Food Safety Dr. Mukul Das, FNAAS, FNASc Scientist G & Area Coordinator Food, Drugs & Chemical Toxicology Group Indian Innstitute of Toxicology Research Lucknow 226 001, India Email:mditrc&rediffmail.com

There has been a global concern about food safety and unfair trade practices in quality and quantity. Food contamination refers to the presence of harmful chemicals and microorganisms which can cause consumer illness through food. The impact of chemical contaminants on consumer health and well-being is often apparent only after prolonged exposure at low levels. Chemical contaminants present in foods are often unaffected by thermal processing (unlike most microbiological agents).The scientific and public deliberates over the safety of chemical additives, contaminants, and adulterants, appearing in foodstuffs have been emphasized since long time. The common contaminants and adulterants could be broadly classified as (a) intentional and (b) non-intentional chemicals. The first category includes deliberate added chemicals like additives and adulterants, the latter for the purpose of disguising inferior commodities and/or earning undue profits. The second group of non-intentional contaminants can come during production, processing, packaging and storage.

Intentionally added chemicals in foodstuff

Colours

Food colours are used for providing visual effects and to meet consumers demand on quality and price. Under the Prevention of Food Adulteration Act of India, 1954 eight synthetic colours, viz, Sunset Yellow FCF, Tartrazine, Ponceau 4R, Carmoisine, Erythrosine, Brilliant Blue FCF, Fast Green FCF and Indigocarmine are permitted to be added to food stuffs. The maximum permissible level of food colours that can be added either individually or in blend form to different food is 100 parts per million (ppm or ug/g) except in canned food where the level of 200 ppm is allowed. It is mandatory to declare the addition of artificial colour on the label of the food item. On the other hand, it has been found that a wide range of foodstuffs from urban and rural markets exceeds the permissible level on these permitted colors. Studies have also shown that various non-permitted colours listed below are being used in foods which are known to produce adverse effects in experimental animals.

• Amaranth, • Auramine • Blue VRS • Congo red • Fast Red E • Green S • Malachite Green • Metanil yellow

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Adulterants in Edible Oil

Argemone Oil

Argemone mexicana is a wild plant and its seeds resemble to that of mustard. Consumption of mustard oil contaminated with argemone oil is known to cause a clinical condition referred to as epidemic dropsy. The problem of adulteration of mustard oil stills exists as evidenced by dropsy at Delhi in 1998, Gwalior in 2000, Kannauj in 2002 and Lucknow in 2005. The toxicity of argemone oil has been attributed to its physiologically active alkaloids – sanguinarine and dihydrosanguinarine. The sites of toxication include skin, liver, lungs, kidneys and heart. Clinical symptoms include vomiting, diarrhea, nausea, fever, erthema, bilateral pitting edema of lower limbs and even death due to cardiac and respiratory failure in severe cases. Butter Yellow Light pale cheaper oils dyed with a fat soluble azo dye, butter yellow along with addition of mustard pungency factor allyl isothiocyanate, are some times sold under the pretext of mustard oil. This azo dye is banned for food usage throughout the world as it can interact with macromolecule like DNA and protein to induce genotoxic and mutagenic effects. It has been shown to produce hepatic epidermal tumors as well as carcinoma in respiratory tracts. Tricresyl phosphate A Tricresyl phosphate (TCP) colorless stable industrial chemical used in varnishes as a plasticizer and in hydraulic fluid.. Many outbreaks of (TCP) poisoning has been reported in USA, Durban, Sri Lanka. In 1988, an outbreak through consumption of rapeseed oil adulterated with TCP took place at Calcutta where almost 600 patients were admitted to hospital. The patients showed signs of paralysis specifically in hands.

