How flash-freezing preserves food quality

this video is sponsored by squarespace hello friend have you heard the good news frozen food isn't terrible anymore in fact modern flash freezing technologies can preserve meat and some fruits and vegetables with virtually no loss of quality i would much rather have a piece of fish that was flash frozen right off the boat or maybe even on the boat as opposed to one that has been slowly decomposing on its thousand mile truck ride to my kitchen or the more likely scenario these days is a piece of fresh fish that arrived at my grocery store frozen the folks behind the fish counter thought it and then it sat in the case for a couple of days waiting for me to buy it and take it home exactly how is that fresher nobody knows for sure but the folks at the national fisheries institute told me they'd guess 80 percent of seafood sold here in the united states was frozen at some point in the supply chain they don't think that's a bad thing and neither do i it's merely the case that i'd rather buy at frozen and thaw it myself whenever possible if you're nervous about thawing stuff yourself or you just think it'll take too long i'm gonna show you a method that i think will change your mind but first flash freezing why is it good to freeze stuff really fast when water turns to ice it expands a little bit and that can cause all kinds of damage to the tissues of the plants or the animal that you're trying to freeze that's dr john coupland a food science professor at my alma mater penn state another problem that happens is the water gets drawn from the plant of the animal into these ice crystals leaving the bits in between kind of dried out what you want to try and do is to get this temperature down really low really quickly and what that what that means is you're driving a process called crystal nucleation ice crystal nucleation the birth of ice crystals this is a process we can see quite clearly by making ice cream half a cup of milk half a cup of cream third of a cup of sugar a big splash of vanilla stir that up and the final ingredient cold this is a block of dry ice frozen carbon dioxide surface temperature minus 109 fahrenheit minus 78 c you can buy it in grocery stores in the states but handle it with gloves or a towel it can give you frostbite i'm just pulverizing it into snow the finer the powder the better then i'm gonna stir it into my ice cream mixture one little spoonful at a time this stuff is so cold that if you were to stir in more than a spoonful your ice cream would lock up hard like that instantaneously and you wouldn't be able to stir it one spoonful at a time and you'll see the mixture appear to boil that's the dry eye sublimating that is changing phase from a solid to a gas and leaving the ice cream when the bubbling calms down go in with another spoonful be sure to work with dry ice in a reasonably large well-ventilated room if you breathe in too much of that sublimated carbon dioxide you're not going to get enough oxygen after four or five spoonfuls i've got this beautiful soft-serve ice cream if you see any big pieces of dry eyes still swimming around try to fish them out those could hurt you if you bite into them and stick the bowl into the freezer for about a half hour to give any remaining dry ice in there the chance to sublimate and leave the bowl the temperature in there is cold enough to keep the ice cream frozen but it's actually warm enough to allow all the dry ice to sublimate the only hitch with this method is that we've literally carbonated the ice cream so it's a little fizzy but that's still the smoothest ice cream i've ever made at home teeny tiny ice crystals compare that to this the same exact cream mixture just thrown in the freezer for a few hours you can see the ginormous ice crystals why did this happen because there was less crystal nucleation early in the freezing process every ice crystal starts with a nucleus a center then the other water molecules crowd around that center and the crystal grows there's a finite amount of water in the food so the size of the crystals depends entirely on the number of nucleation sites across which that water is being distributed if you start freezing at a relatively high freezing temperature you're going to start with just a handful of nucleation sites tons of water is going to crowd around them and you'll have huge ice crystals if you start freezing at a lower temperature you're going to start with a whole bunch of nucleation sites so the same amount of ice present in lots of tiny crystals than a few big ones which are going to cause more damage to your plant tissue or your animal tissue here's two apple slices one i will bury in my dry ice snow before it goes in the freezer and the other i'll just put into the freezer here we are the next day both solid as rocks slow frozen apple slices on the right i'll thaw them out they're both brown due to enzymatic reactions that i could have prevented with acid but the flash frozen apple slice still has the flavor and texture of a fresh apple the slow frozen slice is soft and gummy if these big big slow growing crystals form they can they're just big and spiky they can start to damage cells they can chew up the plant and or the animal tissue in a way that that's going to make the quality very poor the idea is that the initial freezing process should be as fast and as aggressive as possible then maybe you can store it at slightly less cold temperatures and we can see that in action right here at rocking chair ranch this is an organic grass-fed beef producer outside where i live in macon georgia the owner joseph egloff just finished building his own processing plant here this is where the animals are slaughtered the carcasses get hung on the rails up above then they slide into this very cold room called a pre-chiller here's where they hang the sides potentially for weeks for a dry aged product and here they break the sides down into individual cuts they vacuum seal the cuts in plastic and then the cuts go to this blast freezer check out the convection fans blasting crazy cold air across the product because joseph is freezing small little cuts instead of whole sides or sections of beef he's able to freeze them crazy fast hence lots of ice nucleation sites hence lots of tiny ice crystals that won't puncture cell walls we can take things down from 40 degrees down to -10 in a matter of minutes we're used to it took hours it is increasingly common for small boutique little producers like rocking chair ranch to deal exclusively in frozen product if you want to deal in unfrozen product you simply have to turn a much larger volume of business in order to sell it fast enough to make sure that you're selling fresh stuff if you think all that plastic wrapping is wasteful well consider that the product in your grocery store's butcher case probably came to them vacuum packed as well they simply unwrapped it broke it down into smaller cuts and maybe wrapped it up in plastic again for you to take it home flash freezing has particular benefits with fish for example small fish like shrimp these are generally frozen via a process known as iqf you know iqf stands for individually quick frozen this is tori stivers a seafood specialist at the university of georgia's marine extension which works with commercial fishers around where i live of course berries can be done that way as well so that's why you can pull out a few at