photo of tap in tree trunk

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maple syrup

A sugar syrup made from the sap of maple trees. The season begins in early March and lasts for 6 to 8 weeks. Trees begin to be tapped when they have grown to a circumference, at chest height, of 63 centimeters (24 inches). Such a tree could support one hole. Trees with circumferences at chest height of more than 125 cm (50 inches) can have 2 holes, and the maximum of three holes is only used for trees over 189 cm (75 inches). Holes are no larger than 11 millimeters (7/16 inch) in diameter and no more than 6 cm (2 3/8 inches) deep, including the bark, and are fitted with spouts. The number and size of the holes are adjusted from year to year depending on the health of the individual tree and the forest.

An average tree yields 35 to 50 liters of sap per year. Proper tapping extracts about 10% of the tree's sugars.

The sap is concentrated by boiling, now in stainless steel pans, and in recent years, also by reverse osmosis. To make 1 liter of syrup requires about 40 liters of sap.


More than three-quarters of the world supply of maple syrup comes from Canada. Even to be graded, syrup must be produced exclusively from maple sap or by dissolving a maple product in water, “clean wholesome and fit for human consumption”, and have a minimum soluble solids content of 66% as determined by a refractometer or hydrometer at 20°C.

In the descriptions below, a caramel taste is the result of overheating the sap. The “buddy taste” is one found in sap taken too late in the season, when the trees have begun to leaf out.

Colors are determined either with a spectophotometer having 10-millimeter square cells, with light at a wavelength of 560 nanometers and taking 100% to be transmission through analytical grade glycerol; or by comparison with glass color standards, which can be purchased from suppliers approved by the Canadian government. Light color, formely not less than 60.5%, was replaced by Amber, not less than 50%

Grade   Color Class Description of Color
Canada Grade A “Free from fermentation”;
“uniform in colour and free from any cloudiness or turbidity”;
“has a maple flavor characteristic of its colour class”;
“is free from any objectionable odour or taste“.
Golden, Delicate Taste
(former Extra Light)
not less than 75.0% transmission
Amber, Rich Taste less than 75.0% transmission but not less than 50%
Medium less than 60.5% but not less than 44.0%
Canada No. 2 Same as Canada No. 1 Amber Less than 44.0% but not less than 27.0%
Canada No. 3 “has a characteristic maple flavor and is free from any objectionable odour or taste other than a trace of a caramel, buddy or sappy taste.” may be one of the colors above or Dark if Dark, less than 27.0%

C.R.C., c. 289. Access at,_c._289/page-14.html#docCont."

United States

The U.S. standards are voluntary. Described below is the version published 14 December 1979, becoming effective 14 January 1980.

To be called maple sirup [sic], the liquid must have not less than 66% solids by weight.

“Serious damage”, in the descriptions below, is defined as “any defect that seriously affects the edibility or market value of the sirup. Badly scorched sirup, buddy sirup, fermented sirup, or sirup that has any distasteful foreign flavor or disagreeable odor shall be considered as seriously damaged.”

Grade Description of Grade Color Description of Color
U.S. Grade A “Good” color, “good maple flavor characteristic of the color”; “good” odor; clean; “practically free from defects”; “practically clear”; “practically free from damage”; “free from serious damage”.

Color is “bright and typical of maple sirup prepared from sound, properly gathered sap”.
light amber As light or lighter than the USDA Light Amber Glass Color Standard
medium amber Darker in color than the USDA Light Amber Glass Color Standard but no darker than the USDA Medium Amber Glass Color Standard
dark amber Darker in color than the USDA Medium Amber Glass Color Standard but no darker than the USDA Dark Amber Glass Color Standard
U.S. Grade B for Reprocessing “Fairly good” color, “fairly good characteristic maple flavor”; “fairly good” odor; “fairly free from defects”; “fairly clear”; “fairly free from damage”, “free from serious damage”. Considered unsuitable for consumer labeling.   Darker in color than the USDA Dark Amber Glass Color Standard.
Substandard Doesn't meet Grade B requirements.

U.S.D.A., Agricultural Marketing Services, Fruit and Vegetable Division, Processed Products Branch.
United States Standards for Grades of Maple Sirup.
Washington, DC: Federal Register of 14 December 1979. 7 C.F.R. 52.5961-52.5967.

Access at

Standards of Identity for Maple Sirup, 21 CFR 168.41. (Regulated under the Food, Drug and Cosmetic Act.)


