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The relative influence of ball milling for various time periods on the course of enzymatic and dilute acid hydrolysis was investigated. The response of enzymatic hydrolysis to the extent of milling was quite dramatic. Cotton linters pulp was totally hydrolyzed in 10 days with 60 min of milling. The carbohydrates of red oak were 93% converted to sugar in the same time after 240 min of milling. It appears that, with sufficient milling, the carbohydrates of the three lignocelluloses investigated can be made almost totally accessible to enzymatic hydrolysis. Vibratory milling also yields substantial increases in the rates of dilute acid hydrolysis of all four substrates, nearly nine-fold for the cotton linters pulp and about five-fold for the three lignocelluloses. Thus vibratory milling represents an experimentally effective pretreatment.ignin and cellulose crystallinity are major deterrents to the chemical, enzymatic, and microbiological conversion of lignocellulosic residues to useful products. Lignin restricts enzymatic and microbiological access to the cellulose. Crystallinity restricts the rate of all three modes of attack on the cellulose. Thus if we are ever to make full use of the carbohydrate values contained in the many millions of tons of currently unused lignocellulosics generated in this country each year, some form of pretreatment must be employed to alter the fine structure of cellulose as well as disrupt or open up the lignin-carbohydrate complex. 1 Maintained at Madison, WI, in cooperation with the University of Wisconsin. This chapter not subject to U.S.

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