a time so they usually have a little bit of glaze around it so it doesn't stick together but that's a lot more convenient than buying a five pound block of shrimp frozen together and then trying to have to chisel them out one at a time right these are techniques that were pioneered about a hundred years ago by an american inventor named clarence bird's eye to this day it works best on small little bits of vegetable especially peas to individually quick freeze something small you might lay out all the bits on some kind of conveyor belt and blast them with something these days it could be liquid nitrogen it's called cryogenic freezing where we use liquid nitrogen to make very very cold temperatures to freeze things effectively instantaneously that's about the best quality you can get with frozen foods there's another particular benefit of freezing when it comes to seafood and that is safety broadly speaking the big safety concern with fish and shellfish is parasites so parasites are are the worms that are naturally occurring in some species of fish and so if you freeze them for a certain prescribed amount of time at a certain temperature it will kill the worm it will kill the parasite you may still physically see it but it you know if the parasite is dead it's not going to cause that parasitic infection and for that reason federal regulations here in the united states say that most fish sold for sushi has to be frozen for some combination of time and temperature to kill parasites now a lot of sushi or sashimi connoisseurs will say that destroys the texture but better that than having an intestinal parasite and if you want my opinion i think that said connoisseurs are probably just making it up assuming that we're talking about properly flash frozen fish all of which invites the question if i invite more frozen product into my kitchen how do i thaw it well when it comes to things like little bits of frozen vegetable i say don't they can go straight into the pot still frozen solid they'll melt in seconds but what about something bigger like a fish fillet so the safest way to thaw is in the refrigerator or if you're talking about doing something really quickly you can run it under cool running water and that is the technique that really opened up the world of frozen meat to me stuff thaws great in the refrigerator but it takes a long time it might take overnight for something like a fish fillet for something bigger it's going to take days potentially the water method is so much faster i have a whole video about this it's linked in the description the short version is water is way more dense than air so that's way more relatively warm molecules coming into contact with your food and transferring in their heat and because water is so effective at this the water just doesn't have to be warm it's just cool water from the tap by the time it's heat transfers to the food the water temperature probably goes below the bacterial danger zone and even if it doesn't it doesn't really matter because this method works so quickly there just isn't enough time for bacteria to grow especially if you leave the water running for something small like shrimp i don't bother leaving the water running because they thaw in like 10 minutes no matter what but for this really big hanger steak that i cooked in my steak 201 video i think that it helped to leave the water trickling to keep it moving to keep a fresh supply of water molecules circulating around the food this huge piece of meat thawed in 40 minutes now when i've talked about this method before people have raised concerns about water waste and i think if you live in a place where fresh water is scarce that's a legitimate concern but i don't worry about it and i'll tell you why first of all fresh water is not scarce where i live secondly trickling water just doesn't add up to that much i did a little experiment using that tape as a marker this thawing procedure used about six gallons of water total two of those were in the bowl therefore the extra trickle added up to four with a piece of meat this big and thick i would have had to change the water in the bowl once or twice anyway to get it thawed which would have worked out to six gallons of water so it's a wash and speaking of washing six gallons is what a typical dishwasher cycle consumes a typical shower in the united states consumes about 17 gallons and it takes 1800 gallons of water to produce a single pound of beef ranch to freezer so come on let's keep things in perspective there's lots of ways to thaw stuff but thawing under running cold water is in my opinion simply the easiest most reliable and fastest way just as squarespace is the easiest and fastest way to make a website whether you need to sell a product sell a service publish some media or just let the world know that you exist squarespace has a template for you that you can easily customize in minutes the templates tend to be image based so that all you need is some pictures to upload there's a built-in image editor and just by doing that the site looks like yours whatever else you need to do with your site squarespace can do it for you processing sales taking appointments anything they can even connect you with a squarespace expert who can do all of this work for you if your attention is required elsewhere squarespace hosts your site for you they can register your custom domain for you they give you all the analytics for your traffic it's the only company you will need to work with to run your site and you can save ten percent on your first one by going to squarespace.com ragusia you'll be doing us both a favor now go chill oh hey you're still here well that's good because i require your assistance i'm working on a video about washing meat whether you should wash raw meat before you cook it and this is a surprisingly fraught cultural and scientific issue i went looking for some research about global practices on this things that people do differently from place to place and i found absolutely nothing so i'm doing it myself i'm working with some public health scholars over at middle georgia state university and we have put together a survey and i would love it if you would take it it takes about 10 minutes just ask you some questions about what you do in the kitchen visa via washing meat and other kind of basic food safety things and it would be great if you could take it and if you could get all of your friends and family to take it especially if you like live in places that are not here though even if you live here that'd be great if you could take it i want anybody to take it it'll be up for a couple of weeks as a posting of this video and then the results from that will go into a video on this topic that link for that survey is in the description oh and just to provide a little incentive if you take this survey i will enter your name into a drawing and the winner of that drawing will get to do an episode of ask adam with me instead of lauren asking the questions you'll be the one asking the questions and that means that you can sneak in some of your own so if that sweetens the deal for you all the better

Channel: Adam Ragusea

Views: 1,172,239

Keywords: frozen food, food freezing, flash freezing, flash frozen, ice crystals, ice crystal nucleation, crystal nucleation, frozen meat, how to thaw meat, how to thaw frozen food

Id: U_PMnCpaJiQ

Length: 13min 40sec (820 seconds)

Published: Mon Sep 28 2020