Safe temperatures to store Sap vs Concentrate vs Syrup???

[wmick]

Hoping someone can help clarify something for me... Or direct me to some information to study... I'm a little confused about "safe storage"...

I've read on here, that it is safer to store raw sap than to store concentrate...
But then I also read that people add hot syrup to the sap in their float-boxes when shutting down, to avoid spoiling...
Obviously I am misunderstanding, because these two ideas seem to contradict each other....

As, I am about to embark on RO for the first time, I would like some clear(er) understanding about how long and at what temperatures I can safely store Sap vs Concentrate.


Thanks

[ecolbeck]

Its all about bacteria. When you use an RO you are concentrating sugars AND bacteria. Therefore, it will spoil more quickly than plain sap.

Adding hot syrup to a float box is an attempt to sterilize the float box.

Hope this helps!

[DrTimPerkins]

Spoilage is related to (other than microbe type and number initially present) three things: time, temperature and sugar concentration. They are interrelated to a fairly substantial degree.

In general, the longer time (at temperatures above freezing and below boiling), the more growth of microbes. The higher the temperature (above freezing but below boiling), the faster the growth of microbes. The higher the sugar concentration (below 66 Brix), the faster the growth of microbes. The growth of microbes often follows an exponential curve (not linear), so although it starts out slow, growth gets faster and faster as time goes on (if resources...like sugar...are unlimited), kind of like a runaway train going downhill.

Each type of microbe have a certain "window" they like to grow in for temperature and sugar content. Most grow well above refrigerator temperatures (45 deg F) up to below 120 deg F. Many microbes do well in sap, but will grow faster (divide into more microbes) in higher sugar concentration solutions such as concentrate (more food around to feed upon), but most can't grow in syrup (the water "activity" or availability of water) is too low. A few types specific types CAN grow in syrup, but these typically grow very slowly and are either not present or reduced in number if syrup is hot-packed.

So the bottom line for sap is keep it cold and process it quickly. For concentrate...keep it really cold and process it ASAP. Keep in mind that running sap through an RO will warm it up (sometimes a LOT), and recirculating through an RO even more so, with the result that you've now made nice conditions for microbes to grow...a warm, concentrated sugar solution...a perfect place for microbes to make more microbes very quickly.

Depending upon the style and configuration of the evaporator/float box, at the end of a boil some producers will pull hot sap/syrup off the evaporator and dump it into the float box to kill any microbes hanging out there (it's a nice warm -- but not boiling spot -- with a lot of sugar...kind of like a spa for microbes). The alternative is to shut off or plug the opening and drain the floatbox. Some floatboxes are tight to the evaporator and get really hot, so are less susceptible to this problem, whereas others have the floatbox kind of hanging out in space so they don't get hot enough to kill microbes. In this type of evaporator, the floatbox is the ideal spot for microbial growth, the most common of which causes ropey sap/syrup...a very nasty thing.

Similarly, what happens to the sweet in the pan...if you don't boil regularly, it can start to spoil. You can either: boil regularly, draw off and refrigerate it, or fire up for a short time (boil for 5 min) every 2-3 days during warm slack periods to kill anything that starts to grow.

Can we tell you exactly how long and at what concentration you can safely hold sap at. Not really. It all depends upon those things...microbe type and quantity at the start (keep your equipment clean), time (keep it short), and temperature (keep it cold). And if you happen to have that type of evaporator/floatbox...either "sterilize" it at the end of the boil, or drain it. That'll go a long way towards preventing the problem...but those nasty bugs may still occasionally find a way to bite you.

[wmick]

Thank You.... Exactly the type of explanations I was looking for....

As my simple mind sees it, then... In terms of microbe growth compared to volume of liquid... By concentrating the sap (and microbes), I would, essentially, be skipping the first (slower growth) part of the runaway train curve.... and jumping right to the steep growth section of the curve... Which is not a good idea,... However, if I can guarantee very cold storage, I might get away with storing some concentrate for a few days... Eliminating as many microbes as you can, with sanitation, before starting, ensures you are starting as early on the curve as possible.
Am I close??

[DrTimPerkins]

Eliminating as many microbes as you can, with sanitation, before starting, ensures you are starting as early on the curve as possible. Am I close??

Yes, although spout/dropline sanitation is aimed at keeping the taphole clean and reducing "taphole drying" due to microbial effects, not reducing the growth later downstream.

Good filtering of sap will reduce microbes to a significant degree, but will not eliminate them (far from it). Most filtering is only moderately (and temporarily) effective. Filtering is like a counter-attack to cover your retreat. It'll give you a little time, but the only real solution is keep it cold and process it quickly.

