Lactose fermented onions - a recipe?

[bernardsmith]

I am looking for a good recipe for brine pickled onions. What's the optimal brine solution (% salt) for onions? The only recipes I have found seem to suggest what looks like far too diluted brine. should I be aiming for about 4% -5% brine solution (4 g iodine-free salt in 100 ml chlorine-free water)?

 

[renrutle]

I am using a 4% brine by weight. I believe the accepted safe range is 2%-5% salt by weight. I weigh the water and divide by 0.96 to give a final weight. Then add iodine free salt until the scale shows the calculated weight.

4 grams per 100 ml will work fine and should give a concentration of 3.85% 4.17 grams salt per 100 ml should be right at 4.0%

 

[bernardsmith]

Thanks for the confirmation. The Youtube videos would seem to suggest a brine closer to 2-3% which I think kinda nuts (sure, if you are concerned about your sodium intake - but then don't use brine to pickle OR don't eat so much commercially processed food with their mega doses of sodium used to replace the missing flavor).

 

[renrutle]

For my gallon batches of jalapenos and onions I use right at 1/2 gallon of water. It measures pretty close to 4.0 lbs. The 0.17 lbs of salt is almost 1/4 cup. After fermentation I have ~3/4 gallon of liquid but only use 1 quart of that for canning. The other 1/2 gallon I throw out. Of the 1/4 cup of salt (4 Tbls) only 1/3 of that (1 Tbls + 2 tsp) is in the 1 quart of brine that ends up in my jars. There will be only a fraction of this salt in the vegetables. You could drink the brine I suppose; if you needed to keep your blood pressure up.

I would not worry about salt poisoning. (Is that even a thing?)

 

[RPh_Guy]

I would not worry about salt poisoning. (Is that even a thing?)

Yes, it's called hypernatremia.
https://www.merckmanuals.com/profes...disorders/electrolyte-disorders/hypernatremia

For example you will die if you drink only sea water (which is around 3.5% salt) without other sources of hydration.

However, an adequately hydrated person in good health will be able to tolerate a high salt load intermittently, although you might not feel particularly well afterwards.

I am using a 4% brine by weight. I believe the accepted safe range is 2%-5% salt by weight. I weigh the water and divide by 0.96 to give a final weight. Then add iodine free salt until the scale shows the calculated weight.

4 grams per 100 ml will work fine and should give a concentration of 3.85% 4.17 grams salt per 100 ml should be right at 4.0%

To calculate % by volume, you're assuming NaCl is 1 g/cm^3, which is not the case. Its density is 2.17 g/cm^3.
Or if you're calculating by weight you'd need to take into account the actual mass of the water, rather than assuming it's 1g/mL, which it probably isn't.

4g NaCl plus 100mL water gives ~3.93% by volume.

 

[bernardsmith]

But for the purposes of making a brine, RPh_Guy, isn't 3.93 close enough to 4% to be called a bullseye?

 

[RPh_Guy]

Yep!

 

[Miraculix]

Thanks for the confirmation. The Youtube videos would seem to suggest a brine closer to 2-3% which I think kinda nuts (sure, if you are concerned about your sodium intake - but then don't use brine to pickle OR don't eat so much commercially processed food with their mega doses of sodium used to replace the missing flavor).

If you want it to ferment and want a broad range of organisms while still being on the safe side, use 2% by weight. The higher the salt concentration, the smaller the variety of microorganisms that can still survive.

If you would have vegetables that easily go very soft when fermented, like gurkins, a 4% solution will keep them crunchy, however, this is not a problem with onions. Just use 2%.

 

[bernardsmith]

If you want it to ferment and want a broad range of organisms while still being on the safe side, use 2% by weight. The higher the salt concentration, the smaller the variety of microorganisms that can still survive.

If you would have vegetables that easily go very soft when fermented, like gurkins, a 4% solution will keep them crunchy, however, this is not a problem with onions. Just use 2%.

aha... so 2% does make good sense. I am always learning.

 

[Miraculix]

aha... so 2% does make good sense. I am always learning.

Make sure to use good glasses, with rubber sealing, not silicone, and to keep them shut till you want to eat them. They should be ready to eat in 3 to 4 weeks, depending on temperature. Make sure to place them somewhere were leakage won't be a problem as they will bubble over a bit during the first 10 days.

