International Journal of Food Microbiology, 7 (1988) 219-225 219 Elsevier

JFM 00MS3

Mould deterioration of agricultural commodities during transit" problems faced

by developing countries

Ramesh V. Bhat National Institute of Nutrition, lndJan Council of Medwal Research. Jamai Osmanta. IIvderabad, Indta

Huge quantities of agricultural commodities are being either imported or exported by the developing countries. The commodities have to be transported from the fields of cultivation to the centres of consumption, considerable time being taken for the movement not only because of long distances but also because of various socio-economic, environmental and biological reasons. These commcx:lities are likely to be damaged by mould growth and subsequent aflatoxin accumulation. If the contamination occurs during transit, often no insurance cover for the risk is available. Because of different methods of sampling followed in the exporting and importing countries it is often difficult to define the exact responsibility of the development of aflatoxin as having taken place during transit. The statistics of the export of aflatoxin high-risk commodities like red pepper (chillies), cotton seed and groundnut extrac- tions clearly, for the last decade, demonstrate the extent of loss suffered by the exporting countries because of aflatoxins. The problem of mould damage and mycotoxin contamination can be minimised by improving facilities for storage at ports and transit points as well as on ships.

Key words: Agricultural commodities; Transit of agricultural commtxtities: Aflatoxins

Current situation

T h e d e v e l o p i n g c o u n t r i e s o f t he w o r l d h a v e a c o n s i d e r a b l e i m p o r t a n d e x p o r t

t r a d e in a g r i c u l t u r a l c o m m o d i t i e s . D e p e n d i n g o n t he o c c u r r e n c e o f d r o u g h t s , f loods ,

d i s e a s e o r pe s t s w h i c h r e s u l t in p o o r y ie lds a n d p e r h a p s f a m i n e , t he s a m e c o u n t r y

c a n b e e i t h e r a n i m p o r t i n g c o u n t r y o r a n e x p o r t i n g c o u n t r y o f a g r i c u l t u r a l c o m m o d -

i t ies. T h e m a j o r c o m m o d i t i e s e x p o r t e d f r o m d e v e l o p i n g c o u n t r i e s a re o i l seed c a k e

a n d mea l , c o r n , r ice, ba r l ey , s o r g h u m , s o y b e a n , pu l ses , g r o u n d n u t s , c o p r a ( d r i e d

c o c o n u t ) a n d p a l m n u t s ( T a b l e I). O i l s e e d c a k e a n d m e a l a n d g r o u n d n u t s a re

g e n e r a l l y e x p o r t e d f r o m d e v e l o p i n g to d e v e l o p e d c o u n t r i e s . O t h e r c o m m o d i t i e s a re

g e n e r a l l y e x p o r t e d f r o m o n e d e v e l o p i n g c o u n t r y to a n o t h e r n e i g h b o u r i n g d e v e l o p i n g

c o u n t r y o r f r o m d e v e l o p e d c o u n t r i e s l ike the U.S .A. , E .E .C. a n d A u s t r a l i a to the

Correspondence address: Food and Drug Toxicology Research (?entre, National Institute of Nutrition, Indian Council of Medical Research, Jamai Osmania P.O., Hyderabad - 500 007, India.

0168-1605/88/$03.50 O 1988 Elsevier Science Publishers B.V. (Biomedical Division)

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TABI.E I

World volume of export of major agricultural products. (Figures in thousand metric tonnes).

