Volume 17 Part 4 December 1979

JOURNAL

OF THE

ASSOCIATION OF PIJBIIC ANALYSTS

Food Adulteration in Developing Countries

J. A. AUNDepartment of Food Technology, Institute of Management and Technology,

P.M.B. 1079, Enugu, Nigeria

Unscrupulous traders have engaged in the art of food adulteration sinc€ timeimmemolial. An account is given of methods of adulteration that, althoughalmost unknown to the Westem world, are not uncoElmon in parts of theIndo-Pak subcontinent.

The definition of food adulteration has undergone a number of changes withthe development of the science of adulteration. Nichollssa defined adulterationas "the intentional addition to an article, for purpose ofgain or deception, ofanysubstance or substances the presence of which is not acknowledged in the nameunder which the article is sold". This definition has many drawbacks as it can-not be applied to all the different types of adulteration now prevailing.

Minors, offered a more complete definition by stating that an article may besaid to be adulterated if its nature, substance or quality is not what is usuallyexpected from the description of the article. He recognized five types ofadulteration, viz.

(a) deterioration in quality;(b) accidental contamination ;(c) contravention of a standard, provided by regulation or accepted custom;(d) deliberate and fraudulent adulteration;(e) the use ofa false label, calculated to mislead as to the nature, substance ot

quality of the article.

Whatever the definition of adulteration may be, its aims have not changed.In general, these are:

(a) to meet the high demand in cases of short supply by increasing thequantity apparently available;

(b) to reap more profit from the same quantity;(c) to dispose of an inferior commodity.

History"White earth" was reported to be added to baked bread in the days before the

destruction of Pompeii.so Various kinds of food adulteration prevailed in theGreek and Roman Empires for which laws had to be promulgated. Alcoholic

l. Assoc. Publ. Analysts, 1979,17, 115-l2O

0[o4-s7 80 I 79 I o401t s +06 $o1.oo/o O 1979 The Association of Public ADalysts

116 ,. A, AWAN

drinks such as beer and wine, and bread, suffered at the hands offood adulterat-

ors who applied all their skills to provide the consumers with products other than

the genuine article. During the reign of William the Conqueror, brewers were

subjected to severe punishments for adulterating beer. In 1203 the first pro-

clamation regarding the adulteration of bread was made in England. The

thirteenth century may be regarded as a milestone in the history offood adultera-

tion. England, France and Germany enacted laws to curb the menace. Since

then there has been a constant battle between the law and the food adulterators.This has resulted in constant revisions of the laws on the one hand, and develop-

ments in methods and techniques of adulteration on the other.

Ailulteration of Foods

1. ADULTERATION OF MILK

Milk is very susceptible to adulteration. A number of authors have reported

various typei of adulteration in milk and milk products and have described

mgthods of detecting it.z,3,4,e,10'u,23,28,2e,36,3e'40'42'4? The Encyclopaedia

Britannicaso recognizes four principal types of adulteration practised withrespect to milk, viz.

(a) addition of water;(b) abstraction of butter fat in the form of cream;(c) addition of Preservative;(d) addition of colouring matter.

Two other methods have also been employed:

addition of starch to the milk;removal of butter fat from, and addition of water to, milk in such propor-tions as to adjust the specific gravity to that of genuine full cream milk'

(a)(b)

Also a special type of adulteration has been evolved by "specialists" in certain

regions. ihe meihod is such an excellent one that sometimes even foodexlperts or Public Analysts might wonder if it is really a type of adulteration. Itis practised in areas where there are no dairy industries and the purchaser buys

the milk from the producer direct-the cow or buffalo being milked in front ofhim. The method adopted to defraud the consumer is very simple. The milkproducer starts milking his animal in front of the customers. He milks the

hrst portion (about half to three quarters of the total yield of the animal)into i utensil and sells the milk drawn to the waiting customers. The rest ofthemilk is drawn privately and is not sold to the public but taken home by the

producer to make butter. It is well known that the first drawn milk is poorer infat content.

2. eour,renArIoN oF cuRD

Curd or yoghurt is a very popular milk product in the Indo-Pak subcontinent.It is preparld1y culturing boiled fresh milk. The normal procedure employed

for tire production of curd in parts of Pakistan and India includes boiling fresh

FOOD ADULTBRATION 117

milk, pouring it into curd pans (baked earthenwate pans measuring approxi-mately 30cm in diameter and about 10 to 15cm deep), adding culture andallowing to stand overnight. By the morning the curd sets, a layer of cream formson the surface, and the product is sold by cutting out the quantity required (it issiightly softer than the normal cottage cheese). Since the consumer has nocdteria to judge the quality of the milk used, he normally looks at the cream

layer over the surface-the thicker the layer, the better the milk.Producers have tried all sorts of tactics to adulterate the product. Any pro-

cess which would not yield a layer of cream (or something similar) on the pro-duct would reveal the fraud. Therefore the aim ofthe adulterators has been toproduce a thick layer over the surface ofthe curd without having much fat in theproduct, One successful method is to use thick paper (blotting or filter)' Thepaper is cut to fit the pan and placed over the milk after the addition of inoculum.the paper absorbs moisture from the product and while standing overnight italso ibiorbs the odours. The curd is then sold to the consumer complete withthe paper, which has the milk constituents so impregnated that it looks like areal layer of cream.

3, ADULTERATION OF GIIEE AND BUTTM

Ghee is the most expensive milk product, obtained by heating and meltingbutter fat, It has been subjected to various types of adulteration and manymethods have been devised for their detection.6,7,8'16'1?'20'2e'43 The normaladulterants in ghee include animal body fat, starch, moisture and vegetableghee (hydrogenated vegetable oils). When the consumers began to find that theghee they bought might be adulterated, they resorted to the purchase of butter,iince it was thought that the butter would be more difficult to adulterate. In-vestigations by analysts revealed that the consumer was wrong in this assump-

tion. The producer adds a proportionate quantity of hydrogenated vegetable

oil to his cream or milk and inoculates it. After souring and churning the milkor cream the emulsion of combined fats is collected and sold as butter.

4. ADULTERATION OF MEAT

It is quite normal for a Public Analysl to find some meat products Qikesausages, ground meat) to be either adulterated or contaminated. The con-

taminints and adulterants may include dirt and metal particles entering throughhandling, lubricants, starch, etc.31 or even flesh from other animals'?l One

would rather think it impossible for fresh meat to be adulterated. But theingenious profiteers have evolved methods to adulterate the fresh meat in order

to reap more profits. Thus for example, Politikas8 reported a news item fromthe Philippines in which a sales girl increased the weight of her chickens byinjecting half to one litre of water, thus making them look fat.

-In Pakistan, goat meat is preferred to lamb's meat, but the breeding of goats

is almost prohibited by law. The butchers have evolved methods to "convert"the lamb meat into goat meat. Normally the indication of the type of animal is

obtained from the tai1, which is usually left on the carcass and is the last portionto be sold. There are two methods employed for this conversion, as follows.

118 J. A. AWAN

(a) "Welding the tail". The tail from a previous day's goat is stitched to thecarcass of the lamb in such a manner that the customer is unable to see

the stitches.(b) "Dyeing the tail". The lamb's tail is trimmed in such a manoer that it

fully resembles a goat's tail. Since lambs are normally white and goatscoloured, the trimmed tail is coloured with a suitable dye which gives itthe colour and appearance of a goat's tail.

It is only when the meat is cooked and consumed that the consumer realises thathe has been cheated. The "tai1welding" technique is also employed to convertan old cow into a younger one (beefinto veal). In this case the tail ofa calf willbe stitched to the cow's carcass.

