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Food Technology

Food Adulteration

Introduction

Adulteration is as the process by which the quality or the nature of a given substance is reduced through
(i) the addition of a foreign or an inferior substance and
(ii)the removal of a vital element.

Types
  • Intentional adulterants

    Sand, marble chips, stones, mud, other filth, talc, chalk powder, water, mineral oil

  • Incidental adulterants

    Pesticide residues tin from can, droppings of rodents, larvae in foods.

  • Metallic contamination

    Arsenic from pesticides, lead from water, mercury from effluent, from chemical industries, tins from cans.

Intentional Adulteration-Methods of Detection



  • Name of the Food Article

Ghee or Butter
Adulterant
Vanaspathi
Detection of Adulterant
Take about one teaspoonful of melted ghee or butter with equal quantity concentrated. Hydrochloric Acid in a test tube and add to it a pinch of cane sugar. Shake well for one minute and test it after 5 minutes. Appearance of crimson colour in lower (acidic) layer shows the presence of ‘vanaspathi’.

Detection of Adulterant –(Mashed potatoes, sweet potato and other starches)
The presence of mashed potatoes and sweet potatoes in a sample of butter can easily be detected by adding a drop of tincture of iodine. Iodine, which is brownish in colour, turns to blue if mashed potatoes/sweet potatoes/other starches are present.

  • Name of the Food Article

Milk
Adulterant
Water
Detection of Adulterant

  1. The Lactometer reading should not ordinarily be less than 1.026.
  2. The presence of water can be detected by putting a drop of milk on a polished vertical surface. The drops of pure milk either stops or flows slowly leaving a white trail behind it. Whereas milk adulterated with water will flow immediately without leaving a mark.
  • Name of the Food Article

Sweet meat, ice cream, sherbhat
Adulterant
Metanil yellow (a non permitted coal tar dye)
Detection of Adulterant
Extract colour with Luke warm water from food article. Add few drops of conc. Hydrochloric Acid. If magenta red colour develops the presence of metanil yellow is indicated.

  • Name of the Food Article

Dhals
Adulterant
Kesari dhal
Detection of Adulterant
Add 50 ml of dilute Hydrochloric acid to dal and keep on simmering water for about 15 minutes. The pink colour if developed indicates the presence of kesari dal.
Adulterant
Clay, stones, gravels, lead chromate (yellow)
Detection of Adulterant
Visual examination will detect these adulterants. Shake five grams of dal with 5 ml of water and add a few drops of Hydrochloric Acid. A pink colour shows the presence of colour.

  • Name of the Food Article

Tea leaves
Adulterant
Exhausted tea or black or Bengal gram dal husk with colour.
Detection of Adulterant

  1. Tea leaves sprinkled on wet filter paper would immediately release added colour.
  2. Spread a little slaked lime on white porcelain tile or glass plate. Sprinkle a little tea dust on the lime. Red orange or other shades of colour spreading on the lime will show the presence of coal tar dye. In the case of genuine tea, there will be only a slight greenish yellow colour due to chlorophyll, which appears after sometime.
  • Name of the Food Article

Wheat, bajra and other food grains
Adulterant
Ergot (a fungus containing a poisonous substance)
Detection of Adulterant

  1. Purple black longer size grains in bajra show the presence of ergots.
  2. Put some grains in a glass containing 20% salt solution. Ergot floats over the surface while sound grains settle down.
  • Name of the Food Article

Sugar
Adulterant
Chalk powder
Detection of Adulterant

Dissolve in a glass of water, chalk will settle down at the bottom.



  • Name of the Food Article

Turmeric
Adulterant
Coloured saw dust metanil yellow.
Detection of Adulterant
Take a teaspoon full of turmeric powder in a test tube. Add a few drops of conc. Hydrochloric Acid. Instant appearance of violet colour which disappears on dilution with water. If the colour persists metanil yellow (an artificial dye) non-permitted coal tar dye is indicated.

  • Name of the Food Article

Chilli powder
Adulterant
Stones
Detection of Adulterant

Any grittiness that may be felt on tapping the sediment at the bottom of glass confirms the presence of brick powder or sand. Smooth white residue at the bottom indicates the presence of soapstone.

Adulterant
Artificial colour
Detection of Adulterant
Water soluble artificial dye can be detected by sprinkling a small quantity of chilli or turmeric powder on the surface of water contained in a glass tumbler. The soluble dye will immediately start descending in colour streaks.

  • Name of the Food Article

Jaggery powder
Adulterant
Chalk powder
Detection of Adulterant
Add few drops of HCl. Effervescence indicate adulteration. Stir a spoonful sample of sugar in a glass of water. The chalks settle down.

  • Name of the Food Article

Wheat flour (maida)
Adulterant
Atta from which maida suji has been extracted
Detection of Adulterant
When dough is prepared from resultant wheat flour, more water has to be used and chapaties prepared out of this will blow out. The normal taste of chapaties prepared out of wheat is some what sweetish whereas those prepared out of adulterated wheat flour will taste insipid.

  • Name of the Food Article

Common salt
Adulterant
White powdered stone, chalk
Detection of Adulterant
Stir a spoonful of simple of salt in a glass of water. The presence of chalk will make the solution white and other insoluble impurities will settle down.

  • Name of the Food Article

Mustard seeds
Adulterant
Argemone seeds
Detection of Adulterant
Mustard seeds have a smooth surface. The argemone seed have grainy and rough surface and are blacker hence can be separated out by close examination.

