Oat Husk Research Articles

Xylitol production by Barnettozyma populi Y-12728 with different immobilization strategies

One of the new xylitol producer microorganisms is Barnettozyma populi Y-12728 and it has great potential for the industry with its pure xylitol production capability. Different immobilization strategies, the usability of baffled or normal flasks with different agitation speeds, and various lignocellulosic hydrolysates were studied in this research. The highest xylitol production and yield values were 11.99 g xylitol/L and 40.28 % for the C1 trial at 70 ml medium with a suspended cell. For the immobilization strategy, 1 % polyethyleneimine concentration, 1.5 mm surface lattice thicknesses, and 8 3D cubes were determined to be the optimum conditions with 17.84 g/L xylitol production and 0.473 g xylitol/g xylose yield values in a 70 ml volume medium at 200 rpm, 30 °C, and 6.0 initial pH for 3 days. Rice husk, wheat bran, and oat husk hydrolysates were also used as a substrate for xylitol fermentation. The highest xylitol production was 2.26 g/L for lignocellulosic hydrolysates. In this research, FDM (Fused Deposition Modelling) based 3D printed cubes are used for the immobilization agent of Barnettozyma populi NRRL Y-12728 for the first time. The results revealed that FDM-based 3D-printed cubes could be used to immobilize cells and improve productivity for xylitol production.

Cryptococcus laurentii: a wild yeast for xylanase production from agricultural by-products.

The development of technologies that allow the production of enzymes at a competitive cost is of great importance for several biotechnological applications, and the use of agro-industrial by-products is an excellent alternative to minimize costs and reduce environmental impacts. This study aimed to produce endo-xylanases using agro-industrial substrates rich in hemicellulose as sources of xylan in culture media. For this purpose, the yeast Cryptococcus laurentti and five lignocellulosic materials (defatted rice bran, rice husk, corn cob, oat husks, and soybean tegument), with and without pretreatment, were used as a source of xylan for enzyme production. To insert the by-products in the culture medium, they were dried and treated (if applicable) with 4% (w.v-1) NaOH and then added in a concentration of 2% (w.v-1). The cultures were agitated for 96h, and the aliquots were removed to determine the enzymatic activities. Among the by-products studied, the maximum activity (8.7 U. mL-1 at pH 7.3) was obtained where rice bran was used. In contrast, corn cob was the by-product that resulted in lower enzyme production (1.6 U.mL-1). Thus, the defatted rice bran deserves special attention in front of the other by-products used since it provides the necessary substrate for producing endo-xylanases by yeast.

Construction Composites Based on Secondary Thermoplastics and Manufacturing Waste

Abstract The paper presents current trends in the development of environmentally friendly building composite materials. The choice of thermoplastic polymer binder and natural plant-based fillers is substantiated. Highly filled composites based on secondary polypropylene and natural plant fillers have been developed: wood flour; coniferous flour; buckwheat husks; oat husks. Their main physical and mechanical properties, such as impact strength and flexural strength, have been studied. Experimental research has revealed that, in addition to traditional fillers like wood flour and coniferous flour, it is more relevant to use by-products of agro-industrial complexes in the form of buckwheat husks and oat husks. These technological waste products of agro-industrial complexes are quite widespread in Ukraine and are widely available in almost all regions of the country. However, their disposal is usually challenging. For the first time, the influence of the fractional composition of plant fillers in polymeric composites based on secondary polypropylene on the main physical and mechanical properties has been studied. It has been clarified that the developed composites with polyfractional compositions of plant fillers exhibit higher indicators. The high performance of the composites is achieved due to the maximum packing density of natural fillers in the polymer matrix.