5. ADULTERATIoN oF FRUITS

Various types ofadulteration have been reported in fruitjuices and other fruitproducts and a few methods of detection have also been sug-gested.14,15'2s,25,26,30,41'45,4e Except for a recent news report that fresh Israelifruits were found to be contaminated with a poisonous substance, there is hardlyany evidence that fresh fruits have ever been subjected to adulteration. Twoexamples follow to illustrate how even fresh fruits have not escaped the clutchesof adulterators.

At one time a variety of oranges, commonly known as "red blood" (havingred flesh), was very popular in some parts of Pakistan. These oranges fetched ahigher price than the normal variely. The experts found a simple technique for"converting" the ordinary oranges into the "red blood" variety. The techniqueinvolved injecting coloured solution into the ordinary oranges. Any customerwishing to examine the oranges would pick up any one from the lot, the sales-

man would cut it and, ofcourse, since the colour inside would be red, the custo-mer would buy the desired quantity.

Another technique employed for fresh fruits is used mainly with sweet melonsor similar fruits. Sometimes the sweet melons are not actually sweet but thesalesman makes them sweet and sells them. It is normal practice in parts ofPakistan and India for a customer to taste a piece of the fruit before he buys it.The salesman cleans his knife with a piece of cloth already dipped in saccharin(or similar sweetener) solution. While cutting the fruit, the sweetener from theknife makes a fllm over the fruit piece. The customer is given this piece to taste,and after being satisfied that the melon is actually sweet, he buys the whole fruit.

6. eoutrsRArroN rN N'urs

It would not be surprising to find some tree nuts to be adulterated. Almondkernels have quite often been found mixed with apricot kernels as the two arevery similar morphologically, chemically and sometimes in use. Similarly,alnond oil may be adulterated with peach and apricot kernel oils.a8 But noreports have been noticed where whole almonds or walnuts could be adulter-ated. The "expertise" of the food adulterators would fail if they could not findmethods to adulterate these apparently non-adulteratable commodities.

rOOD ADULTERATION 119

In Pakistan there are two varieties available of both almonds and walnuts.One variety has a thin shell, can be cracked with the teeth, and contains sweet

edible meat. The other variety has a coarse rough thick skin and requires muchforce to crack it, even hitting with a hammer. The meat inside these almonds isusually bitter, while in walnuts the quantity is small and not as delicious as thethin-skinned variety. The food adulterators have found a method to convertthese non-edible varieties into apparently edible ones. The trader purchases thenon-edible variety and subjects it to an acid treatment. The nuts remain in theacid bath (the nature of the acid is a secret of the professionals) at a certaintemperature for a certain length of time, after which they are removed andwashed thoroughly. The resultant product has a fine shell which is soft andmay be cracked with the teeth. This is then mixed with the genuinely ediblevariety and sold.

7. aouttrnarroN oF o.tHER FooDs

There is hardly any food that is safe from the hands of unscrupulous traders.Several reports,6,27,44 feviews12,35,3t and books1,13,r8, ,46 have been publishedindicating the extent to which foods can be adulterated. The list of adulterantsand foods adulterated is quite long; the subject has been comprehensivelytreated very recently by Jacob,2a who has listed over 60 foodstufls along withtheir common adulterants. Such a list can never be complete since the "experts"are continuously working to discover new adulterants and techniques.

References

1. Accum, F. C., "Treatise on Adulteration of Food and Culinary Poisons", A. Small, Phila-delphia, Pennsylvania, I 820.

2, Acker. L., Naturwissens.halten, 196s, 56, 12.3, Aschaffenburg, R., "Annual Report of the National Institute for Research in Dairying",

1964a,93.4. Badhe, L., and Dufilho, E., Ann. Fals., 1927,20, 88.5. Bottini, E., Chim. e I d. (Milan), 1957, 39, 93.6. Brooks, R. O. Spice Mill, 1923, 46, 512.7. Butcher, C. H., Food, 1934,3,99.8. Butche., C. H., ibid., 1934,3, 140.9. Casolari, A., Ann. Chin. Appliruta, 1932, 22, 7 53.

t0. Cattelain, E., J. Phatn. ChiDt., 1926,8, 467. 5ll.ll. Cordova, M. R., and McrtineT, M. C.. Ciercia (Med), 1955, 15,41.12. Dixon, 5., J. R. Sanit. lntt.- 1942.62. 137.13. Filby, F. A., "A Hislory of Food Adulteration and Analysis", George Allen and Unwin Ltd.,

London, 1935.14. Fitelson, J., "r. Assoc. of. Agric. Chem. 1967, 50, 293.15. Fitelson, J., ibid., 1968,51,937.16. ciri, K. V., and Bhargava, P. N-, Ind. Eng. Chem. Anal. Ed.,1937,9,395.17. Giri, K. V., and Bhargava, P. N., Proc. Soc. Biol. Chem, India, 1931, l, 44.18. Gerfeldt, E., "Unsere Nahrungs- und Genusmittel. Ihre Zusammensetzung, ihre Verfiils-

chung und die lebensmittelrechtlichen Bestimmungen", G. Thieme, Leipzig, 1935.19. Goded Mur, A., "Le leche y sus adulteraciones". Libreria General, Saragosa, 1943.20. Harrison, W. H., Agr. Res. Inst. Pusa, Sci. Repts,1927-28,10.21. Hayden, A. R., J, Food Sci., 1978, 43, 476.:2. Hermann, K,, Lrndht. -Umsch.. lS7t. 18.410.23. Hiscox. G. 5., ed., "Hanley's Twentieth Century Book of Formulas, Processes and Trade

Secrets". Books, Inc., New York, 1962.24. Jacob,'|, "Food Adulteration", The Macmillan Co. of India Ltd., Delhi, 1976.25. Jorysch, D., and Marcus, 5., J. Atsoc, Of, Agric. Chem., 1966,49,623.26. Koch, J. and Hess, D., Dtsch. Lebensmittel Rdtch.,1971,67,185.21. Lewis, E. W,, Food Manuf., 1930,5,6.28. Manley, C. H,, ,/. R. Sanit. Inst., 1933, 54, 214.29. Marrin, C. R, A., "Practical Food InspectioD", H. K. Ijwis aIId Co., Ltd', London, 1973.

r

120 J. A. AWAN

30. Mattic, L. R., Weirs, L. D., and Robinson, tN.B.,l. Assoc. Off. Agtic. Chen'1967,50,299.31. Miller, A. R., "Meat Hygiene", Lea and Fabiger, Philadelphia, 1952.32. Minor, R. G., J. Ptoc, R. Inst. Chem. Gt. Brit. Ireland, 1943, 216.33. Monselise, J. J., Bull. Res. Coun. Isruel, 1962,11C,283.34. Nicholls, J. R., Science Prog,, 1936, 31, 258,35. Peretti, G-, Afii Accad. Med. Lombada Suppl,,1962,17, 675.36. Pierre, A., and Portmann, A., Ann. Technol. Agr' 1970, 19, 177.37. Platt, B. 5., Brt. Med. J.,1955,1, 179.38. Politika, Daily Ne\rspaper, Beograd, 1974, 18.39. Portmann, A., and Pierre, A., A . Fals. Expert. Chim.,1971,,64, 159.40. Ramchandra, B. V., Dastur, N. N., and Gni,K.y.,Ind, J. Dairy Sci., 1955, 8, 83,41. Rentschler, H.,Mitt. Geb. Lebensmittelunrersuch. Hyg, (Bem),1964,55,501.42. sabati6, A., A n, fals.,1931,21,208.43. Sanyal, P.,

^4.m. Dryt. Agr. lndio. Chen. Ser.. Isl9, 10, 143.

