A Through-chain Analysis of Food Safety Hazards and Control Measures Associated with the Production and Supply of Seed Sprouts for Human Consumption.
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Date
2014-10
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Abstract
Background: Seed sprouts contaminated with pathogenic microorganisms, such as
Salmonella spp. and Shiga toxin-producing Escherichia coli (STEC) present an
unacceptable health risk to consumers. An outbreak that occurred in Australia during 2005
and 2006 due to the consumption of alfalfa sprouts contaminated with Salmonella
Oranienburg resulted in 141 infected cases, and cost an estimated $1.19 million to the
Australian community. In Japan in 1996, consumption of radish sprouts contaminated with
STEC O157:H7 affected more than 10,000 individuals. The outbreak of E. coli O104:H4
linked to the consumption of fenugreek sprouts that occurred in Europe in 2011 was an
unprecedented foodborne outbreak. More than 4,000 individuals were infected by STEC
O104:H4. Among them, 908 developed haemorrhagic uraemic syndrome (HUS), and 50
died of STEC infection. This demonstrates the potential food safety risk arising from seed
sprouts and that the consequences can be devastating.
Food Standards Australia New Zealand (FSANZ) initiated the development of a primary
production and processing standard for seed sprouts in 2009 to enhance the safety of
seed sprouts produced and sold in Australia. After extensive consultations with the State
and Territory food safety regulators, and a thorough investigation of the Australian industry practices in producing seed sprouts for human consumption, a technical paper
was prepared to inform the design of potential risk mitigation measures for a national food
safety standard on seed sprout production. This technical paper described the Australian
seed sprout industry, depicted the steps involved in the production of seed sprouts for
human consumption, and provided an analysis of potential food safety hazards that could
occur during seed sprout production and processing. A food safety standard for the
production and sale of seed sprouts in Australia was finalised in November 2011.
This extended abstract describes the key aspects of the technical paper.
Aims: To provide technical and scientific information to support risk management
decisions aimed at maximizing the safety of seed sprouts produced for human
consumption in Australia.
Study Design: A through-chain qualitative food safety risk analysis.
Place and Duration of Study: FSANZ, Canberra, Australia, between July 2009 and
January 2010.
Methodology: This through-chain risk analysis was prepared upon a comprehensive
review of literature available at the time on: investigations of foodborne outbreaks
associated with consumption of seed sprouts; surveys of microbial contamination of seed
sprouts; specific publications on crop production, seed harvest, post-harvest processing
and storage of seeds; production of seed sprouts; risk assessments on seed sprouts; and
regulatory guidelines published by Australian and international food safety regulatory
authorities on seed sprouts.
Members of the FSANZ project team conducted field studies of sprout production, lucerne
crop production, lucerne seed processing, wholesale and retail sale of seed sprouts. A
survey was conducted on the variety, volume and value of sprouts produced, source and
quantity of seeds used to produce sprouts for human consumption, trend of consumption
of seed sprouts in Australia, as well as the size and the location of sprout producers in
Australia.
Stakeholders were consulted through a FSANZ standard development committee with
participants from State and Territory food safety regulators, peak sprout producer industry
bodies, seed producers and seed processors, major food retailers, and consumer
representatives.
The through-chain analysis of food safety hazards associated with the production and
processing of seed sprouts was prepared in line with the principles of hazard analysis
critical control points (HACCP).
Results:
Key pathogens of concern: Among the range of biological, chemical and physical food
safety hazards that were likely to be associated with seed sprouts produced for human
consumption, pathogenic microorganisms represent the highest risk to consumers.
Outbreaks associated with the consumption of seed sprouts contaminated with
pathogenic microorganisms were seen to be frequent events in developed economies
despite food regulatory interventions. The key pathogenic microorganisms of concern were Salmonella spp. and STEC. Salmonella spp. were found to be the causative
pathogen almost five times more frequently than STEC.
Main varieties of seed sprouts causing foodborne illness: Among the 41 reported
outbreaks that occurred worldwide between 1988 and 2007 involving consumption of seed
sprouts contaminated with pathogenic microorganisms, alfalfa sprouts represented 68% of
the outbreaks, followed by mingbean sprouts (22%), clover sprouts (5%), radish sprouts
(2%) and clover sprouts (2%).
Source of pathogenic microorganisms: FSANZ divided the production and supply of seed
sprouts for human consumption into eleven consecutive steps, starting with seed
production in the field and ending with transportation and distribution of seed sprouts to
retail establishments. This was to enable a systematic identification of the food safety
hazards, sources of the hazards, specific controls that could be applied to control or
eliminate food safety hazards, and the associated requirements of food safety
management practices including food safety knowledge and food safety skills.
Contamination of seeds by pathogenic microorganisms such as Salmonella spp. and
STEC can occur during seed production, seed harvest, seed processing, seed storage
and transportation. The origin of these pathogenic microorganisms is animal faeces and
manure present in the field where the crop is grown. Soil for growing the seed crop, water
used for irrigation, and machinery used for crop management including the harvest of
seeds, can be contaminated with pathogenic microorganisms and can transfer the
contamination to seeds during crop production and seed harvest. Seed processing as a
post-harvest step may also contribute to seed contamination. For example, blending
different harvest lots of seeds for seed cleaning can spread what was originally a localised
contamination into a larger volume of seeds. Rodent, insect and bird activities in seed
processing and seed storage establishments can introduce and spread pathogenic
microorganisms to seeds.
