Previous week summary
Maple syrup producers in mid-season areas from Huron and Grey/Bruce over to the Eastern counties continued to collect sap and process syrup last week. Buddy off-flavour sap began to appear late in the week or during Easter weekend ending the syrup processing season for most southern regions. Those producers still collecting sap after Easter weekend were testing all new sap for the first indication of buddy off-flavour. The final yield in mid-season areas is estimated to range from 75 to 115 percent of an average yield, or .75 to 1.1 litres of syrup per tap. Medium, amber and dark grades were produced last week. The 2014 maple syrup production season is ending positively for southern regions with relatively good production after a late start.
Late areas north of Parry Sound to Ottawa Valley had processed 50 to 80 percent of a syrup crop by the Easter weekend and anticipate more sap collection. Colour grades ranged from medium to amber with excellent maple flavour.
Nearing the end of the 2014 sap collection season
Northern regions from Huntsville up to North Bay and St. Joseph Island will see good sap flows this coming weekend and possibly into next week where daily freeze/thaws are predicted and where buds on sugar maple trees are still dormant. Producers in northern areas can test all new sap for indications of off-flavour once buds begin to swell, likely by the end of next week. A Sudbury area producer reported their first good sap flow occurred April 8.
Photo 1 & 2. Sugar maple buds continue to elongate in southern regions (left) and maple leaves will soon expand to form the canopy during the next few weeks (right – sugar maples will bloom shortly).
Removing taps from maple trees
Many syrup producers in early areas have already removed their taps from the trees as a good management practice. Once sap collection season is finished, taps can be pulled from trees as soon as possible prior to leaf emergence. As new leaves expand and the canopy develops, growth of new sapwood will begin. The majority of new wood growth occurs in spring and early summer. Spiles that remain in the trees during wood growth will not allow the new wood tissue to heal the tap holes. Researchers have found it is best to leave the tap holes empty and not filled with anything to reduce decay organisms and promote healthy trees.
Photos 3 & 4. Taps can be removed easily and quickly with a specially designed pry bar. Removal of hundreds, or thousands of taps from tapped sugar maples is completed quickly once sap collection stops. With good growing conditions the tap holes should heal over completely with new wood growth (right) in one or two seasons. Small diameter tap holes of 5/16 ” or 19/64″ drilled for ‘health spiles’ heal faster than the old 7/16″ tap holes.
Monitoring trees in the sugar bush
Detailed knowledge, planning and record-keeping is necessary to manage a sugar bush. Learning is an ongoing process. For example, spring provides an opportunity to observe the upper branches of sugar bush maple trees to determine whether the maturing trees have adequate room for the canopy to grow larger in diameter. Where an overstory is completely closed with no space between tree canopies, thinning may be required. A few holes will also bring sunlight to the forest floor to encourage regeneration of seedlings, the future sugar bush.
Photos 5 & 6. The canopy of this sugar maple (left) is competing for sunlight with neighbouring trees and has little room to expand outwards. Annual growth of new wood on the trunks can be reduced, which slows the healing of tap holes. A closed canopy will grow vertically, which is ideal for sawlog production but is less suited to maple syrup production. On the right, clear openings between each canopy of 15 to 20 feet on at least two sides will enable new branch growth and a larger leaf surface area. A larger canopy will increase the sugar concentration of sap, will stimulate more annual wood growth on the trunk to heal tap holes faster and, will ensure new sapwood is growing to tap in the future.
Post-season cleaning of sap collection tubing
Methods of cleaning and sanitation are described in greater detail in the North American Maple Syrup Producer’s Manual. Leading maple researchers are currently revising the production manual for 2015. The maple syrup industry is constantly improving methods to clean and sanitize sap collection tubing in addition to improving food-grade plastic that is easier to clean. Hearing from syrup producers at industry meetings, where panel discussions describe various cleaning and sanitizing techniques, is an excellent way to learn what works versus methods that are less effective.
