Moulds and mycotoxins in rice in Swedish retail

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Moulds and mycotoxins in rice in Swedish retailElisabeth Fredlund, Anna Maria Thim, Ann Gidlund, Siv Brostedt, Marianne

Nyberg, Monica Olsen

To cite this version:Elisabeth Fredlund, Anna Maria Thim, Ann Gidlund, Siv Brostedt, Marianne Nyberg, et al.. Mouldsand mycotoxins in rice in Swedish retail. Food Additives and Contaminants, 2009, 26 (04), pp.527-533.�10.1080/02652030802562912�. �hal-00577343�

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Moulds and mycotoxins in rice in Swedish retail

Journal: Food Additives and Contaminants

Manuscript ID: TFAC-2008-074.R1

Manuscript Type: Original Research Paper

Date Submitted by the Author:

16-Sep-2008

Complete List of Authors: Fredlund, Elisabeth; Microbiology Division, Research and Development Department, National Food Administration Thim, Anna Maria; Chemistry Division 2, Research and Development Department, National Food Administration Gidlund, Ann; Microbiology Division, Research and Development Department, National Food Administration Brostedt, Siv; Chemistry Division 2, Research and Development Department, National Food Administration Nyberg, Marianne; Chemistry Division 2, Research and Development Department, National Food Administration

Olsen, Monica; Microbiology Division, Research and Development Department, National Food Administration

Methods/Techniques: HPLC, Mycology

Additives/Contaminants: Aflatoxins, Ochratoxin A

Food Types: Rice

http://mc.manuscriptcentral.com/tfac Email: [email protected]

Food Additives and Contaminants

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Fredlund et al. Moulds and mycotoxins…

1

Moulds and mycotoxins in rice from the Swedish 1

retail market 2

3

E. FREDLUND1, A-M THIM2, A. GIDLUND1, S. BROSTEDT2, M. NYBERG2, & 4

M. OLSEN1 5

6

7

8

9

1 Microbiology Division, Research and Development Department, National Food 10

Administration, P.O Box 622, SE-751 26 Uppsala, Sweden 11

12

2 Chemistry Division 2, Research and Development Department, National Food 13

Administration, P.O Box 622, SE-751 26 Uppsala, Sweden 14

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Abstract 1

A survey of moulds and mycotoxins was performed on 99 rice samples taken from the 2

Swedish retail market. The main objective was to study mould and mycotoxin content in 3

basmati rice and rice with a high content of fibre. Samples of jasmine rice as well as long-4

grain rice were also included. The samples were analysed for their content of ochratoxin A 5

(HPLC), aflatoxin B1, B2, G1, and G2 (HPLC, RIDAQUICK), and mould (traditional 6

cultivation methods in combination with morphological analysis). The majority of samples 7

were sampled according to the European Commission Regulation 401/2006. Sub-samples 8

were pooled and mixed before milling and both mould and mycotoxin analyses were 9

performed on milled rice. The results showed that the majority of basmati rice (71%) and 10

many jasmine rice samples (20%) contained detectable levels of aflatoxin B1 (level of 11

quantification = 0.1 µg aflatoxin kg-1 rice). Two samples of jasmine rice and 10 basmati rice 12

samples contained levels over the regulated European maximum limits of 2 µg kg-1 for 13

aflatoxin B1 or 4 µg kg-1 for total aflatoxins. Aspergillus was the most common mould genus 14

isolated but also Penicillium, Eurotium, Wallemia, Cladosporium, Epicoccum, Alternaria and 15

Trichotecium were found. The presence of Aspergillus flavus in 21% of the samples indicates 16

that incorrect management of rice during production and storage implies a risk of mould 17

growth and subsequent production of aflatoxin. Rough estimates showed that high rice 18

consumers may have an intake of 2-3 ng aflatoxin per kg bodyweight and day from rice alone. 19

This survey shows that aflatoxin is a common contaminant in rice imported to Europe. 20

21

Keywords: basmati rice, aflatoxin, ochratoxin A, jasmine rice, retail, Aspergillus flavus, 22

mould23

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Introduction 1

Rice (Oryzae sativa L) is one of the most important staple foods world-wide. Various 2

varieties of rice are cultivated in different parts of the world and some of them are restricted to 3

specific geographical regions, such as basmati rice in Pakistan and India (Bhattacharjee et al. 4

