Wheat Pulp Research Articles

Ultra-high performance liquid chromatography coupled to ion mobility quadrupole time-of-flight mass spectrometry for the identification of non-volatile compounds migrating from ‘natural’ dishes

Although most new biomaterials for food industry applications are labelled ‘100% natural fabrication’ and ‘chemical-free’, certain compounds may migrate from those materials to the food, compromising the organoleptic characteristics and safety of the product. In this work, the degree of compound migration from dishes made with four different biomaterials: bamboo, palm leaf, wood and wheat pulp was investigated. Migration tests were carried out using three food simulants, 10% ethanol (simulant A), 3% acetic acid (simulant B), and 95% ethanol (simulant D2). Unequivocal identification of non-intentionally added substances (NIAS) is challenging even when using high-resolution mass spectrometry techniques however, a total of 25 different non-volatile compounds from the migration tests were identified and quantified using Ultra-high performance liquid chromatography coupled to ion mobility quadrupole time-of-flight mass spectrometry (UPLC-IMS-MS). In the bamboo samples three oligomers, cyclic diethylene glycol adipate, 3,6,9,16,19,22-hexaoxabicyclo[22.3.1]-octacosa-1(28),24,26-triene-2,10,15,23-tetrone and 1,4,7,14,17,20-hexaoxacyclohexacosane-8,13,21,26-tetrone exceeded the specified limits of migration.

Changes in Straw-Containing Laboratory Papers Caused by Accelerated Ageing

Natural ageing has a major influence on the properties of paper, while light, heat, and humidity are the environmental influences that most disrupt the stability of paper. This research focuses on changes in straw-containing papers caused by accelerated ageing. The papers were made in the laboratory by mixing straw pulp with the pulp of recycled fibers in different weight ratios and were artificially aged by a dry-heat treatment (thermal oxidation) and UV radiation treatment (photo-oxidation) over a 24 h period to simulate natural ageing. The observed changes in the optical, surface, and chemical stability of papers were analyzed and are discussed in this paper. It is evident that, regardless of the origin of straw for pulp production, it forms papers that undergoes similar optical properties (photo-yellowing and brightness lose), while certain differences have been observed in surface and chemical stability. Based on all analyses performed as part of this research, it was found that paper produced with the addition of wheat pulp is the most stable of all laboratory straw-containing papers. However, it must be emphasized that, if lignin-containing straw pulp is used as the main constituent of paper, the brightness stability of such pulp must be improved, or the paper surface must be improved by surface finishing in order to obtain greater stability against ageing.

Determining the optical stability of printed laboratory substrates with wheat pulp after ageing treatment

The use of recovered paper in the paper and board industry worldwide has increased in the last decade. The recycling process affects several properties of the paper, so recovered pulp needs to be enriched with a certain amount of virgin fibre to increase the strength and quality of the paper, and thus the quality of the print. Since the cellulose-based printing substrates are sensitive to photolytic damage caused by exposure to light and high temperature, the focus of the research was to evaluate the stability of digital UV inkjet prints on laboratory substrates with wheat pulp. Assessment of the optical stability of laboratory substrates and prints made on them after ageing treatment was based on the reflectance spectra measurements before and after artificial ageing. In order to observe the optical changes that occur in cellulose printing substrates, unprinted and digital printed substrates were placed in an artificial ageing equipment SunTEST XLS+ test chamber according to standard ASTM D 6789-02. The test chamber emits visible and near ultraviolet electromagnetic radiation in the range from 290 nm to 800 nm. With the deterioration of the optical stability of unprinted and digital printed substrates, it was observed through the reflectance spectra (R) and the Euclidean colour difference (ΔE00*) that the highest colour degradation of all analyzed samples, occurs in the first 48 hours of artificial ageing. The results of this analysis confirm that the addition of wheat pulp in paper pulp provides better optical stability of unprinted and digital printed laboratory substrates.

Migration of volatile compounds from natural biomaterials and their safety evaluation as food contact materials

The concern for environmental conservation is increasing, and a very important factor to consider is the search for alternatives to the use of plastics in the food packaging industry. A good option is the manufacture of containers of biodegradable materials, such as the so-called biomaterials made of vegetable fibre such as wheat, wood, bamboo or palm leaf pulp. The migration of compounds from food packaging can cause alterations in food safety and acceptability. Therefore, their control through studies of specific migration is definitely important in the food industry. Specific migration has been studied in two types of dishes (wheat pulp and wood) in contact with three liquid simulants (ethanol 10%, acetic acid 3% and ethanol 95%). The analysis of migration extracts have been carried out by solid-phase microextraction coupled to gas chromatography (SPME-GC-MS) in the most suitable working conditions. In addition, those identified compounds considered of interest according to existing legislation have been quantified in order to assess whether exceed or not the migration limits established for some of them. The results obtained show that the quantified compounds are well below the specific migration limits (SML) set by the legislation, thereby showing the safety in use of this type of biodegradable dishes.