44. Tolman, I. M., J. Assor. Oif. 4eic. Ch?,n., 1919,22,27.45. Weits, J., ten Broeke, R., Goddijn, J. P,, Gorin, N., and Schi]tz, G. P., Z. Lebensnittel-

Unter such. Forsch., 197 1, l4S, 335.wiley, H. w., "Foods and their Adulteration", Mccraw Hill (Blakiston), New York, 1907.Wood, D. R., Analrst, 1932,57,375,Woodroot J. G., "Tree Nuts, Production, Processing, Products, Vol. I", The AVI Publ. Co.Inc. Westport, Connecticut, 1967.Wucherpfennig, K,, and Franke, 1., Dtsch. Lebeksmittel-Rdsch,, 1969, 65,22.Yus1, W., ed., "Ercyclopaedia Britannica", Encyclopaedia Britannica Ltd., London, 1960.

46.47.48.

49.50.

f, Assoc. Publ. A alysts, 1919,11, 121'-123

The Fat Content of Certain Australian Minceil Meats

A. G. FALLA .rrNP D. MunPnY

Dunn, Son & Stone, 19 BeaconsftelduParade, Port Melbourne' yictofia

The results of a survey of the fat contents of the most commonly purchased

mioced meats in the Australian state of Victoria are rcported. Only 2 samples

had fat contents exceeding 25 per ccnt', the proposed maximum Ievel forminced beef in England.

In the Australian state of Victoria, the Food and Drug Standards Regula-tion for chopped and minced meats has no maximum fat content prescribed

and because minced meat forms a significant proportion of the meat and meatproducts consumed in Victoria a survey of the fat contents of the most com-monly purchased minced meats was undertaken for a period ofone year between

the summers of 1978 and 1979.

The minces sampled were minced topside and minced steak which comprisethe majority of all the minces purchased. In addition, the fat contents of asmall number of other minces were also determined. Although minced meat is

a regularly purchased item there have been no recent surveys on the fat contentsof the minces carried out in Victoria, and the average figure of 21'l per cent. offat for raw mince given in "Tables of Composition of Australian Foods"rdoes not indicate the maximum levels expected to be found naturally. Incontrast to the lack of published Victorian data, several papers concerning thefat contents of minced meat in the United Kingdom have been published''3'a

and a tentative maximum of25 per cent. offat has been proposed.

SamplingTlie simples analysed were all submitted by Health Surveyors in the course

of their normal food sampling programmes and covered both metropolitanand rural areas. Surveyors were not speciflcally asked to sample minces.

Samples containing preservative (prohibited in Victoria) were excluded fromthe survey.

Methoil of AnalysisThe fat contents were determined either by extracting the dried sample with

diethyl ether for eight hours or by use of a Foss-let 15310 fat analyser using a45 g sample size. A detailed description of this instrument and the correlationof iis results with those of the solvent extraction process have been published.s'6

The Foss-let method of fat determination has been appted to a wide range offoodstuffs and comparisons of tle results obtained with standard referenceprocedures have been satisfactory,

l2t0/}O4-s1 80 179 l04or2t +03 s01.00/0 @ 1979 The Associatioo of Public Aaalysts

122 A. G. FALLA AND D. MURPIIY

A summary ofthese comparisons, which include hydrochloric acid hydrolysis-petroleum ether extraction and chloroform-methanol extraction, is also givenin reference 5.

ResultsFifty-one samples of minced topside, 169 samples of minced steak and 17

other minces were analysed and a summary of the results obtained is given inTable L

TABLE IFAT CONTENT OF MINCED MEATS

Totalnumber ol

samples

Fat co[tent, pet cent.

s.D,*

Minced topsideMinced steakOther minces

51169

17

4.394.52580

5.253.651.45

22.4026.7 521 55

12.5511.8514.54

*s.D. : slandard deviatioD.

Table II gives the fat contents of the other minces sampled.

TABLE IIFAT CONTENT OF OTHER MINCES

Type or llameof mince

Total numberof samples Fat cor.tent, per ce l,

HamburgerRissolePork & VealPoikChopped meatRumpPie rneatSpaghettiBladebone

34222

I1.9313.8624.3814.5612.9823.358.578.607.45

11.338.55

17.2912-859-36

16.162l-35 21.55

In all cases the mean fat content is significantly less than 21.1 per cent. andthe values given in reference 4, although the range of values is similar. In thetotal of 237 samples analysed, only two had values above the U,K. tentativevalue of 25 per cent. These samples were both minced meats and had valuesof 26.05 and 26,7 5 per cent. This also contrasts with the published English datawhere 18 out of 310 samples had more than 25 per cent. of fat.4

This distribution of the fat values also differed from those found by Sinaret al.a wherc approximately 74,2 per cent. of the samples had values between5 and 20 per cent. compared with 89.9 per cent. for the Victofian samples overthe same range. Approximately 25.8 per cent. of the English values lay between

Max. Meao

AUSTRALIAN MINCED MEATS

TABLE IIIDISTRIBUT1ON OF FAT CONTENT IN MINCED MEAT

123

20 and 35 per cetrt. whereas only 8'0 per cent. of the Victorian samples fall inthis range. The complete distribution of the Victorian results is shown inTable III.

Range of fatval]ues, per cent. 0-5 5-10 10,15 15-20 20--25 25-30

Number of samples

Mitrced topside

Miuced steak

A1l samples

(0"/.)2

(r.2%)2

(0.8%)

ConclusionThe results obtained for the fat contents of the minced meals show that the

amount of fat present is not excessive and generally well below the suggested

value of 25 per cent. and that there is therefore no need at this time to suggest a

maximum fit value for minced meats in Victoria. Although the main survey

dealt with two types of minces only, the results from the remaining minces

analysed indicate that a similar satisfactory position also occurs here.

The survey also indicated that the fat conteflls of Victorian minced meats

were, in general, less tha.n those found in England and that the normal range offats iay 6'etween 3'65 and 26'75 pet cent. with 75'1 per cent. having values ofless than 15 per cent. of fat.

Referencis-i'. -tn6-niur. S., and Corden, M., "Tables of Composition of Australian Foods"' Commor-

weahh DeDartment of Health. 1970,2- Pearson. D,. J. Assoc, Publ, Analvsts, 1966,4,90.3. Pearson. D...1. Asso.. Publ, Analvsts, 1968, 6,53.i iiri.- i{.- g.ote. c, f.. and Conchie, E. C., J. Assoc. Publ. Analvsrs, 1916,14' 127 'i. pi'-iiiii"ii.'1. D.. a;d swift. c. E., .t. Assoc. of. Anal. Chem., 1e75, s8' I 182.

;: i';iiffiii: i. D., and swift, C. E., l. Assoc. of. Anal. chen .' 1977' 60, 853'

0(0%)

5(2.e%)

5(2.1"/.)

16(31.4%)

62(36.7yo)

83(35.0%)

4(7.8%)

9(5.3%)

t7(7.2%')

19 12{37.3%) (23-5yo)

65 26(38.s%) (1s.4%)

90 40(38.0%) (t6.eyo)

r

l.,-Atsoc. Publ. Anqllttt, 1979,17, 125-127

A Note on the Thin Layer Chromatographic Detection ofMineral.Oil in Whole Black Peppercorns(Piper nigrumL.)

K. L. Cnarn.LvonrvPublic Analyst's Laboratory, Government of Assam, Bamunimaidan,

Gauhati-7 8 I 02 1, As sam, India

Mineral oil is extracted from black pepper, cleaned up through an aluminacolumIl, thinJayer chromatographed using cyclohexane as solvent systemand then examined under an ultra-violet lamp. The preliminary clean-upremoves the interfering essential oils, characteristic of black pepper, whichmay also give fluorescent spots undet u.v. light leading to wrong inferences.

