The Australian Centre for International Agricultural Research (ACIAR) was established in June 1982 by an Act of the Australian Parliament. Its mandate is to help identify agri­ cultural problems in developing countries and to commission collaborative research between Australian and developing country researchers in fields where Australia has a special research competence. Where trade names are used this constitutes nei1her endorsement of nor discrimination against any product by the Centre. ACIAR TECHNICAL REPORTS SERIES This series of publications contains technical information resulting from AClAR-supported programs, projects and workshops (for which proceedings are not published), reports on Centre-supported fact-finding studies, or reports on other useful topics resulting from ACIAR activities. Publications in the series are distributed internationally to selected individuals and scientific institutions. © Australian Centre for International Agricultural Research, GPO Box 1571, Canberra, ACT 2601. Highley, E. and Johnson, G.I., ed. 1996. Mycotoxin contamination in grains. Papers presented at the 17th ASEAN Technical Seminar on Grain Postharvest Technology, Lumut, Malaysia, 25-27 July 1995. ACIAR Technical Reports No. 37, 145p. ISBN 1 86320 171 8 Pre-press production by Arawang Information Bureau Ply Ltd, Canberra. Australia. Mycotoxin Contamination in Grains Papers presented at the 17th ASEAN Technical Seminar on Grain Postharvest Technology, Lumut, Malaysia, 25-27 July 1995 Editors: E. Highley and G.I. Johnson Australian Centre for International Agricultural Research Canberra 1996 Contents Preface 4 Current Knowledge of Fungi and Mycotoxins Associated with Food Commodities 5 in Southeast Asia J.I. Piu and Ailsa D. Hocking Controlling Aflatoxin Contamination in Maize Stored under Tropical Conditions 11 Somkiat Prachayawarakorn, Somchart Soponronnarit, Adisak Nathakaranakule, and Sittichi Inchan Occurrence and Significance of Storage Fungi and Associated Mycotoxins in Rice 18 and Cereal Grains Zofia Kozakiewicz Effect of Drying Control on Mycotoxin Production 27' P.L. Douglas and R. Boyle The Aflatoxicosis Problem and Management of Aflatoxin in Feed in Vietnam 34 Tran Van An and Duong Thanh Liem Surveys on Postharvest Handling, Aspergillus flavus Infection, and Aflatoxin 38 Contamination of Maize Collected from Farmers and Traders O.S. Dharmaputra, I. Retnowati, H.K. Purwadaria, and M. Sidik Relationship between Soil Populations of Aspergillus flavus and Aflatoxin 54 Contamination under Field Conditions in the Philippines Rosalind P. Garcia, Peter J. Cotty, Jay Scot! Angle, and Helen A. Barrios Inhibition of Aflatoxin Contamination in Rice by Cladosporiumfulvum 61 Roberta D. Lauzon, Reynaldo C. Mabesa, and Joy Villaralbo-Sumague Completed-project Economic Assessment of Two ACIAR Projects on Fungi 66 and Aflatoxins: a Discussion of Methodology Issues and Some Estimates of Potential Benefits Godfrey Lubulwa and Jeff Davis Mycotoxin Contamination of Grains-a Review of Research in Indonesia 112 Srikandi F ardiaz Overview of Aflatoxin Contamination of Selected Agricultural Commodities 120 in Malaysia A. Mat Isa and H. Abidin The Challenges of Mycotoxin Research and Development Work on Foods 125 and Feedstuffs in the Philippines Irene L. Villapando Control of Aflatoxin Contamination in Maize in Thailand 139 Suparut Kositcharoenkul Aflatoxin in Animal Feeds and Effects on Poultry Production in Vietnam )43 Duong Thanh Liem and Le Anh Phung 3 Preface THE annual ASEAN Technical Seminars on Grain Postharvest Technology, held since 1978, are the premier regional forum for the presentation of the results of postproduc­ tion research, development, and extension studies on grains and related durable com­ modities. This technical report publishes the papers presented during a session on mycotoxin contamination in grain that was part of the 17th ASEAN postharvest seminar, held in Lumut, Malaysia in July 1995. The seminar was organised by the ASEAN Food Hand­ ling Bureau (AFHB) and supported by the National Paddy and Rice Company of Malaysia (BERNAS) and ACIAR. ACIAR deemed the publication of these papers as important, given the growing con­ cern in ASEAN and elsewhere of the regular occurrence of unacceptable levels of mycotoxins in a number of food and feedstuffs, most importantly maize and peanuts. High levels of mycotoxins are hazardous to human and animal health, and have wider economic implications through loss or devaluation of commodity and by impeding international commodity trade. The papers in this report constitute a detailed account of the status of food-grain fungi and mycotoxin problems and research in the region. There are country papers from all the ASEAN grain-producing countries, covering all staple grains, and