( 'ommodity World Developing countries

Wheat 102 23,1 4 622

Rice 11 986 6663

Barley 18203 1 807

Maize 70001 9 352

Millet 215 131

Sorghum 13 653 6 050

Potatoes 5 135 585

Pulses 2 820 1 292

Soybeans 28 916 2 906

Groundnuts 790 353

Copra 436 266

Palm nuts 137 122

Oil seed cake & meal 27063 11 301

Source: State of Fo{xl and Agriculture 1983, FAO, Rome.

developing countries, normally involving long sea voyages. There is a considerable time lag between the purchase of the agricultural

commodity at the farm centre or village market of the exporting country and the time it reaches the distribution centre in the importing country. The transit chain for the transport of agricultural commodities extends from farm to collection centre, from hinterland to port, from the port of an exporting country to the port at the importing country, and again from the port to the areas of consumption in the country of import. At each of these stages the agricultural commodity has to be stored, the period of storage depending on such factors as the distance involved, the mode and speed of transport, management problems, including the availability of transport, manpower to load or unload, customs clearance, and weather conditions like the monsoon. In many parts of the developing world sub-optimal conditions of storage exist at the various transit points as well as during transportation.

Current trade practices encourage a tendency among farmers, middle men and traders to trade in commodities containing more than the recommended moisture level since drying to a safe water content decreases the weight of the commodity and thus the price obtained. Although sometimes, slightly higher prices are paid for well-dried commodities, these may not compensate the farmer sufficiently to ensure that he will adequately dry his crop. Other factors that often contribute to the storage of commodities with a higher than recommended moisture are the vagaries

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of the monsoon, lack of proper drying yards and lack of time to adequately dry the crop. Also during transit and storage at transit points, insufficient cover or protec- tion may allow wetting by rain, moisture migration or condensation leading to the development of moulds. Mould growth can cause increase in temperature and moisture, discoloration, musty odour, loss of seed viability and the development of mycotoxins such as afiotoxins in agricultural commodities. Even when the average moisture level is sufficiently low, mould growth can start in small p~:kets contain- ing excess moisture. Once moulding has started, moisture can accumulate and the mould might spread throughout the bulk.

Reliable studies on the extent to which mycotoxins develop during transit in developing countries are not available. Studies carried out in the U.S.A. have indicated that aflatoxin concentration can increase approximately 10 fold (200-2300 ng /g) in a 3 day period when a field harvested corn sample is stored with a high moisture content (Shotweil et al., 1983). The factors that affect the mould growth during transit include time of transport, condition and age of grain, proportion of broken grain and foreign matter and its distribution, grain temperature, relative humidity of air when stored, insect infestation and blending history.

Mould deterioration during transit, resulting in the accumulation of aflatoxins, leads to considerable economic, technical and health problems. Insurance cover for the risk of loss incurred by the exporter, because of the development during transit of more aflatoxin than is permissible, is currently not provided in many developing countries.

The aflatoxin clause prescribed by Denmark levies a penalty on the exporter if the aflatoxin in the raw material exceeds 50 ppb and provides for rejection of the consignment altogether if aflatoxin exceeds 125 ppb.

The average aflatoxin content in Indian cotton seed expeller cake exported to U.K. during July-September, 1985, was found by G A F T A Laboratories to be as low as 10 ppb. Thus, it is not very difficult for the Indian exporter to comply with the aflatoxin restriction imposed by the E.E.C. However, although the exporter can control aflatoxins at the port of loading, he has less control at the port of discharge since aflatoxin may be formed in shipment during transit. The risk of rejection of the goods after they have reached European or Japanese ports deters them from undertaking export to these destinations.

Another major economic problem is the price structure of the affected commod- ities. Currently, European importers either totally reject or offer lower prices for aflatoxin-contaminated commodities. Some interested parties are willing to import groundnut extraction cake containing aflatoxins at a discount but the loss incurred because of aflatoxins can reach almost 40%.

