Abstract
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.
Highlights
Until recently, Ghana’s economy has progressively thrived on the performance of her agricultural sector
This factory, the Ayensu Starch Factory, established as part of the Presidential Special Initiative (PSI) on cassava, was projected to work at 70% installed capacity (Business and Financial Times Newspaper, 2013); its operations were fraught with challenges, key among which were power cuts, financial challenges and insufficiency of raw materials (Addo, 2013): the factory could only operate at 20% of its installed capacity (Business and Financial Times Newspaper, 2013)
Optimization of starch extraction from cassava with crude pectolytic enzymes from S. cerevisiae was found to be dependent on variety as well as the dosage-holding time treatment combinations adopted
Summary
Ghana’s economy has progressively thrived on the performance of her agricultural sector. The Food and Agriculture Organization (FAO) estimates that in the year 2015 about 8,405 tons of cassava flour and starch were traded globally and Africa is touted the highest exporter of cassava tuber (exporting about 153,451 tons of global exports of 281,050 tons), only Nigeria contributed significantly (about 150 tons) to exports of cassava flour and starch from Africa (FAO, 2016) They reported that global demand for cassava starch could increase especially as global and regional demands for alcohol, ethanol, starch and animal feed sectors, as well as their lucrative export markets continue to rise (FAO, 2016). Some work have been carried out on enzymatic extraction of starch from native crops in many places worldwide (Sit et al, 2015; Pinyo et al, 2016) and results from these studies have been very remarkable
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