Sushi and sashimi are traditional Japanese dishes that involve several ingredients, the common one being raw fish. These are now popular delicacies worldwide, accessible any time of year and on any budget.
When they’re prepared properly, sushi and sashimi are healthy and delicious. Since they also fall under the high-risk category, these foods need to be carefully acquired, handled and served to make sure they’re safe and don’t result in a food-borne illness.
Sometimes called potentially hazardous foods, high-risk foods are those that are more likely to harbour harmful bacteria and disease-causing pathogens. These foods tend to be high in starch or protein, high in moisture and have neutral acidity (a pH over 4.5). Sushi has all these characteristics — not to mention, shellfish is a common allergen.
Bacteria thrive in temperatures of 4°C to 60°C (40°F – 140°F), which is why this range is called the Temperature Danger Zone. In Manitoba, the Temperature Danger Zone is between 5°C and 60°C (41°F – 140°F). Viruses and parasites can also be found in raw or undercooked meat and shellfish, so it’s crucial to take sushi safety seriously!
When prepared properly and under the right conditions, though, this delicacy can be enjoyable and safe for customers.
The first step is buying the product. Only purchase from reputable suppliers, and be aware that fish intended to be used as sushi should always be bought frozen and delivered at -18°C / 0°F or below. Check for any signs that the fish has defrosted.
Damaged packaging can lead to contaminated foods, so make sure the packaging has no rips or tears, and send it back to the supplier if you see these signs. Better safe than sorry!
The fish you’re receiving should:
Upon receiving fish, store it right away in the freezer. To kill the parasites on fish intended to be used for sushi, freeze the fish to -20°C / -4°F for 7 days or longer, or use a blast freezer to freeze the fish to -35°C / -31°F or below for at least 15 hours. Note that these two methods require fish to be frozen at a lower temperature than conventional freezing temperatures of -18°C / 0°F.
To prevent pathogens from growing, don’t let fish spend time in the Temperature Danger Zone.
Remember that:
When it’s time to defrost the fish, do so in a refrigerator on the lowest shelf. Make sure you allot enough time, as this can take days, depending on the size of the fish. Once it has been defrosted fully, you need to use it that same day.
Never:
The preparation stage requires care and close attention, as contamination leading to food-borne illness can happen easily when handling and preparing sushi.
Ensure anyone handling fish washes their hands thoroughly both before and after preparing the sushi. Clean and sanitize all surfaces — such as cutting boards, plates, knives and other utensils — before and after preparation. A couple of key things to keep in mind when it comes to preparation:
Keep prepared sushi out of direct sunlight, and keep it refrigerated at 4°C / 40°F or below (5°C / 41°F or below in Manitoba). To prevent contamination, remember to keep displayed sushi in cabinets or covered plates.
Vulnerable or high-risk populations are those who are at greatest risk of experiencing severe symptoms and reactions as a result of a food-borne illness. These groups include:
If your business plans to sell or serve a potentially hazardous food like sushi or sashimi, you need to be extra diligent about putting controls in place to reduce the risk for these populations. Food Handlers need to take extra care to:
The best way to minimize food safety risks in your business is to ensure everyone on staff is properly trained in safe food handling practices. The Canadian Institute of Food Safety’s (CIFS) nationally recognized food safety training covers how to properly handle high-risk foods and best practices when providing food service to vulnerable persons. Learn more about the CIFS Food Handler Certification Course.
The most common types of parasites found in sushi include Anisakis simplex, a worm that can cause severe gastrointestinal issues, and Diphyllobothrium latum, a tapeworm that can lead to vitamin B12 deficiency and anemia.
Detection before consumption generally involves a combination of visual inspection, which must be done by trained professionals, and freezing the fish at temperatures lethal to parasites, as specified by food safety guidelines.
Sushi restaurants typically train their staff in food safety practices specific to sushi preparation through a combination of formal training programs, on-the-job training, and adherence to local health regulations.
This training often includes proper handling and storage of raw fish, techniques to prevent cross-contamination, and methods to maintain a clean and sanitized kitchen environment. Staff may also be educated on the specific health risks associated with raw seafood and the importance of following strict guidelines to mitigate these risks.
Yes, there are new technologies and methods being developed to improve the safety of sushi. Innovations include the use of high-pressure processing to eliminate pathogens without altering the texture and flavour of the fish, and advanced spectroscopy techniques for detecting contaminants more effectively.
Additionally, some researchers are exploring the use of natural antimicrobials that can be added to sushi rice to inhibit bacterial growth without affecting taste.