FOOD STABILITY WHEN USED IN MY “DIY FROZEN FOOD FEEDER”

[Rick Mathew]

Many of you have asked me a very good question in my DIY post of “The Frozen Food Feeder” (Here is the link https://www.reef2reef.com/threads/diy-frozen-food-feeder.279232/ ) about the stability of the food over time….will it go bad….will it break down. You got me to thinking. Are my assumptions correct or am I feeding my fish and corals “bad” food? I could not find any relevant posts that had any data, just mostly anecdotal observations. (Some of you might be able to point me in the right direction).So I decided to make some phone calls and do some digging for some relative data on the stability of the food at different temperatures. My sister-in-law is a clinical pathologist so I reached out to her. She pointed me in the direction of the frozen food industry. Her Job consisted of a lot of different kinds of tissue preservation so she had a lot of insight into the matter. Without troubling you with all of the details, I found these two articles very helpful in understanding the issue. (If math scares you you may not want to look at these )

http://www.fao.org/docrep/V7180E/V7180e07.htm

https://seagrant.uaf.edu/lib/asg/30/ASG-30.pdf

From these two articles I calculated what is referred to as “Equivalent Days on Ice” time at my storage temperature of 30⁰-31⁰ F and subtracted that from the “Maximum Shelf Life of Shrimp at 32⁰ F on Ice”( 5 Days) to find my “Remaining Shelf Life” . This shelf life is based on fitness for human consumption, so I had to make the assumption that it would hold true for my fish…not sure this is totally valid.

I found my Remaining Shelf Life was in a safe range for usage given 5 days is the maximum time I keep a batch in the feeder. My calculations give me about 12-24 hours of extra shelf life at my holding temperatures. She (my sister-in-law) also recommended an experiment that I can do to validate the assumptions and calculations, which I will do later.

I have read a number of posts on various websites that say that people thaw the frozen food and then store it in the frig for over a week. The average temperature of a refrigerator is between 32 to 40⁰ F. That means the food is approximately 2-10 days past its useful shelf life. When you read the articles you will see that the changes in remaining shelf life are not linear with temperature which means the spoilage is two times as fast as you go from 32⁰-40⁰ F

Well that’s probably enough for now. I appreciate all of you questions. It motivated me to dig into the data. Not sure it is 100% applicable but it is better than what I had before and I am still in the process of exploring the subject…Will keep you posted as I do my experiment and a bit more digging, but at least it is a move in the right direction.

Thanks

Rick

PS If any of you can point me to additional information that could be used it would be appreciated.

 

[mcarroll]

I have read a number of posts on various websites that say that people thaw the frozen food and then store it in the frig for over a week.

Ew.

I would never make more than I needed in a day. Maybe for exceptional circumstances, but never just "that's the way I do it".

Ew!

What are the first ingredients to go bad? Potentially the most valuable. Enzymes. And and more. Oils oxidize, etc.

Plus, what starts growing? Mold and bacteria.

In fact, none of those charts in Link #1 suggests anything other than keeping your food frozen until usage.

Must run for now, but still reading and thinking about this...

 

[Lionfish Lair]

Rick, I have a lot of research data about this that you may be looking for, yet I won't be back in the country until the end of January. If you could send me a little reminder, I can get you all sorts of stuff.

 

[Rick Mathew]

Ew.

I would never make more than I needed in a day. Maybe for exceptional circumstances, but never just "that's the way I do it".

Ew!

What are the first ingredients to go bad? Potentially the most valuable. Enzymes. And and more. Oils oxidize, etc.

Plus, what starts growing? Mold and bacteria.

In fact, none of those charts in Link #1 suggests anything other than keeping your food frozen until usage.

Must run for now, but still reading and thinking about this...

Thanks for the reply will look forward to additional comments
Rick

 

[Rick Mathew]

Rick, I have a lot of research data about this that you may be looking for, yet I won't be back in the country until the end of January. If you could send me a little reminder, I can get you all sorts of stuff.

Thanks for the reply....will put it on my reminder list to contact you

Rick

 

[mcarroll]

One key point I just noticed is that these papers are addressing muscle foods....not whole foods

 

[Lionfish Lair]

I have articles that deal with flesh and whole fish. The info on the whole fish is terrifying. I'm afraid the info will support mcarroll's hypothesis of "ew", though.

 

[Rick Mathew]

One key point I just noticed is that these papers are addressing muscle foods....not whole foods

Is the breakdown mechanism and or rates different for each?

 

[Rick Mathew]

I have articles that deal with flesh and whole fish. The info on the whole fish is terrifying. I'm afraid the info will support mcarroll's hypothesis of "ew", though.

I don't want to be Terrified...Just informed ...will look forward to seeing them when you get back in Feb...

 

[Lionfish Lair]

It's a whole different ballgame. Different rates and different enzymes and different risks. The GI tract is a nasty beast.

 

[Rick Mathew]

It's a whole different ballgame. Different rates and different enzymes and different risks. The GI tract is a nasty beast.

I have discovered that...thanks to a local restaurant!!

 

[mcarroll]

Is the breakdown mechanism and or rates different for each?

Yes....I don't think thier wording was coincidental....muscle tissue is relatively "pure".

Whereas whole organisms will be replete with (at least some of) their gut bacteria, et al....usually (I think) these are sufficient to digest the creature once homeostasis isn't being maintained.....and we're well past that stage when we're defrosting it tank-side!

And I know I went "Ew!" twice, but really it isn't about that angle.

I'm mostly looking at this from a fresh-is-best since that's the point of all the extra effort and expense vs just using flake food. Isn't it?