Vermont's standards are compulsory and were in effect prior to the U. S. standards. They apply only to syrup made and sold within the state. The abbreviation “U.S.” may be prefixed to the Grade A grades, that is, “U.S. Grade A Dark Amber” is acceptable as a Vermont grade. Labeling Vermont Grade B or Vermont Commercial as U.S. Grade B is not permitted.

All grades of packaged maple syrup must be “pure maple syrup which is free of any material other than pure, clear, clean liquid maple syrup in sanitary condition” and “shall be free of sugar crystals and shall not be damaged in any way.” Damage is defined as “any defect that affects the color, appearance, flavor, aroma, edibility or shipping quality of the maple syrup or sugar. Maple syrup which is fermented or which contains any buddy flavor, scorched flavor, or any other distasteful foreign flavor shall be considered damaged.” Thus a syrup with a trace of buddy flavor that could qualify as Canada No. 3 would not have qualified as Vermont Commercial.

All Grade A grades must have a density of at least 36° Baume (modulus 145) or 66.9° Brix at 60° Fahrenheit, but be no denser than 37° Baume or 68.9° Brix at 60° Fahrenheit.

To describe color, the Vermont regulations refer to USDA glass standards and measurements in which 100%Tc is the amount of light of wavelength 560 nanometers transmitted though a 10-millimeter square cell filled with analytic grade glycerol (that is, the same test as Canada's).

Vermont Grade Standards after 1 January 2017
Grade Flavor USDA
color standard
Transmission, Tc
Grade A Golden Color / Delicate Taste “delicately sweet, original maple flavor characteristic” Golden Color ≥75.0%
Amber Color / Rich Taste “more pronounced than that of Golden Color / Delicate Taste, but which is not strong or unpleasant” Amber Color 74.9% – 50%
Dark Color / Robust Taste “stronger than that of Amber Color / Rich Taste, but which is not sharp, bitter, buddy or off-flavor” Dark Color 49.9% – 25%
Very Dark Color / Strong Taste “stronger than Dark Color / Robust Taste” No
Processing Grade Not to be packaged, exposed for sale
 or sold as packaged maple syrup.

Code of Vermont Rules 20-011-002 (2013) Maple Products Regulations.


The new standards largely rename the old grades, except that a) they did away with Grade B, which was always unnecessarily pejorative, b) Amber Color is permitted to be darker than Grade A Medium Amber was, c) Dark Color is slightly darker than Grade B was, and d) the two commercial grades, which were never permitted to be sold at retail, have been consolidated.

Previous Grades
 Grade   Color Description
Vermont Fancy “has a delicately sweet, original maple flavor characteristic of fancy grade”   No darker than the USDA Light Amber Glass Standard, OR, a measured transmission not less than 75.0%Tc
Vermont Grade A “it may have a flavor which is more pronounced than that of Fancy Grade, but which is not strong or unpleasant and must be of the flavor characteristic of Grade A Medium Amber” Medium Amber No darker than the USDA Medium Amber Glass Standard, OR, a measured transmission between 74.9%Tc to 60.5%Tc
“it may have a flavor which is stronger than that of Grade A Medium Amber, but which is not sharp, bitter, buddy or off-flavor and must be of the flavor characteristic of Grade A Dark Amber” Dark Amber No darker than the USDA Dark Amber Glass Standard, OR, a measured transmission between 60.4%Tc to 44.0%Tc
Vermont Grade B “a flavor stronger than Grade A Dark Amber”   No darker than Canadian No. 2 Amber glass standard (as of 9 June 1989), OR, a measured transmission between 43.9%Tc to 27.0%Tc
Vermont Commercial “may have a strong flavor”; “may not be sold, offered for sale, or exposed for sale as packaged maple syrup.”   Darker than Canadian No. 3 Dark glass standard (as of 9 June 1989), OR, a measured transmission less than 27.0%Tc
Vermont Substandard “Bulk maple syrup which fails to meet the requirements of any other grade.” Not to be sold to consumers.   Doesn't qualify for any of preceding grades.

Title 6 V.S.A., Chapter 32. Vermont Maple Products Law, and regulations approved 7 December 1989.


Notice that, in all these standards, the grade ultimately depends on the judgment of a human taster with a memory of what flavor is “appropriate to the color”.

“Lower” grades do not necessarily represent lower quality, but mainly a difference in color and taste. The light, delicate taste of Vermont Golden Color would be appropriate on some very good vanilla ice cream (a maple sundae), but on a stack of pancakes I would much prefer Vermont Dark Color, and similarly for the other grading systems. The difference between some of the grades is like the difference between cognac and armagnac.