We've actually stopped filtering sap as it comes in, and now only filter prior to the running it through the RO. Saved a huge amount of effort spent changing and washing filters, and did not affect our syrup grade at all. UV lamps can help, but the only one that was really effective is too expensive.

Anyone want to buy 8 used Lapierre sap filters?
21118

[wmick]

The UV thing... Not something I gave a lot of thought to.... and I can see why it would take a pretty good UV unit to keep up the the flow of a large RO system... but it did get me thinking..

Crazy thought.... What about dropping one of these into your storage tank.... doesn't need to keep up with the flow... Just sits there and kills bugs at its own pace for hours on end....
https://www.walmart.com/ip/Water-Killing-UV-Algae-Submersible-Adapter-Clean-Tank-20-30-40-60W-Sterilizer-Lifetime-Aquarium-Light-Moaere-Fish-Bacteria-Supplies-Green/486797078


Thoughts ?

[DrTimPerkins]

UV penetration through sap is on the order of a fraction of an inch. You'll either need a very BIG lamp or a very SMALL tank.

[wmick]

good to know... I was looking for some info on how far it reaches... and hadn't found an answer yet...

[Logan Cabin]

Again, fantastic information! Someone from Vermont spoke about this at the IMSA conference last year (name escapes me at the moment). For someone at a small scale (100-150 taps) would running RO straight into the evaporator be a viable option? Here in southern Indiana sap storage is hard enough, can’t imagine storing concentrate without a walk in cooler.

[therealtreehugger]

I run my ro bucket sweetened sap right into the header tank that then is on a trickle flow into the evaporator. The ro produces concentrate at about the same rate as I evaporate, so it works out well that I start the ro in the morning, get the pan filled, and by the time the fire is going and boiling is happening, my pan and header tank are about full with concentrate.
I had originally thought about running the ro in between boils, but never got around to it. And I have plenty of sap storage space (a 300 gal stainless steel tank right outside the sugar house) for the number of taps I have (40 ish on gravity tubing coming directly to the tank, and another 20+ on buckets). So it works out time-wise, good. I can ro at the same time I am boiling.

[maple flats]

I used to just drain my pre-heater when I shut down, cover all openings (float boxes and pans). Then one time I had to shut down during a boil to clean the syrup pan. I didn't drain the pre-heater in the hood. I ended up getting my first (and hopefully my last) ever ropy syrup. Now when I shut down, in addition to always draining the pre-heater I also drain my cold sap float box, then allow the hot from in the flues pan to fill the float box. Problem fixed!

[maple flats]

Sap is safe for 2-3 days if under 40F, longer if colder. Concentrate is safe if kept just above it's freezing point at whatever sugar concentration it is at. Syrup, awaiting bottling is ok at 40F for 2-3 weeks, maybe longer if a little colder.
A walk in cooler can help but most of any size who set up to hold concentrate for any length of time use an operating dairy tank and cool it according to the sugar %.
Whether your concentrate comes from an RO or from boiling or both does make a little difference. Once boiled the concentrate has had any micro organisms killed or mostly killed, thus that concentrate in the pans can be good longer than what was made solely by an RO. RO'd sap spoils fastest if not refrigerated according to it's freezing point. Recently the Maple News had a chart, (by Dr Perkins and others) showing sugar % vs freezing point. If cooled to 1-3 degrees F above freezing it lasts quite long without degrading.

[DrTimPerkins]

Treat maple sap as it it were milk. Would you be comfortable drinking it after it sat out for a few days? Maybe...if the temperatures were really cold. Probably not if the temperatures were warmer. There is a strong influence of time and temperature on sap quality. Note that running sap through an RO warms up the sap...and it can warm considerably. We've measured concentrate temperatures up to 72 deg F coming straight out of the machine (we were squeezing it pretty hard). If you recirculate or do a double-pass through the RO it'll warm each time it goes through. How do you know when it is bad...hard to tell...kind of like when milk first starts to go sour. When it is warmer in the season and sap flows in the tubing system are low and slow, sap can heavily ferment in the lines before it even reaches the tanks. That stuff needs to be boiled right away, and even then will sometimes result in sour syrup (tastes bad and "fizzy" on the tongue). All depends upon time and temperature.

[vtbackyardmaple]

Last year I buried my sap bin with snow. Only the lid was exposed and accessable. Snow lasted about 2 weeks and kept the sap nice and cold. Not a great solution but it worked.

[Swingpure]

Spoilage is related to (other than microbe type and number initially present) three things: time, temperature and sugar concentration. They are interrelated to a fairly substantial degree.

In general, the longer time (at temperatures above freezing and below boiling), the more growth of microbes. The higher the temperature (above freezing but below boiling), the faster the growth of microbes. The higher the sugar concentration (below 66 Brix), the faster the growth of microbes. The growth of microbes often follows an exponential curve (not linear), so although it starts out slow, growth gets faster and faster as time goes on (if resources...like sugar...are unlimited), kind of like a runaway train going downhill.

