Sugar birch

Patterns of polyphenol accumulation In leaves vary among the few temperate forest species which have been studied. Feeny s (42) classic study on oak leaves (Quercus robur) shows leaf tannin levels rising slowly until August, and then Increasing sharply. In the cases of sugar maple (Acer saccharum) and yellow birch (Betula lutea) (44), respectively. 

Figure 1. Leaf-to-leaf variation in four traits along a single branch of sugar maple (left) and yellow birch (right) on 6/23/81. Horizontal axis is mean of each measure for that branch hatched area is one standard deviation. Each black bar represents the actual value for one leaf, plotted as deviation from the mean. Branch terminus is to right yellow birch leaves D and E are at least 10 days younger than the others.

Over a period of a month, tanning coefficients increased dramatically, and seasonal (2 month) increases in hydrolyzable tannins were observed in trees undergoing defoliation. Preliminary studies of yellow birch and sugar maple suggest that day-to-day responses in phenolic production may be generated by damage to leaves (39). 

Figure 4. Binding of a protein (hemoglobin) to several tannin extracts (tannic acid, sugar maple tannins, yellow birch tannins, quebracho tannins see 29) at various pH values. Ranges of microbial chitinase activity, NPV activity, and Bt toxicity are given. See text for discussion and references.

In the United States, woods which have been used for tight cooperage include white oak, red oak, chestnut oak, red or sweet gum, sugar maple, yellow or sweet birch, white ash, Douglas fir, beech, black cherry, sycamore, redwood, spruce, bald cypress, elm, and basswood (2, 3, 4). In Europe, cooperage for wine or brandy has been made from... 

Many more examples of the relation between sugar structure and taste could be given. Birch et al (10) have studied a number of free sugars, sugar derivatives, and substituted sugars. 

Xylanase (XA) activity was measured through the degradation of birch-wood xylan (7500.1 Roth, Karlsruhe, Germany) according to Bailey et al. (13) based on an estimation of the released reducing sugars by DNS acid (12). 

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