Crops From the Maple Trees

C. O. Willits.

Maple sirup, cream, sugar, and candies all come from the sap of the hard maple tree (Ater saccharum), the black maple (A. nigrum), and the red maple (A. rubrum). Those trees grow from North Carolina and Missouri north to the Great Lakes and along the St. Lawrence River in Canada. The commercial maple area extends westward from the New England States to Minnesota and southward to Kentucky, an area that includes the 10 States that produce most of the crops and the States in which the maple industry is of importance in some localities. It is entirely a North American industry. It is a farm industry. It is unique among all farm enterprises because maple sap, a dilute sugar solution, is the only farm commodity that is unmarketable until it has been processed on the farm.

How long sugar has been made from the sap of maple trees no one knows. The earliest explorers found the Indians making maple sugar for their own use, even producing it in sufficient amounts for trade in some sections, especially along the St. Lawrence. Accounts dating from 1634 show that maple sirup and sugar are among the oldest of American farm products.

Typical is an excerpt from a letter written in 1648: "I have enclosed you some sugar of the first boiling got from the juice of the wounded maple. Mr. Ashton, Secretary to the Royal Society,presented it to me. It was sent from Canada where the natives prepare it from said juice, eight pints yielding commonly a pound of sugar. The Indians have practiced it time out of mind; the French began to refine it and turn it to much advantage."

Perhaps it is this history, wrapped in romance, that makes us associate the production of maple sirup with old-fashioned methods. Most of us, when we think of making maple sirup, think of it as we do of quilting bees just another old-fashioned, backwoods social highlight of the long hard winters. Seldom do we think of the equipment used as anything at all modern. Instead, our artists have fixed in our minds that maple sirup must be made in a big black iron kettle hung over an open fire, with the whole family participating. In reality, it is a far cry from the old open kettle to the present-day, flue-type evaporators. But even these and the methods of processing sap to sirup are much the same as they have been for the past 50 to 100 years. It would shock some people to be told that maple products can be produced by modern, streamlined methods, upon which research has recently started.

Emphasis has been less on improvement of processing and more on protection of the industry by preventing the sale of adulterated products. The need for this protection has not passed; under present conditions of high prices and insufficient supply, adulteration has again become a problem of the industry.

MAPLE PRODUCTS, essentially a forest or woodland crop, come mostly from mountain or hill country, where the acreage of tillable soil is limited. The nature of the place of origin is one of the reasons why maple products are an important cash crop. Processing usually is done in March and April, when most other farm activities are at their slowest and income at its lowest. The income, whether a small or a large part of the total, often is the fraction that spells success or failure to the farm.

THE ACTUAL income from maple sirup and sugar is difficult to estimate, because the season, type of equipment, and cost of labor and wood fuel vary from farm to farm. However, a measure of the profit to the farmer is his hourly income. J. A. Cope, of Cornell University, in a survey of 20 farms in 1947, learned that the farmer got from $0.56 to $3.78 (with an average of $2.08) for each hour of work. The figures were calculated from the total returns, minus all other costs except those for labor. The total return was based on an average price of $4.78 a gallon of sirup. The fixed costs, equipment, trees, and so forth represented only 38 percent of the total cost. According to H. R. Moore and others of Ohio, producers in that State earned as much as $3.51 an hour while making sirup.

From 1945 to 1950, approximately 70 percent of the maple crop was sold in retail trade. Any estimate of the direct sales is difficult to make, because records kept by the farmer-producer are not generally available. In 1944 and earlier, most of the maple crop went into the wholesale trade, so we have an accurate record of the crop. For that year, which was fairly typical, production amounted to 565,000 pounds of sugar and 2,612,000 gallons of sirup, valued at more than 8 million dollars. Were this figure based only on the sugar (sucrose) content, it would have been worth no more than 2 million dollars. The differential of 6 million dollars was due mainly to the premium Price which the commodity commands because of its unique flavor and partly to the high cost of farm processing.

