Evaluation of crude preparations of Saccharomyces cerevisiae (ATCC 52712) pectolytic enzymes in cassava starch extraction: Effects of variety on yield and starch recovery rates

Application of enzyme preparations has shown great potential in aiding extraction procedures. However, the focus has mostly been on single crop varieties, thereby limiting knowledge on the effects of enzyme technology to those (single) varieties studied. The present work compared the effects of various dosages of crude pectolytic enzymes from Saccharomyces cerevisiae (ATCC 52712) on yield and extraction rates of starch from the roots of five indigenous cassava varieties (Nkabom, Afisiafi, Doku duade, Bankye hemaa and Esam bankye). The study aimed to establish whether varietal differences (with respect to response of variety to the technology) existed and to establish which variety is best suited for the technology. Generally, application of the crude pectolytic enzymes with activity of about 4.91 U significantly (P<0.05) increased starch yield and recovery rates in all selected cassava varieties. However, optimization of both yield and recovery rate was dependent on an interplay of variety, enzyme dosage and holding time for enzyme action. An enzyme dosage of 0.02% was found as significant (P<0.05) for peak of starch yield in the Esam bankye and Nkabom varieties at 0.5 and 1 h holding time in the Afisiafi variety; 0.025% enzyme dosage at 0.5 h holding time was the optimum treatment combination for starch yield in both Bankye hemaa and Doku duade varieties. The study therefore showed that although application of pectolytic enzymes for starch extraction enhances yield, the technology is affected by varietal differences. Given the heavy dependence of most Ghanaian industries on starch, the technology if made available would greatly boost the productivity of these sectors at relatively lower cost.   Key words: Cassava varieties, crude pectinase, pectolytic enzyme dosage, polygalacturonase, submerged fermentation.