 

[bernardsmith]

Not a problem - I make pickled cucumbers, beets, cabbage, etc. Had never found onions small enough for me to want to pickle and then a couple of weeks ago my supermarket had bags of small onions. I had made a brine at 4% and then saw a number of videos on Youtube (most involved the use of vinegar!) that suggested a 2% brine and I wondered if that would result in the growth of bacteria that were other than desirable..

 

[Miraculix]

Not a problem - I make pickled cucumbers, beets, cabbage, etc. Had never found onions small enough for me to want to pickle and then a couple of weeks ago my supermarket had bags of small onions. I had made a brine at 4% and then saw a number of videos on Youtube (most involved the use of vinegar!) that suggested a 2% brine and I wondered if that would result in the growth of bacteria that were other than desirable..

Good train of thought, I think, if I remember correctly, below 1.5% it starts to get a bit risky regarding unwanted guests. The further down the concentration goes, the more the risk goes up. 2% however is still easily on the safe side.

 

[renrutle]

I had made a brine at 4% and then saw a number of videos on Youtube (most involved the use of vinegar!) that suggested a 2% brine and I wondered if that would result in the growth of bacteria that were other than desirable..

While there are other microbes that are dangerous and/or unpleasant the big one is the bacterium Clostridium botulinum. It makes the botulism toxin that causes muscle weakness and paralysis. Nice to have if you don't want a wrinkly face, but a high dose can cause the lungs to stop working.

Vinegar brines can get away with a lower salt content due to the addition of vinegar up front; this lowers the pH at the beginning. The combination of salt and low pH retricts/prevents most microbial growth. Most of the recipes I have seen also involve boiling the brine, pouring the brine in the prefilled jars and processing the sealed jars in boiling water for several minutes. The salt, vinegar, and heat should kill all the microbes; lactobacillus included. We don't want the sealed jars to ferment and explode.

With lacto-fermentation we need additional salt to slow/prevent the growth of the bad bugs until the lactic acid brings the pH low enough to inhibit most everything. In both processes the main issue restricting and preventing the growth of botulism.

However, everything I have read indicates that using a 2%-5% brine by weight is safe. This range should keep the bad bugs from proliferating too much before the lacto can get the pH below 4.6 and stop their growth.

I settled on a ~4% brine (just cause, I guess). I am happy with the results so far. I suggest you experiment with different salt concentrations and pick one you are happy with.

 

[renrutle]

Yes, it's called hypernatremia.
https://www.merckmanuals.com/profes...disorders/electrolyte-disorders/hypernatremia

For example you will die if you drink only sea water (which is around 3.5% salt) without other sources of hydration.

However, an adequately hydrated person in good health will be able to tolerate a high salt load intermittently, although you might not feel particularly well afterwards.

To calculate % by volume, you're assuming NaCl is 1 g/cm^3, which is not the case. Its density is 2.17 g/cm^3.
Or if you're calculating by weight you'd need to take into account the actual mass of the water, rather than assuming it's 1g/mL, which it probably isn't.

4g NaCl plus 100mL water gives ~3.93% by volume.

"hypernatremia" of course - should have remembered my The Rime of the Ancient Mariner from school.


I did make the assumption that water is 1g/cm so 100ml = 100 g

For a 4% solution the water would be 96% of the weight.

(100 g/96%) - 100 g = 4.17 g salt

So I don't have to make the volume to weight conversion when making brine I weigh the water; divide the weight by 96%; and add salt until scale shows the calculated total weight.

Should the brine be made on a % volume basis instead?

I hope my math is correct.

 

[RPh_Guy]

Should the brine be made on a % volume basis instead?

I hope my math is correct.

I suspect pretty much everyone making brine at home measures the water by volume, so going by weight will put your numbers slightly off.
Do you have references that describe the brine percentage by weight?

At 68°F (20°C), 100mL of water is 99.823g.

A little algebra to see how much salt we need for 4% by weight ...
0.04 = X ÷ ( 99.823 + X )
0.04 * ( 99.823 + X ) = X
0.04 * 99.823 + 0.04 * X = X
3.9929 = X - ( 0.04 * X )
3.9929 = X * ( 1 - 0.04 )
3.9929 ÷ ( 1 - 0.04 ) = X
X = 4.16

So, if you prefer to go by weight, it's 4.16g NaCl plus 100mL water (at 68°F/20°C) to get 4% by weight.

4g added to 100mL gives only 3.85% by weight, like you said.

