added phosphate in nori ?

[nematode]

I read your article about phosphate and math. One soft conclusion was that soaking food to remove phosphate wasn't worth doing.

I quantified the amount of phosphate I could remove from the brand of Nori I was using (Wang Korea Sushi Nori) after I found very high levels of phosphate in a Q tank with Tangs I had feed lots of Nori for a month.

My conclusion is the brand of Nori I am using may be adding phosphate to the Nori even though it states the only ingredient is seaweed.

I got data for phophorus concentration in Nori from http://takaokayausa.com/html/norifaq.shtml#faq6
This is nutritional information for Yakinori from "standard Tables of Rood Composition in Japan, fifth revised edition " according to the website.
It states that a 2.1 g sheet of nori has 15 mg of phosphorus (or 46 mg of phosphate)

However, I was able to soak out 21 mg of phosphate from a sheet of Nori ( actually 3.5 mg of phosphate from 1/6th of a sheet of Wang Korea Sushi Nori- my usual feeding).

If no phosphate was added that would suggest I could remove a mimimun of about 45% of the phosphate by soaking.

What I did.
I soaked 1/6th of a sheet in 500 ml of RO water for 5 minutes, transfered to 500ml of water again, and then a third time and tested the water for phosphate.
I used a stannous chloride method for measuring phosphate with standards of dilute Phosphate buffered saline at 0 ppm, 1 ppm, 2ppm and 5 ppm phosphate. First soak ~ 5 ppm (maybe more since that was the highest standard I did and the blues were pretty equivelant, but both quite dark) , second soak ~1.5 ppm, 3rd soak ~0.5 ppm. soaking out ~ 7 ppm *500 ml or 3500 ug of phosphate in 1/6th a sheet of Nori. 21 mg of phosphate from a sheet of Nori.

Since I would gather that most phosphate in Nori is in nucleic acids, and most of those are unlikely to be easily soaked out even from the dried plant tissue, I am concluding that these folks might be adding phosphate, perhaps as a preservative.

I am going to try a few other brands of Nori and see if there is significant variability in the amount of phosphate that can be soaked out from different brands.

But, my conclusion is that either soaking can remove a lot of phosphate, or some brands of Nori have added phosphate (which could be removed).

 

[bertoni]

I think there will be a significant amount of phosphate associated with the protein in the food, even though protein itself doesn't contain much (or any) phosphate. I think I should be able to find a thread to where this was discussed. Phosphate is a macronutrient, so it's going to show up in some form in any food. 3.5 mg is a fair chunk of phosphate. What was the weight of the sheet of dry nori?

 

[nematode]

I did not weigh the individual fragment I soaked, but the package is 50 sheets totalling 130 g, so each sheet should be 2.5 g. I used 1/6 of a sheet, so ~400 mg. So ~ 0.8- 1% of the mass of the sheet was phosphate I was able to remove by soaking.

RE phosphate in food. Of course, there is phosphate in food and its an essential component of life. But I was shocked at how high my phosphate levels got from one month of feeding nori in my Q tank, compared to what heavy feeding of flake food does. And I was surprised at how much phosphate I could soak away from the nori.

The phosphate in the nori is not from protein. There is almost no phosphate in protein or in carbohydrates. There is some phosphate in "fat" in terms of phospholipids, and nucleic acids. In vertebrates, bone is also high in phosphate. Cells also have a pool of nucleotides, but I think for most cells phospholipids and nucleic acids (DNA and RNA) are the vast majority of the phosphate my mass.

The lipid membranes are not going to be water soluble, nor should the DNA easily diffuse out of plant tissue. The nucleotide will and the RNAs might. But the amount I am removing by soaking is surprisingly high compared to the published values of phosphorus/phosphate in Nori. That is why I suspect phosphate addition.

 

[billsreef]

Some macroalgaes are capable of storing nutrients pulled from the seawater, above what they need in short term. This can lead to phosphate and Nitrogen loading above what is bound as proteins, etc.

 

[hkgar]

I have started using New Era Marine Grazer. Any ideas on its Phosphate level?

Is there anyway for those of us that have no idea for testing except to use the hobby grade Phosphorous or Phosphate test kits to see how much PO4 is in the foods we feed?

Also, I may have missed it, but how much would a 1/16 piece of Nori contribute, in terms of PPB (Phosphorous) PPM (Phosphate) to a gallon of water?

 

[bertoni]

The phosphate associated with protein mostly is from phosphorylation and possibly other effects. I agree that proteins contains little phosphorus, but phosphorylation can be significant.

 

[tmz]

As I recall nori isn't terribly high in phosphate vs protein relative to other foods particularly boney foods. The brand used may have some extra used as a preservative but I don't know that.