2002) or jasmine rice in Thailand (International Rice Institute, http://www.irri.org/). 5

6

The paddy rice or rough rice is harvested with the hull (or husk) when the water content is 7

approximately 20%. The water content must be further reduced by drying to 13-14% to 8

eliminate microbiological activity during storage. The hull is removed and the remaining 9

brown rice is processed further into various rice products such as whole-grain rice, parboiled 10

rice, polished rice etc. The rice kernels can be of varies sizes and are classified as long-grain 11

rice, medium-grain rice, and short-grain rice. 12

13

During cultivation and subsequent handling of rice, kernels can be contaminated by moulds, 14

which can grow and produce mycotoxins if conditions are favourable. The fungi may later die 15

due to increased temperature or dry periods, but once produced, the stable mycotoxins will 16

remain in the rice. Fungal activity depends on the moisture content and temperature, which 17

can both vary significantly in a silo depending on its design and environmental factors. Post-18

harvest treatment of rice, including adequate drying and conditions of storage, are crucial 19

factors that will determine storage stability. 20

21

Species of Fusarium have been isolated from newly harvested paddy rice (Pitt et al. 1994; 22

Pacin et al. 2002) and low levels of Fusarium-toxins have been detected (Kim et al. 1998; 23

Park et al. 2005). However, Fusarium-toxins are not considered a risk in rice (EC Regulation 24

856/2005). In stored rice, the fungal flora is different from that in newly harvested rice. 25

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Aspergillus spp. are common contaminants of stored rice (Kim et al. 1998; Park et al. 2005; 1

Sales and Yoshizawa 2005) but species of Alternaria and Penicillium have also been reported 2

(Pitt et al. 1994; Park et al. 2005). Several studies have reported detectable levels of aflatoxins 3

and ochratoxin A in rice from different countries including Cuba (Escobar and Regueiro 4

2002), Korea (Park et al. 2005), Malaysia (Abdullah et al. 1998), Sri Lanka (Bandara et al. 5

1991), the Philippines (Sales and Yoshizawa 2005), the United Arab Emirates (Osman et al. 6

1999), India (Toteja et al. 2006), and Côte d’Ivoire (Sangare-Tigori et al. 2006). Rice is a 7

major cereal crop consumed by the European population, yet, reports on the actual mycotoxin 8

content in rice is limited. This was also pointed out by the UK Food Standard Agency, which 9

performed a survey of mycotoxins in rice in 2002 (FSA, 2002). Of the 100 rice samples 10

analysed, none of the samples (including 18 samples of basmati rice) contained mycotoxins 11

over the EC regulated limits. 12

13

Aflatoxins are genotoxic and carcinogenic substances that may induce liver cancer in both 14

humans and animals. Aflatoxins are produced by several species of Aspergillus including A. 15

flavus (aflatoxin B1 and B2) and A. parasiticus (B1, B2, G1, and G2). A toxicological 16

evaluation of aflatoxins was made by the Joint FAO/WHO Expert Committee of Food 17

Additives (JECFA) in 1998 (WHO 1998) and by EFSA in 2007 (CONTAM Panel 2007), 18

which both concluded that aflatoxins should be treated as carcinogenic food contaminants and 19

the intake should be reduced to levels as low as reasonably achievable. Aflatoxins are 20

genotoxic substances and therefore no tolerable daily intake (TDI) levels have been set for 21

these toxins. However, an intake of one ng per kg bodyweight (bw) and day, corresponding to 22

a life-time cancer risk of one extra cancer case for 105 individuals may be considered as an 23

acceptable risk. 24

25

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Ochratoxin A is a nephrotoxic agent with immunotoxic, neurotoxic and teratogenic effects at 1

higher dose levels. The toxin is produced by representatives of the two genera Penicillium and 2

Aspergillus genera. Ochratoxin A was evaluated by JECFA in 2001 (WHO 2001) and by 3