Let see how much we need for 4% by volume...
0.04 = X ÷ ( 100 + [ X ÷ 2.17 ] )
0.04 * ( 100 + [ X ÷ 2.17 ] ) = X
0.04 * 100 + X * 0.04 ÷ 2.17 = X
4 = X - X * 0.04 ÷ 2.17
4 = X * ( 1 - 0.04 ÷ 2.17 )
4 ÷ ( 1 - 0.04 ÷ 2.17 ) = X
X = 4.08

So 4.08g added to 100mL water gives 4% salt by volume (assuming the final volume is the sum of the starting volumes, which is probably close enough within this level of significance).

This is all just academic. There's not really a need for high precision.

 

[renrutle]

so going by weight will put your numbers slightly off.

I would argue that the numbers are not slightly off but give the same information in different units. Just like ABV and ABW give you the same information about the alcohol content of a beverage even though the values associated with these units are different. Ratios by weight == ratios by volume given the proper conversion factors.

Do you have references that describe the brine percentage by weight?

Just college chem classes which referenced all components of a solution by mass/weight. If water was used it was measured in a gradated cylinder and assumed to be 1 g/ml [0.99823 g/ml to 2 significant digits is 1.00 g/ml] at standard temp and pressure 1 ATM and 20°C. [Unless temperature expansion adjustments were required as you noted.] Other liquids were converted to weight using specific gravity. To me a ??% solution has always meant ??% by weight of each component.

This is all just academic. There's not really a need for high precision.

I agree that you could measure either way and be safe. Most recipes do list ingredients by volume (1 Tbls salt per quart water) as we are used to measuring ingredients by volume. [tsp, Tbls, cup, etc.] The textual description of the process typically states use a 2%-5% salt solution leaving off whether that is by volume or weight. Since I have some digital scales measuring the water and salt by weight is quick and easy. Tare container; fill with water; weigh water; divide weight by 96%; add salt until scale reads this weight.

 

[renrutle]

Let see how much we need for 4% by volume...
0.04 = X ÷ ( 100 + [ X ÷ 2.17 ] )
0.04 * ( 100 + [ X ÷ 2.17 ] ) = X
0.04 * 100 + X * 0.04 ÷ 2.17 = X
4 = X - X * 0.04 ÷ 2.17
4 = X * ( 1 - 0.04 ÷ 2.17 )
4 ÷ ( 1 - 0.04 ÷ 2.17 ) = X
X = 4.08

I follow the math but would you explain where the 2.17 comes from?
[edit] is the 2.17gm/cm3 the density of salt? [/edit]

So 4.08g added to 100mL water gives 4% salt by volume (assuming the final volume is the sum of the starting volumes, which is probably close enough within this level of significance).

I may be missing something here as well. Wouldn't you need the salt measurement to be in milliliters and not grams for the volumes to cancel out and get a ratio or %?

For instance 2 Tbls per 1 quart gives a % volume ratio of ~3.1%. 0.125 cups / 4 cups = 0.03125

Time to RDWHAHD.

 

[RPh_Guy]

I would argue that the numbers are not slightly off but give the same information in different units.

Not really. 4% by weight is different than 4% by volume.

If a recipe says to use 4% salt assuming by volume and you use 4% by weight, then your amount of salt will be different.

Just like ABV and ABW give you the same information about the alcohol content of a beverage even though the values associated with these units are different. Ratios by weight == ratios by volume given the proper conversion factors.

Right, so a 5% ABV beer is different than a 5% ABW beer.
The units are not interchangable.

ABV is volume / volume
ABW is mass / volume

0.99823 g/ml to 2 significant digits is 1.00 g/ml

Incorrect. 1.0 g/mL is 2 "significant figures" and using that number limits your calculation result to 2 significant figures.
If you want 3 significant figures in your result you need to use 0.998 g/mL, which has 3 significant figures.

To me a ??% solution has always meant ??% by weight of each component.

That's not how I generally see solution concentrations expressed, especially in brewing.
Examples:
The alcohol level of beer.
Water minerals (ppm = mg/L).
Titratable acidity.
Lab solutions are often expressed as Molarity, which is per volume.

is the 2.17gm/cm3 the density of salt?

Yep.

Wouldn't you need the salt measurement to be in milliliters and not grams for the volumes to cancel out and get a ratio or %?

No, % by volume of solids is generally expressed as mass per volume.

I think literally no one but you expresses solution percentage as mass / mass.

Hope this all makes sense.

 

[renrutle]

Not really. 4% by weight is different than 4% by volume.

