Comparative analysis of physical and functional properties of cellulose nanofibers isolated from alkaline pre-treated wheat straw in optimized hydrochloric acid and enzymatic processes.

Two methods, HCl and enzymatic treatments, were evaluated for diversification of morphological and functional properties of cellulose nanofibers (CNF) from two- stage-alkaline pre-treated wheat straw (WS). The extraction conditions were optimized by a central composite designed experimental approach varying time (4-8 h) and temperature (80-120 °C) for the HCl-based treatment and time (4-8 h), and FiberCare dosage (50-100 endo-1,4-ß-glucanase unit/g) and Viscozyme (10-20 fungal ß-glucanase units/g) for the enzyme-based treatment. The CNF yields, morphological (polydispersity index (PdI), length and diameter), and functional (crystallinity and thermal degradation) properties were compared. The CNF produced by the HCl (HCN) and enzymatically (ECN) attained diameters ~17 nm had PdI, length, and crystallinity of 0.53, 514 nm & 70%, and 0.92, 1.0 µm & 48%, respectively. Thus, the HCN morphology suits homogenous nano-applications, whereas that of the ECN, would suit heterogenous nano-applications. The HCN and ECN yields were similar (~20%) with optimal production time of 7.41 and 4.64 h, respectively. Both the HCN & ECN can be classified as thermally stable nanocolloids with maximum thermal degradation temperatures of ~380 °C and Zeta potential ~-16 mV. The two CNF production methods have potential synergetic effects on CNF production, morphological, and functional properties.

Sequential extraction of protein and inulin from the tubers of Jerusalem artichoke (Helianthus tuberosus L.).

An increase in inulin and plant-protein based nutraceutical demand ultimately puts pressure on available resources. Therefore, there is a need to prospect for supplementary feedstocks and sustainable ways to exploit them. The aim of this study was to explore the technical feasibility of sequential extraction of inulin and protein from Jerusalem artichoke tubers and understand the interrelationships between processes and product functional properties. The response surface methodology was used to determine the optimal parameters for sequential extraction. Protein functional properties analysis was done to identify the effects of the extraction process. The extraction approach adopted in this study was preceded by mechanical pressing of the tuber to yield a protein-rich juice. However, only 40.8% of the protein was recovered from the juice, therefore a subsequent solvent extraction step followed to extract the residual protein and inulin retained in the solids. Selective extraction was achieved when protein was solubilised in the first step of solvent extraction. The overall protein and inulin yields from pressing and both sequential extraction steps were 71.88 and 67.6%, respectively. The inulin yields were substantially higher than the maximum overall yields when inulin extraction, from the pressed tuber, was performed first thus improving yields from 57.3 to 67.6%. Consequently, mechanical pressing improved the overall protein yield. Sequential extraction resulted in an inulin extract with minimal protein contamination compared to the conventional method. Therefore, sequential extraction was efficient in yielding extracts with reduced impurities and good functional properties.

Performance and structural comparison of hydrogels made from wheat bran arabinoxylan using enzymatic and coacervation methods as micro-and nano- encapsulation and delivery devices.

This study evaluated the structural and performance differences between arabinoglucuronoxylan micro-hydrogels that were enzymatically produced from alkaline-extracted wheat bran arabinoglucuronoxylans using recombinant α-L-arabinofuranosidase (AbfB) that selectively removes arabinose side chains, and chemically through coacervation process, as delivery devices for bioactive substances. The encapsulations of model bioactive substance, gallic acid (GA), in the hydrogels, were done either in-situ or ex-situ to identify the most effective encapsulation and delivery method. The hydrogels particle size distribution, polydispersity index, GA encapsulation efficiency, retention and release of functional GA (based on antioxidant activity) were assessed. The hydrogels formed in both coacervation and enzymatic processes had particle size ranges of 469-678 nm, which classify them as micro-hydrogels. However, the latter were monodispersed with polydispersity index (PdI) < 0.4 compared to the former with PdI > 0.7. In addition, enzymatically produced hydrogels attained higher zeta potential (-8.8 mV) and retained and released GA with higher anti-oxidant capacity (91%) than chemically formed micro-hydrogels (zeta potential = - 3.3 mV and antioxidant capacity = 80%). However, GA encapsulation efficiencies (72% in-situ and 68% ex-situ) were higher in chemically formed micro-hydrogels than enzymatically produced micro-hydrogels (59% in-situ and 52% ex-situ). The in-situ encapsulated GA experienced less initial burst during sustained release of 8 h compared to ex-situ encapsulation. Overall, enzymatic modification process and in-situ encapsulation were the most effective methods for production of arabinoglucuronoxylan micro-hydrogels delivery devices and for encapsulation of the GA, respectively, because of maintaining functional GA upon release and having the potential to customize the structural and functional properties of the micro-hydrogels.