Addition of micronized oat husk fiber to gluten-free bread - Effects on chemical, physical and physiolgical properties

Gluten-free (GF) breads available on the market are still mainly produced from refined flours or starch, thus they lack nutritional quality, like dietary fiber, minerals and vitamins. Incorporation of micronized oat husk (MOH) could improve these properties. MOH is a dietary fiber and a food by-product, rich in polyphenols exhibiting antioxidant properties. This study investigated the addition of 0–20% MOH (in 5% steps) to GF breads baked conventionally (deck oven) and by ohmic heating (OH). Incorporation of ≤20% MOH had only a slight effect on the bread texture properties (specific volume, pore properties, crumb firmness and relative elasticity), and was less pronounced for OH baked breads. Both, the crumb and crust color, darkened proportionally to the added amount of MOH. Total phenolic content (TPC) and antioxidative properties were significantly increased by MOH addition, as well as the ability to protect lipids from oxidation. In vitro starch digestibility was improved with MOH addition for OH-baked breads. GF breads containing ≥15% MOH can be claimed as “source of fiber”, ≥20% MOH as “high in fiber”. Overall, this study demonstrated that micronized oat husks have a good potential to enhance the quality of GF breads.

Catalyst-recirculating system in steam explosion pretreatment for producing high-yield of xylooligosaccharides from oat husk

We propose a closed-loop pretreatment process, wherein volatiles produced during steam explosion pretreatment were recovered and reintroduced as acid catalysts into the pretreatment system. The volatiles were separated through a drastic decompression process followed by a steam explosion process and recovered as a liquified catalyst (LFC) through a heat exchanger. The LFC effectively served as an acid catalyst for hemicellulose hydrolysis, significantly decreasing residence time from 90 min to 30 min to achieve 80 % conversion yield at 170 °C. Hydrolysates with high content of lower molecular weight oligomeric sugars were obtained using LFC, and were considered advantageous for application as prebiotics. These results are attributed to the complementary features of acetic acid and furfural contained within the LFC. Computational simulation using Aspen Plus was used to investigate the effects of recycling on LFC, and it demonstrated the feasibility of the catalyst-recirculating system. A validation study was conducted based on simulation results to predict the actual performance of the proposed pretreatment system. Based on these results, the recirculating system was predicted to improve the conversion yield and low-molecular weight oligomers yield by 1.5-fold and 1.6-fold, respectively.

Exploring Oat Husks as Aggregates in Limestone-Based Composites: Effects of Surface Treatments and Binder Selection on Mechanical Performance.

The viability of incorporating agricultural by-products, such as oat husks, not yet explored in limestone-based composites, as more sustainable alternatives for use as novel aggregates may be improved through the adoption of well-known valorisation strategies applied to other plant-based resources. In this context, this work innovates by assessing how treatments on oat husk surfaces and the choice of limestone-based binders impact the mechanical performance of composites. The strategy adopted to achieve these objectives, in addition to carrying out the physical and geometric characterisation of the husks, consists of treating the husks' surface using washing cycles in water, cement/pozzolan binder, and linseed oil. Furthermore, matrices combining cement, calcium hydroxide Ca(OH)2, and microsilica (SiO2) were used. In conclusion, even though the effects of different binder combinations are inconsistent, coating oat husks-especially with linseed oil-works well in delaying particle degradation and improving mechanical strength compared to untreated particles. Furthermore, when aggregates are substituted with the longer and lamellar particles of oat husk, the impact of the water/cement ratio on mechanical performance and composite workability significantly decreases.

Insights into hydrothermal treatment of biomass blends: Assessing energy yield and ash content for biofuel enhancement.

This study explores the Hydrothermal Carbonization (HTC) treatment of lignocellulosic biomass blends, delving into the influence of several key parameters: temperature, additive nature and dosage, residence time, and biomass composition. Rapeseeds, Pinus radiata sawdust, oat husks, and pressed olive served as the studied biomasses. One hundred twenty-eight experiments were conducted to assess the effects on mass yield (MY), energy yield (EY), higher heating value (HHV), and final ash content (ASH) by a Factorial Experimental Design. The derived model equations demonstrated a robust fit to the experimental data, averaging an R2 exceeding 0.94, affirming their predictive accuracy. The observed energy yield ranged between 65% and 80%, notably with sawdust and olive blends securing EY levels surpassing 70%, while rapeseed blends exhibited the highest HHV at 25 MJ/kg. Temperature emerged as the most influential factor, resulting in an 11% decrease in MY and a substantial 2.20 MJ/kg increase in HHV. Contrastingly, blend composition and additive presence significantly impacted ASH and EY, with all blends exhibiting increased ASH in the presence of additives. Higher initial hemicellulose and aqueous extractive content in raw biomass correlated proportionally with heightened HHV.