Mineral oil is used in black pepper as a polishing and glazing agenl. Further-more, the storage life of the berries is improved by the presence of mineral oilwhich inhibits insect infestation and prevents growth of fungus on the berries.The addition of mineral oil to black pepper is not permitted in India. Holde'stest is not normally sensitive enough to detect trace amounts of mineral oilpresent. Again, the essential oils present in black pepper are not normallysaponified by alcohcilic potash so the turbidity formed in Holde's test may leadto wrong interpretation when mineral oi1 is absent. By the chromatographicmethod trace amounts of mineral oil can be detected without any interferencefrom the unsaponifiable matter present in black pepper.

Experimental

APPAR-{TUS

1. Chromatographic column: 15 mm i.d. x 300 mm (height of aluminalayer 200 mm).

2. Chromatographic plate: 20 cm x 10 cm x 0'3 cm.3. Capillary tubes.4. Beaker, 25 ml capacity.5. Ultra-violet lamp.

REAGENTS

1. Alumina, neutral, active.2. Light petroleum.40-60"C.3. Silica gel G, A.R.4, Cyclohexane, Analar.5. Sodium sulphate, anhYdrous.6. Mineral o/s (petrol, kerosine, mobil, diesel and paraffin oil), all 0'05 per

cent. in diethyl ether.7. Black pepper seeds, obtained from local market.

0004-s780/79l040125 +03 $01.00/0

125

@ 1979 The Association of Public Analysts

126 K. L. CHAKRAVORTY

METHOD

Preparation of Sample: Extraction and Clean-upExtract mineral oil from 25 g ofthe sample of black pepper with three 20 ml

portions of light petroleum and concentrate it. Prepare a slurry of alumina inether and transfer in a rapid swirling motion to a clean chromatographiccolumn. Add 1 g ol sodium sulphate as a layer on top of the column. Washthe column with three l0 ml portions of light petroleum adjusting the solventlevel to that of the sodium sulphate layer. Reject the washings. Transfer theconcentrated light petroleum extract ofthe sample to the top ofthe column withminimum rinsing, allowing the solvent level to fall to that ofthe sodium sulphatelayer between additions. Elute the column thrice with 10 ml portions ofetherat the rate of less than 3 ml/min. Mix the eluates, concentrate on a water bathat 70"C, and make up to 2 ml.

Thin Laye r C hr omato gr aphySpot 20 pl of the concentrated eluate on to the Silica Gel G plate (thickness

0.3 mm) previously activated at 120'C for 5min and then cooled to roomtemperature in a desiccator. Develop with cyclohexane as solvent by allowingthe solvent front to run approximately 10 cm from the baseline. Dry the plateat room temperature and observe it under an ultra-violet lamp. A blue orgreenish-blue fluorescent spot is observed rvhen mineral oil is present.

PREPARATIONS OF STANDARDSTake flve 25 g portions of control samples of black pepper containing no

mineral oil. Soak each of the samples with lm1 (:500pg) of differentmineral oil solution in ether. Dry the standard samples and proceed asdescribed in the method and thin layer chromatography beginning ..Extractmineral oil . . . ultra-violet lamp". The fluorescent spots observed in the casesof positive control samples are shown in Table I.

TABLE I-RT VALUE OF PETROL, KEROSINE, DIESEL, MOBIL AND PARAFFIN OIL

USING THIN LAYER CHROMOTOGRAPHY

Types of mineral oil in sample Colour of the spots R. value

PetrolKerosineDiesel

Mobil*Paraffin oil

No spotGreenish blue(a) Green(b) BlueBlueLight blue

ors(a) 0 66(b) 0.76

0.840.40

*A brand trame for liquid paraffn.

Results and DiscussionAt least twenty samples of black pepper were collected from 1oca1 markets.

If mineral oi1 is present in the sample it can be very satisfactorily detected withsensitivity by this method. fn no case were the control samples found to give

MINERAL OIL IN BLACK PEPPERCORNS

any fluorescent spot by this method thus ruling out the possibility of erroneousinterpretation. Experiments were also performed with positive control samples

each containing a different rnineral oil, e.g. petrol, kerosine, diesel, mobil andparaffin oil. The development of fluorescent spots under the u.v. lamp notonly helps detection but the R, value reveals the qualitative nature of themineral oil present in the sample.

It should be borne in mind that R, values are influenced by factors such as theexact composition and quality ofthe solvent, the thickness ofthe adsorbent olthe plate, its activation, room temperature etc. So a slight variation in ,R,

value is probable. To compensate for these variations it is suggested thatR, values for different mineral oils are compared with the sample under theparticular experimental conditions.

127

l. Assoc, Publ. A alysrs, 1979,17, 129-133

A Note on the Application of the Hexabromide Test in theSemiquantitative Determination of Linseed, Oil (Linamusitatissimum) in Mustard Seed Oil (Brassica nigral.)

K. L. CHAKRAVoRTY

Public Analyst's Laboratory, Govemment of Assam, Bammimaidan,Gouhati-79 102 I, Assam, India

Th€ formation of a precipitate of hexabromides when the mustard seed oil istreated with bromine in chloroform and then with alcohol and other indicatesthe presenc€ of linseed oil. With increasing percentage of linseed oil inmustard oil the amount of precipitate increases in an almost linear manner.A calibration curve prepared by plotting percEntage of precipitate (v/v) againstknown perc€ntage of linseed oil in mustard oil may be utilised to evaluate theproportion of linseed oil in an unknown sample of mustard s€ed oil,

Linseed oil contains about 50 per cent. of a highly unsaturated fatty acid,linolenic acid, which undergoes an addition reaction with bromine to give thehexabromide, which is insoluble in ether. Pure mustard oil does not give aprecipitate of this kind. The formation of insoluble bromides may thus lead tothe conclusion that mustard oil is adulterated with linseed oil.

Due to scarcity of oils and fats, adulteration of edible oils by cheaper varietiesof non-edible oils is not uncommon in India, The use of linseed oil as anadulterant for mustard oil is very common due to its low price and the similarityin colour and consistency. A large number of adulterated samples have beendetected in the last few years.

Physical and chemical paraileters such as refractive index, saponificationvalue and iodine value of linseed oil differ widely from those of mustard oildue to the wide difference in the degree of unsaturation ald mean molecularweight between them.

These constants do have an application in detection and the evaluation ofadulteration, There exists, however, a wide range in each constant for eachindividual sample of oil depending on its source and the variation in the fattyacid composition. It is possible that by use of these values lower levels ofadulteration may escape detection.

There is a steady rise in the volume of the precipitate with the increasedpercentage of linseed oil, and up to a certain limit a linear relationship betweenthem is observed. Atr attempt has been made to determine linseed oil semi-quantitatively in a sample of unknown composition by measuring and calculatingthe volume of the hexabromide precipitate per 100 ml of oil and compariug thefigure with a calibration curve.

t29

t-

0004-s78ol79lo4ot29 + 05 $01.00/0 @ 1979 The Asso€iation of Public Aoalysts

.,}

130 K. L, CHAKRAVORTY

Experimental

APPARATUS

1. Test tube 6 in x 1 in with glass stopper.2. Pipette, 1 ml, graduated.3. Gallenkamp hand drive centrifuge model CF 1@ or other suitable model.4. Specially made precipitate-measuring glass apparatus (Figure 1).

Fig. l. Precipitate-measurioS apparatus. (a) The upper part of the aDDaratus consists of abulb of about 30 ml capacity. The diameter of the bulb is desigaed in suah a way that it caD beeasily fitted inthe ceDtrifuge. (b)The lower p-art ofthe appamtus is a loog,thid aod hard graduatedtube. I divisioo : 0.005 n and capacity of lower pan of apparatus : I rI .

REAGENTS

l. Chloroform AR.2. Liquid bromine AR.3. Rectified spirit.4. Ether LR.

