Using in-situ viscosimetry and morphogranulometry to explore hydrolysis mechanisms of filter paper and pretreated sugarcane bagasse under semi-dilute suspensions

Abstract

OATAO is an open access repository that collects the work of Toulouse researchers and makes it freely available over the web where possible. This is an author-deposited version published in : http://oatao.univ-toulouse.fr/ Eprints ID : 18375 a b s t r a c tThe relationship between in-situ viscosimetry, in-and ex-situ morphogranulometry, and biochemistry has been investigated during enzymatic hydrolysis of pretreated sugarcane bagasse (SCB, 3% w/v) and filter paper (FP, 1.5% w/v) at various enzyme dosages (0.3-25 FPU/g cellulose). Semi-dilute conditions (1.5-2 times higher than critical concentrations) were considered in order to generate non-Newtonian rheological behaviors and to avoid neglecting particle-particle interactions in opposition to dilute conditions. Observed phenomena as well as hydrolysis mechanisms including solvation, separation, fragmentation, and solubilization appeared to depend strongly on initial substrate properties. For both FP and SCB, suspension viscosities were correlated with particle size distributions and volume fractions during hydrolysis, but they exhibited strongly different trends. With SCB, a viscosity overtaking was clearly observed at enzyme loading ≤10 FPU/g cellulose. This phenomenon is explained by the separation of agglomerates into individual fragments, leading to an increase in the total number of particles and a morphological shift of particles from sphere-like into fiber-like. With FP, the viscosity collapsed at the initial stage in relation to the volume reduction of coarse particles and the number increase of fine particles. Suspension viscosity was strongly dependent on the fraction of coarse population and nearly independent from the glucose conversion yield.Abbreviations: CLD, chord length distribution; DLS, diffraction light scattering; d SE , diameter of circle equivalent (m); FBRM, focused beam reflectance measurement; FP, filter paper; FPU, filter paper unit; lc , chord length (m); LOD, limit of detection; LOQ, limit of quantification; MO, Metzner-Otto concept; Nc, number of chord counted (/); Np, power number (/); PP, paper pulp; PSD, particle size distribution; Re, Reynolds number (/); SCB, sugarcane bagasse.

Impact of Particle Size on the Rheological Properties and Amylolysis Kinetics of Ungelatinized Cassava Flour Suspensions

“…This study investigates the impact of cassava flour granulometry on the suspension viscosity and hydrolysis yield at low-temperature by a multiscale approach combining in-situ physical and ex-situ biochemical analyses. This multiscale approach has been previously applied to investigate the deconstruction of lignocellulosic-based biomass for biorefinery purposes [18][19][20] and feed additives in animal nutrition [21]. The first step was to characterize the initial viscosity and rheological behavior of suspensions as a function of concentration and granulometry.…”

Combined in situ Physical and ex-situ Biochemical Approaches to Investigate in vitro Deconstruction of Destarched Wheat Bran by Enzymes Cocktail Used in Animal Nutrition

“…Experimental results on our system gave Np 0 = 0.17, α = 0.75, Kp = 115.2 and showed that a laminar regime prevailed up to Re = 41 (Nguyen et al, 2013; Le et al, 2017).…”

“…Pump P1 (archimede screw pump) is used to load progressively the reactor with the wheat bran substrate in order to generate a homogeneous suspension under permanent mixing. Pump P2 (volumetric peristaltic pump) is used to add quickly the enzymatic cocktail at a defined time (From Le et al, 2017).…”

“…This challenge has been therefore addressed by a multiscale approach which combines in-situ physical (i.e., rheological, morpho and granulometric data) and ex-situ biochemical (i.e., solubilization and nature of the products solubilized) analyses, by mean of a multi-instrumented bioreactor. This multiscale approach has been previously applied to investigate deconstruction of lignocellulosic-based biomass for biorefinery purposes (Nguyen et al, 2013; Le et al, 2017). In addition, this methodological approach was very appropriate for our study since at variance of several works employing mixture of pure enzymes with known catalytic activities (Rosgaard et al, 2007; Vaaje-Kolstad et al, 2010; Goldbeck et al, 2014; Frommhagen et al, 2017), here we used an industrial cocktail termed Robavio®.…”

Enzyme-Mediated Lignocellulose Liquefaction Is Highly Substrate-Specific and Influenced by the Substrate Concentration or Rheological Regime

“…While being a powerful tool for real-time analysis, in-rheometer monitoring of enzymatic liquefaction of fibrous lignocellulosic materials is inherently limited to the analysis of low-yield-stress/low-viscosity slurries as the mixing geometry must be able to promote continuous movement of the entire slurry without formation of a slip layer that would lead to sample fracture ( Stickel et al, 2009 ). In previous in-rheometer liquefaction studies ( Szijártó et al, 2011a , b ; Skovgaard et al, 2014 ; Le et al, 2017 ) relatively low solids loadings/low-viscosity slurries were therefore used, despite the fact that other studies have demonstrated that enzymatic hydrolysis kinetics differ substantially between low- and high-solids rheological regimes ( Knutsen and Liberatore, 2009 ; Modenbach and Nokes, 2013 ; Nguyen et al, 2015 ). Thus, we also examined whether the enzymatic liquefaction observed at low solids loadings, as measured via in-rheometer real-time monitoring in a semi-dilute regime, was representative of enzyme-mediated liquefaction in a concentrated (high solids loading) regime, where the slurry behaves as a structured fluid or soft solid.…”