Catalyzed Hydrothermal Pretreatment of Oat Husks for Integrated Production of Furfural and Lignocellulosic Residue.

This study presents a novel approach for biorefining oat husks into furfural, leveraging a unique pilot-scale setup. Unlike conventional furfural manufacturing processes, which often result in substantial cellulose degradation and environmental concerns associated with sulfuric acid usage, our method utilizes phosphoric acid as a catalyst to achieve high furfural yield while minimizing cellulose destruction. Drawing on our research conducted in a distinctive pilot-scale environment, we successfully developed and implemented a tailored biorefining process for oat husks. Through meticulous experimentation, we attained a remarkable furfural yield of 11.84% from oven-dried mass, accompanied by a 2.64% yield of acetic acid. Importantly, our approach significantly mitigated cellulose degradation, preserving 88.31% of the cellulose content in oat husks. Existing catalytic (H2SO4) furfural manufacturing processes often lead to substantial cellulose degradation (40-50%) in lignocellulosic leftover during the pretreatment stage. As a result of the research, it was also possible to reduce the destruction of cellulose in the lignocellulose leftover to 11.69% of the output (initial) cellulose of oat husks. This research underscores the feasibility and sustainability of utilizing oat husks as a valuable feedstock for furfural production, highlighting the potential of phosphoric acid as a catalyst in biorefining processes. By showcasing our unique pilot-scale methodology, this study contributes to advancing the field of environmentally friendly biorefining technologies.

Impact of Oat Husk Extracts on Mid-Stage Cement Hydration and the Mechanical Strength of Mortar

The valorisation of lignocellulosic resources, such as oat husks, as components in cementitious composites presents challenges regarding their compatibility with the matrix due to the solubilisation of their surface components and products from alterations induced by the alkaline environment of lime-based matrices. These negatively affect the matrix. This study aims to fill the knowledge gap regarding the compatibility and effects of the extractives found in oat husks with the cement matrix. It intends to characterise oat husks’ structural composition, evaluate the extractive removal efficiency, assess their influence on cement matrix hydration using thermogravimetric techniques, and analyse mechanical strength development between 3 and 28 days. The study concludes that hot water is more efficient for extractive removal, and the immersion duration is more relevant than the number of washing cycles. Furthermore, it confirms that husks’ extractives inhibit cement matrix hydration products and mechanical strength development, especially in the presence of degradation products. These findings are essential for determining more efficient approaches to enhance compatibility between oat husks and cementitious matrices.

Common Wheat Pasta Enriched with Ultrafine Ground Oat Husk: Physicochemical and Sensory Properties.

Oat husk (hull) is a byproduct of oat processing that is rich in insoluble fiber. The aim of the study was to evaluate the effect of partially replacing wheat flour with oat husk (at levels of 0, 5, 10, 15, and 20 g/100 g) on the physicochemical properties and sensory acceptance of pasta. Additionally, UPLC-MS/MS analysis was performed to identify phenolic acids and flavonoid compounds, and the cooking properties of the pasta were evaluated. The test results indicate that oat husk significantly (p < 0.05) increased the ash and fiber contents in the pasta, while decreasing the protein and fat contents. Moreover, the redness and yellowness of both raw and cooked pasta increased, while lightness decreased as a result of pasta enrichment with oat husk. Oat husk also led to a decrease in the stretching force of cooked samples, although cooking loss increased significantly but did not exceed 8%. The contents of phenolics and antioxidant activity significantly increased with the incorporation of hull in pasta recipes. UPLC-MS/MS analysis showed that the enriched pasta was especially abundant in ferulic acid. Products with up to 10 g of husk/100 g of wheat flour showed good consumer acceptance. However, higher levels of this additive led to notably lower assessments, particularly in terms of pasta texture.

Macromolecular Hydrodynamics and Fractal Structures of the Lignins of Fir Wood and Oat Husks.

