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ABSTRACT: This study evaluated the action of commercial and non-commercial cellulases and pectinases in the hydrolysis of soybean hulls (SH) and corn stover and cobs (CSC), the effect of temperature and agitation on the lignocellulosic substrate hydrolysis and the bromatological characteristics of hydrolyzed substrates. The effect of pretreatment on the hydrolysis of lignocellulosic residues and bromatological analysis were also evaluated. The highest hydrolytic activity occurred at 300 rpm for SH (47.95 and 51.43% for cellulase and pectinase, respectively) and at 350 rpm for CSC (26.05 and 9.23% for cellulase and pectinase, respectively). Non-commercial enzymes achieved 7.26-30% of the amount of hydrolysis obtained with commercial enzymes, on the same substrates. Pretreatment with 7.5% of NaOH and a particle size of the substrate of 0.5 mm significantly increased the hydrolysis of SH and CSC for both enzymes. The bromatological characteristics showed that soybean hulls hydrolyzed with both commercial cellulase and pectinase have potential for large-scale use in animal feed production.
RESUMO: Foram avaliadas a ação de celulases e pectinases comerciais e não comerciais na hidrólise de casca de soja (CS) e palha e espigas de milho (PEM), o efeito da temperatura e da agitação na hidrólise do substrato lignocelulósico e as características bromatológicas dos substratos hidrolisados. O efeito do pré-tratamento na hidrólise de resíduos lignocelulósicos e a análise bromatológica também foram avaliados. A maior atividade hidrolítica ocorreu a 300 rpm para CS (47,95 e 51,43% para celulase e pectinase, respectivamente) e a 350 rpm para PEM (26,05 e 9,23% para celulase e pectinase, respectivamente). As enzimas não comerciais atingiram 7,26-30% da quantidade de hidrólise obtida com as enzimas comerciais, nos mesmos substratos. O pré-tratamento com 7,5% de NaOH e um tamanho de partícula do substrato de 0,5 mm aumentou significativamente a hidrólise de CS e PEM para ambas as enzimas. As características bromatológicas mostraram que a casca de soja hidrolisada com celulase e pectinase comercial tem potencial para uso em larga escala na produção de ração animal.
RESUMO
Sol-gel technique aiming enzymatic immobilization in situ with ionic liquids as additives is poorly studied. In this process, the addition of the enzyme is carried out in the synthesis of the support. The characteristics of ionic liquids, such as low vapor pressure, thermal stability, and non-flammability, make them strong candidates for use as immobilization additives. The objective of the present study was to immobilize the Candida antarctica B lipase by the sol-gel technique using ionic liquids as additives. The optimum points determined for ionic liquids 1-butyl-3-methylimidazolium chloride, 1-octyl-3-methylimidazolium bromide, and 1 hexadecyl-3-methylimimidazolium were 0.30, 0.27, and 0.22 g/mL of enzyme and 1.60, 1.52, and 1.52% of additive, respectively. The amount of enzyme and ionic liquids used in aerogel immobilization was the same as the optimized values in the xerogel immobilization process (for each ionic liquid). Ionic liquids proved to be good additives in the enzymatic immobilization process. Xerogel, regardless of the ionic liquid, presented a greater number of use cycles and better thermal stability compared to aerogel.