An Account of the Sugar Maple of the United States
by Benjamin Rush, M. D.
Professor of the Institutes of Medicine in the University of Pennsylvania

The acer saccharinuni of Linnaeus, or sugar maple tree, is found in great abundance in the western counties of all the middle states of the American Union. Those which grow in New York and Pennsylvania yield the sugar in a greater quantity than those which grow on the water of the Ohio. They are when at maturity, that is, when about twenty years old, as tall as an oak, and from two to three feet in diameter. They put forth a beautiful white blossom in the spring before they shew a single leaf. The colour of the blossom distinguishes the sugar maple from the acer rubrum, or common maple, which has a red flower. Its small branches were cut by the first settlers for the support of cattle during the winter, who throve greatly upon them. The wood is extremely inflammable, and therefore makes fine fire-wood. Its ashes afford a great quantity of pot-ash, exceeded by few, or perhaps by none, of the trees that grow in the woods of the United States.

The acer saccharinum is not injured by tapping; on the contrary, the oftener it is tapped, the more syrup is obtained from it. The effects of a yearly discharge of sap from the tree in improving and increasing the sap, is demonstrated from the superior excellence of those trees which have been perforated in an hundred places by a small wood-pecker which feeds upon the sap. The sap of such trees is much sweeter to the taste than that obtained from trees which have not been previously wounded, and more sugar is afterwards procured. In this last particular it follows a law of the animal economy. It is well known, that when a person has been once tapped, the process requires afterwards to be more frequently repeated. A single tree has not only survived, but flourished after forty-two tappings in the same number of years.

A tree of an ordinary size yields, in a good season, from twenty to thirty gallons of sap, from which are made from five to six pounds of sugar. To this there are sometimes remarkable exceptions. Samuel Low, Esq. a justice of peace in Montgomery county, in the State of New York, informed Arthur Noble, Esq. that he had made twenty pounds and one ounce of sugar from the 14th to the 23d of April, in the year 1789, from a single tree that had been tapped for several successive years before. The quantity obtained per diem varies from five gallons to a pint, according to the variations of the weather. The influence which this has in increasing or lessening the discharge of the sap is very remarkable. I have seen a journal of the effects of heat, cold, moisture, drought, and thunder, upon the discharges from the sugar tree; which disposes me to believe there is some foundation in Dr. Tongue's opinion, who supposes that changes in the weather of every kind might be as readily ascertained by discharges of sap from trees, as by the barometer. (Vide Philosophical Transactions, N° 68.) Warm days suceeeding frosty nights are most favourable to a plentiful discharge of sap. If frosty nights succeed a warm day, there is always a total suspension of the discharge.

The sap usually flows for six weeks, varying according to the temperature of the weather. The season for tapping is in February, March, and April. During the remaining part of the spring months, as also in the summer, and in the beginning of autumn, the maple tree yields a thin sap, but not fit for the manufactory of sugar.

Baron La Hontan gives the following account of the sap of the sugar maple tree, when used as drink, and the manner of obtaining it. The tree, says he, yields a sap which has a much pleasanter taste than the best lemonade or cherry water, and is the wholesomest drink in the world. This liquor is drawn by cutting the tree two inches deep in the wood, the cut being made sloping to the length of ten or twelve inches; at the lower end of this gash, a knife is thrust into the tree slopingly, so that the water runs along the cut or gash, as through a gutter, pervades the knife, and falls upon some vessels placed underneath to receive it. The gash does no harm to the tree. Some trees will yield five or six bottles of this water in a day, and many inhabitants of Canada might draw twenty hogsheads of it in one day, if they had a mind to notch all the maple trees upon their plantations; but common things are slighted, and scarce any but children think of extracting this liquor from the trees.

The mode of tapping is different, and is performed with an axe or an auger. The latter is preferred, from experience of its advantage. It is introduced about three quarters of an inch, and is afterwards deepened gradually to the extent of two inches. A spout is introduced about half an inch into the hole, and it projects from three to twelve inches. The operation of tapping is first done on the south side; and when the discharge of sap lessens, an opening is made with the auger on the north side, when an abundant flow takes place.

