Sap flow and syrup crop summary
This past week has provided a range of fair to excellent conditions for sap flow in the province. Several producers using modern vacuum collection reported record quantities of sap in a single flow. Sap sugar concentration was slightly lower as is expected nearing the end of the harvest season.
Sap harvest has finished in early southwestern sugar bushes, where buds have begun to expand and grow. With the season ended, southwest and Niagara producers report that 2015 has been a good production year, where many have reached or exceeded their average yield.
Grey / Bruce counties reported a range of 100 to 110 percent crop yield with possibly one more boil. Simcoe reported 60 to 70 percent syrup crop so far. In the Haliburton and Kawartha regions and further north, buds on sugar maples are still dormant and snow cover remains.
St. Joseph Island reports 50 to 70 percent syrup crop so far with light syrup and no filtration problems. They are boiling again today. The weather this year has not provided a good large sap flow yet on the island and metabolism that appeared in the first few sap runs was a significant problem.
Late season syrup operations may still have one or two more sap runs ending by early next week. It will be most frustrating where buds on maple trees are still dormant and sap quality would be good however, no freeze / thaw conditions occur to induce sap to flow. Fingers are crossed.
Eastern areas report a syrup crop of 60 to 75 percent so far while boiling is ongoing today. Possibly there will be more sap early next week to finish off the season by mid-week. Snow still covers half the forest floor in Lanark and buds are still dormant. Mainly light colour grades so far, little to no extra-light syrup has been produced.
Photo 1. These two buds of sugar maple, collected 8 days apart off the same tree, show the first signs of growth. The change is small by about 2 – 3 mm, however significant development has occurred inside the bud.
Photo 2. From the buds in photo 1, the young shoot has begun to elongate at the growing point sliding the outer bud scales apart. Flower parts and tiny leaves are enlarging into recognizable features, causing the bud to swell. As buds break winter dormancy, the chemistry of sap changes to impart a ‘buddy’ off-flavour in any syrup that is processed. Producers can monitor the buds for elongation and swelling to help determine when the season is finished for the year.
A more accurate report of maple syrup production in Ontario will become clearer after producers have completed cleaning and sanitizing the sap collection tubing and processing equipment over the next few weeks, followed by a moment of well-earned rest.
Cleaning and sanitizing sap collection tubing
Proper cleaning and sanitizing of sap tubing after the harvest season is a two-step process. It is best to complete cleaning and sanitizing as soon as possible after the final sap collection while the sugary biofilm is still moist, and before spring temperatures warm up. If allowed to dry, the residue becomes very hardened or cemented onto the inner walls of tubing and will be much more difficult to remove. Biofilm left in the tubing has been found to populate larger quantities of spoilage bacteria during the following harvest season, which can reduce sap yield at the tap hole and reduce the quality of sap.
Cleaning sap tubing is the first step. All remnant sap should be removed from lateral and mainlines by leaving the vacuum turned on until all liquid is removed. Gravity flow tubing has no vacuum to remove sap completely and can be cleaned as described below. There are several methods used to clean sap lines and the method chosen is a matter of preference.
A common method is to use a pressure washer that pumps an air-water mixture through the tubing outwards into the sugar bush. This method won’t work where check-valve spouts are installed directly to droplines. Air bubbles add turbulence to the water for better cleaning compared to using water alone. The water and loosened biofilm residue flows from the pump outwards into the sugar bush.
With the pump turned on, each spile is pulled systematically from the trees along every lateral line moving towards the far end of each mainline. Once all laterals and mainlines have been cleaned, the remaining water can be removed using the vacuum. Unfortunately with this method, pumping the washwater and loosened biofilm outwards from the pumphouse can load lateral lines, drop lines and spouts with biofilm residue from the mainlines, where some lines may have been relatively clear of biofilm before cleaning.
Another method is to pull clean water inwards from each spout, down through the tubing towards the sugar house with the vacuum system turned on. Workers start at the farthest spout on the most distant lateral lines and move down each mainline towards the vacuum pump. Cleaning sap tubing using the vacuum pump may be preferable where the semi-solid biofilm is washed into increasingly larger tubes towards the pumphouse.