The topological structure of the macromolecules of lignins isolated from oat husk and fir wood was studied by means of macromolecular hydrodynamic methods. The macromolecular properties were analyzed by evaluating the intrinsic viscosity and coefficients of the translational diffusion and the sedimentation velocity of the lignins in dilute dimethylformamide solutions. The average molecular weights (MDη) and polydispersity parameters were calculated based on the results of the fractionation, as follows: Mw = 14.6 × 103, Mn = 9.0, and Mw/Mn = 1.62 for lignins from fir wood and Mw = 14.9 Mn = 13.5 and Mw/Mn = 1.1 for lignins from oat husks. The fractal analysis of the lignin macromolecules allowed us to identify the distinctive characteristics of the fractal and topological structures of these lignins. The measurements indicated that the fractal dimension (df) values of the guaiacyl-syringyl lignins from oat husks were between 1.71 and 1.85, while the df of a typical guaiacyl lignin from fir wood was ~2.3. Thus, we determined that the lignin macromolecules of oat husks belong to the diffusion-limited aggregation-type cluster-cluster class of fractals of the Meakin-Kolb type, with a predominance of characteristics common to a linear configuration. The lignins of softwood fir trees exhibited a branched topological structure, and they belong to the diffusion-limited aggregation-type particle-cluster class of fractals of the Witten-Sander type. Lignins from oat husks have the linear topology of macromolecules while the macromolecules of the lignins from fir wood can be characterized as highly branched polymers.

Chemical composition, particle geometry, and micro-mechanical strength of barley husks, oat husks, and wheat bran as alternative raw materials for particleboards

Particleboards are used worldwide in various industry segments, like construction and furniture production. Nevertheless, increase in wood prices and logistical challenges urge the particleboard industry to find alternative raw materials. By-products and residues from the agricultural and food industries could offer possibilities for material sourcing at a local level. This study aimed to investigate the chemical composition, particle geometry, anatomical structure, and microtensile characteristics of such material, specifically barley husks (BH), oat husks (OH), and wheat bran (WB). BH and OH were found to have comparable hemicelluloses and lignin contents to industrial wood chips but contained more ash. WB was rich in extractives and showed high buffering capacity. Light microscopy and microcomputed tomography revealed details of leaf structure for BH and OH as well as the multi-layer structure of WB. The ultimate microtensile strength of BH, various OH samples, and WB were respectively 2.77 GPa, 0.84–2.42 GPa, and 1.45 GPa. The results indicated that the studied materials could have potential uses as furnish materials in non-load bearing particleboards, where thermal or acoustic insulation properties are desirable.

Selection of herbaceous cellulose-containing raw materials for biotechnological processing

The use of cellulose-containing plant materials for obtaining bioproducts comprises a relevant research direction in the field of sustainable economic development. Herbaceous cellulose-containing raw materials are among the most widespread and easily renewable resources. In this study, we set out to identify herbaceous cellulose-containing raw materials suitable for biotechnological processing among the following plants: cane, miscanthus (Soranovsky variety), water hyacinth, iceberg lettuce, Sudan grass, oat husk, flax straw (Linum usitatissimum L.). Preliminary chemical treatment of raw materials was carried out by the conventional method of alkaline delignification at atmospheric pressure. The obtained substrates were converted into a solution of reducing sugars by enzymatic hydrolysis. The method of alkaline delignification of initial raw materials was found to be suitable for obtaining products with the cellulose mass content of 82.9–93.1% by the Kurschner method. This conversion rate can be considered a good indicator for further enzymatic hydrolysis. According to the results of enzymatichydrolysis of alkaline delignification products, the highest reactivity to enzymatic hydrolysis was demonstrated by the alkaline delignification products of miscanthus (Soranovsky variety), iceberg lettuce and oat husk. For these plants, the concentration of reducing substances reached 25.0, 28.4 and 26.9 g/l, under the yield of reducing substances from the substrate mass of 75.0, 85.2 and 80.7%, respectively. Therefore, the high reactivity of these plant materials makes them prospective candidates for further biotechnological processing. Other investigated plant materials require optimization of the alkaline delignification stage to increase their reactivity to enzymatic hydrolysis.