Wooden troughs large enough to contain three or four gallons are placed under the spout to receive the sap, which is carried every day to a large receiver made of wood. From this receiver it is conveyed, after being strained, to the boiler. The following facts have been ascertained by experiment: The sooner tbe sap is boiled, after it is collected from the tree, the better. The larger the vessel the more sugar is obtained. The sugar is also improved by straining the sap through blankets, or cloth, either before or after it is half boiled. Some fatty substance is added to the sap in the kettle, to prevent its boiling over. Lime, eggs, or new milk, is mixed with it in order to clarify it. I have seen clear sugar made without the addition of either of them. A spoonful of slack lime, the white of one egg, and a pint of new milk, are the usual proportions of these articles, which are mixed witb fifteen gallons of sap. The maple sugar clarified with milk alone had the evident superiority of all others. After being sufficiently boiled, it is grained, and clayed, and afterwards refined, or converted into loaf sugar. The method of conducting each of these processes is so nearly the same with those which are used in the manufactory of West India sugar; and are so generally known, that I need spend no time in describing them.

There are two other methods of reducing the sap to sugar. The first is by freezing. This method was tried by Mr. Scott, a farmer in this state, with great success. He says, that one half of a given quantity of sap reduced in this way, is better than one third of the same quantity reduced by boiling. If the frost should not be intense enough to reduce the sap to the graining point, it may afterwards be exposed to the action of fire for that purpose.

Secondly, by spontaneous evaporation. The hollow stump of a maple sugar tree, which had been cut down in the spring, and which was found some time after filled with sugar, first suggested to our farmers this method of obtaining sugar. So many circumstances of cold and dry weather, large and flat vessels, and above all so much time is necessary to obtain sugar by either of the above methods, that the most general method among our farmers is to obtain it by boiling.

The kettles and other utensils of a farmer's kitchen will serve most of the purposes of making sugar, and the time required for the labour (if it deserves that name) is at a season when it is impossible for the farmer to employ himself in any species of agriculture. His wife, and all his children above ten years of age, may assist him. The following receipt was published in the Albany Gazette: "Received of William Cooper, Esq. sixteen pounds for 640 pounds of sugar, made with my own hands, without any assistance, in less than four weeks, besides attending to all the other business of the farm. John Nicholls."--A single family consisting of a man and his two sons, on the Maple Sugar Lands between the Delaware and Susquehannah, made 1800 pounds of maple sugar in one season. Not more knowledge is necessary for making this sugar, than is required to make cyder, beer, &c. and yet one or all of them are made in most of the farm-houses in the United States.

Let us now take a comparative view of this sugar with that obtained from the cane, with respect to its quality, price, and the quantity that might probably be made in the United States, each of which I shall consider in order:

1. The quality of this sugar is necessarily better than that which is made in the West Indies. It is prepared in a season when not a single insect exists to feed upon it, or to mix its excretions with it. The same observation cannot be applied to the West India sugar. The insects and worms which prey upon it, and of course mix with it, compose a page in a nomenclature of natural history. I shall say nothing of the hands which are employed in making sugar in the West Indies; for slaves have not that obligation to cleanliness which those have who work for their own benefit, and have received a proper education. It has been conceived that the maple sugar is inferior to the West India sugar in strength. The experiments which led to this opinion I suspect have been inaccurate, or have been made with maple sugar prepared in a slovenly way. I have examined equal quantities by weight of both the grained and the loaf sugar, in hyson tea, and in coffee, made in every respect equal by the minutest circumstances that could affect the quality or taste of each of them, and could perceive no inferiority in the strength of the maple sugar. The liquors which were to decide this question were examined at the same time by Alexander Hamilton, Esq. secretary of the treasury of the United States, Mr. Henry Drinhur, and several ladies, who all concurred in the above opinion.

2. Price. Whoever considers that the gift of the sugar maple tree is from a benevolent Providence; that we have many millions of acres in our country covered with them; that the tree is improved by repeated tappings; and that the sugar is obtained by the frugal labour of a farmer's family; and at the same time considers the labour of cultivating the sugar cane, the capitals sunk in sugar works, the first cost of slaves and cattle, and the expences of provisions for both, &c. will not hesitate in believing that the maple sugar may be manufactured much cheaper, and sold at a considerably less price than that which is made in the West Indies.