EFSA in 2006 (CONTAM Panel 2006). The PTWI for ochratoxin A was set to 100 ng per kg 4

bw by JECFA (WHO 2001) and to 120 ng per kg bw by EFSA (CONTAM Panel 2006). 5

6

Within the European Union, contamination of mycotoxins in food are regulated by the EC 7

regulation 1881/2006, which regulates the maximum level (ML) of mycotoxins allowed in 8

food, and the EC Regulation 401/2006, which regulates the sampling for mycotoxin control of 9

foods. The ML’s in cereals for ochratoxin A is three µg kg-1, for aflatoxin B1 two µg kg-1 and 10

for the sum of aflatoxin B1, B2, G1, and G2 four µg kg-1. There are no regulated levels for 11

mould in food. However, the presence of aflatoxin-producing species such as Aspergillus 12

flavus, A. parasiticus and A. nomius or the ochratoxin-producing species Penicillium 13

verrucosum, A. ochraceus, A. niger, A. carbonarius, and A. westerdijkiae may indicate the 14

presence of these toxins. 15

16

In 2006, high levels of aflatoxin M1 was detected in milk in the companies own quality 17

controls. The source of contamination was aflatoxin-contaminated rice bran, a by-product 18

from a rice-mill, which was used as an ingredient in cattle feed in the south of Sweden. In 19

contrast to milk, rice is not routinely controlled for the presence of aflatoxin. Rice has become 20

an important stable food for the Swedish consumers. In 2006, Swedes consumed 5.4 kg rice 21

per person, which can be compared to 9.5 kg pasta per person, which is another important 22

staple food (JORDBRUKSVERKET, 2008). 23

24

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The objective of this survey was to investigate the presence of mould, aflatoxins and 1

ochratoxin A in rice available for purchase in he Swedish retail market. The results were used 2

to estimate the intake of these mycotoxins from rice by Swedish consumers. Rapid semi-3

quantitative methods, such as lateral-flow devices, for the analysis of aflatoxin in various food 4

items (nuts, figs etc.) have been developed. To evaluate whether such methods may be 5

suitable also for screening for aflatoxin in rice, one such method, RIDA®QUICK Aflatoxin 6

(R-Biopharm AG, Darmstadt, Germany) was used in parallel with HPLC analysis. 7

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Material and Methods 1

Sampling and sample treatment 2

The majority of rice samples were purchased from retail outlets in the South and Central parts 3

of Sweden in Malmö, Stockholm, Uppsala, and Gothenburg. Rice samples were purchased 4

from large retail stores, small local shops, health shops, shops with organic products and 5

shops with products of mainly ethnical origin. Most samples (73 of 99 samples) were taken 6

according to the alternative sampling plan for official control of mycotoxins in food (EC 7

401/2006). 8

9

Sub-samples (0.5-2 kg) were pooled and mixed for 15 min (IGF 2400/S382, Svea, Linköping, 10

Sweden) and 1 kg of the pooled sample was then ground to fine powder (Retsch GmbH & Co, 11

Haan, Tyskland) and stored in room temperature until analysis. The particle size after 12

grinding was below 1.5 mm and approximately 80% of the particles were below 0.3 mm. 13

Water-activity (aw) was analysed in all samples (Aqua Lab, Series 3 TE, Decagon Devices, 14

Inc., Pullman, WA, USA). 15

16

Quantification and identification of mould 17

Ground rice samples (40 g) were diluted (1:10 and 1:100) in 0.1 % peptone water (BD, 18

Becton, Dickinson and Company, Sparks, MD, USA) and poured or spread on 18 % dichloran 19

glycerol agar (DG18; Samson et al. 2004) plates. These were incubated in 25 ± 0.5°C for 20

seven days and colonies were thereafter counted and presented as the number of colony 21

forming units (cfu) per g rice. The level of quantification was one log unit cfu g-1, which 22

equals 10 cfu g-1 rice. 23

24

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Colonies of P. verrucosum was identified directly on DG18 by their bright orange-yellow 1

reverse whereas other Penicillium-species were re-inoculated on CREA, Czapek, YES, and 2

CYA and incubated at 25°C for 7 days for further morphological and biochemical 3

characterization (Samson et al. 2004). Colonies of Aspergillus were identified by 4

morphological characteristics (Samson et al. 2004) and potential colonies of A. flavus and A. 5

parasiticus were confirmed on Aspergillus Flavus Parasiticus Agar (AFPA; Pitt et al. 1983). 6