  • Name of the Food Article

Honey
Adulterant
Molasses (sugar and water)
Detection of Adulterant
A cotton wick dipped in pure honey when lighted with a match stick burns. If adulterate the presence of water will not allow the honey to burn. If it does it will produce a crackling sound.

  • Name of the Food Article

Cinnamon
Adulterant
Cassia bark
Detection of Adulterant
Cinnamon barks are very thin. Cassia barks are thick and stiff. Cinnamon barks can be rolled.

  • Name of the Food Article

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

Incidental Poisoning

  1. Regular ‘market basket’ surveys to warn people of dangerous build up of toxins in food.
  2. Stepping up the integrated pest management programme to teach farmers to use pesticides judiciously. No spraying should be done a week before harvest.
  3. Taking up on a warfooting the control of pest using their natural predators.
  4. Preventing industries from dumping poisonous effluents.
  5. Considering health costs while deciding pesticide policy.
  6. Use safer pesticides like synthetic pyrethroids or Malathion.
  7. A thorough washing of vegetables does help to get rid of much of toxin.

Food Borne Diseases Caused by Some Pathogenic Organisms

Pathogenic OrganismsFood Commonly involvedIII effects and diseases
  • BACTERIAL
Bacillus cereusCereal ProductsNausea, vomiting, abdominal pain.
Clostridium botulinum toxinsDefectively processed meat and fish.Botulism (muscular) paralysis, death due to respiratory failure.
Clostridium perfringens (welchii)Defectively processed meat and fish.Nausea, abdominal pain and diarrhoea.
SalmonellaDefectively processed meat, fish and egg products, raw vegetables grown on sewage.Salmonellosis (vomiting diarrhoea and fever)
Shigella sonneiFoods kept exposed or sale in unhygienic surroundings.Bacillary dysentery
Staphylococcus aureusFoods kept exposed or sale in unhygienic surroundings.Increased salivation, vomiting, abdominal pain and diarrhoea.
Streptococcus pyogenesFoods kept exposed or sale in unhygienic surroundings.Scarlet fever, septic sores throat.
  • FUNGAL
Aspergillus flavus (aflatoxin)Corn and groundnutLiver damage and cancer
Claviceps purpurea (Ergot)Rye and pearl millet infested with ergot. Peripheral gangreneErgotism (burning sensation in extremities)
Fusarium sporotrichiodiesCereals and millets infected with fusarium.Alimentary toxic aleukia.
Penicillium islandicumRiceLiver damage
  • PARASITIC
Trichinella spiralisPork and pork productsNausea,vomiting,diarrhoea, Colic and muscular pains(trichionosis)
Ascaris lumbricoidesRaw vegetables grown on sewage farm.Ascariasis
Entamoeba histolyticaRaw vegetables grown on sewage farm.Amoebic dysentery
Ancylostoma duodenale (hookworm)Raw vegetables grown on sewage farm.Epigastric pain, loss of blood, anaemia.

Toxic Effects of Some Metals and Chemicals

NameFoods commonly involvedToxic effects
ArsenicFruits sprayed by lead arsenate.Dizziness, chills, cramps paralysis leading to death.
BariumFoods contaminated by rat poison (barium carbonate)Violent peristalsis, muscular twitching and convulsions.
CadmiumFruit juices and soft drinks that come in contact with cadmium and plated vessels.Excessive sallvation, liver, kidney damage, prostate cancer, multiple fractures (painful ‘Itai-Itai’ disease reported from Japan due to cadmium poisoning)
CobaltWater, beerCardiac failure
CopperAcid foods in contact with tranished copper ware.Vomiting, diarrnoea, abdominal pain.
Lead Some processed foods Lead water pipes.Paralysis, brain damage.
MercuryMercury fungicide treated seed grains or mercury contaminated fish.Paralysis, brain damage and blindness.
TinCanned foodsColic, vomiting, photophobia.
ZincFoods stored in galvanised iron ware.Dizziness, vomiting
pesticidesAll types of foodsAcute or chronic poisoning causing damage to liver, kidney,
brain and nerves leading to death.
Diethyl stilbestrolPresent in meat of stilbestrol fed animals and birds.Teratogenesis, carcinogenesis.
antibioticsMeat from animals fed antibiotics.Drug resistance, hardening of arteries, heart disease.

Packaging Hazards

Polyethylene, polyvinyl chloride and allied compounds are used to produce flexible packaging material. While this method of packaging is very convenient, it must not contain any noxious thermal breakdown products, which could be injurious to health. Further, temperatures used for heat sealing, or sterilization should not result in formation of toxic residues. To avoid such incidences, it is essential that only food grade plastic packaging materials be used for packaging foods.

Toxicants Naturally Present In Some Foods

Some foods contain toxic substances, which may cause serious illness, when consumed in large amounts. An important example is the legume, Lathyrus sativus which contain a toxin which may produce neurotoxic effects. The alcoholic extract of lathyrus sativus seeds contain a toxin B-N-oxalyt amino-L-alanine (BOAA).

When consumed in large amounts, it subjects develop a crippling disease known as lathyrism. The toxin can be easily removed by soaking the pulse in hot water and discarding the water.

Some varieties of mushrooms contain toxic substances which when consumed produce serious ill-effects. For example, ananita phalloides contains the toxin called phalloidin which causes hypoglycaemia and convulsions, vomiting in human subjects. Liver and kidney damages also occur.