If a recipe says to use 4% salt assuming by volume and you use 4% by weight, then your amount of salt will be different.

Right, so a 5% ABV beer is different than a 5% ABW beer.
The units are not interchangable.

ABV is volume / volume
ABW is mass / volume

I never said they were the same. In fact I stated that they were different.
I did not say that a 5% ABV beer has the same quantity of ethanol as a 5% ABW beer.

I said you have to use a conversion factor to change from one set of units to another.

A 5% ABV beer has the same has the same quantity of ethanol as a 3.9% ABW beer.
A 6.3% ABV beer has the same has the same quantity of ethanol as a 5% ABW beer.
ABV * 0.795 = ABW.

Here is a conversion tool
https://www.probrewer.com/tools/percent-alcohol-conversion-calculator/

The %weight to %volume conversion factor for salt is somewhere on the order of 4.17/4.08 = 1.02.

Incorrect. 1.0 g/mL is 2 "significant figures" and using that number limits your calculation result to 2 significant figures.
If you want 3 significant figures in your result you need to use 0.998 g/mL, which has 3 significant figures.

My typo here. 0.99823 g/ml to 2 significant digits is 1.0 g/ml. I used 2 since 0.04 is also 2 significant digits. Either way the difference in our answers is 0.01 grams or 1/400th of a teaspoon. My smallest teaspoon is a 1/64 used in cheese making for measuring mold.

That's not how I generally see solution concentrations expressed, especially in brewing.
Examples:
The alcohol level of beer.
Water minerals (ppm = mg/L).
Titratable acidity.
Lab solutions are often expressed as Molarity, which is per volume.

No, % by volume of solids is generally expressed as mass per volume.


I think literally no one but you expresses solution percentage as mass / mass.

I disagree. See links below for others who use % weight.

https://www.chem.purdue.edu/gchelp/howtosolveit/Solutions/concentrations.html

Selecting liters and grams in the calculators below for the units will clearly show that the calculations are by % weight. They then can be converted to common volumes of teaspoon or tablespoon.
I have not found a brine calculator that uses volume of water in the calculation unless it is first converted to weight.

https://myfermentedfoods.com/tools/brine-calculator/
https://preserveandpickle.com/pickling-brine-calculator/
https://sciencing.com/make-nacl-solution-8242471.html
https://www.fermentools.com/blog/salt-calculator/

 

[RPh_Guy]

I would argue that the numbers are not slightly off

I never said they were the same.

^^^ Forgive my confusion.
Clearly we both understand the difference.

My typo here. 0.99823 g/ml to 2 significant digits is 1.0 g/ml. I used 2 since 0.04 is also 2 significant digits. Either way the difference in our answers is 0.01 grams or 1/400th of a teaspoon. My smallest teaspoon is a 1/64 used in cheese making for measuring mold.

No....
You don't understand significant figures. https://en.wikipedia.org/wiki/Significant_figures
0.99823 has 5 significant figures
4.17 has 3 significant figures
1.0 has 2 significant figures
0.04 has 1 significant figure, however it doesn't affect our precision in this case.

Significant figures are important for determining the precision of a calculation result.

I disagree. See links below for others who use % weight.

Fair enough. It is sometimes used.

I have not found a brine calculator that uses volume of water in the calculation unless it is first converted to weight.

Huh?

Link 1: cups, quarts, gallons, liters, and (g = mL), which as I pointed out is incorrect depending on your level of precision.
Link 2: liters or quarts.
Link 3: says to use w/w but then immediately says to use w/v in the next newer article: https://sciencing.com/make-five-percent-solution-salt-8076940.html
Link 4: cups.

They overwhelmingly measure water by using volume.

 

[bernardsmith]

Seems to me that measuring water by volume is one thing but measuring salt in the same way will lead to solutions whose salt content varies wildly: how many grams of sea salt is in a tablespoon compared to grams of table salt compared to kosher salt? My working assumption is that 1 kg of water = 1000 ml of water at the temperature of any room I am comfortable in but that 40 g of salt = 40 g of salt.

 

[Miraculix]

Seems to me that measuring water by volume is one thing but measuring salt in the same way will lead to solutions whose salt content varies wildly: how many grams of sea salt is in a tablespoon compared to grams of table salt compared to kosher salt? My working assumption is that 1 kg of water = 1000 ml of water at the temperature of any room I am comfortable in but that 40 g of salt = 40 g of salt.

Weighing is the only sensible solution. I don't know where this habit to "measure" solids by volume came from, but it is horribly inaccurate.