7

Analysis of aflatoxin B1, B2, G1 and G2 8

Ground rice samples (50 g) were transferred to glass bottles (500 ml) and mixed with 200 ml 9

of 84 % acetonitrile (HPLC grade) on a shaking table for 30 min. The samples were then 10

filtered (Munktell V150) and six ml were further transferred to a MultiSep AflaZON 226+-11

column (Romer Labs, Germany). Two ml were collected and nitrogen-evaporated to dryness 12

before re-suspension in 300 µl acetonitrile:water:acetic acid (50:450:5). The samples were 13

filtered (0.45 µm) before injection (20 µl) on the HPLC column (C18 3 µm, 100 x 4.6 mm) 14

equipped with a fluorescence detector (excitation 365 nm, emission 450 nm). Derivatisation 15

was performed with a KobraCell. The mobile phase was water:acetonitrile:methanol (15:3:4) 16

supplemented with one mM KBr and 1.4 mM HNO3, the flow was 1.0 ml min-1 and column 17

temperature 40°C. The level of quantification (LOQ) was 0.1 µg kg-1for aflatoxin B1, B2, G1, 18

and G2. 19

20

In addition to HPLC analysis, 76 samples were also analysed for aflatoxin with the rapid 21

method RIDA®QUICK Aflatoxin by R-Biopharm AG, Darmstadt, Germany. Ten g of ground 22

rice was mixed with 20 ml of 70 % methanol by vortexing for 3 min. The samples were 23

centrifuged (3400 g) for two min and 50 µl were transferred to eppendorf tubes and mixed 24

with 100 µl mobile solvent supplied with the RIDA®QUICK kit. A hundred µl was applied 25

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on the lateral flow strip. Results were read after four (>20 µg kg-1), eight (10-20 µg kg-1), and 1

16 (4-10 µg kg-1) min. The LOQ was four µg aflatoxin kg-1 sample. 2

3

Analysis of ochratoxin A 4

Ground rice samples (50 g) were transferred to glass bottles (500 ml) and mixed with 200 ml 5

of 60 % acetonitrile (HPLC grade) supplemented with NaHCO3 (0,4 %) on a shaking table for 6

30 min. The samples were then filtered (Munktell V150) and four ml of the sample was 7

mixed with 50 ml 0.01 M PBS (Merck) and further transferred to an immunoaffinity column 8

Ochraprep 50 (R. Biopharm Rhône Ltd.). The column was washed with 20 ml 0.01 M PBS-9

buffer (Merck) and then eluted with three ml methanol:acetic acid (49:1). The elute was 10

nitrogen-evaporated to dryness before re-suspension in 500 µl mobile phase 11

(acetonitrile:water:acetic acid; 50:50:1) and injected (20 µl) on the HPLC column (Spherisorb 12

3 µm, ODS 50 x 4.6 mm) equipped with a fluorescence detector (excitation 333 nm, emission 13

460 nm). The flow was 1.0 ml min-1 and column temperature 30°C. The LOQ for ochratoxin 14

A was 0.1 µg kg-1. 15

16

Intake estimations 17

The daily intake of aflatoxins from a specific type of food depends on the concentration in the 18

food and the amount of food consumed. To estimate the concentration of aflatoxin in rice 19

mean values from this study were used as no additional data were available. Three different 20

mean values were calculated (mean value for the total number of rice samples, for the basmati 21

rice samples, and for the rice samples purchased in stores with products of mainly ethnical 22

origin). Negative samples were included as half the LOQ, i.e. 0.05 µg kg-1. This treatment of 23

negative data may result in an overestimation of mycotoxin in rice. 24

25

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The consumption data for rice was based on a consumption study of Swedish consumers 1

performed in 1997-98 (Becker and Pearson 1997). This study included adult consumers 2

between 18 and 74 years old from approximately 2000 house holds. To compensate for the 3

100% increase in rice consumption for Swedish consumers reported by FAOSTAT, FAO 4

(Food and Agriculture Organisation of the United Nations) Statistics Division 2007, intake 5

estimations were also performed based on a 100% increase of the consumption data from 6

1997-98 (Becker and Pearson 1997). Consumers that originate from other countries than 7

Sweden, such as India, Pakistan, Korea etc., are likely to consume rice more than 1-2 times 8

per week as estimated for the mean consumer in the consumption survey Riksmaten 1997-98 9

