Keeping track of large quantities of sap

[PCFarms]

I hope you all have had a great season.
I have been looking into our season records and I have a few questions and thought that perhaps someone in the industry longer here has experienced a similar issue.

We have 16,500 taps, the majority of which we bring into our sugar shack in our sap truck. We have kept detailed records of our flows with flow meters and also by tracking the amount of sap we truck in. When I add up all the sap we have collected (about 350,000 gallons) and using Jones rule of 87.1, and the sugar content of the sap on each load (we used a sap refractometer), I calculated that we should have made 7600 gallons of Maple Syrup. However, we only actually made 6,600 (if I add in the split sap/syrup, I think we could have made about 6,750). I am wondering where all the sugar went.

I have a few theories:
1) The sap hydrometer we were using is not accurate for some reason. We did double check with a digital refractometer a few times, but not consistently.
2) We have a 13,000 gallon silo storage tank. It is a vertical poly tank. I am wondering that perhaps in the time it was stored, the bacteria ate the sugars. I would say that on average we processed half our sap the day it was collected and the rest the following day. We never cleaned the poly tank as there is no man-port on the side. (Its not ideal, but we got it really really cheap). Thats a lot of sugar for the bacteria to eat.

Few more points to note:the volume recorded by our flowmeters (h2O Smartrek ones) match almost exactly the volume of sap we recorded when we add up the volume delivered by our truckloads. We checked our RO, there is no sugar going in the permeate down the drain. We have a simple sugar shack; I cant think of any way we could possibly have somehow otherwise lost sap without us knowing.

Are tere any tricks I am missing? How do those how buy in a lot of sap find the relationship between bought sap and actual syrup produced? Its a 10% discrepancy and it adds up.

Thanks

[Thompson's Tree Farm]

What brix was your final product?

Did you fully flush your RO membranes to the head tank before rinse and wash?

Was filter press fully flushed of sweet before changing?

[ecolbeck]

A couple of thoughts before a actual scientist shows up:

1. I would think that there could easily be errors in hydrometer readings. 10% error in 2% sap is 0.2%.
2. How are you doing your calculations? Are you calculating a theoretical syrup yield from each sap batch and then adding them up at the end or are you combining all sap batches into one group and then calculating syrup yield?
3. The Jones rule is just a guide and large extrapolations using it could be prone to large errors.
4. I don't know how quickly bacteria eat sugar and there are lots of factors to consider but do know that their growth is exponential....

[spud]

Each load coming into the sugarhouse must be tested for sugar and the amount of gallons. A calculation at that time should be determined as to how many gallons of syrup will be made from that load of sap. If things don't add up then its your Hydrometer. I sell my sap and have to replace my Hydrometer every year. My numbers and my buyers numbers are usually very close but not always the same. Hydrometers are calibrated to work on cold sap. After sap is pumped a few times the readings can be off. I tested some sap in my tank one time and it was 1.1% and then I put the same sap in my fridge for three hours and tested it again. The sap then tested 1.3% using the same tester and sap. Sap really should be tested from your tank before it has been pumped into trucks for hauling.

Spud

[maple flats]

Have you ever tested the accuracy of your flow meter(s)? To be close they must have no elbows leading into or out of them for 3-4', could that be an issue?

[JoeJ]

Could very well be your hydrometer. I bought a new one before my season started in February. When I started to boil, it seemed that I was producing more syrup than I should according to the sap hydrometer. Checked it with the refractometer and I got higher reading than the hydrometer. The inaccurate hydrometer was reading .2% low. Went to CDL to get a new one and the lady told me that they had a number of Vermont State Tested hydrometers that were inaccurate.

Joe

[Russell Lampron]

I hope you all have had a great season.
I have been looking into our season records and I have a few questions and thought that perhaps someone in the industry longer here has experienced a similar issue.

We have 16,500 taps, the majority of which we bring into our sugar shack in our sap truck. We have kept detailed records of our flows with flow meters and also by tracking the amount of sap we truck in. When I add up all the sap we have collected (about 350,000 gallons) and using Jones rule of 87.1, and the sugar content of the sap on each load (we used a sap refractometer), I calculated that we should have made 7600 gallons of Maple Syrup. However, we only actually made 6,600 (if I add in the split sap/syrup, I think we could have made about 6,750). I am wondering where all the sugar went.

As far as I know you should be using 88.2 for the Jones Rule number. I think that I read it in another thread. I started using it and my sap to syrup ratio more closely match my sap sugar content now.

[motowbrowne]

As far as I know you should be using 88.2 for the Jones Rule number. I think that I read it in another thread. I started using it and my sap to syrup ratio more closely match my sap sugar content now.

There's an even more accurate formula, 87.1/X-0.32 (for 66 brix syrup) or 88.2/X-0.32 (for 66.9 brix syrup) but I use the MES app on my phone. I think it works very well either for sap or concentrate. I don't know for sure, but I think it uses 66 brix syrup as the finished product.

[ennismaple]

John - I know you've probably done the line calcs to convert units that we were taught in 1st year engineering but did you make sure to convert properly from the US gallons your tanks are probably measured in? Another thing could be the SS drums you are likely using are 35 Imperial Gallons which is 42 USG or 159L.

To further confuse things: most producers I know call a 4L jug a gallon but it is actually 1.057 USG.

Not sure if I helped or confused you more...

[PCFarms]

Thanks for the comments, there are a lot of questions so I will go through one by one. Here are the answers:

• Final brix was targeted for 67. I have used the jones rule of 88.1/x-.32, this accounts for about 50 gallons of finished product. Not a big difference but something.
• We fully flushed our RO membranes before a cleaning back into the holding tank
• We flushed our filter press until the brix was about 5, and then we switched
• If we have a 10% error in the sap hydrometer, that could account for the difference, its about 600 gallons. But we did verify with the electronic refractometer. Our average was about 1.9 brix, so it seems in the right ballpark, but who knows.
• We tested every load of sap for brix, we had good record keeping this year. I didn’t consider the temperature, but thinking about it, the warmer the sap is, the errors should work in my favour. i.e. – the warm sap is less dense and would have a lower sugar reading. We would make more syrup than the Jones rule would predict. Cold sap will have a higher reading as you experienced once you put it in the fridge.
• Regarding flowmeter accuracy – it checked out when we looked at how much we trucked. The numbers matched.
• Regarding the syrup barrel size – we made that mistake 2 years ago. We sold 40 gallons for the price of 35. Fortunately the customer was good about it and paid up nearly a year later when we figured it out.

I will calibrate the sap hydrometer/test it and get back to you.