Briefly for this report, cleaning and sanitizing can be conducted as two separate operations. It is best to clean sap tubing as soon as possible before the biofilm residue on the inner surface has had time to dry and harden. Once hardened it is difficult to re-wet and soften the biofilm, just like dirty dishes after a meal. After the sap tubing is cleaned it can then be sanitized.
Pressurized air / water. A common cleaning method for sap tubing is to use a mixture of pressurized air and water that is pumped through the collection tubing from the sugar house out into the sugar bush. Wash pumps with air injectors are available from maple equipment dealers. The blasting of water spray creates frictional turbulence that can effectively remove biofilm and bacteria residue that is formed by spoilage organisms.
Acid cleaners. The product Tub-o-Net (phosphoric acid) is an accepted acid cleaner for maple sap tubing and should be handled and used with caution to protect the person who is doing the work. Read the label carefully on how to use chemical cleaners safely and effectively.
Photo 7. Tub-o-Net sap tubing cleaner
Hydrogen peroxide is a strong oxidizer that some producers use to sanitize sap tubing with good results. Researchers have tested peroxide concentrations up to 1000 ppm in sap tubing. Producers generally prepare the peroxide solution in a portable backpack tank and use it immediately upon mixing. With the vacuum pump turned on, each spile is systematically treated with peroxide until the entire network of droplines, lateral and mainline tubing has been treated. The sap tubing should be rinsed with potable water prior to the next season of sap collection.
Chlorine solution or sodium hypochlorite, was previously a common sap line sanitizer, however is used less now in sap tubing. Chlorine solution can be prepared using common household bleach 5% concentration and is applied in sap tubing at approximately 500 ppm active ingredient diluted in potable water. Bleach is an effective sanitizer on food processing equipment at 200 ppm, however it can be difficult to rinse the residue from plastic sap tubing. Large quantities of potable rinse water are required to remove chlorine residue. Remnant residue can impart off-flavour in the sap during the following production season. Chlorine sanitizer also leaves a salt residue that leads to chewing and puncture damage to the tubing by wildlife, mainly by squirrels to get to the salt. Damage to tubing by wildlife can be severe and costly due to chlorine salt residue.
Isopropyl alcohol, or IPA is a recent sap tube sanitizer that effectively prevents growth of bacteria, yeast and algae inside tubing during the spring and summer. The Canadian Food Inspection Agency accepts only specific name brand formulations of IPA for sanitizing maple sap tubing. Maple equipment dealers can supply federally accepted IPA. IPA is applied to sap tubing as a 70% solution diluted with potable water. A specialized hand-dispenser with a backpack tank should be used to apply IPA at the recommended dosage (see photo 9). Producers report significantly less chewing damage on tubing by wildlife where IPA is used as a sanitizer.
Maple researchers in Quebec and Vermont are conducting studies to determine whether IPA has any negative effects on the plastic formulations used in maple sap tubing and plastic connectors. Syrup producers and the maple syrup industry will be kept informed of new research pertaining to the use of isopropyl alcohol as a sap tube sanitizer.
Photo 8. The label on an accepted formulation of isopropyl alcohol should state the use of the product as a sanitizer of maple sap tubing, provide instructions on how to use it and provide precautions to the user. For example, isopropyl alcohol is flammable and should be handled with caution.
Photo 9. A handheld dose injector with backpack tank (CDL Maple Equipment) can be calibrated to dispense 15 mL of 70% IPA solution into each spile with the vacuum pump turned on. After applying a dose into the spile and dropline, the spile should be immediately capped to contain the alcohol vapour inside the tubing. Once all spiles are treated and capped on a mainline, 2 litres of IPA solution can be poured into the end of each mainline and then the valve closed to contain the vapour. The vacuum is then turned off and the sap lines are left closed during the off-season. The IPA vapour leaves no residue once the sap tubing is opened, vented and rinsed with potable water the following fall, or rinsed just prior to the next sap collection season.