Adulterants in pulses

Among cereals, Khesari dal (Lathyrus sativus) and its flour are at times mixed in dal arhar (Cajanus indicus) and dehusked Bengal gram flour (Besan). Its continued consumption in appreciable quantities for a period of 2-3 months causes progressive spastic paralysis of lower limbs, which is commonly referred to as lathyrism. The outbreak of this disease is highly prevalent in Ethiopia, Bangladesh, India and Afghanistan. The etiological agent for neurolathyrism was found to be an unusual amino acid, beta oxalyl amino alanine (BOAA) In India, majority of the states have imposed restrictions on its cultivation/ sale excluding West Bengal, Bihar and Madhya Pradesh. Efforts should be made to propagate genetically engineered low toxin varieties of L. sativus. Once the toxin is removed, lathyrus has all the potential to offer a legume which is pest resistant, low irrigational need, hardy crop which is otherwise quite rich in high protein, economical and palatable too. Non-Intentional food contaminants Mycotoxins Mycotoxins are toxic secondary metabolites produced by fungi growing on agricultural produce that can adversely affect animals and human health. Mycotoxins can be produced in grain during pre and post harvest stages. Tropical conditions in India, harvesting practices, post harvest

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storage practices, temperature, monsoon season, unseasonal rains, sudden floods, damage standing crops and stored food grains, which become conducive for fungal invasion, proliferation, contamination and elaboration of mycotoxins. Some mycotoxins formed in agricultural produce are:

• Aflatoxins, • Fumonisins, • Trichothecenes • Ergot alkaloids • Ochratoxins • Patulin, • Zeralenone.

It has been estimated that one quarter of world's food crops is at risk owing to-mycotoxins contamination. They are well known for their Carcinogenicity Teratotoxity, nephrotoxicity hepatotoxicity etc At present, the PFA Act of India has limits for total content of aflatoxins and trichothecenes. Limits for individual aflatoxins like B/B2 & M1 and various other mycotoxins have not yet been prescribed. There is an urgent need to formulate these limits and monitor their levels in different food commodities. Metals The rapid industrialization and use of fertilizers and pesticides has introduced metals in our environment. The metals (Fe, Cu Cd, Zn, Mn, Co, Mo, Se. Cr, Pb, Hg, As) have been detected in air, soil and water leading to absorption in food crops. Thus, food and water is the main sources through which human exposure to metals have been observed. The regulatory guidelines for metals have been prescribed by BIS and PFA. In general all the metals are probably toxic if consumed in large dose and hence it is difficult to make clear distinction between essential and toxic metals. Food is the major source of Pb exposure for humans. Food grains, vegetables, fruits etc contain variable amount of Pb. Absorption of Pb is higher in children and infants than adults. Pregnant women and developing fetuses appear to be more sensitive to Pb due to enhanced food intake. The problem of As in water has been a cause of global concern. Bangladesh and West Bengal are one of the major endemic areas; however, in recent times Ballia town of Uttar Pradesh has also shown several cases of As poisoning due to contaminated ground water. Chromium can also enter through food chain either through the tannery effluents or in soil rich in chromite ore. Cr has been detected in various foodstuffs such as sugar, milk, vegetables, nuts etc. Cr exist in trivalent state, which is inert, however, conversion to hexavalent state enhances the toxicity. Metallic contaminants in some items, which are used in food commodities, are not known. Silver foil (Chandi Ka Warq) is one such item for which specifications have not been prepared except that it should be 99.9% pure.

Polycyclic Aromatic Hydrocarbons: Polycyclic aromatic hydrocarbons (PAHs) are formed through a number of combustion processes and are present as a complex mixture of many individual PAHs. Studies of various environmentally relevant matrices, such as coal combustion effluent, motor vehicle exhaust,

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used motor lubricating oils and tobacco smoke have shown that PAHs in these mixtures are mainly responsible for their carcinogenic potential. The lung is supposed to be the main site of PAHs induced cancer.

