2. Brief Review of Risks

Consumption Risks of Sashimi of Freshwater Aquatic Animals

26/07/2023

Summary

 

  • In the past, there were food poisoning cases in Macao due to consumption of food products made of marinated raw freshwater aquatic animals.
  •  “Freshwater fish sashimi” is susceptible to many food safety risks in the processes of aquaculture, distribution logistics and processing. A slight negligence in any of these stages can easily lead to parasitic infection and pathogenic bacterial contamination, thus enhancing the risk of foodborne diseases.
  • In December 2019, the Administration for Market Regulation of Foshan published the association standard “Technical Standard for Whole-Industry-Chain Management and Control of Fish Sashimi of Shunde”, which is the first standard nationwide to regulate “freshwater fish sashimi”.
  • Due to the absence of heat sterilisation to kill bacteria in the preparation of freshwater aquatic animals for consumption as sashimi, the food industry of Macao should refrain from using freshwater aquatic animals for processing or preparation into ready-to-eat raw food.
  • Use of spicy and pungent seasonings (e.g. wine and vinegar) to marinate raw aquatic animals cannot kill the bacteria and parasites in them.
  • Elderly individuals, pregnant women, infants and young children, as well as people with weakened immune systems should avoid eating sashimi.

 

Introduction

 

In the past, there were food poisoning cases in Macao due to consumption of food products made of marinated raw freshwater aquatic animals. Since the preparation process of freshwater aquatic animals for consumption as sashimi does not involve heat sterilisation, the food industry ought to purchase food ingredients and choose sashimi-grade seafood from reliable and reputable stores in good hygiene condition, and refrain from using freshwater aquatic animals for processing or preparation into ready-to-eat raw food. However, “freshwater fish sashimi” is a culinary tradition of Mainland China, especially in Shunde district of Guangdong province. In view of this, the Administration for Market Regulation of Foshan published the association standard “Technical Standard for Whole-Industry-Chain Management and Control of Fish Sashimi of Shunde” in December 2019, which is the first standard nationwide to regulate “freshwater fish sashimi”. “Freshwater fish sashimi” is susceptible to many food safety risks in the processes of aquaculture, distribution logistics and processing. A slight negligence in any of these stages can easily lead to parasitic infection and pathogenic bacterial contamination, thus enhancing the risk of foodborne diseases.

 

Risk of consumption of sashimi prepared with freshwater aquatic animals

 

Sashimi is a generic term for marine fish fillets, mollusks, crustaceans, fish roe and other seafood intended to be eaten without cooking.

 

Risk of parasitic infection

According to the Food and Agriculture Organization of the United Nations and the Codex Alimentarius Commission, both farmed and wild-caught fish and aquatic animals are at risk of parasitic infection. In aquaculture, the water quality and the feed may be affected by risk factors of parasitic infection. In the case of wild fish, their growing environment is hardly controllable. In this respect, the aquaculture industry has to handle fish intended for raw consumption with proper care, strictly monitor and control the quality of water and feed, as well as other aspects in aquaculture, and develop an effective system for prevention and control of parasites to reduce the risk of parasitic infection in fish intended for raw consumption.

 

Among the many parasites, those of particular concern include roundworms, tapeworms, flukes, etc. Parasites reproduce inside the hosts or in the intestinal tract of humans and benefit at the expense of their hosts. They also release toxins that damage cells or tissues, and cause mechanical or biochemical damage to organs. Moreover, they compete for nutrients and take up space in the body cavity of their hosts. Consuming sashimi made of fish infected with parasites may lead to allergic reactions, intestinal discomfort or even complications.

 

Bacterial and Viral Risks

Harmful microorganisms include bacteria (e.g. vibrio parahaemolyticus) and viruses (e.g. norovirus). Among them, vibrio parahaemolyticus is a type of halophilic bacterium widely found in marine environment and a common causative agent of food poisoning. Foodstuffs prone to contamination by this bacterium are mainly seafood, including fish, shellfish, mollusks and crustaceans. Vibrio parahaemolyticus is heat-intolerant, and thorough heating can effectively destroy it. Seafood dishes that are not subject to thorough heating, like marinated raw shrimps, pickled crab and cockles, carry a higher food safety risk. Elderly persons, pregnant women and people with weakened immune systems should avoid eating these raw dishes as far as possible. The incubation period of vibrio parahaemolyticus-induced food poisoning is between 2 and 48 hours, and the major symptoms include watery diarrhoea, abdominal pain, nausea, vomiting and fever, which can last for 2 to 5 days.