Several technical problems are encountered in detecting the mycotoxins in agricultural commodities during a voyage. The major technical problem is sampling. At the ports of the developing countries, commodities are normally stored and loaded into the containers of ships in jute or high density polyethylene bags. For estimation of the content of aflatoxin, samples are taken at random from the bags. However, at the unloading port in developed countries, the shipment is unloaded mechanically which provides good mixing and allows a more representative sam-

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TABLE 11

Export of agricultural commodities and by-products which can develop mycotoxins from India

( 'ommtydity Estimated export

1985-1986 1977-1978

Quantity " Value b Quantity Value

1. Peanut kernels

2. Groundnut (peanut) 150 270.(I extract

3. Cottonseed 54 59.7 extract/expeller

4. Rice bran extract 290 145.0

5. Sesame extract

6. Soyabean extract 51(1 1060.0

7. Sunflower seed extract 25 15.0

8. Sal seed extracts 13 3.0

9. Rape seed extract 100 60.0

130 652.4

550 850.0

156 238.6

307 146.3

6 '9.0

Thousand tonnes. h Million Rupees.

p i i n g : m y c o t o x i n s w h i c h h a d d e v e l o p e d in r e s t r i c t e d p o c k e t s d u r i n g t r a n s i t a r e m o r e

l i k e l y to b e d e t e c t e d .

T h e p r a c t i c a l p r o b l e m s f a c e d b y t h e d e v e l o p i n g c o u n t r i e s w i t h r e g a r d to a f l a t o x i n

c o n t a m i n a t i o n c a n b e s t b e i l l u s t r a t e d w i t h t h e h e l p o f a c a s e s t u d y o f I n d i a . E x p o r t s

o f a g r i c u l t u r a l c o m m o d i t i e s h a v e b e e n r e d u c e d c o n s i d e r a b l y in r e c e n t y e a r s b e c a u s e

TA BLI:. 111

Presence of aflatoxin B; in Indian peanut cake

Year % of samples containing aflatoxin (ng-g i )

Up to 250 250- 500 500 1000 Over 1000

1971 15.6 34.7 32.1 17.6 1972 11.4 37.0 32.4 19.2 1973 3.8 31.0 44.7 20.5 1974 6.6 34.3 32.3 26.2 1977 16.7 83.3 1978 28.6 57.1 9.5 4.8 1979 57.8 25.6 19.3 1.3 1980 31.9 4(1.6 26.8 O. 7

Total number of samples: 8907. Source: JB B~xta Marine & General Survey Agencies Pvt. Ltd.. Bombay (personal communication}.

TABLE IV

Aflatoxin content of Spanish type, raw shelled peanuts imported into Japan from India

223

Year Aflatoxin B~ No. detected Total

> 10 rig.g-1 < 10 ng-g- i None detected

1972 0 0 1 1 1973 0 0 2 2 1974 1 1 51 53 1975 3 10 75 88 1976 4 2 173 179 1977 0 0 36 36 1978 - 0 1979 1 5 16 22 1980 2 0 57 59 1981 -- - 0

Total 11 18 411 440

Source: Mycotoxin Research Association. Japan (personal communication).

o f a f l a tox in . T h e q u a n t i t a t i v e a n d qua l i t a t i ve p a t t e r n o f c h a n g e is d e p i c t e d in T a b l e

II. R e s u l t s o f ana ly s i s o f a f l a t o x i n in p e a n u t cake i n t e n d e d for e x p o r t a re s h o w n in

T a b l e III. S a m p l e s w h i c h c o n t a i n m o r e t h a n t h a n a g r e e d l imi ts o f a f l a t o x i n s are

r e j e c t ed for e x p o r t a n d u l t i m a t e l y e n d up in the d o m e s t i c ma rk e t , c a u s i n g p r o b l e m s

to the i ndus t ry . T h e i m p o r t i n g c o u n t r i e s i nva r i ab ly a c c e p t the c o m m o d i t i e s a f t e r

p r o p e r ana ly t i ca l con t ro l . T a b l e s IV a n d V s h o w the levels o f a f l a t o x i n s in raw

she l l ed g r o u n d n u t s a n d red p e p p e r s (chi l l ies) r e spec t ive ly , e x 0 0 r t e d to J a p a n f r o m

Ind ia . T h e a n a l y s e s w e r e ca r r i ed ou t at Y o k o h a m a by the M y c o t o x i n R e s e a r c h

TABLE V

Aflatoxin content of dried red chilli imported into Japan from India

Year Aflatoxin B~

No. with Total

> 10 ng .g- t < 10 ng-g- t None detected

1977 1 0 0 1 1978 0 2 1 3 1979 0 1 1 2 1980 1 5 2 8 1981 - 0

Total 2 8 4 14

Source: Mycotoxin Research Association, Japan (personal communication).