 

[bernardsmith]

In the US cookbook recipes have used volume measures (cups and spoons) for decades, perhaps centuries, in the UK we used scales but presumably anyone who ate food would have volume containers (though your "cup" might be twice as large as mine until such volumes were standardized), but not everyone would have had tools to measure weight, so perhaps volume measurement was more "democratic", certainly more "popular"?

 

[Miraculix]

In the US cookbook recipes have used volume measures (cups and spoons) for decades, perhaps centuries, in the UK we used scales but presumably anyone who ate food would have volume containers (though your "cup" might be twice as large as mine until such volumes were standardized), but not everyone would have had tools to measure weight, so perhaps volume measurement was more "democratic", certainly more "popular"?

Was never a thing in Germany due to the obvious inaccuracy.

 

[renrutle]

You don't understand significant figures.

D@mn dyslexia 0.40 or 0.04 I usually catch those errors but I missed it this time.

Link 1: cups, quarts, gallons, liters, and (g = mL), which as I pointed out is incorrect depending on your level of precision.
Link 2: liters or quarts.
Link 3: says to use w/w but then immediately says to use w/v in the next newer article: https://sciencing.com/make-five-percent-solution-salt-8076940.html
Link 4: cups.

They overwhelmingly measure water by using volume.

1 g = 1 mL is also correct depending on your level of precision. Mine currently is what is practical and helpful for someone on this forum to make use of in their endeavor to mix up a safe lacto-ferment brine.

I included link 3 and the link to Purdue University to show that the % weight formula I am using is accepted in the scientific and chemistry communities as an appropriate way to calculate the % concentration of a solution.

My previous understanding of % volume concentration was with only liquids involved; as explained in this article.
https://www.thoughtco.com/calculate-volume-percent-concentration-609534

Thank you for showing me another method to calculate the % concentration. I will come back to this in a bit.

I didn't say that the measurements were not by volume. I stated the calculations were by weight. In all of these calculators if you convert the volume of water to grams at 1 g/mL and select grams for the measurement of salt you will readily see that the calculations are by % weight and not by % volume.

However, after further review I see that these calculators are using a different third formula entirely.

For reference 1 gallon of water weighs ~3785 grams.

Link 1 for a 10% 1 gallon solution 378.5 grams salt
Link 2 for a 10% 1 liter solution 100 grams salt - selecting gallons gives salt in ounces
Link 4 for a 10% 1 gallon solution 379 grams salt.

Deconstructing this their "Web Formula" seems to be: gram Salt = gram Water * % salt.

This leaves us with 3 different ways to calculate the salt needed for a particular concentration of brine.

For the following:
"W" is the weight of water
"V" is volume of water in mL
"X" is the percent concentration of salt
"S" is the weight of salt
2.17 is density of salt in g/mL

Answers below are for 1 gallon and 5% salt are and are shown to the nearest gram.

% Weight Method
S = (W / (1 - X)) - W
S = 199 grams = 35.03 teaspoons = 1/2 cup + 3 Tablespoon + 2 teaspoon

% Volume Method
S = (2.17 * V * X) / (2.17 - X)
S = 194 grams = 34.06 teaspoons = 1/2 cup + 3 Tablespoon + 1 teaspoon

% Web Method
S = W * X
S = 189 grams = 33.27 teaspoons = 1/2 cup + 3 Tablespoon + 1/4 teaspoon

If you use work these equations backwards from say 1 gallon water and 194 grams salt the % concentrations are:

4.88% for % Weight
5.00% for % Volume
5.13% for % Web

These are all safe concentrations of salt for a lacto-ferment brine. Regardless of the method one uses you should get a safe ferment. 5.13% is a bit on the high side but some vegetables such as olives call for up to 10% salt. The biggest difference in the final product will be taste and possibly crunchiness but with good notes the salt levels can be adjusted on future batches.

After all this I am still left with one un-answered question. What is the method used by the folks who came up with the safe range of 2%-5%? I have yet to see a definitive answer on this.

One could split the difference and use the % volume method that @RPh_Guy has laid out but for or now I will continue to use the % weight method. Pick one that you are comfortable with and go for it.

 

[RPh_Guy]

For reference 1 gallon of water weighs ~3785 grams.

Not at 68°F.
This is where significant figures come into play. If you use 1.0 mL = 1.0 g for your conversion, the result is limited to 2 significant figures. Therefore 1.0 gallon is 3800 mL and any further calculation results will also be limited to 2 significant figures, like 380g of salt.