Provided that seeds delivered to sprout production sites are free of pathogenic
microorganisms, activities of rodents, insects, and infected workers in seed receipt,
storage, sprout production, sprout storage and transportation at sprouting establishment
can lead to contamination of seed sprouts by pathogenic microorganisms. So is the use of
contaminated water for sprouting. Much of these are also applicable to retail handling and
storage of seed sprouts.
Investigations into the source of sprout contamination for outbreaks that occurred between
1988 and 2007 found that in almost every case the pathogenic microorganisms causing
the outbreaks were present in the seeds used for sprout production. In approximately 20%
of the outbreaks, contamination in sprouting establishments was also identified as a likely
source of contamination.
Identified risk mitigation measures: Based on an analysis of a wide range of possible
recommendations aimed at improving the safety of seed sprouts, the though-chain
analysis recommended the following good agricultural practices to be implemented in the
primary production phase of seeds:
· Environment - soil and environment where seeds are grown for the production of
seed sprouts as a human food should be suitable.
· Inputs - manure, biosolids and other natural fertilisers should only be used for the growth of seed crops when a high level of pathogen reduction has been achieved;
equipment (bins, containers, silos, vehicles) and machinery are maintained and
used in a manner that minimises and/or avoids contamination of seeds with
pathogenic microorganisms.
· Protection - grazing animals and wild animals are prevented from entering the
field where seeds are grown; and seed crops are protected from contamination by
human, animal, domestic, industry and agricultural wastes.
· Segregation - seeds produced for the production of sprouts for human
consumption are segregated from seeds produced for the production of animal
feed and are clearly labelled.
The through-chain analysis also recommended the following components to be included in
a Food Safety Program that must be effectively implemented in sprout production
establishments:
· Environment – the sprouting facility (including the seed storage area) should not
allow access of rodents, insects, pests or animals; sprouting facility and
equipment are effectively cleaned and sanitised to ensure the environment is
suitable for producing ready-to-eat foods.
· Input – each seed lot is tested for the presence of microbial pathogens of concern
and seeds should not be used unless the testing results are negative; solid
medium supporting sprout growth and water for sprouting are treated to eliminate
pathogenic microorganisms; seeds are disinfected prior to sprouting to eliminate
microbial pathogens.
· Separation – seed rinsing and microbiological decontamination, seed
germination/sprouting, and storage of seed sprouts are physically separated from
each other to prevent cross contamination.
· Monitoring – implement appropriate sampling/testing programs to regularly
monitor microbial pathogens during and at the end of production of seed sprouts.
Implementation of food safety controls on farm presents many challenges. One of the
main obstacles is the inability to control environmental factors under conventional farming
practices. The environment under which seeds are produced for the production of seed
sprouts for human consumption should exclude animal grazing and minimise and avoid
pest and wildlife interference. The cost involved in growing seeds under these conditions
can be prohibitive unless sprout producers are willing to pay a premium price for such
seeds. As a result, the primary production and processing standard developed by FSANZ
limited the control measures to sprout production. The standard is available at
https://www.comlaw.gov.au/Details/F2012L00023.
A number of chemical and physical means have been investigated by different research
organisations around the world for effective seed decontamination. As a result of the
FSANZ standard development activity, a subsequent research and development study
funded by the Australian Government and the Australian sprout industry investigated the
efficacy of various disinfectants applied to seed decontamination. The study, Improving
Seed Sprout Food Safety – a farm to retail assessment, recommended the use of multiple
hurdles, such as a combination of heat treatments and chemical decontamination of
seeds, to control the potential presence and growth of foodborne pathogens during sprout
production. The full report of this study is available at
https://rirdc.infoservices.com.au/items/13-010. Conclusion: Seed sprouts, particularly those that are consumed raw, are one of the food
vehicles frequently implicated in foodborne outbreaks. Pathogenic microorganisms, such
as Salmonella spp. and STEC, are key food safety hazards associated with past
outbreaks involving consumption of seed sprouts.
Seeds used for sprouting are the primary source of contamination with pathogenic
microorganisms that originate from animal faeces, untreated fertilisers, contaminated soils
and water.
Seed decontamination prior to sprouting is considered the critical control point in
producing safe seed sprouts.
Through-chain food safety management presents the ultimate solution to the reduction of
foodborne illnesses associated with the consumption of seed sprouts. In addition to sprout
producers, seed producers, seed processors and seed merchants have a role to play in
ensuring seed sprouts produced for human consumption are safe.
Description
Keywords
Seed sprouts, alfalfa sprouts, mungbean sprouts, shiga-toxin producing Escherichia coli, Salmonella, HACCP, risk assessment, food safety
Citation
Jin Hong, Craig Duncan, Blenman Patricia, Yates Adele, Crerar Scott, Healy Marion. A Through-chain Analysis of Food Safety Hazards and Control Measures Associated with the Production and Supply of Seed Sprouts for Human Consumption. European Journal of Nutrition & Food Safety. 2014 Oct-Dec; 4(4): 424-428.