Sulfitation, sugar extract

The pilot plant-scale extract used in this study was made from bark obtained from old trees decked at a plywood plant. When 4.0% sodium sulfite and 0.4% sodium carbonate (on dry bark weight basis) were used to extract this finely ground bark for 2 hours at 100 °C, extract yields were only 18% of dry bark weight. The extract had a Stiasny polyphenol number of only 0.52 it gave a total of 18% sugars after hydrolysis, and contained 5.8% sodium and 3.8% sulfur. When bark from pulpwood-aged trees is extracted under similar conditions, extract yields typically vary between 20 and 24% and Stiasny polyphenol numbers are typically 0.60 to 0.75. The extract used for this work was also dried by a hot-pan evaporation method rather than being spray dried. So, the extract used represented a near worst-case example. 

Traditionally, the organic components of expander formulations are derived from natural products such as wood pulp. The composition of such materials is poorly defined. Lignin extracts, frequently obtained from waste sulfite liquors in the papermaking industry, are purified by removing sugars and various metals, and then depolymerized to different degrees. Lignin molecules are formed from three primary precursors, p-coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol the... 

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