In between serving virtual food to avatars on facebook and calling in predator missles and harrier strikes in MW2, I caught a show on the BBC regarding food waste and sustainability. The show depicted Britain consumerism and the effects to the environment from packaging and waste. Though I disagree with some of their arguments correlating decomposition of food to greenhouse gases and global warming, it is very clear that we, as humans, have rather wasteful habits. I consulted the Google gods to find an article from the NY Times that furthermore shows what a family of four throws out on an annual basis.
It’s interesting to note that meat and fish’s spoilage weight was half of fresh fruit and vegetables. I wonder if it has anything to do with people thinking they’re healthy because they buy veggies and apples? Or is it because meat is expensive and we usually take extra precaution to eat that before microbes can. Maybe both? So expanding on last week’s post regarding refrigeration, I will share some tips to increase the shelf life of some of the most expensive proteins out there, seafood.
To prevent any confusion, I will follow the FDA terminology by defining “fish” as, any sea creature such as shellfish, squids, sea cucumbers, or squirtles. Ok, time to dip your feet into a small biology lesson about sea creatures and their ecology. Unlike their terrestrial brethren whom have adapted to land life, aquatic organisms are constantly immerged in an aqueous solution. Because of the liquid milieu, there are chemical differences for a fish to survive. To counteract the osmotic pressure of the saltwater, fish generally have a higher concentration of savory amino acids (glutamate) increasing cell rigidity. Because of this, saltwater can’t just flow through into the body of cell like it can with humans.
Did I lose you in all of that? This is an example I used in my Nutri Sci reviews. Imagine taking a bubble bath listening to Enya with pomegranate candles lit (don’t judge). After 20 minutes, your skin is as wrinkly as a Shar Pei. Compare this to Red Lobster who can chill in a tank all of his life without looking like a raisin. Yes, you’re a land mammal, therefore there would be no reason for you to be immersed in water for extensive periods of time (unless you’re Michael Phelps). What I’m trying to say is that land and ocean animals behave differently in a given environment, and it’s because of their biological chemistry.
[Source: http://www.lasharpei.com/LaurensSharpei.jpg]
Deterioration is inevitable and it’s caused by the natural enzymes in the fish. Primarily found in the gills, stomach, and outer-slime that coats a fish’s surface, the microbes consume the yumyum amino acids/proteins into unappealing and obnoxious compounds. Because amino acids contain nitrogen and sometimes sulfur, bacterial digestion creates many of these foul odors that sound like a mortuary; putrescine, cadaverine and methanethiol…the same stuff skunks produce. The warmer the temperature, the greater the activity of the fish decomposition microbes which have evolved to be most efficient when removed from their native oceanic climate (34-38° F). So by increasing the surrounding climate, these microbes work at a quicker rate to convert those amino acids into those nasty by products.
With that reasoning in mind, it’d only make sense to store seafood near their environmental temperature of 34.0° F. If held at the optimal temperature, fatty saltwater fish (salmon, herring, mackerel, sardines) can be held for about a week while leaner cold-water fish (cod, sole, tuna, trout) can be held for about two. If you’re a warm-water fish (snapper, cafish, carp tilapia or mullet) you’re given three! But don’t forget to account for the elapsed time in transit and on the market shelves, so you can subtract anywhere between 1-5 days. So let’s reexamine that whole salmon fillet you bought at CostCo.
Shelflife (when held at optimal temperatures) | 7 d |
Transportation to market | 1-2 d |
Time spent on shelf | 0-3 d |
Days remaining in your fridge | 2-6 d |
Here’s more bad news, your fridge is probably around 40- 45° F (and higher if air circulation is impeded). A 10° F increase can decrease shelf life by a half. Suddenly, your weeklong salmon dinners diminish to only 1-3 days.
If you can’t control the temperature of your fridge, there’s many things you can do to drop the ambient temperature. First, wrap your fish in any foodwrap (for example, Syran) and take any deep bowl. Then place a plastic insert that allows for drainage and fill the upper compartment with ice. Place the nicely-wrapped fish over the bed of ice. Any melted ice drains through to the bottom layer and the syran wrap prevents any flavors and nutrients from leaching out of your protein. Change ice every 8-12 hours and booyahshaka, salmon burgers all week!
Here are some tips that were shared to me by an expert in the fish and shrimp industry, if you buy your fish whole from your store’s seafood department. First, the cavity should be visible and all organs should be removed; the gut is a breeding ground for microbes. Secondly, pull the skin near the lining of the stomach- the bones should be rigid and the skin should stay intact. If the bones are flexible and pull like rubberbands or the flesh splits easily, then that’s an indication that your fish has been there for a while. Finally, smell the stomach, it should smell like the ocean or fresh crushed leaves. Also, make sure your fish has been thoroughly rinsed prior to purchasing because the same microbes are coaxed along the surface of the fish “slime.”
[Source: http://www.gastronomydomine.com/uploaded_images/extent-of-digestive-tract-747915.JPG]
The period between shopping and the time you place your products in the fridge is as critical as storage. Microbial activity increases (exponentially) once the temperature change occurs so Alton Brown suggests carrying a well-insulated container filled with bags of crushed ice while you shop. After picking up your proteins, securely wrap and place in your deep-freeze vessel. Sure, it might look weird carrying it around Safeway, but your stomach will appreciate it much more.
By the way, the U.S. FDA and the National Oceanic Atmospheric Administration require all seafood distributors to transport their products in cold-fridge transportation units either filled with ice or utilize a refrigeration system that has a non-tamperable time/temperature reading. In addition, HACCP records and verification is required from any company that receives shipments and any temperatures above 40° F is to be documented. However, what the company does with the product differs; some still accept while others reject the product.
No one likes to see food go to waste (especially an Asian like me) and I hope this post has helped extend the shelf life of your shell fish. Next week’s post will be a list of what to look for when buying seafood so look out for that!
No comments:
Post a Comment