Test for common adulterants which can be carried out in school laboratories

S.No. Food Commodity

Adulterant Test

1. Milk Milk Milk

Water Starch Urea

Put a drop of milk on a polished slanting surface. Pure milk will flow slowly leaving a white trail behind; whereas water admixed milk will flow immediately without trailing. Add a few drops of tincture of Iodine or 1% Iodine solution*. Formation of blue colour indicates the presence of starch. Take 5 ml of sample and shake for 5 min with 1/2 teaspoonful of powdered Arhar dal or Soybean flour. Dip turmeric indicator paper**in the mixture. If the paper turns red, which on adding a drop of ammonia turns green, confirms that the sample is adulterated with urea.

2. Khoya, paneer and their products

Starch Boil a small quantity of sample with some water, cool and add a few drops of Iodine solution. Formation of blue colour indicates the presence of starch.

3. Ghee/ butter Ghee/ butter Ghee

Vanaspati or Margarine Coal tar dye Mashed Potatoes, Sweet Potatoes and other starches.

Take one tea spoon melted sample of ghee/ butter with equal quantity of concentrated Hydrochloric acid in a stoppered test tube and add a pinch of sugar. After shaking wait for five minutes. Appearance of crimson colour in lower (acid) layer indicates the adulteration with Vanaspati or Margarine. Pour 2 ml of melted sample of ghee in a test tube and add 3 ml of ether. Shake it thoroughly and add 1 ml of concentrated HCl. Shake well and allow to stand. Appearance of pink colour indicates the presence of colouring matter. Boil a small quantity of sample with some water, cool and add a few drops of Iodine solution. Formation of blue colour indicates the presence of starch.

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4. Oils and Fats Oils and Fats

Argemone oil Mineral oil

Take small quantity of oil in a test tube. Add equal quantity of concentrated Nitric acid and shake carefully. Red to reddish brown colour in lower (acid) layer would indicate the presence of Argemone oil Take 2 ml of the oil sample and add an equal quantity of 12 N ethanolic KOH solution (67.2 gm dissolved in 100 ml ethanol). Keep in boiling water bath for about 15 minutes and add 10 ml of water. Appearance of turbidity indicates the presence of mineral oil.

5. Sugar Chalk powder Add 10 gm of sample in a glass filled with water and stir gently till it dissolves. Leave it for few minutes. Chalk will settle down at the bottom.

6. Honey Sugar solution A cotton wick dipped in pure honey when lighted with a match stick burns and shows the purity of honey. If adulterated with sugar solution, wick will not burn, or it will produce a cracking sound.

7. Sweetmeats, Ice-cream and beverages

Metanil yellow (a non-permitted coal tar colour)

Extract colour with luke-warm water from food articles. Add few drops of concentrated Hydrochloric acid. If magenta red colour develops the presence of metanil yellow is indicated.

8. Silver foil Aluminum foil Rub a foil in between the palms. Aluminum foil will leave a ball like structure, while silver foil will disappear.

9. Wheat, Rice, Maize, Jawar, Bajra, Chana, Barley etc.

Ergot (a fungus containing poisonous substance)

(i) Purple black longer sized grains in Bajra show the presence of Ergots. (ii) Put some grains in a glass tumbler containing 20 per cent NaCl solution Ergot infected grains float over the surface while non-infected grains settle down.

10. Sella Rice (Parboiled Rice)

Metanil yellow

Add a few drops of dilute Hydrochloric acid to a few rice grains mixed with small volume of water; pink colour indicates presence of Metanil yellow.

11. Channa and Arhar Dal

Khesari Dal Metanil yellow

Khesari dal has edged type appearance showing a slant on one side and bulged portion on the other side while other pulses are bulged on both sides. Take 5 gm of the sample with 5 ml of water in a test tube and add a few drops of concentrated Hydrochloric acid. A pink colour shows the presence of Metanil yellow.

12. Atta, Maida Suji (Rawa)

Iron filings By moving a magnet through the sample, iron filings can be separated.