 

While norovirus is commonly found in contaminated seawater seafood, improper separation of food ingredients during display or preparation of sashimi may result in cross-contamination, and norovirus may also exist in freshwater fish sashimi. Norovirus is currently the major pathogen that leads to non-bacterial acute gastroenteritis, and is one of the common causes of food poisoning in Macao. It is primarily transmitted through consumption of contaminated water and food, such as eating shellfish contaminated with the virus (e.g. raw oysters), undercooked vegetables and salad. Furthermore, it can be transmitted through person-to-person contact, direct contact with contaminated substances (e.g. faecal matters and vomitus of an infected person), or aerosol spread with contaminated droplets of splashed vomitus. Norovirus infection can happen all year round, but with a higher incidence in winter. The virus has high infectivity and survivability, and can survive in the temperature range of 0°C to 60°C. It can cause acute gastroenteritis outbreaks in crowded places, such as schools and residential care facilities.

 

Risk of chemical contamination

Aquatic animals are also subject to the risk of chemical contamination, including pesticide residues, hormones and residues of veterinary drugs, such as malachite green (It is an industrial dye and bactericide that has potential carcinogenic risks and may lead to developmental hazards. It is banned from use in food in Macao and not allowed to be detected in any foodstuffs sold in Macao.). In addition, pollution of the growing environment is also a factor. Therefore, in regard to aquatic animals intended for raw consumption as sashimi, the breeding environment must be strictly regulated and clearly labelled, with the whole transportation process closely monitored. Any aquatic animals of unknown origin or subject to improper distribution logistics or processing are at risk of chemical contamination and not suitable to be used for preparation of ready-to-eat sashimi.

 

In summary, raw consumption of the freshwater aquatic animals commercially available in Macao, such as grass carp and bighead carp, poses the risks of parasitic infection and diseases. Therefore, for health reasons, freshwater aquatic animals should not be processed or prepared into ready-to-eat sashimi for raw consumption.

 

Regulation conditions

 

In accordance with Law No. 5/2013 “Food Safety Law” of Macao, the food industry has the responsibility to ensure the safety of the food supplied. They have to adopt appropriate risk prevention measures based on the types of food they sell to ensure that the food available for sale does not pose any harm to human health. As such, the local food industry ought to use food ingredients intended for raw consumption for the preparation of sashimi. It is crucial to know the origin of the food ingredients and their specifications before purchase. Food ingredients must be stored at the appropriate temperatures and conditions, while raw and cooked food should be handled separately to avoid cross-contamination. Moreover, freshwater aquatic animals should not be processed into ready-to-eat food for raw consumption.

 

However, “freshwater fish sashimi” is a culinary tradition of Mainland China, especially in Shunde district of Guangdong province. In December 2019, the Administration for Market Regulation of Foshan published an association standard “Technical Standard for Whole-Industry-Chain Management and Control of Fish Sashimi of Shunde”, which is the first standard nationwide to regulate “freshwater fish sashimi”. The standard provides technical specifications for management and control of food safety and product quality throughout the various stages in the industry chain of production of freshwater fish sashimi of Shunde district, covering the aquaculture, transportation, distribution and processing. For instance, the standard requires that grass carps used for preparation of sashimi undergo depuration for over ten days, and parasites must not be detected in sashimi. In addition, practitioners in the industry must pass the training before they are allowed to work, and the collective mark of “Freshwater Fish Sashimi of Shunde” is to be used by the food and catering sector as a verification of adherence to the standard.

 

Internationally, the “Code of Practice for Fish and Fishery Products” developed by the Codex Alimentarius Commission requires that in addition to stringent monitoring of the fish during aquaculture, fish sashimi intended for raw consumption has to go through freezing at -20°C or below for seven days or at -35°C for about 20 hours. The specific freezing process can kill the parasites in the fish body.

