We have new grading instruments to show off during our open house this weekend. Previously we used a hydrometer and a visual grading kit to determine whether we had the proper sugar content in our syrup and what grade it is. Both worked adequately but depended on the skill of the operator in determining the reading and some skill in interpreting the reading.
A hydrometer measures density or specific gravity of a liquid at a specific temperature by floating at a certain height in a sample. Since almost all of the dissolved solids in maple syrup are sugars this instrument ends up measuring sugar content at a specific temperature. The problem is knowing what temperature your syrup is at when you test it and making sure the hydrometer is free of congealed syrup which would make it float lower in a sample thus giving you a lower reading of sugar content than was actually there. Our new instrument is a refractometer which measures sugar content over a broader range fo sugar content and at any temperature using refraction of light. We can measure the sugar content in syrup or sap at any temperature. This allows for more accurate production. We still use a hydrometer as it gives a much quicker reading but we then recheck with the refractometer to get better accuracy.
When we grade syrup we grade both taste and color. Taste is still a subjective judgement but we can now be more accurate on color. color closely correlates with grade so that lighter syrups have a smoother, more delicate flavor and darker syrups have a heavier more robust flavor. Up until this year we used a grading kit that compared a sample of syrup to colored plates that represented the limits of a grade of syrup. We had to judge for ourselves whether the sample was lighter or darker than the grading standard which is the glass plate. Our new grading kit measures light transmittance and gives a number from 1 to 125 for the amount of light the sample will let pass through it. Each grade of syrup has a band of numbers representing the amount of light transmittance allowed in that grade. We can pinpoint exactly what grade the syrup is without any subjectivity.
We will demonstrate both at our open houses. Both are pictured below:
Grading kits on the left and hydrometer and refractometer on the right.