Boiling Sugar: How to Avoid Unwanted Goo

[Hornbein]

I boil water to sterilize it, then add granulated sugar. Sometimes the sugar partially fails to dissolve, even though sitting in very hot cooling water for an hour or so. It forms a sort of goo instead. ?

 

[Mayhem]

Makes no sense and doesn't correspond with my culinary or chemical experiences. The only thing that could explain this if you are using sugar containing some sort of starch, like powdered sugar. Especially since you mention "goo".

 

[rbelli1]

How much water and sugar?
Does this happen if you stir it after adding the sugar?
Is the "goo" yellowish or brownish? You may be caramelizing the sugar when it hits the hot bottom of the pot.

BoB

 

[.Scott]

I boil water to sterilize it, then add granulated sugar. Sometimes the sugar partially fails to dissolve, even though sitting in very hot cooling water for an hour or so. It forms a sort of goo instead. ?

Every year I make another 1-gallon batch of a very concentrated solution of sugar. I then add a touch of red dye and put it in the frig labelled "jet fuel". It's purpose is to sustain a local humming bird population for the season.

My method is:
-- 1) to bring a pot of water to a strong boil (just as full-size bubbles are easily making it to the surface but before it boils over).
-- 2) add copious sugar while stirring with a wooden spoon. As sugar is added, the dissolving process will slow. Since both the sugar and the stirring subdue the boiling action, it is easy to see the dissolving process. If a quarter cup of sugar takes more than 30 seconds to stir into oblivion, I finish the stirring, turn off the stove heating element, move the pot to a cold element, and count the sugar-adding process as done.
-- 3) In my case, the sugar concentration at that point is higher than I want it - because it could cause a problem for the humming birds when ingested. So I add cool water and stir for another 25+ seconds until fully mixed.

Responding to @Mayhem and @rbelli1 : Here is a grade school link related to sugar solution saturation: Saturated Solutions
It claims:

The maximum amount of sugar that will dissolve in a liter of 20 °C water is 2000 grams. A sugar-water solution that contains 1 liter of water and 2000 grams of sugar is said to be saturated.

I would definitely take that "2000 grams" as accurate to about 1 decimal place. I would also note that trying to measure the quantity of sugar that can be dissolved in "water at 20 °C" would be a mind-numbing exercise of patience if you did it by never allowing the water temperature to go over 20C. But, if instead of looking for how much sugar can be mixed, you look for how much sugar can be held, things are much easier. Follow the procedure I described above and then cool the solution back down to 20. If it precipitates, you went to far.
BTW: I have never caused it to precipitate.

 

[JT Smith]

Every year I make another 1-gallon batch of a very concentrated solution of sugar. I then add a touch of red dye and put it in the frig labelled "jet fuel". It's purpose is to sustain a local humming bird population for the season.

Why add red dye?

 

[.Scott]

Why add red dye?

There are two purposes:
1) The fluid is hanging in a transparent container and the red is attractive to those birds.
2) When the fluid ferments or becomes contaminated, the red color usually fades very noticeably. And it can fade just from extended exposure to sunlight. So it's a good indicator of when it's time to dump the fluid, bleach out the feeder, and tap into that 1-gallon reserve in the second refrigerator.

There are concerns that the red dye (usually FD&C Red Number 3) might cause problems for the birds. But I've been feeding them for decades with the dye and they have persisted generation after generation.

For more info: Red Dye effects
It seems the most serious issue is that the dye may collect on their GI tract. But I notice that one of the first potential side-effects noted in that article was "increased hyperactivity and reduced attention span". I suppose I must admit that those hummers do show those attributes in the extreme.

 

[JT Smith]

Yes, ha ha, detecting ADHD in hummingbirds might be a challenge. Probably/hopefully the risk to them is minimal.

My feeder, like many, is already red so coloring the water isn't necessary as an attractant. Yours could easily be red as well, if you chose to make it so.

Using the color as an indicator for a bad solution is another matter. By the time the color changes has it already started to go bad? It seems to me a better solution (no pun intended) is to replace it regularly, with some attention to the weather. That's actually the reason I stopped feeding our local birds. I was too lazy to keep their sugary fix fresh. I thought I might be doing more harm than good. They still come by for the flowers though.

 

[hutchphd]

I have a Rose of Sharon that seems impossible to kill and blooms most of the summer. Not my favorite but it does seem to attract hummingbirds and butterflies. I have recently hung a plastic hummingbird feeder whose yellow and red facade reminds me of the golden arches . Hummers like it.

