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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.
What makes a food high-risk?
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.
How to receive and prepare raw fish
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:
- be firm and springy to the touch
- not have a “fishy” odour
How to chill, freeze and thaw sushi
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:
- Fish that’s frozen for too long can become unsafe and will need to be discarded
- You must store fish in airtight, labelled and dated containers
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:
- defrost fish at room temperature
- refreeze fish that has already been defrosted
The best prepping, handling and displaying methods
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:
- Use batch preparation: This means only preparing the amount of sushi you need to fill the current order or request. Only take the amount of fish from the refrigerator that you need and can prepare in a short window of time. This makes it easier to ensure fish doesn’t spend time in the Temperature Danger Zone.
- Never rinse fish in a sink before preparation: When rinsing food in a sink, bacteria can splash onto other nearby surfaces.
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.
Caring for high-risk customers
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:
- children under 5 years old
- pregnant women and unborn children
- elderly people
- people with compromised immune systems
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:
- properly thaw fish in the refrigerator rather than at room temperature
- prevent cross-contamination by using non-porous cutting boards and clean equipment and utensils before and after use
- wash hands thoroughly before and after handling different food types (such as raw and ready-to-eat foods)
- list all potential allergens on menus and properly label all ingredients
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.
Frequently Asked Questions
What are the most common types of parasites found in sushi and how can they be detected before consumption?
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.
How do sushi restaurants train their staff in food safety practices specific to sushi preparation?
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.
Are there any new technologies or methods being developed to improve the safety of sushi without compromising its quality?
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.
