Running sap through reverse osmosis twice?

[ferngully]

I am wondering that if our Hobby R/O is able to run sap through it twice until we reach the desired 8 brix? If so does it matter whether we recycle from one tank until its at 8 or is it best to pump into a seperate tank and then run it again?

[VT_K9]

I am not sure what brand hobby R/O you have. We bought a CDL Hobby 250 R/O and started using it this year. When we bought it we were told we could run the sap through it twice by Bascoms and then by the CDL rep who helped do the test run on it. I have also read some people will just cycle the sap through until it reaches the bri they want (through testing with a sap hydrometer).

We pump our sap from the woods into a 230 gal. tank. Run it through the R/O into a 160 gal. tank. Then run it through once more to a 100 gal. tank to feed the evaporator. Last Sunday we processed about 400 gallons of raw sap this way and it worked out great. I have about 192 as of this morning and hope to run the system again tomorrow or Thursday at the latest.

Mike

[DrTimPerkins]

I am wondering that if our Hobby R/O is able to run sap through it twice until we reach the desired 8 brix? If so does it matter whether we recycle from one tank until its at 8 or is it best to pump into a seperate tank and then run it again?

You should be able to do either -- run it through twice or recirculate until you hit the desired brix level. Be aware that each time the liquid runs though the RO it will heat up, so it is very important that if you do either of those things, you should boil it immediately as the combination of high brix and high temperature will result in very rapid microbial growth and fermentation of the concentrate and darker syrup.

[ennismaple]

We'll run the concentrate back into the sap tank for a few hours before we send it to the evaporator head tank and fire up. All you're doing is dumping water and as long as you don't fowl the membrane and you keep the pressure within the recommended range you can do either method.

[ferngully]

A very big thanks guys. Our primary cooker is a hard working 72 year old wonderful man that is concerned of different concentrations of sap going into our evapourator. He said things may come off in weird ways (eg lower concentration going in followed by higher going in) and the latter of the two actually being ready to draw off before the first stuff causing burning/darkening. My theory is it mixes enough through the evapourators channels and the more we R/O the less wood.

I will continue to browse some chats but is there safe ways to hold over sap after the r/o process other than the coldest temp possible? (UV, bleach, some sort of additive to extend our 3 hour limit for sitting sap) The three hour time frame seems IMPOSSIBLE

[Jshmohr]

You should be able to do either -- run it through twice or recirculate until you hit the desired brix level. Be aware that each time the liquid runs though the RO it will heat up, so it is very important that if you do either of those things, you should boil it immediately as the combination of high brix and high temperature will result in very rapid microbial growth and fermentation of the concentrate and darker syrup.
How much does it need to be cooked down? Like finished? We just got a RO this year but years passed we cook down every day but wait until we get enough run through the evaperator to finish 10-15 gallons. Kind of concerned that if we concentrate it we have to finish it that same day? Thanks

[Jeff E]

The last two posts had comments that I want to comment on.
'Holding over' sap that has been concentrated is a bad idea, as the Dr. Perkins noted. It becomes a hot tub for bacteria, and you know what happens in hot tubs!
I always process sap within a few hours of RO concentration, and I am sure to end the day with all the sap that has been concentrated getting into the evaporator and boiled a bit, to kill bacteria that may have started.

You certainly don't want to do any tricks to hold concentrated sap (bleach). Also, I have read that UV is not very effective as the higher sugar content stops the UV from penetrating more than a inch into the sap.

The note on the experienced evaporator operator being concerned with sap of different concentrations going into the evaporator is a real concern. That is the value of doing the recirculating method of concentrating, as it mixes in the big tank. You will find the more you concentrate the more difficult the evaporator is to run, or at least, the more attentive the operator has to be.

[DrTimPerkins]

I will continue to browse some chats but is there safe ways to hold over sap after the r/o process other than the coldest temp possible? (UV, bleach, some sort of additive to extend our 3 hour limit for sitting sap) The three hour time frame seems IMPOSSIBLE

Adding bleach or anything else to concentrate (or sap) would be adulteration, and thus illegal.....besides the fact that it would make very crappy tasting syrup.

[Clinkis]

I have added a UV light to my RO and use very high sanitation practices in my RO and sap handling equipment. I usually concentrate from about 3% to 8%. I have had no trouble storing concentrate for 12 to 24 hours, as long as I keep it cold, and still been making very light, high quality syrup. If good sanitation practices are used it is possible to store concentrate for a reasonable period of time. That said, if you are concentrating higher the 8% your going to decrease this available storage time I would assume.

[KevinS]

how much does ROing warm the sap? in degrees on average.

[mapleack]

how much does ROing warm the sap? in degrees on average. Everyone will be different, and depend on pressure but I'd say 4 or 5 degrees.