Getting freeze dried foods to sink

[bekateen]

Hi All,

What I'm about to write is not rocket science, and it's probably not even news to most of you. But it's something I just discovered two days ago by trial and error, so it was a watershed moment for me, and it's a handy and simple idea for anyone struggling with the same issue:

How to get freeze dried foods (blood worms, tubifex, grubs, krill, brine shrimp) to sink quickly for bottom feeders

In the past, I always solved this by adding some freeze dried food to some water, then either trying to press it with my fingers into a dense wet blob (which is not difficult, but can be inefficient), or soaking the food for many minutes in a sealed jar and shaking vigorously. Both of these methods are messy and time-consuming.

I discovered that if I put my desired serving of freeze dried food in a small microwave-safe cup (tea cup, finger bowl, whatever) with about an ounce of water, then microwave the cup for about 15-45 sec (depending on amount of water and amount of food; the key is that you must get the water/food mixture to boil or foam up) ...Voilà - the freeze dried food is water logged and sunken to the bottom of the cup. Then I just dump it in the tank.

Again, not a brain strain or revelation, but helpful if you're struggling with the same issue.

Cheers, Eric

[TwoTankAmin]

Years back I stopped using freeze dried foods for a number of reasons. Almost anything one can get freeze-dried can also be found frozen. Frozen sinks better and I believe it is more healthful than a freeze-dried version of the same food. For me daphnia were the biggest problem until I switched to the Hikari frozen. However, frozen is more expensive, especially if shipping is involved.

[bekateen]

Other drawback of frozen foods are (1) you have to be wary of products at time of purchase: Did they thaw and refreeze when transported from wholesaler, or has retailer allowed food to thaw and refreeze (sometimes this is visible in the product and you just don't buy that package); (2) even if properly shelved in store, frozen food has a shorter shelf life than freeze dried food.

[backstreetgambler]

That's good advice, Eric. Kind of the things I scan all these aquaristic fora in hope to come across. So thanks for sharing. When it comes to freeze dried tubifex I use to drill a hole trough the cube with a small nail. The nail is attached to about a meter of fishing line. I drop the cube in the aquarium where it will float for a couple of minutes before sinking. This works pretty well for feeding my corys. They usually get to eat about half the cube before it detaches itself and floats to the surface. Midwater and surface fish takes care of it from there.

Niklas

[MChambers]

Interesting technique and new to me. Thanks for posting this!

[TwoTankAmin]

I have never bought frozen food from a store. I buy it online. I buy it between Oct. and Apr. It arrives with tons of still frozen solid cold packs. To date I have never fed frozen and had deaths. So either I am very lucky or it is not quite that risky if you buy from the right sources.

If you get freeze dried it to boil up, doesn't that effectively cook it to some degree? And if so, doesn't cooking remove some of the nutritional value?

When I did feed freeze dried I simply put warm water into a clear container, dropped in the FD food and waited until it had sunk to pour it into tanks.

Given frozen foods vs freeze dried, which process results in maintaining the higher degree of overall nutritional value? I know they lose different things, but not the overall effects.

I do know that freeze dried has a longer shelf life and is less expensive. But I have always had in my head the idea that frozen is closest to being, would be the best option in many cases.

[bekateen]

Hi TTA,
I agree that properly frozen and stored foods are (or at least seem like they should be) more nutritious than freeze-dried foods. I am not contesting that issue.

Unlike your approach, I have never ordered frozen foods by mail order. I've bought all of my frozen fish foods at my LFS. Some LFS have very good freezer systems, others do not. But even if the food is frozen when I buy it, there is a good chance that it will at thaw or at least partially thaw while I drive home. I could avoid that if I added freezer packs in my styrobox before leaving home on the day of purchase, but my brain is small and I don't plan that far ahead.

All that is to say I do not use freeze-dried foods because I consider them a superior nutritional source, but rather I use them for their practical values. That said, I do not believe they are a "bad" source of nutrition either... just not as "good" as fresh or frozen.

Also, when I pulverize foods to prepare fry food powder (I've described my recipe elsewhere), I use dry foods for that home recipe - flakes, pellets, and freeze-dried foods.

If it works, don't mess with it. If it doesn't work, change it. Right now, my fish are eating a lot of the freeze dried foods, so I'm just ensuring the foods sink to the fish.

Cheers, Eric

[TwoTankAmin]

@bekateen


It is OK to have frozen foods defrost some- almost into slush. This is the method I have used for years to make medicated food. I allow the frozen to become more like slushy snow than ice, the meds go in stir and refreeze solid. Never any issues.