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13. Besan Khesari Flour Add 50 ml of dilute Hydrochloric acid to 10 gm of sample and keep on simmering water for about 15 minutes. The pink colour indicates the presence of Khesari flour.

14. Black pepper Papaya seeds Light black pepper Coated with mineral oil

Papaya seeds can be differentiated from black pepper as they are shrunken, oval in shape and greenish brown or brownish black in colour. Float the sample of black pepper in alcohol (rectified spirit). The black pepper berries sink while the papaya seeds and light black pepper float. Black pepper coated with mineral oil gives Kerosene like smell.

15. Cloves Volatile oil extracted

Exhausted cloves can be identified by its small size and shrunken appearance. The characteristic pungent smell of genuine cloves is less pronounced in exhausted cloves.

16. Mustard seed Argemone seed (i) When a seed is rolled between a fore finger and thumb, mustard seeds can be felt by smooth surface, while argemone seed has a protrusion at a point. (ii) Seeds are dropped in a glass filled with 15% salt solution. Mustard seeds sink in the solution, while Argemone seeds float.

17. Powdered spices

Added starch Add a few drops of tincture of Iodine or Iodine solution. Indication of blue colour shows the presence of starch (not for turmeric).

18. Turmeric powder

Synthetic colour (Metanil Yellow) Chalk powder

Take a tea spoon full of turmeric powder in a test tube and add 5 ml of water. Add a few drops of concentrated Hydrochloric acid. Appearance of pink colour which disappears on dilution with water shows the presence of turmeric. If the colour persists, metanil yellow is present. Take about 1 gm of turmeric powder in a test tube containing 2-3 ml of water. Add a few drops of concentrated Hydrochloric acid, effervescence indicates the presence of chalk powder.

19. Chilli powder

Brick powder, salt powder or talc powder/soapstone

Take a tea spoon full of chilli powder in a glass of water. Coloured water extract will show the presence of artificial colour. Any grittiness that may be felt on rubbing the sediment at the bottom of glass confirms the presence of brick powder/sand, soapy and smooth touch of the white

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Oil soluble colour

residue at the bottom indicates the presence of soap stone.

Take 2 gm of the sample in a test tube, add few ml of ether and shake. Decant ether layer into a test tube containing 2 ml of dilute Hydrochloric acid (50%) and shake. The lower acid layer will show red colour, indicating presence of oil soluble dye.

20. Hing Soap stone or other earthy matter

Shake little portion of the sample with water and allow to settle. Soap stone or other earthy matter will settle down at the bottom.

21. Common salt White powdered stone

Stir a spoonful of sample of salt in a glass of water. The presence of chalk will make solution white and other insoluble impurities will settle down.

22. Tea leaves Exhausted tea or tur or gram dal husk with colour Iron filings

Take a filter paper and spread a few tea leaves. Sprinkle with water to wet the filter paper. If coal tar colour is present it would immediately stain the filter paper, while tea leaves shall not stain it. By moving a magnet through the sample, iron filings can be separated.

23. Catachu powder

Chalk Chalk gives effervescence with concentrated Hydrochloric acid.

24. Vinegar Mineral acid Test with the Metanil yellow indicator paper***, in case, the colour changes from yellow to pink, mineral acid is present.

25. Coriander powder

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

26.

Cumin Seeds (Jeera)

Grass seeds coloured with charcoal dust

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

* 1% Iodine solution: Dissolve 1.6 g of potassium iodide in 3 ml distilled water and add 1

g solid iodine. Swirl the mixture till all the solid iodine dissolves. Make the volume to 100 ml with distilled water and store in dark.

** Turmeric indicator paper: Turmeric indicator paper can be prepared by dipping a strip

of filter paper in turmeric solution (1 gm turmeric in 4 ml ethanol, let it stand for sometime and filter) in ethanol.

*** Metanil yellow indicator paper: Metanil yellow indicator paper can be prepared by dipping a strip of filter paper in metanil yellow solution (1%) in water.

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