Experimental evaluation of black liquor carbonation for carbon dioxide capture

Carbon dioxide is one of the main if not the most potent greenhouse gases responsible for climate change. Scientists put great efforts to tackle this problem and carbon dioxide capture seems to be a promising solution. The present study proposes a novel method of carbon dioxide capture using black liquor, a side stream from the paper and pulp industry. Its content in sodium hydroxide makes it an attractive candidate for carbon dioxide capture via carbonation. The black liquor was prepared from oat husks, a non-woody biomass, using the soda-pulping process. To estimate its carbon dioxide absorption capacity, a mixture of nitrogen and carbon dioxide (70:30%) was sparged into a bubble column reactor and computational fluid dynamics simulations of this setup were used to evaluate the mixing process. The formation of carbonate and bicarbonate ions throughout the carbonation process was followed using a Fourier-Transform Infrared (FTIR) probe and a pH meter. The absorption capacity was measured from the weight increase of the reactor. It was found to be around 30 g of carbon dioxide/L of black liquor. The carbonate and bicarbonate species in black liquor before and after carbonation were further characterized with 13C Nuclear Magnetic Resonance (NMR), X-ray Diffraction (XRD), Scanning Electron Microscope (SEM) and optical microscopy. Using industrial side-streams might enable an economically feasible process without the need for production of virgin absorbents or their recovery. Furthermore, this capturing process, which is performed at atmospheric conditions might reduce the overall energy consumption. The results demonstrated that black liquor could be an attractive absorbent for carbon dioxide, paving the way for a circular and resource-efficient economy.

An Overview of Current and Prognostic Trends on Synthesis, Characterization, and Applications of Biobased Silica

Silica has shown numerous applications in different fields such as environmental, biomedical, agriculture, and even in chemical processing. However, due to high energy-intensive and cost-effective issues, researchers show interest to replace the conventional methods with biobased environmentally-friendly techniques for biosilica production from renewable biomass sources. Generally, silica is found to be available in amorphous and crystalline structures. For commercial purposes, silica is produced from alkyl orthosilicates ore that consists of polyethlydiorthosilicate, tetraethyl ortothosilicate, and tetramethyl orthosilicate. Another form of silica, silica gel, is produced from the selected resources of biomass, such as palm tree, wheat straw, maize leaves, teff straw, sugarcane bagasse, rice husk, rice straw, sugarcane leaf, oat husk, bamboo leaf, and corn cob. The production of biobased silica gel from agricultural residues is found to be a sustainable which receives a significant attention that can be replaced with inorganic-based silica gel for environmental concerns. Based on this context, there is a huge look for developing a process to produce biobased silica and silica gel from biomass resources with low energy utilization as promising alternatives to conventional methods. Keeping in view, current trends and methods for synthesis, the characterization of biobased silica and silica gel, as well as its wide prognostic applications were focused on a comprehensive review.

Valorization of oat husk ash in metakaolin-based geopolymer pastes

Geopolymeric binders are materials with properties equivalent to Portland cement, which may present lower CO2 emissions associated with the production cycle. To produce sustainable geopolymeric binders, it is necessary to use raw materials with a low carbon footprint and energy consumption, characteristics found in biomass ash. In this sense, this work proposes the evaluation of oat husk ash (OHA) as a partial replacement material for metakaolin in the production of geopolymer paste. OHA has replaced metakaolin at levels up to 20%. In addition to routine microstructural (XRD and FTIR) and mechanical analyses, i) the pore size distribution by nitrogen adsorption in cubic samples, and ii) an extensive rheological investigation in which it was determined the model that best fits the analyzed matrix. Furthermore, the determination of CO2-e emission embodied energy and the cost of the pastes was carried out. The results showed that the insertion of 20 wt% of OHA i) increased the dynamic yield stress (40.2%) and the equivalent viscosity (13.7%) compared to plain paste, ii) reduced the cumulative heat after 168 h by 29.7%, which is related with the lower reactivity of OHA compared to MK. Nevertheless, iii) did not cause significant chemical and mineralogical changes, (iv) maintained compressive strength statistically equal to the control mixture, and v) reduced up to 34% and 23%, respectively, the embodied energy and the cost of producing the matrices. Thus, the investigation made possible the valorization of OHA for the production of technically and economically viable and environmentally friendly geopolymer matrices.

Insoluble fibers affect digesta transit behavior in the upper gastrointestinal tract of growing pigs, regardless of particle size.

