Acid hydrolysis of sunflower seed husks for production of single cell protein |
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Authors: | Eva Eklund Annele Hatakka Annikka Mustranta Paula Nybergh |
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Institution: | (1) Department of Microbiology, University of Helsinki, SF-00710 Helsinki, Finland;(2) Biotechnical Laboratory, Technical Research Centre of Finland, SF-00121 Helsinki 12, Finland;(3) Department of Chemistry, Helsinki University of Technology, SF-02150 Espoo 15, Finland |
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Abstract: | Summary Sunflower seed husks were chosen as a typical lignocellulosic waste product of low value. This model substrate was hydrolyzed with sulphuric acid at 120°C. The hydrolysis was carried out in two steps: hydrolysis of the pentosan fraction and subsequent hydrolysis of the cellulose fraction. The pentosan fraction was nearly quantitatively hydrolyzed. For the cellulose hydrolysis the yield was 79% of the theoretical yield. The hydrolyzates were neutralized to pH 5 with solid calcium hydroxide and used for preparation of growth media forCandida yeasts andPaecilomyces variotii. For the pentosan hydrolyzates the yields of yeast biomass were 35–36 g per 100 g available reducing sugars (supplied to the medium). In cellulose hydrolyzates the corresponding yields were 45–48 g withCandida utilis andC. tropicalis and about 30 g withC. pseudotropicalis. P. variotii was noticeably superior to the yeasts. In pentosan hydrolyzates it produced 63 g dry mycelium from 100 g reducing sugars supplied; in cellulose hydrolyzates, 94 g. This suggests that it must be an effective utilizer of a wide range of compounds, for example, organic acids in the medium. |
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