ME'THOD

Pipette 0.5 to 1.0 ml, accurately measured, of the oil into a dry test tube,fitted with a ground glass stopper. Add 5 ml of chloroform. Add I ml ofbromine dropwise till the mixture is deep red in colour and cool the test tube inan ice-water bath. Add about 1.5 ml of rectified spirit dropwise while shakingthe mixture until the precipitate which is first formed just dissolves and then addl0 m1 of ether, Mix and place the test tube in an ice-water bath for 30 minutes.The appearance of a precipitate indicates the presence of linseed oil. Transferthe precipitate along with the liquid to the precipitate-measuring apparatus(Figure 1). Transfer the residual precipitate, if any, remaining in the test tubeto the apparatus with 5 m1 of ether. The apparatus containing the liquid andthe precipitate is centrifuged for 2 minutes and the volume of the precipitate readand calculated for 100 ml of the oil. The experiment is repeated for eachsample using initially different volumes of oil varying from 0.5 ml to 1.0 ml andalso for various control samples containing different known percentages oflinseed oil. A calibration curve is prepared by plotting the volume of precip!tate per 100 ml of oil against known percentage of linseed oil in mustard oil(Figure 2).

Fo\hhNF-R6p:hES€3sra+

i

:1-?| eoo\..1V)@t',* :1]a--@F\DdiN6=s::r d+o.iA Pi* ^"ri-d(.ir€66'+:;N ^.@-"i^-;; - -ilsisii:ex3=fSFfEt'gi3

,-*3'oo6

,ooo999Q

ooo

i|!:9!le.ooooooo-o:'gd{q{iYi'ddoooooooqqi6\d \d vi ridi vioooo6ooo"-"--ui-hh\ohhF66''

oooooo;6

i !: ...! i .,i .i ..,i ,-.: _ i

Es.EEEEEEEE. E. E. E. E. E. E. E. E.8F88e::-[

o

ir6o6,

6o6o

6o66

OoO6,

o6oor

6\(i

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,..]

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zF]

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132 K. L. CHAKRAVORTY

Fig. 2. Variation of volume of hexabromide precipitate from various mixtues of mustard oiland linseed oil.

Results and Discussions

Experiments were performed with 100, 90,75,60,50,25,15, 10, 5 and 2.5 percent. of linseed oil mixture in mustard oil. Each experiment was repeated fourtimes using a diferent volume of oil so that the most probable result could bearrived at (Table I). The average value of volume of precipitate per 100 ml ofoil plotted against different known percentages ofthe linseed oil gives a graph asshown in Figure 2.

From Table II it is clear that up to about the 5 per cent. level of adulterationroutine examination fails to detect the presence of linseed oil in mustard oil.The calibration curve as shown in Figure 2 can help in semiquantitative deter-mination even with only 2 per cent. adulteration.

TABLE IIPHYSICAL AND CHEMICAL DATA OF SAMPLES OF MUSTARD OIL

ADULTERATED WITH LINSEED OIL

E

E

Sample

Butyrorefracto-meter reading

at 40'CSaponification

value loCide ralue

Linseed oil, p€r cent.

100 per cent. LiNeed oil90 per cent.75 per cent.60 pe. cent.50 per cent.25 per cent,l0 per cent.5 per cent.

2.5 per cent.Mustard oil

71.870.269.168.466.062.060.559.058.5

19,+ i193.0183.618S.0l5 /.51S3.9181.1t77-0115.6174.0

t14.5167.8158.2149.8140.0129.0115.2108.1105.9103.2

Since the volume of hexabromide precipitates depends on many factors, e.g.,quality of the reagent, temperature of the experiments, centrifuge time etc,,care should be taken to ensure that identical conditions prevail during experi-

I

LINSEED OIL IN MUSTARD SEED OIL 133

ments performed for the calibration curve and for examination ofthe unknownsample. The precipitate measuring apparatus must have a properly graduatedlower part such that minimum of 0.005 ml can be measurcd accurately, other-wise there may be errors in the result which would lead to wrong interpretatioand evaluation. Adulteration of mustard oil is common and the application ofthe hexabromide test in this way does give the analyst a fairly rapid means ofconfirming the presence of linseed oil and estimating it approximately.

The author thanks Mr P. K. Das, M.Sc. (London), D.I.C., Public Analyst tothe Government of Assam for his interest and valuable suggeitions in this work.

J, Assoc. Pabl. Anolytrt,1979, 17, 135-138

Letters to the Editor

Corcosrnouar, R-ecwerloNs ron Pnotrn Fooos*

Sir,Existing U.K. Regulations on the composition of meat and fish products

require ttrat certain products should contain a minimum amount of meat of fish.Enforcement of these regulations requires reliable methods of analysis and, overthe years, the method of Stubbs and Morel (modified to meet changing needs)has become accepted as the best ayailable one for meat and fish products; it has,however, certain drawbacks.

First, it is indirect and is difficult to explain to a non-scientist. Secondly,while the basic analyses for nitrogen, moisture, fat, ash and, possibly, carbo-hydrate can be carried out with reasonable accuracy, the calculation of meat orfish content requires the use of a number of somewhat arbitrary factors whichmay be subject to error in any particular case. Thus, if carbohydrate is notdetermined directly, the initial step is to multiply total nitrogen by 6.25 to givetotal protein; this requires the assumption that the multiplier is 6.25 for all pro-teins present, both animal and vegetable. Specific values for this protein factorcan range from 5.55 (gelatin) to 6.68 (egg). The total protein result is added tofat, moisture and ash and subtracted from 100 to estimate carbohydrate;alternatively, carbohydrate may be determined directly. The carbohydrate,estimated or measured, is multiplied by 0.02, the mean nitrogen content ofcereal; this figure again is subject to some uncertainty. The cereal nitrogeo sodetermined is subtracted from total nitrogen and the difference is then dividedby a nitrogen factor to give meat or fish content, Because ofthe natural varia-tions in moisture content this nitrogen factor is subject to much greater un-certainty than the other factors; for example, the recommended mean valuefor cod js 0.0285 but the total range is from 0.0221 to 0.0320. The possibleerror arising therefrom can be seen by considering three samples of uncookedfish fingers with the same content by weight (70 per cent.) of raw fish butprepared from fish having nitrogen factors 0.0221, O.O285 and 0.0320. Use ofthe recommended nitrogen factor 0.0285 for the calculation of fish contentwould give apparent contents of 55, 70 and 79 per cent., respectively. For-tunately, extreme values are relatively infrequent and, since both manufactulersand Public Analysts are aware ofthe pitfalls, such discrepancies are less import-ant than might appear at first.

Some other complications can arise. The method of calculation gives aflgure for fat-free meat: real meat contains fat and it is usual 1o apportion eitherall or an arbitrary amount of fat (depending on t1le product) to the "true" meatcontent. Substantial errors could arise in products made from raw material ofvariable fat content; fatty fish can contain anything from nearly zero to over30 per cent. fat. Again, products required to have a very high meat or fish

* Crowri copyright reseryed.

