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Enzymic decortation of sorghum grain
Dissertation (MSc (Food Science))--University of Pretoria, 2006.
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University of Pretoria
2013
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| _version_ | 1867613629935779840 |
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| access_status_str | Open Access |
| author2 | Taylor, J.R.N. (John Reginald Nuttall) |
| author_browse | Taylor, J.R.N. (John Reginald Nuttall) |
| author_facet | Taylor, J.R.N. (John Reginald Nuttall) |
| collection | Thesis |
| dc_rights_str_mv | © 1999 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. |
| description | Dissertation (MSc (Food Science))--University of Pretoria, 2006. |
| format | Thesis |
| id | oai:repository.up.ac.za:2263/30188 |
| institution | University of Pretoria (South Africa) |
| last_indexed | 2026-06-10T12:39:11.828Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from UPSpace — University of Pretoria Institutional Repository |
| publishDate | 2013 |
| publishDateRange | 2013 |
| publishDateSort | 2013 |
| publisher | University of Pretoria |
| publisherStr | University of Pretoria |
| record_format | dspace |
| source_str | UPSpace — University of Pretoria Institutional Repository |
| spelling | oai:repository.up.ac.za:2263/30188 Enzymic decortation of sorghum grain Taylor, J.R.N. (John Reginald Nuttall) upetd@up.ac.za Dewar, J. Siwela, Muthulisi Sorghum milling Sorghum commercial processing UCTD Dissertation (MSc (Food Science))--University of Pretoria, 2006. Sorghum is a drought resistant indigenous African cereal and traditional food crop. Unfortunately. milling sorghum. as is normally done using a Prairie Research Laboratory (PRL)-type abrasive dehuller is not effective. Because in sorghum the germ is integral in the grain. the process of removing the outer bran layers by abrasion leads to high losses, up to as much as 40% if a flour of less than I% fat is to be produced. The pericarp of sorghum is rich in cellulose and hemicelluloses, and the germ, lipids. Specific hydrolytic enzymes should degrade these chemical components and thus remove the bran and germ with minimal loss of grain material. In this work. four industrial enzymes. endo-β-glucanase. xylanase. pectinase and lipase were applied either singly or in combination to two different commercial batches of sorghum to determine whether hydrolytic enzymes could be used to decorticate sorghum grain. Sorghum grain was either de-waxed with hexane or scraped to remove the waxy material on the pericarp and seed coats. The grain was then soaked in a 10% (w/w) solution of either single or combined enzymes in flasks which were then incubated at 50°C in a water bath and left overnight with shaking. SEM showed that endo-β-glucanase caused decortication of the sorghum grain at the seed coat/aleurone layer interface with both the hexane de-waxed grain and the scraped one. The germ was not removed. The results suggested that endo-β-glucanase hydrolysed the exposedpericarp cell wall material and thus loosened the pericarp, and hence its removal. The germ could not be removed perhaps due to the fact that, in sorghum grain the germ/endosperm interface is at right angles to the surface of the grain, thus enzymes have only a small area to act on and all the underlying interface is not accessible. Different endo-β-glucanase concentrations were applied to partially decorticated sorghum grain to establish the optimum concentration to be used to remove the pericarp material to an acceptable level. The lowest level when there was a good decortication effect, as indicated by grain ash content and colour, was at 0.01% endo-β-glucanase concentration (ml/l00 g grain). The effectiveness of enzymic and mechanical decortication was compared in terms of the relationships between decortication yield and grain ash content, and between decortication yield and grain colour. To reduce the grain ash to an acceptable level (about 1.1%), enzyme decortication resulted in about 10% saving in grain material relative to the mechanical process. However. at the same decortication yield. the mechanical process gave a lighter product than the enzymIc process. It appears that endo-β-glucanase can remove the pencarp from sorghum grain at an economically feasible concentration (0.01%). and that there is significant reduction of grain material loss relative to the mechanical process. However, more work needs to be done to improve the colour of the product. and to find a way to remove the germ. Food Science unrestricted 2013-09-07T18:13:27Z 2006-12-07 2013-09-07T18:13:27Z 1999-12-01 2006-12-07 2006-12-07 Dissertation Siwela, M 1999, Enzymic decortication of sorghum grain, MSc dissertation, University of Pretoria, Pretoria, viewed yymmdd < http://hdl.handle.net/2263/30188 > H1105/ag http://hdl.handle.net/2263/30188 http://upetd.up.ac.za/thesis/available/etd-12072006-112327/ © 1999 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. application/pdf University of Pretoria |
| spellingShingle | Sorghum milling Sorghum commercial processing UCTD Enzymic decortation of sorghum grain |
| title | Enzymic decortation of sorghum grain |
| title_full | Enzymic decortation of sorghum grain |
| title_fullStr | Enzymic decortation of sorghum grain |
| title_full_unstemmed | Enzymic decortation of sorghum grain |
| title_short | Enzymic decortation of sorghum grain |
| title_sort | enzymic decortation of sorghum grain |
| topic | Sorghum milling Sorghum commercial processing UCTD |
| url | http://hdl.handle.net/2263/30188 http://upetd.up.ac.za/thesis/available/etd-12072006-112327/ |