Isolation and characterization of lignocellulose nanofibers from different wheat straw pulps

Wheat straw was cooked under different pulping processes: Soda (100°C, 7% NaOH, 150min), Kraft (170°C, 16% alkalinity, 25% sulfidity, 40min) and Organosolv (210°C, 60% ethanol, 60min). Once the pulps were obtained, lignocellulose nanofibers (LCNF) were isolated by mechanical process and TEMPO-mediated oxidation followed by a high pressure homogenization. After pulping process, the different pulps were characterized and its chemical composition was determined. The pulps characterization indicates that the Soda process is the process that, despite producing less delignification, retains much of the hemicelluloses in the pulp, being this content a key factor in the nanofibrillation process. Regarding the LCNF obtained by mechanical process, those nanofibers isolated from Organosolv wheat pulp (OWP) and Kraft wheat pulp (KWP) show low values for nanofibrillation yield, specific surface area and greater diameter. However, those nanofibers isolated from Soda wheat pulp (SWP) reach much higher values for these parameters and presents a diameter of 14nm, smaller than those obtained by TEMPO-mediated oxidation from OWP. Smaller diameters are generally obtained in TEMPO-oxidized LCNF. This work concludes that the lignin content does not affect greatly to obtain LCNF as does the hemicellulose content, so it is accurate to use a soft pulping process.

Lead adsorption with sulfonated wheat pulp nanocelluloses

Low-cost sorbents derived from abundant natural resources, industrial by-products, or waste materials are considered amongst the most viable novel materials for heavy metal removal. In this study, wheat straw pulp fine cellulosics were used as a biosorbent for the removal of Pb(II) in aqueous solutions after nanofibrillation and sulfonation pretreatments. The effect of the initial lead concentration, sorption time, and solution pH were studied, and the isothermal data were modeled with the Langmuir and Freundlich isotherm models. Pb(II) was adsorbed efficiently (1.2mmol/g) from the model solution by sulfonated nanocelluloses which had a width between 5 and 50nm and a sulfonic acid content of 0.45mmolg−1. This adsorption capacity is comparable to those of commercial adsorbents. The Pb(II) adsorption onto nanofibrillated and sulfonated cellulosics followed the Langmuir isotherm model and showed rapid initial kinetics. Thus, nanofibrillated and sulfonated cellulosics are promising green alternatives for the recovery of metals from aqueous solutions.

Thermo-alkali-stable xylanase of a novel polyextremophilic Bacillus halodurans TSEV1 and its application in biobleaching

The production of thermo-alkali-stable and cellulase-free xylanase of polyextremophilic novel Bacillus halodurans TSEV1 (MTCC 10962) was optimized in batch fermentation using statistical approaches. Plackett–Burman (PB) design identified temperature, inoculum size, KH2PO4 and wheat bran (WB) as the significant variables that affect xylanase production, and therefore, these variables have been optimized by Central composite design (CCD) matrix of response surface methodology (RSM). A 7.35-fold enhancement in xylanase production was attained due to optimization. The UV absorption spectrum of the compounds released by the enzyme action on unbleached pulp showed a characteristic peak at 280 nm indicating the presence of lignin related compounds in the filtrate. The materials released after biobleaching also displayed strong absorption at 237 and 465 nm. The enzyme dose 40 Ug−1, pH 10.0, and treatment time of 3 h are optimal for enzymatic pre-bleaching of wheat pulp that caused 14.6% reduction in kappa number and 5.6% enhancement in brightness of hand sheets without noticeable change in viscosity. This is the first report on xylanase production by a wild type polyextremophilic B. halodurans in submerged fermentation and its application in pre-bleaching of paper pulps.

Hydrolysis of organosolv wheat pulp in formic acid at high temperature for glucose production

Organosolv methods can be used to delignify lignocellulosic crop residues for pulp production or to pretreat them prior to enzymatic hydrolysis for bioethanol production. In this study, organic solvent was used as an acidic hydrolysis catalyst to produce glucose. Hydrolysis experiments were carried out in 5–20% formic acid at 180–220°C. Wheat straw pulp delignified with a formicodeli™ method was used as a raw material. It was found that glucose yields from pulp are significantly higher than yields from microcrystalline cellulose, a model component for cellulose hydrolysis. The results indicate that cellulose hydrolysis of real fibers takes place more selectively to glucose than hydrolysis of microcrystalline cellulose particles does. The effect of the particle size on pulp hydrolysis was investigated, the crystallinity of hydrolyzed pulp was measured by XRD analysis, and the product distribution and its influence on the process was discussed.