I have also used a similar method the make medicated flake. I will put the flake into a small bowl, add a small amount of water and then sprinkle in the meds, stir gently and feed a portion, then the bowl goes into the freezer. When I want to feed again, I chip off pieces and put them into the tank, the flakes then separate and the fish get them.

When it comes to freeze dried vs frozen for nutritional considerations, I still wonder about your heating to the point where they froth. That still implies some degree of cooking potentially and I think that may degrade the nutritional values beyond what ever the freeze drying process does. With frozen there will be no potential cooking.

I also have never done much shopping for fish or supplies at brick and mortar stores. The exception would be tanks. I buy almost everything else online and have since I set up tank #1. I now tend to buy fish as imports, via wholesale sources or from breeders. So no stores there either. In my early years, when I did not know better, I got fish on Aquabid until I learned to deal with the few reputable sellers directly. But since early 2005 I think I have only bought plants one time there and nothing else.

I am not arguing against using frozen foods, I am just curious about whether your method for heating might have a downside. If it were not a decent feeding regimen, your fish would not be doing so well. I guess I am curious about the optimal way v.s. something not quite that good. I cannot say for sure how I do it is any better than how you do it nutritionally speaking. I also do not make my own foods at all.

One last comment here, I hate paying retail for my supplies. So I buy stuff in bulk. When I wanted rooibos tea, I purchased an 18 kilo bag, I will probably die before I can use and sell it all. I do the same with the catappas and alder cones. I will also stock up on things from online retailers when they get cheap because they are on sale. I can't say that I am not being penny wise and pound foolish doing this. But it makes me feel smarter

[Bas Pels]

I quote

When it comes to freeze dried vs frozen for nutritional considerations, I still wonder about your heating to the point where they froth. That still implies some degree of cooking potentially and I think that may degrade the nutritional values beyond what ever the freeze drying process does. With frozen there will be no potential cooking

Obviously, when freeze drying anything, water will evaporate. However, that does not imply any cooking is involved, and certainly no cooking as we all feel cooking is (100 C)

As a student I did some experiments exposing fish (Tilapia) to heavy metals, then killing them and freeze drying them before I could determine the amount of metal in the body.

This freeze drying involved putting them under vacuum and waiting. You will wonder where the freeze comes - the evaporating water will need heat to evaporate, and the only possibility is that this comes from the corpse. This corpse is thus robbed of much of its heat, and therefore it freezes.

Freeze drying is intended as a way of very gently remouving water (a 2 gram fish took 2 or 3 days @ 10 mm Hg) while not disturbing the rest of the matter.

Wheter one feels better feeding frozen food (I don't) or freeze dried food (I do) is a personal matter, but I just wanted to say that freeze drying will not deminish the content of minerals or vitamins in the food.

However, as these will, given enough time, oxydize, in most cases the producers will add some vitamins and minerals in order to expand shell life.

In case one has problems with fish needing vitamins - I'd suggest feeding them exclusively with freeze dried food - freshly bought, in order to have the extra.

[bekateen]

Obviously, when freeze drying anything, water will evaporate. However, that does not imply any cooking is involved, and certainly no cooking as we all feel cooking is (100 C)

Hi Bas Pels,

Your points about the freeze drying process and its impact on nutrients are well taken, but I believe you misinterpreted TTA's point.

He was not referring to the process of freeze drying as "cooking," but rather he was referring to my method of rehydrating the food with water using a microwave for less than a minute, but causing the solution to foam up. Even though my cooking process is typically 30-45 seconds, if it makes the mixture of freeze dried food and water foam up, then some level of boiling occurred.

Cheers, Eric

[TwoTankAmin]

If I am not mistaken, frozen foods are actually heated before being frozen whereas freeze dried are frozen without heating and then put into an even colder vacuum chamber. This permits the water which is in now the form of ice to be turned directly into its gaseous state with no liquid phase. This removes most of the moisture.

The heating of frozen is done to help kill "nasties" before freezing. I would assume the need for this, and lack of it for freeze dried, is that the nasties cannot survive without sufficient moisture even if that is in a frozen state.

I believe my greatest risk using frozen is how long I store it. I will go to one year and I am thinking six months would be better. But we all make some concessions.

[bekateen]

Okay, if you don't want to use the microwave, but you're not satisfied with the old standard "squeeze between your fingers" method, I have another method to offer, which I experimented with today.

Two words: Garlic press

Here's my technique, shown in 9 pictures. FYI, the cup is filled with a small amount of tank water, not tap water. And after the press, I dump the water back into the tank.

The result? Not as effective as the microwave at getting food to sink, but still better than the finger pinch method.