 

[JT Smith]

I forget the name of the flowering bushes we have but they also bloom and bloom and bloom. They were what made me aware of the hummingbirds in the first place. I put the feeder up not so much because I thought they needed my help but simply because it brought them in for close viewing next to the window. And my foster kitties were fascinated by them too.

 

[BillTre]

Tissue culture media usually has a pH indicator chemical (phenol red) in it.
It usually starts out red and then changes to gold (mixed red and yellow) and then to yellow (time for new media) as metabolic acids accumulate and the pH drops in the media.
Contamination with bacteria or yeast would also produce acids.

Phenol red also responds to changes in CO2 levels (making it more acid).

I don't know the mechanisms of the red #3 color change, but I think both phneol red and red #3 cause cancer in lab tests.

A sugar solution might ferment and produce alcohol.
When I was a kid we had some birds eat some berries off some bushes in the winter.
The birds were acting weird (I guess they were tipsy). My mom thought they were drunk from eating berries that fermented.

 

[JT Smith]

The drunk bird thing I've witnessed as well. For me it was in a pear orchard next to where I was working. Every year they'd get totally sauced. I couldn't help but think it might have been intentional, something they learned that they liked. Apparently elephants do this too and probably other animals.

With the bird feeders I've been told and also read that pathogens can grow in the water. But to be honest I really don't know what the truth is. When I first started doing it, before I'd been warned to change the water, I left it out there for much longer than recommended. I didn't see any dead birds!

 

[gmax137]

I would definitely take that "2000 grams" as accurate to about 1 decimal place.

It is actually very close, as least per
https://www.engineeringtoolbox.com/sugar-solubility-water-d_2193.html

My interest in this thread is as a former maple-sugarer. Boiling maple syrup is "complete" at 11 pounds per US gallon; that is, a specific gravity of 11/8.33 ~ 1.32 which is just below the value shown on the above graph (at 20F) - as expected, since syrup still has water in it (typically, 66% sugar, so 34% water).

Anyway, if your bird food is close to 2 kg sugar per liter of water, it is going to be very sweet and sticky.

 

[.Scott]

It is actually very close [to 2000g/liter] ...

Anyway, if your bird food is close to 2 kg sugar per liter of water, it is going to be very sweet and sticky.

I saw mention of 211/100 (w/w) in a couple of places ( place1, place2 ), but none with citations.
There is also mention that a supersaturated solution can stay supersaturated because the long molecules don't readily fall into a crystal formation.

The other problem with supplying a saturated solution to the birds is that they would need to supplement it with water - at least initially, it would make them thirsty.

 

[JT Smith]

You also probably want to mimic the concentration of nectar found naturally by the birds. There is a wide variation but the average is around 30%. For some reason the most common solution recipe, 1:4 volumetric, produces a concentration of around 17%. Why so much lower than nature? Maybe they'd actually like it even more concentrated. How hard would it be to offer them some water next to the sugar feeder?

And isn't it the case that a highly concentrated sugar solution is less susceptible to the growth of microorganisms?

 

[BillTre]

And isn't it the case that a highly concentrated sugar solution is less susceptible to the growth of microorganisms?

High enough sugar concentrations osmotically draw water out of microorganisms. This at least keeps most of them from growing if it doesn't kill them.

 

[.Scott]

You also probably want to mimic the concentration of nectar found naturally by the birds. There is a wide variation but the average is around 30%. For some reason the most common solution recipe, 1:4 volumetric, produces a concentration of around 17%. Why so much lower than nature? Maybe they'd actually like it even more concentrated. How hard would it be to offer them some water next to the sugar feeder?

My concoction may be a over 30%. I put my formula together a couple of decades ago. I kept on raising it until it seemed to be as attractive as possible. I call it "Jet Fuel" because of its high caloric content. I have never tasted it myself, but a visiting Sister-in-Law found it in my basement fridge and thought it was some kind of strawberry Kool-Aid (despite the prominent "Jet-Fuel" label). Apparently she found it satisfying. We should have asked her how she liked it before telling her what it was.

 

[JT Smith]

You could measure it pretty easily. Just buy a simple refractometer (e.g. amazon for $25), one that measures Brix up to 80% or so. That should do it.

I would also note that trying to measure the quantity of sugar that can be dissolved in "water at 20 °C" would be a mind-numbing exercise of patience if you did it by never allowing the water temperature to go over 20C.

Same thing. Put in too much sugar and then measure the solution periodically to see what limit it is approaching.

 

[Nik_2213]

IIRC, from watching my dad concoct syrupy 'wort' for home-brew beer, also saturated gin for sloe-gin, dissolving much sugar is complicated by the dissolved sugar significantly increasing volume...
Jam-making neighbours agree. But, beyond 'rules of thumb', you'll need to refer to 'industry tables'...