I would simply look at it as a guidline – the less time the food item spends unfrozen-unused, the better. To me a week is really pushing it, but I admit I don't have anything empiric to base that one.

Do you have a microscope to do any kind of cool, nerdly observation of the microbe content in the food over time?

 

[Rick Mathew]

Yes....I don't think thier wording was coincidental....muscle tissue is relatively "pure".

Whereas whole organisms will be replete with (at least some of) their gut bacteria, et al....usually (I think) these are sufficient to digest the creature once homeostasis isn't being maintained.....and we're well past that stage when we're defrosting it tank-side!

And I know I went "Ew!" twice, but really it isn't about that angle.

I'm mostly looking at this from a fresh-is-best since that's the point of all the extra effort and expense vs just using flake food. Isn't it?

I would simply look at it as a guidline – the less time the food item spends unfrozen-unused, the better. To me a week is really pushing it, but I admit I don't have anything empiric to base that one.

Do you have a microscope to do any kind of cool, nerdly observation of the microbe content in the food over time?

I agree...The general learning is keep the time short from thaw to use and keep the temperature as low as possible during use and storage...

Actually as to the microscope I may have a better opportunity. My sister-in-law is a pathologist and may be able to give me some assistance in looking at this issue more in depth...I do dave a digital scope but not sure I would know what I was looking for or if the magnification is high enough to see the critters...Biology is not my strong suit...I am a mathematician by education and researcher in practice which is why I need to reach out for understanding about this. As I mentioned this practice of "thaw and store in the frig for extended periods of time (a week or more)" does not to seem to be uncommon...and because I am curious by nature I wanted to explore the validity of the practice and its limits...Based on what you are telling me and what I have found so far it looks like a really bad idea.

What I would really like to know is how long storing at 29-30F the food is ok for use. This will then direct me as to how long before I have to direct my "Reef Sitter" to rotate the food in my "Frozen Food" feeder while I am out of town...or if it even a good idea to do it...IE use the feeder at all...Sure appreciate you input...very helpful...will keep you posted

Happy Holidays

Rick

 

[mcarroll]

If it's only for now and then, I don't think the odds would come out against you. I just wouldn't use it as an everyday practice.

My gut says and overnight in the fridge would be all I'd tolerate. One night of "leftovers" if you will.

It will be interesting if you can get some digital scope pics and do see how things progress!!

Even if you don't know what you're looking at in the scope specifically, maybe you can get an idea of what's normal and at least recognize changes.

Of course if you can get a pathologist on the clock...

But I would neither hold out nor wait if I had a digital scope. Which scope do you have, how much $$ (if you don't mind) and how do you like it so far?

One person I know deals with fresh, whole seafood more than anyone else I know: @Paul B

Perhaps he has some experience in storing it refrigerated that could help.

 

[mcarroll]

@Rick Mathew I forgot to mention that after some more reading in that article it looks like they do address whole fish to at least some degree. Will try to finish reading later when I get more time and give you some more feedback. (What a cool study that was! Those Aussies!!)

 

[Rick Mathew]

If it's only for now and then, I don't think the odds would come out against you. I just wouldn't use it as an everyday practice.

My gut says and overnight in the fridge would be all I'd tolerate. One night of "leftovers" if you will.

It will be interesting if you can get some digital scope pics and do see how things progress!!

Even if you don't know what you're looking at in the scope specifically, maybe you can get an idea of what's normal and at least recognize changes.

Of course if you can get a pathologist on the clock...

But I would neither hold out nor wait if I had a digital scope. Which scope do you have, how much $$ (if you don't mind) and how do you like it so far?

One person I know deals with fresh, whole seafood more than anyone else I know: @Paul B

Perhaps he has some experience in storing it refrigerated that could help.

Always best to error on the side of caution...I agree.... as for the digital microscope...I got it when I was working to raise my own brine as well as to identify "strange Critters"...It is a an inexpensive USB device 400 times magnification...you can also take pictures with it or record video...here is what it looks like and a link to Amazon where I got it...

https://www.amazon.com/gp/product/B005P40OXY/ref=oh_aui_search_detailpage?ie=UTF8&psc=1

 

[Rick Mathew]

@Rick Mathew I forgot to mention that after some more reading in that article it looks like they do address whole fish to at least some degree. Will try to finish reading later when I get more time and give you some more feedback. (What a cool study that was! Those Aussies!!)

Actually that article is what set me on my "Quest" to understand the relationship between temperature and sopolage rates

 

[mcarroll]

Cool! At first glance I thought that was just a stand for a microscope like I've seen before, but that's an endoscope!! That means it is waterproof, correct?

#microscope

Getting off topic, so maybe PM or another thread would be better, but do you have any photos/movies you've taken with it that you wouldn't mind sharing?

 

[Rick Mathew]

Cool! At first glance I thought that was just a stand for a microscope like I've seen before, but that's an endoscope!! That means it is waterproof, correct?

#microscope

Getting off topic, so maybe PM or another thread would be better, but do you have any photos/movies you've taken with it that you wouldn't mind sharing?

I will look to see if I have any photos or video...I will send you a PM when I locate them

Rick

 

[Rick Mathew]

Cool! At first glance I thought that was just a stand for a microscope like I've seen before, but that's an endoscope!! That means it is waterproof, correct?

#microscope

Getting off topic, so maybe PM or another thread would be better, but do you have any photos/movies you've taken with it that you wouldn't mind sharing?

It is not submersible...The LED lighting at the time is not water tight as I understand it