135

136 LETTERS TO THE EDITOR

content, say 95 per cent., could appear to have considerably more than 100 per

cent. if made from raw material of high nitrogen content. Finally, Wood2 has

recentiy pointed out the difficulty of estimating the raw content of a product pre'pared irbm an already cooked material such as shrimp. Most of the above

fufficulties, and others, have been discussed by Pearson'3

Many of the uncertainties and difficulties in the estimation of meat or fish

conteni could be overcome by writing regulations in terms of total protein con-

tent. Mostof the analytical complications justexamined would thenbe avoided'

Only one type of analysis, for nitrogen, would normally be required (thor:gh

separate deierminationi of total and non-protein nitrogenrrould be desirable inorder to derive a value for true protein). The only arbitrary factor required

would be the protein conversion factor, whose variability is ml]ch less than thatof the nitrogen factor: a constant vatw, 6'25, would perhaps be acceptable, butseparate values for different species could readily be applied. A statutory re-

q,ri."-.rt for a minimum protein content would be more closely related to the

nutritional value of the product (and a statement of protein content could be

required if nutritional labelling were to cross the Atlantic)' Some problems ofcontrolling added water would be eased.a The proposal would avoid both the

need to dehne raw fish or meat precisely and controversy about nitrogen factors'

There would be disadvantages, ofcourse. All protein, animal and vegetable,

would be included in a minimum requirement. While this might arguably be oflittle consequence nutritionally, the temptation, which already exists under the

present rulei, to substitute inferior proteins micht !av-e to.b9 grrarded against'

The scope foi any large substitution is probably limited-by labelling regulations

and the general provisions of the Food and Drugs Act; detection by chemical orelectrop[oretic methods should be possible in most circumstances' While the

proposal would reduce the complexity ofthe analysis-of products and make en-

io.".*"ot more straightforward, it might cause difficulties for some manu-

facturers whose standird recipes are written in terms of meat content. A code

of practice might ease any problems. Other disadvantages will no doubt

occur to readers.It is not claimed that this suggestion is original. Protein content declarations

are required under the Fertilisers and Feeding Stuffs Regulations, and the Food

Standards Cornmittee Report6 on Novel Proteins envisages the possibility ofcontrol by protein content.

This leitir, which expresses my personal views, will, it is hoped, stimulate

some discussion.

Referenceg

r- stubbs- G.. and More. A., Analvst, 1919.44, 125.i- wood.'8. C,. J. Assoc. Publ- Analvsts, 1977'15,99'3. Pearson. D.. Analvst,I975, 100' ?1.4. Aitken. A., Chemy lr\tt., 1916.1048.l- i".,i St'aiiiii& 6o..1ti"", i'Rep&t on Novel Protej! Foods", H'M's'o', Londo4 1974

p.77,

A. ArrrsNMinistry of Agriculture, Fisheries and Food,

Tony Research Station, Aberdeen

LETIERS TO THE EDITOR

Aurtron's Rsply

137

Sir,Dr Aitken's letter, a copy of which he sent to me in the course of correspond-

ence on this subject, is interesting and thought-stimulating.The Stubbs-More system for the analysis of meat and fiih products has been

used by Public Analysts for about 60 years. The validity of the assumptionsmade when estimating meat content by this means and, in pafticular, the widerange for the minimum to maximum concealed by the use of a mean nitrogenfactor have been critically examined by several authors. The many publicati6nson the subject by the Meat Products Sub-Committee of the Analytical MethodsCommittee of the Society for Analytical Cbemistry have provided the basis ofthe present accepted factors.

Very many analyses of individual samples were made, often from differentparts of the animal and at different stages of maturity. The range of theseanalyses was usually 10 to 20 per cent. either side of the mean.

This is the uncertainty which has the greatest effect on the precision of theestimate of meat content. At first sight the argumenls put ?orward by DrAitken and the facts noted in my previous paragraph makelt difficult to under-stand how "Stubbs-More estimates" have been found over the years not merelyto be reasonable approximations to the ruth but to be suffcientiy close to be putforward as crucial evidence by prosecuting Local Authorities, rarely rebuttedbythe defence and accepted by magistrates as justifying a conviction. ThLanswer lies in the statistical fact that if the standard deviation of a long series ofobservations is s, that of the means of random groups of z observations each issl\/n.

Commercially prepared pork sausages and fish cakes are made not fromindividual pigjoints or codfish but from batches weighing scores of kilogrammesor even tonnes. True randomisation will not occur, but nevertheless, the nitro-gen content ofthe mixed meat will vary from batch to batch much less than didthe individual samples analysed for the S.A.C. For example, if the range ofanalyses ofsingle codflsh is 20 per cent. about the mean, that ofportions diawnfrom successive batches ofthe mixed flesh of 50 fish will be not much more than3 per cent., which is (to coin a phrase) a very different kettle of fish.

There is, however, another source of error in the use of the ,,Stubbs_Moreestimate" that has become serious only in recent years*the assumption that allthe nitrogen present is derived from the assumed source. For ixample, thepossible preseuce of small proportions of soya flour and/or skimmed milkpowder in pork sausages has been appreciated by analysts for many years, andmethods for their detection and quantitative estimation were devised-by publicAnalysts before 1939; but there is now the problem created by the increasing useofthe so-called "novel" proteins, which are not so easy to detect and much iroredifrcult to determine quantitatively. Dr Aitken suggests that we should solvethe problem_by by-passing it; that legal standards of compositional quality formeat and fish products should be based on protein content, defined as proteinnitrogen x 6.25 or other appropriate factor; and that the only correction the

oN4-57 80 I 79 I 0401 37 +02 $0r.00/0 @ 1979 The Association of Public Analysts

L

138 LETTERS TO THE EDITOR

analyst would need to apply would then be one for non-protein nitrogen' which

usuillv would be negligible.-"it ii *"JJt" qrl[- icceptable to the nutritionist, since the biological value of

" ;il;;i-";ilJ p-t"ltt *itn

" t'aller proportion^of soya or other "novel"

i*"i" **fJ ,"t be significantly different irom that of the animal protein itself'

ii;;;r"l^;i;;;;J;;i.' *o'ld, u' Dr Aitken savs' b-e sirnl,rfied; -q +';fi;;;;;;",h G anatltical work per sample and the calculatioa of the

;;i't*.;t; protein iather than 6eat content would' from the analyst's

point of view, be positively deliehtful'There is however one cogent argument against the proposal' All laws and

..nJuitot i"ruting to food irust ha'vt u' u pt.imury "onsideiation

the interests of

ffiffi;r--;ffi i-rrit piir"ipr" is enshrined in the famous Section 2 of tle

""rr""ii""O ""a Drugs lcq and contained in every such Act since 1875' namely

;;ilil;;il-oi rl-"a sold must be of the nature' substarce and qualitv

;;r;;;e by-in" prrr.nur... Rightlv or wrongly, the great majoritv of the

i;il"i-l-n;ril take rhe view rhat h-owever sarisfaatory a product may be nutri-

ffi;11;iffi;;iga"oi"pti.uuv), if it is sold under a description such as steak

;;;;'.i .uorue"., "6d

firg".s or'even strawberry jam, it must coatain a goodly

:::i;i";;;i;iru*.J iigt.ai""t, and the purchaser would regard himself as

f;;ffil;r;iffi; ir-t Jurt".*i'a' discovered that the manufacturer had

r.pfu""ea purt of the said ingredient by some other substance'- -'For

this reason I am sure that evenif the Mjnjstry were to adopt Dr Aitken's

-""""*i'i" ..-" future amending legislation, every Public Analyst would.con-

ffi"" il;;"k;;;;;;tr;ii; a.;'rm"ine the content of the named ingredient'

ili*.r* iim"rft tfri, *igttt t"; u"Aif the result were significantly less than the

ill"i-rr- ifr"t he regarJed as'satisfactory, he-would gtify the sample to be

il.n-.i.ril, it rGerJaient ana therefore not of the quality demanded' More-

;;;;I;;a;dhure that a prosecution based on iuch a certificak would' ifin" J"r.'*"td .".petently presented to the Court, result in a conviction'*Th;d;i;itt;Jiionur

uni*"irtods is falling short of the increasins world

a.Jrral"r{* trrortage will become more and more serious; and in conse-

q""o"a it -uV U*ome iecessarv to dilute animal with non-animal protein and to

combine reasonable cost, acceptable taste and nutritional adequacy' It will be

#;;.il;;;;;;i" ir," s.iti,h p'tlic to tolerate such a departure from their

;;;;'rl i."dtrg habits. Evenihen, I hold strongly that there must be accom-

;ffi;; H;i;;isi.n"" tt ut traditional names such as "steak pie" must not be

A;il;J; n-ew narnes must be ;oined for new products and a product honestly

of"i"a i. "neo-steak pie" will sell on its merits'

Until that day comes, standards based on nutritional considerations alone

*o"riJ^.oi-"t "r'g"

the Public Analyst's attitude to his job-ttrat the primary

;;;;;i il;;sten"e is to muke'possible the enforcement of section 2 of the

Food and Drugs Ac' " "*yr}?io

I

J. Atsoc. Publ. Analyrts, 1919, 17, 139-142

Book Reviews

A HANDBooK oF DEcoMposrrroN MErHoDs rN ANALYTTCAL Cnrursrnv. ByRt DoLF BocK, translated and revised by I. L. Marr. Intemational Text BookCompany, 1979. Price f,19.75. 444 pp. * xii.

