Enzymatic hydrolysis of carbohydrates in by-products of processed rice/Hidrolise enzimatica de carboidratos em coprodutos do arroz beneficiado

• Published in: Ciência rural 2021-11, Vol.51 (11), p.1
• Main Authors: Turini, Camila da Silva, Nogueira, Roberta Ma, Pires, Evaldo Ma, Agostini, Juliana da Silva
• Format: Article
• Language: English
• ISSN: 0103-8478
• DOI: 10.1590/0103-8478cr20200522

Over post-harvest steps of rice, from pre-cleaning to processing, a large amount of by-product is generated. Some of these byproducts, due to their high starch and fiber content can be used in ethanol production. The objective was to evaluate the effect of enzymatic hydrolysis conditions on the production of reducing sugars, from pre-cleaning residue and type III paddy rice, as well as the effect of the pretreatment of its fibers, targeting the use of these residues in ethanol fuel production. The proximate analysis was performed, followed by the pre-treatment of samples. Enzymatic hydrolysis was conducted in two ways: using one enzyme at a time or applying them simultaneously. The starch content was 41.18 and 53.41 %; the fibers were 30.44 and 23.39%, of which 6.53 and 4.41 % were lignin, for the pre-cleaning residue and paddy rice, respectively. Alkaline pre-treatment reduce lignin content by 47.94 and 18.23% for the pre-cleaning residue and type III paddy rice, respectively. Hydrolysis efficiency was 22.61 and 15.32% for the cellulase enzyme, and 82.18 and 87.07% for the amylolytic enzymes in the pre-cleaning residue and type III paddy rice, respectively. The hydrolysis with the separated enzymes presented higher reducing sugar yields. Therefore, the pre-cleaning residue and type III paddy rice can be used for ethanol production by its enzymatic hydrolysis, aiming to add value and to increase the sustainability of the rice production chain. Key words: enzyme, Oryza sativa, reducing sugar, residue, starch. Durante o processamento do arroz sao gerados grandes volumes de residuos, desde a pre-limpeza ate o beneficiamento. Alguns destes residuos, por apresentarem elevado teor de amido e fibras, podem ser utilizados na produgao de etanol. O objetivo foi avaliar a viabilidade tecnica do residuo da pre-limpeza e do arroz em casca tipo III como materia-prima para a produgao de etanol, a partir da hidrolise enzimatica. Foi analisada a composigao centesimal dos residuos e, em seguida, o pre-tratamento. A hidrolise enzimatica foi realizada por dois procedimentos, o primeiro com as enzimas separadas e o segundo com as enzimas atuando simultaneamente. O teor de amido foi de 41,18 e 53,41%; de fibras 30,44% e 23,39%, dentre as quais 6,53 e 4,41% foi de lignina, para o residuo da pre-limpeza e o arroz em casca, respectivamente. Com o pre-tratamento alcalino, a lignina reduziu em 47,94 e 18,23% para o residuo da pre-limpeza e para o arroz em casca tipo III, respectivam