Disappointment with syrup quantity

[jbuckwalter]

This is our third year of sugaring and seeing our end product quantity less than desired. We have a 40 gal jacketed steam kettle with wood stove built under it. Process: boil and add, boil and add up to 80 gal in 13 hour period. We re-calibrated refractometer and tested 10 trees consistently at 2% with 1 at 3%. Tested 40 gal first batch at 2%, assuming should yield 4 qts. Boiled all day, adding 30+ gal more and ended up with 4 ½ qts of high quality 68%. Expected 6-7 qts. Seems like there may be a variable we are unaware of. Any ideas would be helpful. Didn’t know if boiling the same pot for 13 hours could reduce/breakdown sugar content? The syrup is amazing!

Central Pennsylvania
2015 – 35 taps – 340 gal sap = 32 qts
2017 – 40 taps – 160 gal sap = 12 qts
2018 – 75 taps – 280 gal sap = 16 qts (so far)

[DrTimPerkins]

Boiling will not break down sugar (unless it turns into black char). Your refractometer might be off. Is it automatically temperature compensated?

[jbuckwalter]

I do not know that is it automatically temperature compensated. I did re-calibrate using distilled water and adjusted down one %.

[jbuckwalter]

I do not know that is it automatically temperature compensated. I did re-calibrate using distilled water and adjusted down one %. We boil down to about 10-15% before moving to finishing pots on propane. So, not black char. The other morning I was finishing off from the night before, two pots with about 6 qts each at 37%. I assumed I should get at least half of that at 68%, however ended with 4 1/2.

[DrTimPerkins]

Besides being greatly affected by the amount of dissolved material (sugar) in solution, the refractive index of a liquid is also very much affected by temperature (similar to the way that a hydrometer density reading is affected by temperature).

You either need to:

1. Have an ATC (automatic temperature compensating) refractometer and allow the refractometer and material being measured to come to thermal equilibrium (important when measuring cold sap or hot syrup),
2. Measure only at the temperature that the refractometer is rated at - often 60 deg F, OR
3. Take a measurement and correct for the temperature.

Otherwise your readings may be giving you a very incorrect impression of what is really happening.

[jbuckwalter]

Thank you Dr. Perkins. I was unable to access my account until now. I checked the instructions for my refractometer and read that it must be used at 68 degrees and sap should be read after 30 seconds to moderate temps. I recalibrated and measured 40 gal at 2% and it held out to almost 4 qts. Much appreciated!