 

Advices to the industry and the public

 

  • Freshwater live aquatic animals should not be processed or prepared into ready-to-eat food for raw consumption;
  • Use of spicy and pungent seasonings (e.g. wine and vinegar) to marinate raw aquatic animals cannot kill the bacteria and parasites in them;
  • Wash hands thoroughly before handling food intended to be consumed raw. Wear disposable gloves or make use of kitchen appliances to minimise direct contact with food;
  • Elderly individuals, pregnant women, infants, and people with weakened immune systems should avoid eating sashimi;
  • In case of experiencing symptoms of discomfort after consuming sashimi, seek medical attention promptly.

 

References:

1.      “Learn about Norovirus”, Department of Food Safety of the Municipal Affairs Bureau of Macao, 1 January 2019.

https://www.foodsafety.gov.mo/c/science/detail/752370f2-0ff7-4f98-9239-9ddb93d89ae6

 

2.      “Common Parasites in Food”, Department of Food Safety of the Municipal Affairs Bureau of the Macao SAR Government, 1 January 2019.

https://www.foodsafety.gov.mo/file?p=foodsafetyinfo/imgnews/636803004811878.pdf

 

3.   “Sashimi is an Attractive Food Item, but be Mindful of Food Safety Risks”, Department of Food Safety of the Municipal Affairs Bureau of Macao, 5 October 2016.

https://www.foodsafety.gov.mo/c/sensetips/detail/e4293400-d3f8-442e-af2f-537631d49367

 

4.      “Risk to Food Safety Posed by Parasites in Fish for Raw Consumption”, Department of Food Safety of the Municipal Affairs Bureau of Macao, 25 April 2017.

https://www.foodsafety.gov.mo/c/sensetips/detail/ec0610a1-22fa-43fd-8d3b-08845ff8108f

 

5.   “Veterinary Drug Residues in Aquatic Products Supplied to Macao and their Safety”, Department of Food Safety of the Municipal Affairs Bureau of Macao, 4 May 2016.

https://www.foodsafety.gov.mo/c/science/detail/6d0e541e-33c5-4bb8-ad28-a018fbbc20ad

 

6.      “Food Safety of Freshwater Fish Sashimi”, Centre for Food Safety of Hong Kong, November 2018.

https://www.cfs.gov.hk/tc_chi/multimedia/multimedia_pub/multimedia_pub_fsf_148_01.html

 

7.      “Raw Aquatic Food Products – A Source of Pathogens and Parasites”, Centre for Food Safety of Hong Kong, May 2016.

https://www.cfs.gov.hk/tc_chi/multimedia/multimedia_pub/multimedia_pub_fsf_118_01.html

 

8.   “Treatment for Killing Parasites as Safety Measures for Fishery Products to be Eaten Raw”, Centre for Food Safety of Hong Kong, 16 September 2015.

https://www.cfs.gov.hk/tc_chi/committee/files/TCF_51/51TCF_Treatment_to_kill_parasite_c.pdf

                                

9.      “Malachite Green in Foods”, Centre for Food Safety of Hong Kong, March 2016.

https://www.cfs.gov.hk/tc_chi/programme/programme_rafs/programme_rafs_fc_02_06.html

 

10.  “Malachite Green Found in Freshwater Fish”, Centre for Food Safety of Hong Kong, 5th Issue, December 2006.

https://www.cfs.gov.hk/tc_chi/multimedia/multimedia_pub/multimedia_pub_fsf_05_04.html

                 

11.  “Avoiding raw freshwater fish is the best way to prevent liver fluke infections”, Taiwan Centers for Disease Control of the Ministry of Health and Welfare, 7 October 2003.

https://www.cdc.gov.tw/Category/ListContent/Hh094B49-DRwe2RR4eFfrQ?uaId=iIcpelqrpoCTod5QEoQ_cQ

 

12.  “Speaking the plain truth about ‘food’ - One bite of sashimi of Shunde is an unforgettable experience”, Guangdong Administration for Market Regulation (Guangdong Intellectual Property Administration), 16 March 2022.

https://amr.gd.gov.cn/ztzl/myswt/shss/content/post_3884577.html

 

13.  “Technical Standard for Whole-Industry-Chain Management and Control of Fish Sashimi of Shunde – Section on Grass Carp”, Administration for Market Regulation of Shunde of Foshan City, 25 December 2019.

 

BRR 006 DAR 2023