Valorization of rice husk by hydrothermal processing to obtain valuable bioproducts: Xylooligosaccharides and Monascus biopigment

Astrid Corrales Centeno, Salvador Sanchez Muñoz, Igor Severo Gonçalves, Fabio P. Sanchez Vera, Marcus B. Soares Forte, Silvio S. da Silva, Júlio C. dos Santos, Ruly Terán Hilares

Research output: Contribution to journalArticlepeer-review

2 Scopus citations

Abstract

Rice husk is a readily available residue which can be used for producing bioproducts in a biorefinery context. In this study, the hemicellulose fraction was hydrolyzed in a hydrothermal process to produce xylooligosaccharides (XOS), whereas the cellulosic hydrolysate was used for red pigment production by Monascus ruber Tieghem IOC 2225. The highest XOS (X2-X4) production (24 g per 1 kg of rice husk) was achieved at 180 °C for 68 min in a non-stirred Parr reactor (50 mL). Subsequently, using a stirred parr reactor (1 L) at 180 °C for 60 min, 40 g of XOS (42% of xylobiose, 35% of xylobiose, 13% of xylotriose, 7% of xylotetraose, and 3% of xylopentaose) per 1 kg of rice husk were obtained. The XOS was then purified by using ultrafiltration (UF) with two diafiltration membranes at 6.5 pH, recovering approximately 92% of total XOS. Further purification was conducted with nanofiltration (NF) at 3.8 pH, recovering approximately 86.4% of XOS in the retentate. This process yielded XOS with a purity of 77%. Additionally, the enzymatic process yielded 132 g/kg of sugar, and the hydrolysate was used to produce 2.1 UA490nm of red pigment by fungi after 7 days.

Original languageEnglish
Article number100358
JournalCarbohydrate Polymer Technologies and Applications
Volume6
DOIs
StatePublished - Dec 2023

Keywords

  • Red pigments
  • Rice husk
  • Xylooligosaccharides

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