Effects of wheat-bran arabinoxylan as partial flour replacer on bread properties.

Effects on physical properties of white bread of adding crude (E1) and partially purified (E2) arabinoxylans (AX) from wheat bran to partially replace flour during baking, were investigated to identify optimal dosage. The E1 and E2 had molecular weights of 620,000 and 470,000Da with arabinose to xylose ratio of 0.7 and 0.6, respectively. However, ferulic acid of 1.5mg/100g, was detectable only in E1. The AXs were added to 100g white bread formulae at dosages of 0.8-1.2% with flour removal of 2-3%(w/w). The dough increased water absorption by 2% in the specified dosage range. An optimum dosage of 0.8% with 2.5% flour removal maintained similar weight, volume, height and firmness as standard white bread. At this dosage, AX addition in white bread holds both increased health and economic benefits because of combined roles as soluble dietary fibre and flour replacer.

In situ enzyme aided adsorption of soluble xylan biopolymers onto cellulosic material.

The functional properties of cellulose fibers can be modified by adsorption of xylan biopolymers. The adsorption is improved when the degree of biopolymers substitution with arabinose and 4-O-methyl-glucuronic acid (MeGlcA) side groups, is reduced. α-l-Arabinofuranosidase (AbfB) and α-d-glucuronidase (AguA) enzymes were applied for side group removal, to increase adsorption of xylan from sugarcane (Saccharum officinarum L) bagasse (BH), bamboo (Bambusa balcooa) (BM), Pinus patula (PP) and Eucalyptus grandis (EH) onto cotton lint. The AguA treatment increased the adsorption of all xylans by up to 334%, whereas, the AbfB increased the adsorption of the BM and PP by 31% and 44%, respectively. A combination of AguA and AbfB treatment increased the adsorption, but to a lesser extent than achieved with AguA treatment. This indicated that the removal of the glucuronic acid side groups provided the most significant increase in xylan adsorption to cellulose, in particular through enzymatic treatment.

The influence of sorghum grain decortication on bioethanol production and quality of the distillers' dried grains with solubles using cold and conventional warm starch processing.

Very high gravity hydrolysis-fermentation of whole and decorticated sorghum grains were compared using conventional and cold hydrolysis methods to assess the extent by which decortication could minimize enzymes dosages and affect the quality of the distillers' dried grains with solubles (DDGS). All processing configurations achieved ethanol concentrations between 126 and 132 g/L (16.0-16.7%v/v), although decortication resulted in a decreased ethanol yield. Decortication resulted in a decreased volumetric productivity during warm processing from 1.55 to 1.25 g L(-1)h(-1), whereas the required enzyme dosage for cold processing was decreased from 250 to 221 µl/100 gstarch. Cold processing decreased the average acid detergent fibre (ADF) from 35.59% to 29.32% and neutral detergent fibre (NDF) from 44.04% to 32.28% in the DDGS compared to the conventional (warm) processing. Due to lower enzyme requirements, the use of decorticated grains combined with cold processing presents a favourable process configuration and source of DDGS for non-ruminants.

Modifying solubility of polymeric xylan extracted from Eucalyptus grandis and sugarcane bagasse by suitable side chain removing enzymes.

α-l-Arabinofuranosidase (AbfB) and novel α-d-glucuronidase (Agu1B) enzymes were applied for selective hydrolysis of beechwood (Fagus sylvatica) xylan (Sigma-Aldrich) as well as xylans extracted from Eucalyptus grandis and sugarcane (Saccharum officinarum L.) bagasse, leading to precipitation of these carbohydrate biopolymers. Hemicellulose extraction was performed with two mild-alkali methods, Höije and Pinto. Precipitation occurred after removal of 67, 40 and 16% 4-O-methyl-d-glucuronic acid (MeGlcA) present in polymeric xylans from beechwood, E. grandis (Pinto) and E. grandis (Höije), respectively. Precipitation was maximized at Agu1B levels of 3.79-7.53mg/gsubstrate and hemicellulose concentrations of 4.5-5.0% (w/v). Polymeric xylan from sugarcane bagasse precipitated after removal of 48 and 22% of arabinose and MeGlcA, respectively, at optimal AbfB and Agu1B dosages of 9.0U/g and 6.4mg/g, respectively. Both the purity of polymeric xylans and structure thereof had a critical impact on the propensity for precipitation, and morphology of the resulting precipitate. Nano-to micro-meter precipitates were produced, with potential for carbohydrate nanotechnology applications.