3. The resources for making a sufficient quantity of this sugar, not only for the consumption of the United States, but for exportation, will appear from the following facts:- There are in the states of New York and Pennsylvania alone, at least ten millions of acres of land which produce the sugar maple tree in the proportion of thirty trees to one acre. Now, supposing all the persons capable of labour in a family to consist of three, and each person to attend 150 trees, and each tree to yield 5 pounds of sugar, the product of labour of 60,000 families would be 135,000,000 pounds of sugar, and, allowing the inhabitants of the United States to compose 600,000 families, each of which consumed 200 pounds of sugar in a year, the whole consumption would be 120,000,000 pounds a year, which would leave a balance of 15,000,000 pounds for exportation. Valuing the sugar at 6-90 of a dollar per pound, the sum saved would be 8,000,000 dollars of home consumption, and the sum gained by exportation would be 1,000,000 dollars.

The maple sugar also affords excellent vinegar; its molasses is capable of affording a very pleasant summer beer. The sap is also capable of producing spirit; but we hope this wholesome juice will never be prostituted to such a purpose. A diet consisting of a plentiful admixture of sugar has many advantages.

Sugar affords the greatest quantity of nourishment in a given quantity of matter of any substance in nature. Hence the Indians use it in their excursions. They mix a certain quantity of maple sugar with an equal quantity of Indian corn, dried and powdered. This mixture is packed up in little baskets. A few spoonfuls of it mixed with half a pint of spring water, afford them a pleasing and strengthening meal. From the great degree of strength and nourishment which are conveyed into animal bodies by a small bulk of sugar, it may be given to horses with great advantage. A pound of sugar with grass or hay, I have been told, has supported the strength and spirits of a horse during a whole day's labour in one of the West India islands. A larger quantity given alone has fattened horses and cattle during the war before last in Hispaniola, for a period of several months, in which the exportation of sugar and the importation of grain were prevented by the want of ships.

3[sic].  A plentiful use of sugar is the best preventative of worms. The author of nature seems to have implanted a love for sweets in all children for their growth, and to ward off the disease of worms.

4. I think it probable, that the frequency of malignant fevers of all kinds has been lessened by this diet, and that its more general use would defend that class of people who are most subject to malignant fevers from being so often affected by them.

5. It has been said, that sugar injures the teeth; but this opinion now has so few advocates, that it does not merit a serious refutation.

It has been a subject of enquiry, whether the maple sugar might not be improved in its quality, and increased in its quantity, by culture. From the influence which culture has upon forest and other trees, it has been supposed, that by transplanting the maple sugar tree into a garden, or by destroying such other trees as shelter it from the rays of the sun, much advantage might accrue. I know but of one fact. A farmer in Northampton county, in the state of Pennsylvania, planted a number of these trees above twenty years ago in his meadow, and he declares that the quality is so improved, that from three gallons of the sap he obtains every year a pound of sugar; and it is a known circumstance that, to produce the same quantity of sugar from the trees which grow wild in the wood, it requires five or six gallons of sap. To transmit to future generations all the advantages which have been here enumerated, it is necessary that this tree ehould be cultivated in the old and improved parts of the United States, and a bounty given upon the maple sugar by Government. Afterwards men would find out their own advantage in rearing them. An orchard consisting of 200 trees, planted upon a common form, would yield more profit than the same number of apple or any other trees. If a greater exposure of a tree to the action of the sun has the same effect upon the maple that it has upon other trees, a larger quantity of sugar might reasonably be expected from each tree planted in an orchard. Allowing it to be only seven pounds, then 200 trees will yield 1400 pounds of sugar; and deducting 200 from the quantity for the consumption of the family, there will remain for sale 1200 pounds, pounds, which at 6-90 of a dollar per pound will yield an aunual profit to the farmer of 80 dollars. Should this mode of transplanting for the purpose of obtaining sugar be successful, it will not be a new one. The sugar cane of the West Indies was brought originally from the woods of the East Indies by the Portuguese, and cultivated at Madeira, from whence it was transplanted directly or indirectly to all the sugar islands of the West Indies.

In contemplating the present opening prospects in human affairs, I am led to expect that a material share of the happiness which Heaven seems to have prepared for all mankind, will be derived chiefly from the manufactory and general use of the maple sugar, which I flatter myself will not be confined to us, but will extend itself to other nations. With this view of the subject, I cannot help contemplating a sugar American maple tree with a species of affection and even veneration; for I have persuaded myself to behold in it the happy means of rendering the commerce and slavery of our African brethren in the West India islands as unnecessary as it has always been inhuman and unjust.

The Philosophical Magazine (London, August, 1798). Vol 1. pages 182-191. “Communicated by Robert John Thornton, M. D. Lecturer on Medical Botany at Guy's Hospital.” A footnote on sap flow in vines has been omitted.

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