You can't get precise calculation results using imprecise numbers. This is why all your calculation results are incorrect.

In all of these calculators if you convert the volume of water to grams at 1 g/mL and select grams for the measurement of salt you will readily see that the calculations are by % weight and not by % volume.

You're completely wrong on this point.

Let's take calculator 1 as an example.
To make 1.0L of 4.0% brine it says to use 40.g salt.
This fits perfectly with % by volume.

On the other hand 40.g of salt plus 960g of water (4% by weight) does not make 1000mL, because the salt is more dense. 40.g of only adds about 18 mL, so it would give only about 980 mL in total.
With 40.g of salt topped up to 1000mL, it would be 3.9% by weight.

Your formulae are incorrect as well.
For example to calculate salt % by volume it's a very simple equation:
[grams of salt] = [% brine as a decimal] * [total volume in mL]

This is also what the web calculators are using.

Hope this makes sense.

 

[bernardsmith]

So this may be too fine a point to question but if I take 1 L of water (1000ml) and add 40 g of salt, is that too weak a solution to call a 4% brine solution as understood by folk who are using accuracy to one unit ( one ml or one g) ? (the solution with the salt having a greater volume than 1000 ml)..

 

[Miraculix]

So this may be too fine a point to question but if I take 1 L of water (1000ml) and add 40 g of salt, is that too weak a solution to call a 4% brine solution as understood by folk who are using accuracy to one unit ( one ml or one g) ? (the solution with the salt having a greater volume than 1000 ml)..

No that's fine but instead use 20g per 1000ml to get a 2% solution. 4% is the upper end and already inhibits a lot of potentially good bacterias in your ferment.

 

[RPh_Guy]

So this may be too fine a point to question but if I take 1 L of water (1000ml) and add 40 g of salt, is that too weak a solution to call a 4% brine solution as understood by folk who are using accuracy to one unit ( one ml or one g) ? (the solution with the salt having a greater volume than 1000 ml)..

If you put 40.00g of salt in the container and add enough water to reach 1000.mL, it will be precisely 4.000% brine (by volume).

Or 20.00g/L to make 2.000%, whatever you want.

I don't know exactly what salt % inhibits which microbes.

 

[renrutle]

Not at 68°F.

So your point is that to get this precisely right and not die everyone should pull out their physics and chemistry books to get the proper expansion coefficient of water not to mention that they need to precisely measure the water temperature to 3 decimals? I understand your point but these calculations do not need that level of precision!

Not at 68°F.
Let's take calculator 1 as an example.
To make 1.0L of 4.0% brine it says to use 40.g salt.
This fits perfectly with % by volume.

Yes because 1 L = 1000 g.

To even get to the precision that you are wanting, one would need to measure the volume of liquid to at least 3 significant digits. So your use of 1 liter is woefully inappropriate. You would need to measure the volume to at least this accuracy: 1.00 liters. For reference 0.01 liter is ~2 teaspoons.

 

[RPh_Guy]

So your point is that to get this precisely right and not die everyone should pull out their physics and chemistry books to get the proper expansion coefficient of water not to mention that they need to precisely measure the water temperature to 3 decimals? I understand your point but these calculations do not need that level of precision!

I agree, the brine percentage doesn't need to be super precise.

This formula is simple and doesn't require any textbook:
[grams of salt] = [% brine as a decimal] * [total volume in mL]

Relax, we're just discussing a little science.

To even get to the precision that you are wanting, one would need to measure the volume of liquid to at least 3 significant digits.

Nah, as I said:
To get 1L of 4.0% salt by volume, one only needs to measure volume to 1.0 L and salt to 40. g.

All these numbers are 2 significant figures, and this level of precision is easy to reach with inexpensive instruments.

If you choose to measure the water by weight, that does complicate matters if you want to use % by volume to be on the same page as the rest of us.

Here's the formula for calculating the amount of salt w/v but measuring water in grams:
[grams of salt] = [% brine as a decimal] * [grams of water] ÷ [density of water] ÷ ( 1 - [% brine as a decimal] ÷ [density of salt] )

 

[renrutle]

I agree, the brine percentage doesn't need to be super precise.
Relax, we're just discussing a little science.

Agreed.

For those who don't have any scales etc. using ~1/4 cup salt per quart of water will give a brine of ~4%. You can then adjust up or down from to suit your tastes.