This paper is describing the effect of pectinase as a pretreatment of several dissolving pulps and one paper grade pulp prior to dissolution in NaOH. Two main studies were performed, first with a pure pectinase, then with a mixture of pectinase and endoglucanase. Despite the amount or presence of pectin on the starting pulps was too low to be determined, the incubation of different pulps with pectinase preparations lead to an increase of the accessibility of the fibers, reaching dissolution yields increase higher than 150%. The enzymatic treatments were not affecting all the studied pulps on the same manner, showing that the pretreatments history of the dissolving pulps have an influence on the enzymatic efficiency. Using a mixture of endopectinase and endoglucanase showed that the synergistic effect of these two enzymes is more effective than each enzyme taken alone on cellulose activation. Endopectinase treatments show a great improvement on cellulose accessibility to NaOH without any significant changes of the chemical composition or macrostructure and without material losses. The increase on the dissolution yield in NaOH is directly proportional to the enzyme concentration and to the time of the enzymatic incubation. For the range of concentration and time investigated, the enzymes have shown to be stable and, when keeping constant the total endopectinase activity, the enzymatic performance is independent of the time or enzyme concentration. This allowed the definition of a new parameter that is useful on the interpretation of results, the “total activity units”, defined by the product of the initial activity units (units per gram of pulp) by the incubation time (in hours). Although it is clear that endopectinase treatments are improving the chemical accessibility of the cellulose fibers, the mechanisms behind this effect has not been fully understood. Some hypothesis about this effect will be given.

Influence of pectinase treatments on the dissolution abilities of cellulose pulps in NaOH-water

249th National Meeting (2015)

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Influence of pectinase treatments on the dissolution abilities of cellulose pulps in NaOH-water<br />