Physicochemical characteristics of dietary fibers may modulate digesta transit behavior. The present study was conducted to clarify the effect of level and particle size (PS) of insoluble fibers on digesta mean retention time (MRT) in the proximal gastrointestinal tract (mouth-ileocecal junction). Six ileal-cannulated pigs (26.8 ± 2.08 kg) were assigned to 3 dietary treatments in a 3 × 3 replicated Latin-square design. Finely ground (1 mm screen) or coarse (intact) oat husks (OH) and soybean hulls (SBH) were added (50:50, w/w) to a maize-whey protein-wheat-based diet at 50 (low) or 250 g/kg (high) inclusion levels to obtain a low-fine fiber (LF), high-fine fiber (HF), and high-coarse fiber (HC) diet. Markers to follow liquids (Co-EDTA), fine solids (Y3O2), or fibrous particles (Yb-mordanted OH and Cr-mordanted SBH) were given as a single pulse dose and marker concentrations were subsequently measured hourly in digesta for 13 h after administration. Mean retention time values were obtained from the concentration of markers in digesta observed over time by fitting a generalized Michaelis-Menten equation and calculating the time of peak. Fiber addition and fiber particle size neither affected the MRT of liquid nor solid digesta phases (P = 0.903). Segregation between solid and liquid digesta phases was observed for all diets (P < 0.0001), although the extent of segregation was greater for LF compared with HF and HC (P = 0.0220). The MRT of SBH particles, but not of OH-particles was longer for coarse vs fine PS (96 min, P < 0.05). In conclusion, digesta MRT was influenced by the dietary concentration but not by PS of insoluble fibers. The addition of insoluble fibers reduces digesta phase segregation from mouth to distal ileum in growing pigs.

Shortbread Cookies Enriched with Micronized Oat Husk: Physicochemical and Sensory Properties

Oat (Avena sativa L.) by-products are valuable sources of many bioactive compounds and minerals. This paper aimed to study the possibility of using micronized oat husk (hull) as a partial replacement for wheat flour (at levels 5, 10, 15, and 20%) in shortbread production. The physicochemical and sensory properties of control and enriched cookies were studied. The incorporation of oat husk into shortbread increased the fiber and ash content, and decreased the available carbohydrates in the cookies. The color of the enriched shortbread significantly changed and the total color difference between the control and enriched cookies ranged from 4.76 to 11.00. Moreover, the total phenolics content and antioxidant activity linearly increased with the percentage of husk in the cookie recipe. Importantly, micronized oat husk at a level of 20% had little influence on the sensory acceptability of cookies. However, replacement of wheat flour higher than 10% resulted in a harder texture of cookies and lower scores for this attribute were obtained. To summarize, in this work we showed that micronized oat husk can be a valuable additive for cookie fortification.

Characterization and investigation of the use of oat husk ash as supplementary cementitious material as partial replacement of Portland cement: Analysis of fresh and hardened properties and environmental assessment

The use of biomass has been emerging as a worldwide trend. Although biomass is a renewable energy source, the disposal of generated by-products is an issue. A material with great potential for this purpose is oat husk. Nevertheless, no study has systematically investigated the influence of burning temperature on the characteristics of oat husk ash (OHA) and the use of this by-product as a supplementary cementitious material (SCM) and its influence on the properties in the fresh and hardened state of cementitious materials. The results showed that replacing up to 20 % of Portland cement with OHA burned at a temperature of 600 °C without compromising the cement pastes 7-d and 28-d compressive strength. The environmental analysis demonstrated the potential of oat husk as biomass and ∼ 24 % reductions in the eco-efficiency index of the composite matrices with 20 wt% OHA. Thus, this work identified the technical and environmental potential for the use of OHA as SCM for the production of sustainable cement-based materials.

Comparison of Biogenic Amorphous Silicas Found in Common Horsetail and Oat Husk With Synthetic Amorphous Silicas.

The present study summarizes the current literature on the presence and the structure of biogenic amorphous silica (BAS) in nature. Based on this review, it is shown that BAS is ubiquitous in nature and exhibits a structure that cannot be differentiated from the structure of synthetic amorphous silica (SAS). The structural similarity of BAS and SAS is further supported by our investigations—in particular, specific surface area (BET) and electron microscope techniques—on oat husk and common horsetail. Many food products containing BAS are considered to be beneficial to health. In the context of the use of SAS in specific applications (e.g., food, feed, and cosmetics), this is of particular interest for discussions of the safety of these uses.