(Becker and Pearson 1997). These consumers are more likely to consume rice twice a day, 10

seven days a week. Therefore, an estimated intake was also performed on this group of high-11

consumers. Aflatoxin intake estimations are based on results from analysis of aflatoxin in 12

dried rice. However, recent research by Park et al. (2005, 2006) have shown that the aflatoxin 13

content in rice may be reduced by approximately 30% during traditional cooking and 80% 14

during pressure cooking. It is therefore more likely that the intake is lower in ready-to-eat rice 15

than in dried rice due to the 30% aflatoxin reduction during cooking (Park et al. 2005). 16

Pressure cooking is rarely used in Swedish homes. 17

18

Results & Discussion 19

Rice samples 20

A total of 99 rice samples were purchased from retail outlets. The majority of rice samples 21

were taken from local shops with products of mainly ethnical origin (56 samples) and samples 22

from larger retail stores (35 samples), but samples were also taken from organic (five 23

samples) and health food shops (three samples). The majority of samples were basmati rice 24

but also rice with higher fibre content, i.e. brown rice or whole-grain rice, jasmine rice and 25

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long-grain rice were sampled (Table 1). The group of rice samples with higher fibre content 1

included long-grain rice (nine samples), basmati rice (three samples), jasmine rice (two 2

samples), and short-grain rice (one sample). The group of organic rice samples included 3

basmati rice (three samples), brown basmati rice (one sample), brown short-grain rice (one 4

sample), and brown long-grain rice (four samples). 5

6

Mycotoxin analysis 7

All samples were analysed for aflatoxin B1, B2, G1, G2, and ochratoxin A with HPLC. 8

Aflatoxin B1 was detected in 71% of the basmati rice samples and in 20% of the jasmine rice 9

samples (brown rice included; Table 1). Aflatoxin was not detected in short- or long-grain 10

rice (brown rice included) nor in any of the organically grown rice samples (Table 1). 11

Aflatoxin G1, G2, and ochratoxin A were not detected in any of the rice samples. 12

13

Seventy-six samples were also analysed for the total amount of aflatoxins with the rapid 14

lateral flow method RIDA®QUICK Aflatoxin (R-Biopharm AG). The RIDA®QUICK 15

method has previously been evaluated for aflatoxin detection in food items such as grain, soy, 16

flour, nuts, and dried fruit and was included in this study to evaluate weather it can also be 17

used as a screening method for aflatoxin in rice exceeding more than four µg kg-1. Of the 76 18

samples, 11 samples contained more than four µg aflatoxin kg-1 (HPLC, LOQ 0.1 µg kg-1). 19

These were identified with RIDA®QUICK as positive (LOQ 4 µg kg-1; Figure 1) showing 20

that no positive samples were identified as false negatives. Only one sample containing 0.5 µg 21

aflatoxin kg-1 was falsely identified as above 4 µg aflatoxin kg-1 by RIDA®QUICK. 22

23

The RIDA®QUICK method gave a rough indication of the level of total aflatoxin in the rice 24

samples (Figure 1). The method RIDA®QUICK Aflatoxin may therefore be used as a rapid 25

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screening to identify rice samples that contain levels exceeding the European maximum limit 1

for the sum of aflatoxins. However, samples that contain between 2 and 4 µg aflatoxin B1 kg-2

1, thus exceeding the European maximum limit for aflatoxin B1 of 2µg kg-1, will be missed in 3

such a screening. 4

5

Fungal species isolated from the rice samples 6

Fungal contamination analysis was performed by dilution plating of the ground rice samples. 7

The level of fungal contamination were generally low (log one to four cfu g-1 rice) and no 8

significant difference could be found between the different types or origin of rice with regard 9

to contamination level and fungal species isolated. Species of Aspergillus were the most 10

frequently isolated genus but also species of Penicillium and Eurotium were common (Table 11

2). The most frequently isolated species was A. candidus, being present in 50% of the 99 rice 12

samples and completely dominating in 22% of the samples (including samples of basmati 13

rice, jasmine rice, long-grain rice, and brown rice). A. candidus has previously been reported 14

to contaminate rice (Park et al. 2005) and is known to contaminate other cereals (Samson et 15

al. 2004). However, this species is not known to produce any regulated mycotoxins. Less 16

frequently found species were A. flavus (21%), A. fumigatus (13%), A. niger (5%), P. 17

polonicum (2%), and P. chrysogenum (2%). Occasional colonies belonging to the genus 18