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Association of Japan. These examples show very low levels of aflatoxins in the small number of samples examined. It also indicates that if proper care is taken it would be possible to transport agricultural commodities with very little risk of them being contaminated with aflatoxins.

P r e v e n t i v e me&sures

The problem of mould damage and mycotoxin contamination could be mini- raised by proper drying and improving facilities for storage at ports and transit points as well as on the ships. Nuts collected from equatorial forests are often cited as a good example of contamination occurring during transportation. They are then transported to the processing plants in bulk by boat, but the journey can last up to two months. During the journey, the nuts are subject to humid conditions in which fungal development and toxin production are likely to occur. This could be avoided if the nuts were dried adequately and kept dry during transit.

Attempts could be made to construct godowns and silos at the ports and appropriate storage structures at the transit points. Indeed, in India it was recom- mended that the construction of silos be limited to the ports only and not in other places (Administrative Staff College of India, 1976). For reasons of economy and logistics it is not always possible to construct permanent storage structures at transit points, including ports. Temporary covers and plinth storage (CAP) are possible alternatives. This type of storage, practised successfully in India for over a decade consists of selecting a suitable site in a comparatively elevated position and storing the agricultural commodities in bags on 15 cm high platforms made of wood or iron bars. The stocks are totally covered by black high density polyethylene sheets and tied securely to prevent them being blown away by wind. Such CAP storage structures have the advantage of being cheap and can be easily erected or disman- tled at short notice by unskilled labourers. Even fumigation can be easily applied. Using CAP storage, the Food Corporation of India has found that commodities like wheat can be stored successfully for as long as 3 years even under adverse weather conditions.

One of the barriers to reducing aflatoxin in agricultural commodities is the lack of facilities for quick transport. Poor roads and bridges often cause slow transport of commodities. Communication facilities should be improved. Appropriate cover should be used during transit especially under monsoon conditions.

Poor management (the failure of the human factor) has often been the cause of damage to food grains in developing countries. These include the lack of vehicles for transport on time, carelessness of the workers in not covering the consignment properly, unhygienic storage facilities and transport vehicles, bureaucratic bottle- necks such as customs clearance at ports and excise checks at check-points on the roads. Such delays and carelessness could be minimised by proper educational and extension programmes at appropriate levels on the harmful effects of mould damage.

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In the past, disputes and disagreements have arisen between impor t ing and export ing countr ies on the methodology of sampling, use of different analytical methodology for es t imat ion of aflatoxins as well as fixing of tolerance limits. If an in te rna t iona l agreement could be arrived at on these sensitive issues, mycotoxin control and prevent ion programmes would improve considerably.

Acknowledgements

The author is grateful to Dr. B.S. Naras inga Rao, Director, Nat ional Inst i tute of Nutr i t ion, Hyderabad for useful discussions. The valuable informat ion provided by the J.B. Boda Marine and General Survey Agencies, Bombay and the Mycotoxin Research Association, Tokyo is gratefully acknowledged.

References

Adnunistrative Staff College of India (1976) All India Grain Storage and Distribution Port Handling. A Study Sponsored by Government of India. Administrative Staff College, Hyderabad.

FAO (1984) State of Food and Agriculture, 1983. Food and Agriculture Organization, Rome, pp. 221. Ministry of Agriculture and Irrigation, Government of India (1978) Report on Task Force on Agricult-

ural Exports, New Delhi, pp. 51. Shotwell, O.L., Bennet, G.A., Kwolek, W.F. and C.W. Hessehine (1983) Treatment of harvested 1980

Georgia dent corn samples collected for aflatoxin analysis. J. Assoc. Off. Anal. Chem. 66, 204 207.