more general papers on grain drying and other means of preventing or reducing fungal infection and mycotoxin contamination. There is also a paper giving a detailed economic assessment of the costs and potential benefits from two ACIAR-supported research projects which gathered information about fungal infection and mycotoxin contamination in staple food and feedstuffs in Southeast Asia. The assessment focuses on aflatoxin contamination of peanuts and maize and its impact on human health and animal production. It suggests that substantial benefits will accrue from technological advances in pre- and postharvest practices likely to be stimulated by the research. Mycotoxins are a real problem in ASEAN and the wider Asian region, with pro­ found implications for human and animal health, national economies, and international trade. ACIAR will continue to support wen-founded collaborative research to further characterise the problem and develop cost-effective solutions. 0.1. Johnson Coordinator ACIAR Postharvest Technology Program 4 Current Knowledge of Fungi and Mycotoxins Associated with Food Commodities in Southeast Asia J.I. Pitt and Ailsa D. Hocking* Abstract A five-year study was carried out on the occurrence of fungi and mycotoxins in all major food commodities traded in Thailand, Indonesia, and the Philippines. More than 1700 samples were examined, including maize, peanuts, rice, soybeans, mung beans, sorghum, cashews, spices, and herbs. Samples were collected randomly from farm storage, middlemen, and retail shops, to follow the time course of infection. Fungi were detected and enumerated by direct plating on Dichloran Rose Bengal Chloramphenicol agar and Dichloran 18% Glycerol agar after surface disinfe,:tion in 10% chlorine solution. By this means only fungi actually growing in the foodstuffs were detected. More than 35000 fungi were isolated and identified. The major fungi found in maize were Aspergillus flavus and Fusarium moniliforme. In peanuts. the predominant fungi were A.flavus and A. niger. The most common Fusarium species were F. semitectum and F. equisefi, while Penicillium citrinum and Eurotiurn species were isolated frequently also. Infections in rice and beans were dominated by field fungi. In paddy rice, Trichoconiella padwickii (- Alternaria padwickii) was most commonly encountered. The dominant Fusarium species was F. semitecfum. Aspergillus species, including A. flavus, were less common. Polished rice was practically free of fungi. presumably duc to the heat generated during the dehulling process. Infection levels in most bean samples were low. F. semitectum was the species most commonly isolated from mung beans, while higher levels of A.flavus were found in soybeans than other beans. Selected samples were assayed for aflatoxins. High levels were often found in maize and peanuts. The potential for production offumonisins in maize due to the high presence of F. moniliforme is also important. FuNGAL invasion of commodities before and after lot, and because such commodities are difficult to harvest, and during distribution and storage, is a well obtain in any systematic way. Most samples studied recognised problem throughout the world. This is were of acceptable visual quality, free of visible mould especially true in tropical countries, where mycotoxin and insect damage. contamination of food supplies remains a major threat. More than 1700 samples were examined. Major Over a period of five years, we studied the occurrence commodities studied in each country were maize, of fungi and mycotoxins in all major food commod­ peanuts, soybeans, mung beans, and rice. This paper ities traded in Thailand, Indonesia, and the Philippines. provides an overview of the results obtained, and of The work was confined to good grades and com­ over 700 aflatoxin assays in maize and peanuts. mercial channels. No attempt was made to study lower Results for commodities examined in less detail, or grade commodities. both because lower grade in only one or two countries, including cashews, materials are highly variable in quality, even within a sorghum, black and red beans, copra, black and white sesame seeds, cassava, black rice, copra, wheat, spices, and herbs, have been reported elsewhere (Pitt et al. * CSIRO Division of Food Science and Teclmology. P.O. 1993, 1994) or will be covered in papers in prepa­ Box 52. North Ryde. New South Wales 2113. Australia. ration. 5 Materials and Methods Aflatoxin assays Aflatoxins were assayed essentially by the method Samples of Beebe (1978). Samples were ground, subsampled, Samples of major commodities were obtained as far extracted with methanol: O.IN HCI (4: I), washed with as possible from throughout the distribution chain, hexane, then extracted with chloroform. If necessary,