Many analysts, particularly food analysts, will be aware ofthe book by T, T.Gorsuch enlilled The Destruction of Organic Matter (Pergamon Press, 1970)which fust brought together information on the generally neglected problemsinvolved in destroying an organic matrix prior to analysing for trace inorganicconstituents. The present volume acknowledges Gorsuch's pioneer work asproviding much inspiration for its own compilation. The German edition ofthe book appeared in 1972 ar,d opportunity has been taken, in producing therecent English translation, to expand the text considerably in the light of laterdevelopments. The book is, in fact, a detailed review of the literature and is,furthermore, much wider in scope than that of Gorsuch in that it deals with thedecomposition and "opening out" of inorganic samples as well as organic ones.

There are six chapters, occupying three hundred pages which review the tech-niques classed by way of general principle (e.g. Chapter 5-"Oxidising Pro-cedures"). Next are almost 100 pages of references, listed and numbered bychapter and containing some 3500 entries. The book continues with 34 pagesof appendices and concludes with an index.

Looking at the text in more detail, chapter I is an introduction discussingpractical matters such as container materials for corrosive liquids and melts, andtheir limitations. This chapter also deals with sources of error arising from t}redestruction of a sample, including losses as spray and losses by volatilization,adsorption and reaction with the container and concluding with a discussion ofblank values and of automation.

The short chapter 2 reviews methods of dissolution not accompanied by achemical reaction.

The third chapter discusses methods of decomposition based on supplyingenergy to the sample, concentrating mainly on thermal decomposition. Here isincluded, for example, a table ofthe main breakdown products of high polymersat specified temperatures, which is useful when analysing an unknown polymerby pyrolysis gas chromatography.

Chapter 4 deals with procedures involving chemical reaction other than oxida-tion and reduction and includes the use of reagents such as complexing agents,hydrogen fluoride and other fluoro-compounds, the other hydrogen halides,phosphoric acid, enzymes and alkali metal hydroxides and carbonates. Alsoincluded is a discussion of pyrohydrolysis. As in all other chapters, someexperimental detail is given, tho,,gh slearly only the "bare bones" can be statedfor most methods and this usually takes a tabular form, including sample typeand weight, the reagents and conditions, and a reference.

139

r

140 BOOK REVIEWS

Chapter 5, "Oxidising Procedures", presents a rer.iew of the many methodsused to destroy a sample by oxidation and is the largest chapter in the book, areflection of the widespread use ol such techniques. Gaseous oxidation methodsreviewed include dry ashing in the atmosphere and oxvgen flask techniques. Inthe former process, very widely used because of its great simplicitl,, the authorpresents detailed information, in smaller type, ol the behariour of some fiftyelements during ashing; this includes precautions to be used to orevent losses,such as recommended ashing aids, maximum temperatures and acceptablecrucible materials. Detailed information is also given for the orlgen flasktechnique. Other oxidation procedures discussed include the use of oridisingacids, both singly and in mixtures, and the use of many other oxidising sub-stances in melts or otherwise, including nitrates, iodates, hydrogen peroxide andsodium peroxide. It is noteworthy that safety precautions are detailed for suchmaterials as perchloric acid and hydrogen peroxide.

The final Chapter, "Decomposition Procedures involving Reduction",reviews reduction methods involving fusion with metals, and by reaction withother reductants such as hydrogen, ammonia and carbon; these methods areused for determination of non-metals.

Following the references, the book continues with three appendices. Thefirst presents a useful one-page scheme summarising a systematic approach todissolution of a sample of unknown composition. The second is a one-pagehistorical survey of method development, too brief to be of much use to thosewith an interest in historical chemistry and irrelevant to others. The thirdappendix is a 32-page tabular summary of "decomposition methods that haveproved themselves satisfactory in routine use", again referelced. This lattersummary deals entirely with the opening out of inorganic samples, such as

silicates, and is a useful quick source ofa method for dealing with such difficultsamples.

The book concludes with a l4-page index. The volume is clearly printed andgenerally well presented, with very few errors.

The major part of the book is concerned with the opening out of inorganicsamples, such as metals, ores, silicates, alloys etc., and this reflects the fact thatsuch samples are more varied and difficult to deal lvith than organic samples.This does not mean that opening out of organic samples is not adequately dealtwith, but may mean that food analysts and others concerned with predominantlyorganic matrices may feel that the cheaper revierv by Gorsuch, supplemented bymore recent review papers in the literature, is adequate for their needs. Labora-tories dealing with a wide range of sample types, including the modern localauthority laboratory, will probably find that, although the book does not con-tain sufficient practical detail for direct use at the bench, it is nevertheless a usefullibrary reference book that will enable the analyst to decide quickly on a basicline of approach to sample preparation and on where to obtain the necessarydetailed practical information.

P. M. HoLRoYD

BOOK REVIEWS t4t

TrrE CHEMTcAL ANa.rvsrs oF MANGANEsE. By R. S. YouNc. Paris: TheManganese Centre. Gratis. 32 pp.

This is a useful little book giving a brief description of many procedures fordetermining manganese from small to large amounts.

It does not pror.ide detailed information on the detemination of manganesei the vast ran,se of natural and artificial materials in which it is present.

The late Dr W. T. Elwell, in a review of this bookinThe Analysl, wrote that amore critical comparison of the various methods of determining the elementri'ould have been useful and that the title may be a little misleading as only 2]pages are devoted to the "Determination of Impurities in Manganese".

This reviewer echoes these words and it would have added to the usefulness ofthe book, which has a fairly comprehensive bibliography of over 70 references.

G. V. JAMES

JouRNAL op ANALyTTCAL AND AppLrED PyRoI,ysts. Amsterdam: ElsevierScientific Publishing Company. Published quarterly, annual subscriptionDfl.14s.00 (c. $64.s0 U.S.).

When large molecular size precludes the use of direct chromatographicanalysis (either gaseous phase or liquid phase), as in the cases of man-madepolymers and many natural compounds, analysis must be preceded by controlledbreakdown ofthe molecule into fragments which can be so analysed. One ofthemost successful approaches here is pyrolysis, and there now appears a quartedyjournal devoted entirely to developments in this technique.

The "Analytical pyrolysis" of the title refers to the analytical application out-Iined above, whereas "Applied pyrolysis" refers to the preparative uses ofpyrolysis.

The technique has many potential applications in analytical chemistry, thoughit is essential in both qualitative and quantitative analysis to secure accuratelyreproducible breakdown conditions.

Most official laboratories will not flnd it sufficientiy justifiable to subscriberegularly to such a specifically orientated journal at this time, especially since theinstrumentation required for the technique will often include expensive itemssuch as mass spectrometry and computerised information sorting. However, itwill repay most analysts to maintain a general interest in this field.

P. M. HoLRoYD

Fooo Mlcroscopy. Edited by J. G. VAUGHAN. London: Academic Press,1979. 651pp. Price f29.60.

This is a most timely volume and intended to bridge the gap between light andelectron microscopy in its applications to food and food adulteration.