Wallemia, Cladosporium, Epicoccum, Alternaria, Trichotecium or to the taxonomical group 19

of Zygomycetes were also isolated. A. fumigatus is commonly isolated from food and indoor 20

environments. It does not produce any regulated toxins but may pose an environmental risk to 21

the workers in the rice industry due to its pathogenicity and allergenic properties (Hedayati et 22

al. 2007). 23

24

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No correlation was found between the occurrence of A. flavus and the level of aflatoxin 1

detected in the samples. This is likely due to the long storage period under dry conditions, 2

which eventually leads to the reduction of viable mould count compared to the initial value. In 3

addition to aflatoxin B1 and B2, which are produced by both A. flavus and A. parasiticus, A. 4

parasiticus is also able to produce aflatoxin G1 and G2 (Frisvad et al. 2006). A. parasiticus 5

was not isolated from the rice samples, nor were aflatoxin G1 and G2 detected. This may 6

indicate that A. flavus is the main producer of aflatoxin in rice. 7

8

A. niger was isolated from five samples, however, few A. niger are capable of producing 9

ochratoxin A and the low incidence of potential ochratoxin-producing species correlated well 10

with the absence of ochratoxin A. 11

12

The low level of mould infection as well as the low water-activity (aw) of the rice samples 13

(0.50±0.08) may indicate that mould growth and mycotoxin production took place before 14

drying and dehulling of the rice kernels. 15

16

Intake and consumer health 17

For genotoxic compounds, such as aflatoxins, the TDI cannot be used as a safety factor as the 18

intake of such substances should be kept as low as reasonably possible. However, a 19

provisional maximum TDI of one ng aflatoxin kg-1 bw day-1 may be used as a guiding value 20

in the risk assessment of aflatoxin from food (JECFA 1998). Rough estimations of the intake 21

of aflatoxin from rice for Swedish consumers showed that high-consumers (defined as the 22

95th percentile), of both women and men, that consume mainly basmati rice and rice bought 23

in shops with products of ethnical origin were in the range of 1.1-2.0 ng aflatoxin kg-1 bw day-24

1 (Table 3) and that the group of consumers that base all their meals on rice were in the range 25

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of 2.3-3.7 ng aflatoxin kg-1 bw day-1 (Table 3). The reduction of aflatoxin during cooking 1

should be considered when discussing aflatoxin intake from rice. Park et al. (2005, 2006) 2

showed that the aflatoxin content was reduced by 30% during cooking. The most extreme 3

group of rice consumers is therefore likely to have an intake closer to 1.6-2.6 ng aflatoxin kg-1 4

bw day-1, which is still above the guiding value of one ng aflatoxin kg-1 bw day-1, rather than 5

2.3-3.7 ng aflatoxin kg-1 bw day-1. Aflatoxin intake from more traditional sources of aflatoxin 6

such as nuts, spices, milk, dried fruit and figs have previously been estimated for Swedish 7

consumers to 0.8 ng aflatoxin kg-1 bw day-1 (Thuvander et al. 2001). This study did not 8

include rice. 9

10

To reduce the aflatoxin content in rice, preventive measures such as improved farming 11

systems, post-harvest handling, proper drying and storage must be taken. In addition, 12

intensified internal and official control may be necessary to improve the quality of the rice 13

available on the market. 14

15

Concluding remarks 16

The main sources of aflatoxin from food are traditionally considered to be nuts, maize and 17

dried fruit. However, this study showed that 71% of the basmati rice and 20% of the jasmine 18

rice samples analysed contained detectable levels of aflatoxin. Only few samples of other 19

types of rice were included in this survey and conclusions on the aflatoxin prevalence in other 20

rice than basmati and jasmine rice cannot be drawn. Aflatoxin was not only a common 21

contaminant but also occurred in levels exceeding the EC limit values in 13% of the basmati 22

samples and 20% of the jasmine rice samples. The mould content was generally very low in 23

stored rice and no correlation was found with the content of aflatoxin. Intake estimations 24

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showed that high-consumers of rice (basmati and jasmine rice) have a higher intake of 1

aflatoxin than recommended by JECFA (1998). 2

3

Acknowledgement 4

We acknowledge FOOD DIAGNOSTICS, Gothenburg, Sweden, for good collaboration on 5

the RIDA®QUICK Aflatoxin kit from R-Biopharm AG. 6

7

References 8

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aflatoxins in Malaysian starch-based foods. Mycopathologia. 143:53-58. 10