Each type of microbe have a certain "window" they like to grow in for temperature and sugar content. Most grow well above refrigerator temperatures (45 deg F) up to below 120 deg F. Many microbes do well in sap, but will grow faster (divide into more microbes) in higher sugar concentration solutions such as concentrate (more food around to feed upon), but most can't grow in syrup (the water "activity" or availability of water) is too low. A few types specific types CAN grow in syrup, but these typically grow very slowly and are either not present or reduced in number if syrup is hot-packed.

So the bottom line for sap is keep it cold and process it quickly. For concentrate...keep it really cold and process it ASAP. Keep in mind that running sap through an RO will warm it up (sometimes a LOT), and recirculating through an RO even more so, with the result that you've now made nice conditions for microbes to grow...a warm, concentrated sugar solution...a perfect place for microbes to make more microbes very quickly.

Depending upon the style and configuration of the evaporator/float box, at the end of a boil some producers will pull hot sap/syrup off the evaporator and dump it into the float box to kill any microbes hanging out there (it's a nice warm -- but not boiling spot -- with a lot of sugar...kind of like a spa for microbes). The alternative is to shut off or plug the opening and drain the floatbox. Some floatboxes are tight to the evaporator and get really hot, so are less susceptible to this problem, whereas others have the floatbox kind of hanging out in space so they don't get hot enough to kill microbes. In this type of evaporator, the floatbox is the ideal spot for microbial growth, the most common of which causes ropey sap/syrup...a very nasty thing.

Similarly, what happens to the sweet in the pan...if you don't boil regularly, it can start to spoil. You can either: boil regularly, draw off and refrigerate it, or fire up for a short time (boil for 5 min) every 2-3 days during warm slack periods to kill anything that starts to grow.

Can we tell you exactly how long and at what concentration you can safely hold sap at. Not really. It all depends upon those things...microbe type and quantity at the start (keep your equipment clean), time (keep it short), and temperature (keep it cold). And if you happen to have that type of evaporator/floatbox...either "sterilize" it at the end of the boil, or drain it. That'll go a long way towards preventing the problem...but those nasty bugs may still occasionally find a way to bite you.

Just reading this older post and it really made me rethink a few things.

For my fifth steam pan, my preheat pan, if it does not come to a boil (which I am hoping that it will), that I should make sure that it is empty at the end of a boil and I should clean the pan.

I still have to make my RO, but I can see from a microbial point of view, it makes sense to run it while you are boiling (perhaps start it while you are collecting sap, just before you start to boil) and have it positioned right by the evaporator and use the concentrate close to the time you produce it. I may have to add some raw sap time to time, to keep up with the boil.

[Swingpure]

Getting away from storing the concentrate, as I will be using it almost right away, but i have a question about the storage of syrup.

If I bottle it correctly with heated bottles and syrup at 180 to 190°, and have them on their sides to seal the lids and kill any mold or bacteria, can I just store the syrup at room temperature in a pantry for a year or more, or does it have to be stored more in root cellar or fridge or freezer?

Now that I have moved up to 110 taps, I likely am going to have some syrup hang around for a few months.

Thanks

Gary

[aamyotte]

If you hit the brix correctly and bottle to the temps you note, the syrup should be fine at room temperature.

[wobbletop]

Yep, until opened and then should be refrigerated, although I know people that don't bother. Depends on how long it takes to go through a bottle I guess.

[TheNamelessPoet]

Getting away from storing the concentrate, as I will be using it almost right away, but i have a question about the storage of syrup.

If I bottle it correctly with heated bottles and syrup at 180 to 190°, and have them on their sides to seal the lids and kill any mold or bacteria, can I just store the syrup at room temperature in a pantry for a year or more, or does it have to be stored more in root cellar or fridge or freezer?

Now that I have moved up to 110 taps, I likely am going to have some syrup hang around for a few months.

Thanks

Gary

I just last month opened a bottle that was in my cabinet in the kitchen at home, since I made it last year (pleasant surprise since I thought I was out), and it tasted great!

[NhShaun]

As long as it is bottled like you said and at the right brix it will last for more than a year in glass at room temp. I actually have a bottle from my first season in 2015 still sealed and hasn't formed mold yet.
Just remember sunlight will darken the grade, if that matters to you. I prefer my syrup to be very dark some people don't.

[TheNamelessPoet]

Funny side note on the fancy vs dark... When someone says they like "Fancy"... I tell them I don't care about fancy, I care about taste and quality. Food doesn't have to look good, it has to taste good!