The taste of Pure Maple Syrup is one of natures the most enjoyable flavors. If it is produced properly the taste ranges from sweet delicate flavor to a pronounced robust, uniquely maple flavor. However, maple syrup that is improperly made or handled can be just as unforgettable for other reasons. Maple producers need to be very conscious of how easy it is to destroy the quality of the product they are producing. They need to take every precaution to preserve the integrity of this unique product. How sap is handled during the course of the season will determine the volume of high quality syrup produced. Maple syrup is made up of 98.5% sugar. The level of sugar is measure in brix’s or a percentage of the percent sugar present in the product. For all practical purposes and because pure maple syrup is almost 100% sugar we simply say that the product is maple syrup, when it reaches 66 brix or 66 % sugar. For this reason in the State of Ohio maple syrup must be finished at 66 Brix. The primary sugar in maple syrup is sucrose. There are small amounts of Glucose and a trace of Fructose present. These sugars are referred to as the invert sugars. The level that is present can determine if a maple syrup from a specific batch is usable to make certain maple sugar products. The remaining portion of the syrup is composed of various minerals Amino acids and organic acids. The most common Organic acids are Malic and Fumaric acid. These are the same organic acids found in fruit juices. The presence of these acids is a relevant fact and has a bearing on how maple syrup is processed.
The quality of maple syrup normally seems to decline as the season progresses. The sap that comes from the tree when the weather is cold and the taps are fresh will most often produce the lightest and the highest quality syrup of the season. The primary reason for this is the relatively low level of bacteria found in the sap. Research done at the University Of Vermont by Mariafranca Morselli documented the fact that sap inside the maple tree is sterile2. Because sap is normally 1.5 to 2.5 % sugar it becomes an ideal medium for bacterial growth. Once the sap reaches the taphole environmental conditions cause bacterial colonies in the sap to flourish. This bacterial growth is responsible for two processes, one inside the tree another outside. Bacteria will cause the taphole to dry out and heal thus reducing the flow of sap from that tap. Outside the tree, sap that is contains large numbers of bacteria will produce a darker grade of syrup. A study by Legace, Petri, Jacques and Roy found that “The presence of microorganisms in the sap has the ability to breakdown the sucrose molecules, the main organic component sap, into glucose and fructose subunits. These subunits react with the heat in the evaporation process to cause the darkening of the syrup and an intense, caramelized flavor.” Morselli & Wahlen also found that if you could keep the sap from being contaminated with bacteria it would produce light colored syrup almost to the end of the season. Maple producers can learn much from these studies. Keeping tapping procedures clean not blowing in the hole to dislodge wood chips, drilling holes straight and clean will help prevent bacterial growth. Cleaning spouts thoroughly before use or using some of the newer disposable spouts.
Bacterial growth that starts at the taphole will multiply and flourish as the sap is collected and stored prior to evaporation. This is the reason that sanitation is so important during the collection process Tubing systems have solved many problems when it comes to collecting sap. They have also created a few. Sap being collected with a vacuum tubing system moves sap quickly away from the tree to the collection point. It creates a cleaner environment for sap collection unless it is improperly maintained. Poorly maintained tubing presents one of the highest risks for increased bacterial growth. Stagnate sap sitting inside of a tubing will warm quickly. Research done by Morselli and Wahlen5 at the Univ. of Vermont found that the bacteria populations, sitting inside warm tubing system, will double every twenty minutes. Therefore, tubing systems need to be installed properly and maintained. Lines need to be tight and sloped toward the collection point. Research at the University of Vermont Proctor Research Center, Center Acer and Cornell University has changed the way we work with tubing. We use to set a tubing system so that you could rinse it during the season. Now we have found that by changing spouts every season and rotating drop lines at a regular interval that you can achieve a high level of vacuum line sanitation. The invention of the Check Valve Adapter by the researchers at Proctor Research Center has totally changed the way we think of taphole sanitation. The research done at proctor documented that sap actually back siphons into the tree when vacuum is no longer present. The CVA prevents that back siphoning from occurring. The other thing that was learned was that if we can maintain vacuum on the lines even during periods of minimum flow we can keep the lines cooler and bacterial growth at a minimal level. The result is that in many maple operations the only time that vacuum is turned off is when the temperature goes below freezing. We are definitely changing the way we run our vacuum tubing systems and it has not only improved syrup production but also syrup quality. At the end of the season all of the collection lines need to be thoroughly cleaned and drained. If possible they should be rinsed before the start of the next season. Sanitation is no less important in bucket operations. Buckets should be washed before the start of every season. During the season sap needs to gathered often.. At the end of the season buckets need to be washed and dried and stored quickly.
Once the sap arrives at the sugarhouse it should be processed quickly. Do not allow sap to sit in open tanks for long periods of time. Collection tanks need to be drained and washed down between runs. To speed up processing evaporator size needs to be properly matched to the volume of sap coming into the sugarhouse. Producers who struggle to keep ahead of the sap flow and allow large volumes of sap to sit un-processed for long periods of time often struggle to make top quality syrup. There are several techniques that can slow bacterial growth and speed up the processing time. Sap can be exposed to ultra-violet light. Morselli and Wahlen found that sap treated with in-line ultraviolet lamp will reduce bacteria by 99.4 % early in the season and reduce bacteria by 86.2 % late in the season. The evaporation rates can be increased by using pre-heaters or enhanced evaporator units such as the Steam-A-Way or Piggyback. By far the most popular means of cutting down on processing time is by using a Reverse Osmosis Machine. The invention of the RO has revolutionized the maple syrup industry. Because of the use of modern RO technology, extensive expansion of maple operations is now possible. Modern RO machines can concentrate sap from 2% to up to over 20% before it ever goes through the evaporator. However, a word of caution, the sap that has been run through a reverse osmosis process is subject to increased bacterial growth. Concentrated sap needs to be processed as soon as it comes out the RO. to prevent darkening of the finished product.
The final step in the process is the proper setup and operation of the evaporator and the maple syrup filtering systems. Once again proper sanitation of all the processing equipment is very important if quality is to be maintained. There is an extensive look at operating and maintaining evaporators in previous posts on this blog. The purpose of this post is to get you to thinking about the importance of sanitation and the part it plays in the process of making maple syrup. The beginning of the season is the time to adopt good sanitation practices.