Because ofthe vast amount ofwork which has been done in this field it wouldbe difficult for one person to suNey and write about it all; hence chapters ofthe book are produced by experts in particular flelds, the whole being co-ordinated by J. G. Vaughan of Queen Elizabeth College, London.

142 BOOK REVIEWS

The book is the product of the experience of 19 authors drawn from theacademic world, industrial and government research laboratories as well as theprivate sector and credit is given to the collection of literature headings made byG. W. White and published in this journal in several parts (Annotated Biblio-graphy of Food Microscopy).

Sixteen chapters have been written, each of which is comDlete s'ith references,drawn from reputable world-wide scientific journals, and is ccrmpleied rvith anauthor and a subject index, each of several pages.

The subjects cover Fruit and Vegetables; Oil Seeds; Cereal and BakeryProducts; Cereal Starches and Proteins; Meat; Meat Products: \,Iilk and itsProducts; Eggs; Fish; Animal Feeds; Oils and Fats; Ice Cream; Su-uar; \ovelProtein Foods and a short chapter on computer-aided identification of foodmaterials.

This last chapter is an entirely new fleld and the authors point out that com-puter-aided identification of vegetable drugs has already existed for about 3years. The approach is based on the ability of the computer to scan anddescribe, to display and classify information from a matrix bank. So far,identification ofpowdered samples involves microscopical examination followedby relerence to suitable keys, atlases, punched cards or relevant text books. This,however, is not really systematic and the existing methods require an experiencedmicroscopist as inexperience does lead to error and loss of time. A programmeis presented based on twelve characters and in the programme is a data bank ofcoded information produced by examination of ailthentic materials and pub-lished literature.

Final confirmation of the identity is obtained by comparison with authenticreference material. A programme is given as an example involving 161powdered food materials. A list of chemo-microscopical reagents is given andin conclusion the authors state that on the application described 94.4 per cent. ofthe foods have a discrimination factor index 75.

The other chapters are all of interest and are, as previously mentioned,written by experts following a system of general description of the structure, themethodology of light microscopy followed by electron microscopy, both trans-mission and scanning as may be required.

The book is well illustrated with black and white photomicrographs which arewell annotated, occupy many pages and have been very well produced,

In my opinion this is a most useful book both to analysts and microscopists,public and private, including industrial chemists, and the money would be wellspent in acquiring this book for the library of an analytical ,uboru8lrr.

,nru,

J. Assoc. Pabl. Analytts, 1979,17, 143-144

Roland Gordon Minor, F.P.S., M.Chem.A., C. Chem.,F.R.I.C. 19tt-1979

It was with profound shock and deep regret that members of the Association learned of thedeath of their esteemed colleague Gordon Minor on 17 May 1979, it having been but a few shortdays since they had enjoyed his con)pany at the Association's Silver Jubilee Annual Dinner.

Following his eaaly education at the Howard Gardens Crammar School, Cardiff, Minor'scareer commenced with a 3-year apprenticeship in retail pharmacy followed by 4 years' study at theCardifi Technical College, during which he obtained both the Pharmaceurical Chemist Diploma(later to be redesignated as Fellowship of the Phatmaceutical Society), in 1933 and the Ass6ciate-ship of the Royal Institute of Chemistry, in 1934. Then foliowed 4 yean' experience in thepharmaceutical manufacturing industry with his employment first as a chemist wjth Messts.Burgoyne Burbidges & Co. of London and then with the Glaxo Laboratories at Middlesex.

With this sound educational and pharmaceutical experience behind him, Cordon Minofsdistingu ished career in the Publ ic Ana lytical service commenced in i 938 when h€ \ as appoin ted asassistant to Stanley Djxon at the Cardiff City Councii Laboratorv, undcr whom he seived for 8years, passing the Royal lnstitute ofChemistry (Branch E) examination for Fellowship in 1940. In1946, Minor moved to London on taking up the Deputy Public Analyst appointmeot to SouthwarkBorough Council, a position which he held until 1968 when he was appointed Public Analyst on theretirement of D. H. Button. SeNices \rere then also being provided by the Southwark departmentto the London Borough of Islington and Gordon Minot served as Public Analyst to both of theseAuthorities and to the LondonBoroLrgh of Greenwich, whose rvork rvas undirtaken from 1971,until his own rctirement in 1973. Throughout his prolessional career Minor was an untiringsupporter ofthe Association of Public Analysts, giving service both as a member of Council and ofthe Standards Committee, in addition to representing the Association in various negotiations andconsultations with associated official bodies. It is in these roles that he will be warmly rememberedby many of his colleagues.

The other, and major, role in which Gordon Minor will be appreciatively remembered is asorganisidg lecturer of the postgraduate evening course in food and drngs hcld originally at ChelseaCollege and transferred in its later years to the Polytechnic ol the South Bank. Miror conductedthis course for a period of some 22 yeals and it is with a special debt of gratitude that so many ofhis past studeflts, from both the food and pharmaceutical industries in addition to the PublicAnalyst Service, will remernber him lor the encouragement, thorough guidance and enlightenmertgiven to them in this valuable course of study.

When Minor retired from his firll-time appointment in 1973 he remained an active supporter oflhe q)5ociarion and, characrcristically. it \aas at that time ihal he accepred rhe appoiitimenr asHonorary Editor of the Joumal, giving sterling service in thrs capactly for almost 4 years.

Minor's love of golf and the open air will be well known to his l'riends and colleagues, his othetforms of relaxation including music, garde[ingand reading. Heleaves hisdevoted wife Madge andtwo sons Derek and Philip. both of ra hom have lollowed their father's general profes.ional calliogin having adopted careers in chemistry and biochemislr) respectively. The Associalion, in sharingwith his family this sad loss, will long remember the friendship and esteemed selvice ofa respectedcolleague

G. R. B. GARDTNER

Stanley Dixon 1895-1979

Stanley Dixon was born in Gainsborough, Lincs. in 1895 and was educated at GainsboroughGrammar School and then Sheffield University, where he obtained his M.Sc. in 1917. His workingcareer started as an assistant to the Public Analyst of the Cities of Shefreld and York and after ashort spell of service in the Royal Navy he became chief assistant to the Public Analyst of DerbyCounty. In 1920, he passed the Branch E examination of the Institute of Chemistry (nowM.Chem.A.) and became a Fellow in the following year.

In 1929, Stanley Dixon became Public Analyst arld Official A$icultural Analyst to the City ofCardiffand was appointed in the same capacity to the County Borough ofswansea in 1943. Theseposts he held foi the rcmainder of his working life, retiring in 1961 after many yea$ of faithfulservice. He always took a keen and active interest in his professional societies and was a Membeiof Council of the S.A.C. on several occasions and Chairman of the Local Section, as \rell as taking a

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144 OBITUARIES

ve keen intercst irl thi Association of Public Analysts du.ring the very early years' Mr Dixoawa; fortutrate in having a very happy family life, having married Phyllis, the third daughter ofJohnWhite, a former Count Anaiyst to the County ofDerby. He wasjustly proud of his two sons, theelder being Professor oiBacteriology at the University ofAlberta and the other Director of Mathe-matical Slridies at Churchill College, Cambridge.

However. slanlev Dixon will be remembered bv his colleagues as a meticulous analyst and anambassador for the profession ol Public Analysls. He was a jovial and I ikeable person who, to mycertain knowledee. did not have an enemv in lhe world, ll was a privilege and a pleasure lo haveworked for him ind ro have known and eirioved the companv of his familv and friends. He leavesa widow. two sons. two daughters-inlaw and two grandchildren, who, like many others, miss himuery mu6h. He passed awa-y Iairly suddenly on 3rd Apdl, 1979 in his eightv-fifth year after a fulland active life'

L. B. co,-Es