Variations in structure and saccharification efficiency of biomass of different sorghum varieties subjected to aqueous ammonia and glycerol pretreatments

    Joy, S P and Kumar, A A and Gorthy, S and Jaganathan, J and Kunappareddy, A and Gaddameedi, A and Krishnan, C (2020) Variations in structure and saccharification efficiency of biomass of different sorghum varieties subjected to aqueous ammonia and glycerol pretreatments. Industrial Crops and Products (TSI), 159. pp. 1-12. ISSN 0926-6690

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    Abstract

    Sorghum biomass is a potential feedstock for lignocellulosic bioethanol production. The selection of suitable sorghum variety is essential to obtain high ethanol yield. In this paper we screened sorghum varieties belonging to sweet sorghum, post rainy sorghum, and hybrid sorghum. These varieties were screened based on their agronomic traits, amenability to pretreatment methods, and enzymatic digestibility. The sorghum biomass was pretreated using glycerol (60 %) at 190 ̊C for 60 min and aqueous ammonia (15 %) at 120 ̊C for 60 min. The digestibility of the pretreated biomass was determined using commercial cellulase (Cellic CTec2) at 10U/g loading, and the structural changes in the pretreated biomass were analyzed by spectroscopy and scanning electron microscopy. Sweet sorghum varieties showed significant variations in phenotypic traits such as fresh stalk yield, dry fodder yield, and juice yield. The cellulose digestibility among the sorghum varieties after the pretreatment also differed significantly. The cellulose digestibility levels of glycerol range from 64 % to 89 % and ammonia pretreated sorghum from 63 % to 81 %. The total sugar yields varied from 227 mg/g to 356 mg/g and 209 mg/g to 313 mg/g for sorghum pretreated with ammonia and glycerol, respectively. Although the delignification of sorghum varieties was higher (31%–65%) after ammonia pretreatment than glycerol pretreatment, the cellulose digestibility was higher for the glycerol pretreated biomass. These results indicated that effect of delignification on cellulose digestibility is trivial. This study explores factors affecting pretreatment and cellulose digestibility of sorghum varieties for maximum sugar yield in the cellulosic ethanol process.

    Item Type: Article
    Divisions: Research Program : Asia
    CRP: UNSPECIFIED
    Uncontrolled Keywords: Sorghum, Glycerol pretreatment, Ammonia pretreatment, Cellulose digestibility, Xylan removal, Extractives
    Subjects: Mandate crops > Sorghum
    Depositing User: Mr Arun S
    Date Deposited: 31 Mar 2021 09:19
    Last Modified: 31 Mar 2021 09:19
    URI: http://oar.icrisat.org/id/eprint/11775
    Official URL: https://doi.org/10.1016/j.indcrop.2020.113072
    Projects: UNSPECIFIED
    Funders: UNSPECIFIED
    Acknowledgement: The authors greatly acknowledge IIT Madras for the award of half time teaching assistantship to Shereena Joy.
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