Cleaning sponges are also available from equipment dealers and are sized to the diameter of the mainline. The sponge is basically vacuumed down each mainline to gently scrape biofilm off the inner surface as the sponge is pulled down the line. If all goes as planned, the sponge should reappear in the sap extractor tank.
Photo 3 & 4. Sap tubing is engineered to remain permanently set up in the sugar bush for up to 15 years. Tubing is made of food-grade plastic. The inner surface is very smooth to help reduce buildup of biofilm and improve cleaning and sanitation following the harvest season. Without effective cleaning and sanitation, the tubing would become mouldy as spoilage organisms contaminate the sugary biofilm during warm summer months. Right photo – a junction of mainlines shows two white valves having quick-connect adaptors. The valves are modern additions, located at the farthest end of each mainline to allow easier cleaning and sanitation. Cleaning sponges can be inserted, and the sanitizer can be poured into the tubing at the valve.
Sanitizing sap tubing occurs after cleaning is completed. Isopropyl alcohol (IPA) has become the popular sap tubing sanitizer in Ontario and Quebec due to its ability to keep sap lines free of mould throughout the summer and to the next sap collection season. Other sanitizers, such as chlorine and hydrogen peroxide are used less frequently now due to good short-term results but poor season-long control, often with mould in the tubing by fall. Using IPA in tubing results in less chewing damage by squirrels, unlike chlorine.
It is important to follow the proper guidelines when using IPA to sanitize sap tubing. The IPA product must be accepted for use by the Canadian Food Inspection Agency, similar to pest control products. An accepted IPA product will have the directions for use in maple sap tubing printed on the label. If maple sap tubing is not included on the IPA label, it is not likely recognised by the CFIA. Sani-Marc Inc. isopropyl alcohol is an example of an acceptable IPA product.
Photo 5 & 6. Maple researchers at the Centre ACER research facility in Quebec have developed a guide on the proper use of isopropyl alcohol (IPA) to sanitize sap tubing. Simple diagrams and step-by-step directions make the guide very easy to use. Any producer planning to use IPA should get a copy of the guide. The manual is available in English or French and can be purchased from maple equipment dealers in Canada. Isopropyl alcohol is currently not registered for use in the United States. The ISBN for the manual is 978-2-9813463-4-6.
Photo 7 & 8. A backpack tank with a handheld dose syringe is used to treat sap tubing with isopropyl alcohol and can be set to dispense 15 millilitres into each spout. Using the proper equipment will prevent overdosing the tubing with higher than the recommended amount. The objective is to fill the tubing with IPA vapour, not liquid, and then seal the vapour inside the tubing to prevent mould. It is a privilege to have such an effective registered sanitizer.
Photo 9 & 10. After sap tubing is cleaned and sanitized, spouts are capped during the off-season to keep the lines clean. Right photo – where isopropyl alcohol is used to sanitize sap tubing, a specialized cap tightly seals IPA vapour inside the tubing and also keeps the outer surface of the spile sanitized and ready to tap into the trees for the next syrup processing season.
It is important to know that isopropyl alcohol is also being studied by researchers at Centre ACER in Quebec, to determine whether there are any problems created by using IPA on the plastics that are used to manufacture sap tubing and fittings.
Birch syrup production
As maple syrup production ends, harvest of birch sap and processing of birch syrup begins. Both white birch and yellow birch can be tapped for sap. Alternative tree syrups are relatively new to Ontario and market demand has already been established by production outside of Ontario. Birch sap drinks are common products in east Europe.
Photo 13 & 14. Birch syrup is in demand as a culinary ingredient, less as a pancake syrup. As demonstrated by George Brown College culinary school in Toronto, for example, birch syrup can be served on crepes, or as a component of BBQ sauce or glaze for meats, such as venison or salmon.
The flavour of birch syrup is very different from maple syrup. Birch sap sugar concentration is around 1 percent, or half of sugar maple sap. The sugars are mainly invert sugars of glucose and fructose that react to cooking differently than sucrose sugar in maple. Reverse osmosis is necessary to produce birch syrup, to reduce the cost of production and to prevent burning of the invert sugars that can occur when cooking continues for too long.
Maple researchers at the University of Vermont and Cornell University are looking closely at alternative tree syrups to assist in the development of thriving industries, as they have with maple syrup.