11

Bandara J, Vithanege A, Bean G. 1991. Occurence of aflatoxin in paraboiled rice in Sri 12

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Bhattacharjee P, Singhal, RS, Kulkarni, PR. 2002. Basmati rice: a review. Int J Food 15

Microbiol. 37:1-12. 16

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Becker W, Pearson M. 1997. Kostvanor och näringsintag i Sverige - Metod och 18

resultatanalys. Uppsala: Livsmedelsverket. 19

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[CONTAM PANEL] Panel on contaminants in the food chain. 2006. Opinion of the scientific 21

panel on contaminants in the food chain on a request from the commission related to 22

ochratoxin A in food. The EFSA Journal. 365:1-56. 23

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[CONTAM PANEL] Panel on contaminants in the food chain. 2007. Opinion of the scientific 1

panel on contaminants in the food chain on a request from the commission related to the 2

potential increase of consumer health risk by a possible increase of the existing maximum 3

levels for aflatoxin in almonds, hazelnuts and pistachios and derived products. The EFSA 4

Journal. 446:1-127. 5

6

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10

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information sheet 22/02 (http://www.food.gov.uk/multimedia/pdfs/22rice.pdf) 12

13

Frisvad J, Thrane U, Samson R, Pitt J. 2006. Important mycotoxins and the fungi which 14

produce them. New York: Springer. 15

16

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Osman N, Abdelgadir A, Moss M, Bener A. 1999. Aflatoxin contamination of rice in the 2

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polished rice destined for humans. Int J Food Microbiol. 103:305-314. 9

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Park W, Kim Y. 2006. Effect of pressure cooking on aflatoxin B1 in rice. J Agric Food Chem. 14

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Pitt J, Hocking A, Bhudhasamai K, Miscamble B, Wheeler K, Tanboon-Ek P. 1994. The 17

normal mycoflora of commodities from Thailand. 2. Beans, rice, small grains and other 18

commodities. Int J Food Microbiol. 23:35-53. 19

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Pitt J, Hocking A, Glenn D. 1983. An improved medium for the detection of Aspergillus 21

flavus and A. parasiticus. J Appl Bacteriol. 54(1):109-114. 22

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Sales A, Yoshizawa T. 2005. Updated profile of aflatoxin and Aspergillus section Flavi 1

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Centraalbureau voor schimmelcultures. 6

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occurence of aflatoxin B1, fumonisin B1, ochratoxin A and zearalenone in cereals and 9

peanuts from Côte d'Ivoire. Food Add Contam. 23(10):1000-1007. 10

11

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Dietary intake of some important mycotoxins by the Swedish population. Food Add Contam. 13

18(8):696-706. 14

15

Toteja G, Mukherejee A, Diwakar S, Singh P, Saxena B, Sinha K, Sinha A, Kumar N, 16

Nagaraja K, Bai G, Krishna Prasad C, Vanchinathan S, Roy R, Sarkar S. 2006. Aflatoxin B1 17

contamination of parboiled rice samples collected from different states of India: A multi-18

centered study. Food Add Contam. 23(4):411-414. 19

20

WHO, Food Additives Series 40. 1998. Safety evaluation of certain food additives and 21

contaminants. In WHO Food Additives Series. Geneva: World Health Organisation. 22

23

WHO, Food Additives Series 47. 2001. Safety evaluation of certain mycotoxins in food. In 24

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1

2

3

4

5

6

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Figure captions 1

Figure 1. Correlation between the aflatoxin content analysed by HPLC and the lateral flow 2

method RIDA®QUICK Aflatoxin (R-Biopharm) in 76 rice samples. Each cross (×) represents 3

one rice sample. The level of quantification was 0.1 µg kg-1 rice for the HPLC method and 4

four µg kg-1 rice for the RIDA®QUICK method. The RIDA®QUICK method only gave the 5

result in intervals. 6

7

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Fredlund et al. “Moulds and mycotoxins…”

Table 1

Table 1. Number of samples and aflatoxin (µg kg-1

) content for each type of rice (n= 99 rice samples). The

number of samples exceeding European maximum limits and the number of samples below LOQ (0.1 µg kg-1

) are

also given. The analytical uncertainty was 0.4 µg aflatoxin kg-1

rice (nd=not detected).

