOH to the other tube. Shake well and allow to stand. Presence of pink colour in acidic solution or yellow colour in alkaline solution indicates added colouring matter.

3

Honey

Invert sugar/jaggery

1.      Fiehe’s Test: Add 5 ml. Of solvent ether to 5 ml. Of honey. Shake well and decant the ether layer in a petri dish. Evaporate completely by blowing the ether layer. Add 2 to 3 ml. Of resorcinol (1 gm. Of resorcinol resublimed in 5 ml. Of conc. HCl.) Appearance of cherry red colour indicates presence of sugar/jaggery.

 

 

 

2.      Aniline Chloride Test : Take 5 ml. Of honey in a porcelain dish. Add Aniline Chloride solution (3 ml of  Aniline and 7 ml. Of 1:3 HCl) and stir well. Orange red colour indicates presence of sugar.

 

4.

Pulses/Besan

Kesari dal(Lathyrus sativus)

Add 50 ml. Of dil.HCl to a small quantity of dal and keep on simmering water for about 15 minutes. The pink colour, if developed indicates the presence of Kesari dal.

5

Pulses

Metanil Yellow(dye)

Add conc.HCl to a small quantity of dal in a little amount of water. Immediate development of pink colour indicates the presence of metanil yellow and similar colour dyes.

 

 

Lead Chromate

Shake 5 gm. Of pulse with 5 ml. Of water and add a few drops of HCl. Pink colour indicates Lead Chromate.

6

Bajra

Ergot infested Bajra

Swollen and black Ergot infested grains will turn light in weight and will float also in water

7

Wheat flour

Excessive sand & dirt

Shake a little quantity of sample with about 10 ml. Of Carbon tetra chloride and allow to stand. Grit and sandy matter will collect at the bottom.

 

 

Excessive bran

Sprinkle on water surface. Bran will float on the surface.

 

 

Chalk powder

Shake sample with dil.HCl Effervescence indicates chalk.

8

Common spices like Turmeric, chilly, curry powder,etc.

Colour

Extract the sample with Petroleum ether and add 13N H2SO4 to the extract. Appearance of red colour (which persists even upon adding  little distilled water) indicates the presence of added colours. However, if the colour disappears upon adding distilled water the sample is not adulterated.

9

Black Pepper

Papaya seeds/light berries, etc.

Pour the seeds in a beaker containing Carbon tetra-chloride. Black papaya seeds float on the top while the pure black pepper seeds settle down.

10

Spices(Ground)

Powdered bran and saw dust

Sprinkle on water surface. Powdered bran and sawdust float on the surface.

11

Coriander powder

Dung powder

Soak in water. Dung will float and can be easily detected by its foul smell.

 

 

Common salt

To 5 ml. Of sample add a few drops of silver nitrate. White precipitate indicates adulteration.

12

Chillies

Brick powder grit, sand, dirt, filth, etc.

Pour the sample in a beaker containing a mixture of chloroform and carbon tetrachloride. Brick powder and grit will settle at the bottom.

13

Badi Elaichi seeds

 

Choti Elaichi seeds

 

Separate out the seeds by physical examination. The seeds of Badi Elaichi have nearly plain surface without wrinkles or streaks while seeds of cardamom have pitted or wrinkled ends.

14

Turmeric Powder

Starch of maize, wheat, tapioca, rice

A microscopic study reveals that only pure turmeric is yellow coloured, big in size and has an angular structure. While foreign/added starches are colourless and small in size as compared to pure turmeric starch.

15

Turmeric

Lead Chromate

Ash the sample. Dissolve it in 1:7 Sulphuric acid (H2SO4) and filter. Add 1 or 2 drops of 0.1% dipenylcarbazide. A pink colour indicates presence of Lead Chromate.

 

 

Metanil Yellow

Add few drops of conc.Hydrochloric acid (HCl) to sample. Instant appearance of violet colour, which disappears on dilution with water, indicates pure turmeric. If colour persists Metanil yellow is present.

16

Cumin seeds

(Black jeera)

Grass seeds coloured with charcoal dust

Rub the cumin seeds on palms. If palms turn black adulteration in indicated.

17

Asafoetida(Heeng)

Soap stone, other earthy matter

Shake a little quantity of powdered sample with water. Soap stone or other earthy matter will settle at the bottom.

 

 

Chalk

Shake sample with Carbon tetrachloride (CCl4). Asafoetida will settle down. Decant the top layer and add dil.HCl to the residue. Effervescence shows presence of  chalk.

18

Foodgrains

Hidden insect infestation

Take a filter paper impregnated with Ninhydrin (1% in alcohol.) Put some grains on it and then fold the filter paper and crush the grains with hammer. Spots of bluish purple colour indicate presence of hidden insects infestation

 

 

 

Criteria for selection of food

 

            Selection of wholesome and non-adulterated food is essential for daily life to make sure that such foods do not cause any health hazard. Although it is not possible to ensure wholesome food only on visual examination when the toxic contaminants are present in ppm/ppb level. However, visual examination of the food before purchase makes sure to ensure absence of insects, visual fungus, foreign matters, etc. Therefore, due care  taken by the consumer at the time of purchase of food after thoroughly examining can be of great help. Secondly, label declaration on packed food is very important for knowing the ingredients and nutritional value . It also helps in checking the freshness of the food and the period of best before use. The consumer should avoid taking food from an unhygienic place and food being prepared under unhygienic conditions. Such types of food may cause various diseases. Consumption of cut fruits being sold in unhygienic conditions should be avoided. It is always better to buy certified food from reputed shop.

 

 

 

DR.P.K.JAISWAL

DIRECTOR OF LABORATORIES

CENTRAL AGMARK LABORATORY

NORTH AMBAZARI ROAD

NAGPUR

Phone No: 0091-712-2534748

E-mail: calnag@nagpur.dot.net.in