Is There Something Fishy About Homemade Sushi?
By: Drew Barkley
Last year, I was chatting with a friend about different foods we liked to prepare at home. Having grown up in the south, I mentioned that some staples of my cooking were various casseroles, fried chicken, and homemade biscuits. My friend, having been raised in an Asian-American household, was used to preparing different stir-fries, dumplings, and ramen. While all of that sounded delicious and got me thinking about dinner prematurely, the next food she mentioned caught me off guard. She told me that she and her sister love making homemade sushi together.
I was initially taken aback. The idea that anyone was making sushi at home on their own seemed risky to me. Yet, here was someone I knew that was preparing sushi regularly in their own home. I immediately became curious asking for all the details of how she and her sister made their own sushi. She said that they went to the store and bought whatever fish looked good to them that day. To make the rolls, they would lay a bed of sticky white rice over seaweed and top with the fish, cucumber, avocado, cream cheese, and whatever else sounded good to them that day. Then they would roll it up, slice it up into individual rolls and enjoy. Sensing that I was nervous about her homemade sushi, she reassured me that neither she nor her sister had ever gotten sick and they always use what she referred to as “fresh” fish. While I wanted to mention that “fresh” fish is not the same thing as “safe” fish, I let the conversation end there as I went to go do some research on my own.
First, I want to make the disclaimer that I have never made homemade sushi. While I do enjoy eating sushi, I will leave its preparation to skilled, trained professionals working in fully inspected restaurants. However, I wanted to highlight specific actions you can take to insure your sushi is safe if you are making it at home (or even if you are eating it at a restaurant).
Perhaps the most important element to making safe sushi is using sushi-grade fish. Reputable commercial retailers will only give this grading to their highest quality fish that they feel confident can be eaten raw. Further, well-educated fishmongers (people that sell raw fish and seafood) will know what fish is sushi-grade and safe to consume raw, but it is possible to encounter fishmongers that do not know what sushi grade fish is. While there is no official standard for using this label, the only federal regulation that must be met is that parasitic fish, such as salmon, should be frozen to kill any parasites before being consumed raw (2017 FDA Food Code 3-402.11)1. However, parasites are just one of the hazards that may be associated with eating raw fish. The hazards may also include chemical hazards like mercury or other heavy metals, pathogenic bacteria such as Vibrio spp., or physical hazards such as bone fragments or pieces of metal. Here, it is also important to note that freezing will only stop the growth of pathogenic bacteria, it will not kill them. Sushi grade fish will be more expensive, but you can be assured that you have received a higher quality product that is safer to consume raw, as it does not contain any parasites. To read more about safe sushi preparation, please consult the websites below that I found helpful when conducting my background on this topic. The first is the FDA Food code section on parasitic destruction, the second is a Canadian guideline for safe sushi preparation, and the third is an article from Food Safety Magazine back in 2015.
Another important point is to keep the fish refrigerated as long as possible. This will prevent the growth of any pathogens and keep the fish safer until it is ready to be prepared and eaten. In the same vein, preparing sushi rice properly with vinegar can also help prevent pathogens from growing. By preparing the rice in vinegar, the rice becomes acidic and will drop to a pH below 4.6. This is beyond the point most pathogens are able to grow. Thus, acidifying the rice helps prevent any bacteria present on the fish from cross-contaminating the rice and vice versa.
The last important point to mention is to make sure you are using clean utensils. Avoid using any wooden utensils as they can be harder to clean and can harbor more bacteria. Given that most people eat sushi with disposable wooden chopsticks, be sure to only use the chopsticks once and do not try to reuse the disposable chopsticks. When preparing the sushi, using clean stainless-steel knives and utensils can ensure that you are reducing the risks of cross-contaminating your sushi.
Graduate Research Associate
CFAES Department of Food Science and Technology