Designing and Building Centrifuges to Clarify Maple and Walnut Syrup

Progress report for LNE20-410R

Project Type: Research Only
Funds awarded in 2020: $49,824.00
Projected End Date: 04/01/2022
Grant Recipients: Future Generations University; Marshall University
Region: Northeast
State: West Virginia
Project Leader:
Dr. Michael Rechlin
Future Generations University
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Project Information


Problem, Novel Approach, and Justification

Centrifugation could provide an opportunity for maple and walnut syrup makers to reduce costs, increase environmental sustainability, reduce health risks, and increase profits. Producers typically use a filter press with diatomaceous earth (DE) as a filter aid (North American Syrup Producers Manual, 2006). This process creates waste in the form of spent diatomaceous earth, niter, and filter paper.  Inhaling DE’s minute silica particles during handling also poses a possible health risk to producers.  For these reasons, many maple producers would prefer not to use DE. Centrifugation would also make it easier for walnut syrup producers to clarify their product which has higher pectin concentrations that quickly plug up conventional filter presses.


Our hypothesis is that with the proper knowledge inputs and engineering expertise a basket centrifuge can be designed and constructed to efficiently and safely clarify maple and walnut syrup.  Further, we hypothesize that this device will be a cost-effective improvement on presently used syrup clarification techniques.

Outreach Plan:

Research findings will be shared with farmers in the maple syrup production business through presentations at trade shows, and national-reaching trade publications like The Maple News and the Maple Syrup Digest. If successful, Project advisors will also facilitate discussions with maple equipment manufacturing companies to launch broader manufacturing and distribution of the new clarification technology.

Project Objective: 

The project objective is to design, test, refine, and scale a cost-effective centrifugal separator for maple and walnut syrup clarification.

Project Objective:

 To design, test, refine, and scale a cost-effective centrifugal separator for maple and walnut syrup clarification. 


Materials and methods:
  • literature review of maple and walnut syrup composition
  • lab analysis of maple and walnuts syrups and sap composition
  • review of "off the shelf" option for centrifuge as filtration system: "Extreme Raw Power" Centrifuge
  • Photometric analysis of syrups filtered through centrifugation: Hanna Instruments maple syrup grading photometer


Moving forward into 2021, work has pivoted to focus on walnut sap and pectin. The reasoning behind the pivot includes that by February, Walnut sap-flow season will be underway and there will be a ready supply of fresh sap to experiment with.

The Marshall University team, Kolling and O’Dell, will be working with other faculty in the chemistry department to come up with analytical procedures to measure the amount of pectin in the sap. In the meantime, Greg Christian (Toms Creek Maple), will be taping walnut trees and collecting the sap for further analysis. Christian is planning on continuing his centrifuge experiments, working with various chelating agents to bind the pectin before centrifugation to remove it from the sap. The goal of the next few months is to reduce the pectin concentration in the sap to a level where it is practical to concentrate the sugars in the sap by running it through RO (reverse osmosis process).

Research results and discussion:

Centrifugation studies

  • 3,000 rpm was a threshold speed for separating solids (called niter or sugar sand) from syrup.
  • 8,000 rpm was a threshold speed for pellet (presumed pectin) formaton in walnut sap.
  • Late season sap spun at 8,000 rpm results in a gel (presumed pectin) as part of the pellet.

Centrifuge studies

  • The Extreme Raw Power centrifuge, spinning at 6,000 rpm, removes a significant portion of the niter or sugar sand. Issues remain with foaming.
  • Pectin can be spun out of walnut sap. We expect higher efficiencies with the proper filter aid.   


We received notice that the project was funded and less than one month later, our partners, Marshall University and RCBI were fully engaged reacting to the COVID-19 situation. This caused unforeseen delays in the research timeline and meant that most of the research work was not able to begin until their facilities reopened in June. At this point, a progress report brought everyone up-to date and a 6-month work plan was developed. (appendix 1, and 2). The meeting was also important in that walnut sap and syrup needed for the lab work was delivered to Derrick Kolling at Marshall University.

Kolling was able to move forward by hiring undergraduate chemistry student Hayden O’Dell to begin the lab analysis on walnut sap and maple syrup. Additionally, an “Extreme Raw Power” centrifuge was purchased for Greg Christian to begin experimenting with the workings of an “off the shelf” machine. Also purchased was a Hanna Instruments Maple syrup grading Photometer for Marshall University to test the clarity of their centrifuge experiments.

Over the summer Marshall labs were more-or-less closed, therefore O’Dell worked on a literature review focusing on the chemical composition of maple say and syrup (appendix 3) and in the lab on the maple and walnut syrup particle analysis whenever possible.

On September 24, 2020 a second research team meeting was held at RCBI. By this time, particle analysis work was nearly complete, and the analysis prepared by Hayden was reviewed (appendix 4). This analysis gave Christian the information he needed to use with the results of his experimentation with the Extreme Raw Power centrifuge and plan the modifications to move forward with the centrifuge redesign. Examples of Christian’s lab book notes and observations are provided in appendix 5.

Participation Summary
1 Farmer participating in research

Education & Outreach Activities and Participation Summary

Educational activities:

1 Workshop field days

Participation Summary:

15 Farmers
Outreach description:

Outreach activities, just like the research process, were curtailed by the pandemic. However, RCBI held a new syrup producer workshop in November at Tom’s Creek Maple at which the work of this project was explained.


Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.