Aflatoxina (µg kg

-1),

interval for positive samples (mean)

Type of

rice

Number

of

samples

Number of

samples B1>2 (µg

kg-1

) Aflatoxintotal

>4 (µg kg-1

)

Number of

samples

<LOQ B1 B2 Total

Basmatib 73 9 21 0.1-9.4 (1.2) 0.1-1.1 (0.3) 0.1-10.5 (1.3)

Basmatic 76 10 22 0.1-46.2 (2.0) 0.1-4.5 (0.5) 0.1-50.7 (2.2)

Jasminb 8 1 7 23.2 2.1 25.3

Jasminc 10 2 8 7.4-23.2 (15.4) 0.6-2.1 (1.4) 8.0-25.3 (16.7)

high fibre

content

15 2d 12 0.6-46.2 (18.1) 0.1-4.5 (1.7) 0.7-50.7 (19.8)

organic 9 0 9 nd nd nd

long-grain 3 0 3 nd nd nd

aaflatoxin G1 and G2 were not detected in any of the rice samples and are therefore not included in Table 1;

brice

with higher fibre content excluded; crice with higher fibre content included;

done jasmin rice, one basmati rice.

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Fredlund et al. ”Moulds and mycotoxins…”

Table 2

Table 2. The most common mould species isolated from the rice samples.

Mould species Isolated from

number of samples

(n=99)

Level of infection (log cfu g-1

)

Aspergillus spp. 63

A. candidus 49 Dominating flora in 22 rice samples from log 1-1.5 to 3-3.5 cfu g-1

A. flavus 21 Mostly low levels (log 1-1.5 cfu g-1

) but dominating in one sample

(log 3 cfu g-1

)

A. fumigatus 13 Mostly low levels (log 1-1.5 cfu g-1

) but dominating in one sample

(log 2 cfu g-1

)

A. niger 5 Low levels (log 1-1.5 cfu g-1

)

Penicillium spp. 38 Mostly low levels (log 1-1.5 cfu g-1

)

P. polonicum 2 Dominating flora in two samples (log 4.3 and 2.2 cfu g-1

)

P. chrysogenom 2 Low levels (log 1-1.5 cfu g-1

)

Eurotium spp. 28 Mostly low levels (log 1-2 cfu g-1

)

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Table 3

Tabell 3. Intake estimations of aflatoxin from rice by different consumer groups (bw=bodyweight).

Intake of aflatoxin (ng aflatoxin kg rice-1

kg bw-1

day-1

)

Consumer group Rice intake

(g dried rice

day-1

)

Mean value for all

99 rice samples

(1.34 µg kg-1

)a

Mean value for the 73

basmati rice samples

including brown rice

(1.67 µg kg-1

)a

Mean value for the 56 rice

samples purchased in

shops with ethnical

products (2.18 µg kg-1

)a

Woman, mean

consumer

8b 0.2 0.2 0.2

Woman, high

consumerc

24b 0.5 0.6 0.7

Man, mean

consumer

10b 0.2 0.2 0.3

Man, high

consumerc

32b 0.6 0.8 1.0

High consumerc

with rice as the

main stable food

120d 2.3 2.9 3.7

High consumerc

woman/man if

100% increase of

rice consumption

from 1997 to 2005

48/64e 0.9/1.2 1.1/1.5 1.5/2.0

a mean value from HPLC analysis of aflatoxin B1, B2, G1, and G2. Samples with levels <LOQ were set to 0.05 µg

kg-1

, i.e. half the LOQ; b consumption data based on results from Riksmaten 98-97 (Becker and Pearson 1997);

c

based on consumption data of the 95th percentile; d based on consumption of rice (60 g dried rice per meal)

twice a day, seven days a week; e consumption data based on a 100% increase of rice consumption in Sweden

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Table 3

from 1997 to 2005 [FAOSTAT, FAO (Food and Agriculture Organisation of the United Nations) Statistics

Division 2007].

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Fredlund et al. “Moulds and mycotoxins... ”

Figure 1

0

10

20

30

40

50

60

<4 4-10 10-20 >20

RIDAQUICK (µµµµg kg-1)

HP

LC

(µµ µµ

g k

g-1)

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Moulds and mycotoxins in rice in Swedish retail