[bekateen]

Pics 5-9

In the top photo, where I'm squeezing the worms with the garlic press, I performed this action in a pulsatile fashion while under water - squeeze, relax, squeeze, relax, repeated about five times.

[TwoTankAmin]

@eric

I have always simply put freeze dried foods into a cup of water and let it sit for a bit until it become water logged and sinks on its own. From there is is easy to pour into tanks.

As an aside, when I kept bristlenose I fed zucchini. I used to pre-slice it and freeze the slices between wax paper sheets (it was easy to detach from wax paper). To get it to sink I would nuke slices in a cup of water in the microwave trying not to have it boil. There was one minor issue with this. Zucchini, when warm/hot floats. Also, if it was not sufficiently warmed, when it cooled it still would not sink. As a result I would use cold water to cool it down, Then if it did not sink to the bottom of the cup, I would warm it a bit longer.

When you nuke the freeze dried, do you find it still tends to float if it is warm or do you let it cool some first? Also, does it appear as if dealing with zuke as I did would degrade the nutritional value some?

[bekateen]

I have always simply put freeze dried foods into a cup of water and let it sit for a bit until it become water logged and sinks on its own. From there is is easy to pour into tanks.

TTA, That was my method in the past, or at least something like it: (I'd add some food and water to a small capped jar, shake it vigorously, then wait and pour). Unless the wait time is really long, I don't find that technique to be particularly effective. So that's why I started exploring for alternative mechanisms that might be more complete in their ability to get more of the food bits to sink in a shorter time.

As an aside, when I kept bristlenose I fed zucchini. I used to pre-slice it and freeze the slices between wax paper sheets (it was easy to detach from wax paper). To get it to sink I would nuke slices in a cup of water in the microwave trying not to have it boil. There was one minor issue with this. Zucchini, when warm/hot floats. Also, if it was not sufficiently warmed, when it cooled it still would not sink. As a result I would use cold water to cool it down, Then if it did not sink to the bottom of the cup, I would warm it a bit longer.

When you nuke the freeze dried, do you find it still tends to float if it is warm or do you let it cool some first?

I do let it cool first, but not all the way to room temperature. Even at nearly 200F, adding 1-2 ounces of hot water to even a 10 gal tank at 78F is going to be of little consequence. But either way (still hot or cooled down), the food is submerged in the cup before I pour it into the tank, and it sinks immediately in the tank.

If your zucchini is still floating, then there is probably still gas trapped inside; obviously hotter air expands relative to cool air, so that may be a factor in your experience. My purpose for boiling the freeze-dried food is not to cook the food, but to heat the trapped air so much that it is forced out of the food (and gets replaced by water). That's why the microwaved food sinks.

Now, over time (several hours if uneaten) it will float again. I suspect that's due to microbial gas production inside the food creating trapped gas pockets. With sweet potato, if that happens and the piece begins to float before the veggie rots and gets slimy, I simply compress the veggie between two fingers to expunge the gas, and the veggie sinks again. A similar phenomenon occurs with freeze dried worms, etc.

Also, does it appear as if dealing with zuke as I did would degrade the nutritional value some?

I don't see why it wouldn't. Microwaved nutrients are still microwaved, regardless of whether the food was previously freeze-dried or raw.

As an aside, when I kept bristlenose I fed zucchini. I used to pre-slice it and freeze the slices between wax paper sheets (it was easy to detach from wax paper). To get it to sink I would nuke slices in a cup of water in the microwave trying not to have it boil. There was one minor issue with this. Zucchini, when warm/hot floats. Also, if it was not sufficiently warmed, when it cooled it still would not sink.

Although not exactly the same, I've found sometimes that when I cut cubes or thick (1/2" or more) slices of raw sweet potato (which in my house I store in the fridge, not on the counter), it doesn't sink easily. And because it's so thick, there's a good chance that the fish don't eat the whole chuck quickly. Then it starts to rot in the warm tank and it floats. To avoid this in the first place, I now cut my raw sweet potato thin, like potato chips. The slices are so thin that they almost always (but not always) sink immediately without ANY weights whatsoever. And because they are so thin, the moment fish start eating them, they crumble. The advantage is that by crumbling, accumulating gases are released immediately, so the slices aren't as likely to float a day or two later, if they aren't fully consumed. I get much less waste that way, and without the slimy rot, the tank stays cleaner too. The other obvious advantage is that with the potato cut so thin, I get more pieces from the same mass of potato, so I can spread them around the tank, allowing more fish to feed at once, instead of having more aggressive plecos fighting off the smaller or weaker ones. I rarely need to go in and pull out uneaten veggie with this method.

Cheers, Eric