MAPLE SAP is essentially a dilute solution of sugar in water. Its sugar Content averages 2 to 3 percent. The Sap 'nay contain less than 1 percent and as much as 9 percent, as typified by sap from a few trees at the New York, Vermont, and New Hampshire Agricultural Experiment Stations. It takes 86 gallons of a 1-percent-sugar maple sap to produce 1 gallon of sirup. Given the percentage of sugar in any particular maple sap, the number of gallons required to yield a gallon of sirup can be calculated merely by dividing 86 by the percentage of sugar in the sap. That is known as the rule of 86. Thus, a 3-percent-sugar sap requires less than 29 gallons for a gallon of sirup. It is plain, then, that it would be desirable to have for maple sirup production only trees that yield sap with 4 percent or more of sugar and to cull the trees that yield sap of low sugar content.

RESEARCH WORKERS at the Vermont Agricultural Experiment Station have begun a study to find the causes for the high concentrations of sugar in the sap from some few sugar maples. Already they have demonstrated that this sweetness is characteristic of the few trees that consistently yield sap high in sugar year after year. They hope to develop trees of increased sirup-producing capacity by vegetative propagation of selected, proved trees or by the development of a better tree through hybridization. Should it become possible to have available stocks of maple trees that are rapid growers and that will produce large volumes of sap rich in sugar, the cost of production would be reduced materially and the quality of the sirup would be improved. At present, it takes more than 20 years for an orchard of wild seedling transplants of uncertain sap yields to come into production.

The processing of maple sap to sirup or sugar involves the evaporation of large volumes of water, perhaps the most costly of all industrial operations. The concentration of sap must be done so that the maple flavor is retained without the development of off-flavors.

For reasons of economics it would be desirable to process sap in centrally located evaporating plants, each serving a large area. That is done in a few places, but the plan is usually impractical because of the inaccessibility of the sugar bush, the cost of transportation of large volumes of sap, and the danger of spoilage. One way to avoid some of the difficulties is to concentrate the sap partly and ship the concentrate to a vacuum evaporating plant for finishing off. According to Orval Polzin, superintendent of the Antigo Milk Products Cooperative, such a plan was inaugurated at Antigo, Wis. The cost of the method may be too high unless the evaporating unit employed is part of an existing industry.

In any case, until an economically feasible method of centralized concentration is developed, the sap will be processed on the producing farm. For this, new equipment that is efficient and simple in design and inexpensive enough to justify its purchase for use only a few weeks a year is urgently needed.

MAPLE SIRUP contains about 35 percent water and about 65 percent solids. Of the solids, the sucrose accounts for about 92 percent; reducing sugars as invert, 5.5 percent; and ash, 1 percent. The undetermined constituents that make up the remaining 1.5 percent are proteinaceous material (proteins, amino acids, and polypeptides), organic acids, and phenolic compounds. The accompanying table gives the analyses of five samples of sirup, which represent the four classified and the one unclassified grades. The samples were produced in the same grove under identical conditions.

They can be compared to the maximum and minimum analytical values typical of sirups produced in the United States and Canada.

The analyses show nothing to justify the luxury prices of maple products, except the 1.5 percent of undetermined constituents. It is in this fraction that we must surely find the flavor, which alone justifies the cost. Until more is known about this substance, little can be done toward improving processing practices and processing equipment, or the development of new uses for maple products. For that reason, the major effort of a current research program is directed toward a better knowledge of the substances that are either directly or indirectly responsible for the maple flavor.

Already we have strong evidence that the flavor does not exist as such in the sap as it comes from the tree, but is developed by what happens to the sap after it leaves the tree, namely heating. The amount of the flavoring material, or the amounts of the substances that make up the material, are extremely small. They account for less than 0.1 percent of the weight of the sirup. We know that the flavoring material is of a complex nature, and so the task of isolating and identifying it at best will not be simple. Fortunately, the past few years have brought the development of the new analytical tools, which will help reveal this unknown quantity.