High-purity lignin fractions and nanospheres rich in phenolic hydroxyl and carboxyl groups isolated with alkaline deep eutectic solvent from wheat straw.

A combined pretreatment based on alkaline deep eutectic solvent (DES) of K2CO3 and glycerol and sequential acid fractionation was developed to extract reactive lignin from wheat straw biomass. This process exhibited excellent purification performance in lignin isolation, and the lignin fractionated at low pH displayed high reactivity, having hydroxyl and carboxyl groups up to 9.60 and 2.52 mmol/g, respectively. Silica was selectively separated and removed during the precipitation stage, avoiding the "silica interference". Moreover, DES-lignin nanospheres created by self-assembly using lignin fractions obtained by acid precipitation possessed a high zeta potential, large particle size and high content of hydrophilic groups. Overall, the findings related to the dissociation mechanism and fractionation of reactive lignin during alkaline DES pretreatment and the acid sequence precipitation are crucial for facilitating lignin valorization in high-added value products.

Evaluation of Analysis Methods for Formaldehyde, Acetaldehyde, and Furfural from Fast Pyrolysis Bio-oil.

Fast pyrolysis bio-oil (FPBO), a second-generation liquid bioenergy carrier, is currently entering the market. FPBO is produced from biomass through the fast pyrolysis process and contains a large number of constituents, of which a significant part is still unknown. Various analytical methods have been systematically developed and validated for FPBO in the past; however, reliable methods for characterization of acetaldehyde, formaldehyde, and furfural are still lacking. In this work, different analysis methods with (HS-GC/ECD, HPLC, UV/Vis) and without derivatization (GC/MSD, HPLC) for the characterization of these components were evaluated. Five FPBO samples were used, covering a range of biomass materials (pine wood, miscanthus, and bark), storage conditions (freezer and room temperature), and after treatments (none, filtration, and vacuum evaporation). There was no difference among the methods for the acetaldehyde analysis. A significant difference among the methods for the determination of formaldehyde and furfural was observed. Thus, more data on the accuracy of the methods are required. The precision of all methods was below 10% with the exception of the HPLC analysis of acetaldehyde with an RSD of 14%. The concentration of acetaldehyde in the FPBO produced from the three different biomasses and stored in a freezer after production ranged from 0.24 to 0.60 wt %. Storage at room temperature and vacuum evaporation both decreased significantly the acetaldehyde concentration. Furfural concentrations ranged from 0.11 to 0.36 wt % for the five samples. Storage and after treatment affected the furfural concentration but to a lesser extent than for acetaldehyde. Storage at room temperature decreased formaldehyde similarly to acetaldehyde; however, after vacuum-evaporation the concentration of formaldehyde did not change. Thus, the analysis results indicated that in FPBO the equilibrium of formaldehyde and methylene glycol is almost completely on the methylene glycol side, as in aqueous solutions. All three methods employed here actually measure the sum of free formaldehyde and methylene glycol (FAMG).

Sourdough cultures as reservoirs of maltose-negative yeasts for low-alcohol beer brewing.

De novo sourdough cultures were here assessed for their potential as sources of yeast strains for low-alcohol beer brewing. NGS analysis revealed an abundance of ascomycete yeasts, with some influence of grain type on fungal community composition. Ten different ascomycete yeast species were isolated from different sourdough types (including wheat, rye, and barley) and seven of these were screened for a number of brewing-relevant phenotypes. All seven were maltose-negative and produced less than 1% (v/v) alcohol from a 12 °Plato wort in initial fermentation trials. Strains were further screened for their bioflavouring potential (production of volatile aromas and phenolic notes, reduction of wort aldehydes), stress tolerance (temperature extremes, osmotic stress and ethanol tolerance) and flocculence. Based on these criteria, two species (Kazachstania servazzii and Pichia fermentans) were selected for 10 L-scale fermentation trials and sensory analysis of beers. The latter species was considered particularly suitable for production of low-alcohol wheat beers due to its production of the spice/clove aroma 4-vinylguaiacol, while the former showed potential for lager-style beers due to its clean flavour profile and tolerance to low temperature conditions.

Comparison of Lignin Fractions Isolated from Wheat Straw Using Alkaline and Acidic Deep Eutectic Solvents.

This study aims to examine the characteristics of two solid lignin fractions isolated from wheat straw using alkaline and acidic deep eutectic solvents (DESs). The chemical properties and morphological characteristics of the two lignin fractions were evaluated by measuring their purity, elemental composition, molecular weight and particle size distributions, and microstructure. Their chemical structure was evaluated using DRIFT (diffuse reflectance infrared Fourier transform) spectroscopy, GPC (gel permeation chromatography), TGA (thermogravimetric analysis), 13C NMR (nuclear magnetic resonance), 31P NMR, and HSQC NMR. Our findings showed that the lignin isolated using alkaline DESs was less pure and had a smaller particle size, higher molecular weight, and thermal stability compared to the lignin isolated using acidic DESs. Their lignin structure was also determined to be different due to varying selective fractures on the linkages of lignin. These results suggest that the DES treatments could selectively extract lignin from wheat straw with different yields, compositions, morphologies, and structures, which could then provide a theoretical basis for the selection of DESs for specially appointed lignin extraction.

Plant cells as food - A concept taking shape.

Plant cell cultures from cloudberry, lingonberry and stoneberry were studied in terms of their nutritional properties as food. Carbohydrate, lipid and protein composition, in vitro protein digestibility and sensory properties were investigated. Dietary fibre content varied between 21.2 and 36.7%, starch content between 0.3 and 1.3% and free sugar content between 17.6 and 33.6%. Glucose and fructose were the most abundant sugars. High protein contents between 13.7 and 18.9% were recorded and all samples had a balanced amino acid profile. In vitro protein digestion assay showed hydrolysis by digestive enzymes in fresh cells but only limited hydrolysis in freeze-dried samples. The lipid analysis indicated that the berry cells were rich sources of essential, polyunsaturated fatty acids. In sensory evaluation, all fresh berry cells showed fresh odour and flavour. Fresh cell cultures displayed a rather sandy, coarse mouthfeel, whereas freeze-dried cells melted quickly in the mouth. All in all the potential of plant cells as food was confirmed.

Hydrothermal treatment followed by enzymatic hydrolysis and hydrothermal carbonization as means to valorise agro- and forest-based biomass residues.

The suitability of several abundant but underutilized agro and forest based biomass residues for hydrothermal treatment followed by enzymatic hydrolysis as well as for hydrothermal carbonization was studied. The selected approaches represent simple biotechnical and thermochemical treatment routes suitable for wet biomass. Based on the results, the hydrothermal pre-treatment followed by enzymatic hydrolysis seemed to be most suitable for processing of carbohydrate rich corn leaves, corn stover, wheat straw and willow. High content of thermally stable components (i.e. lignin) and low content of ash in the biomass were advantageous for hydrothermal carbonization of grape pomace, coffee cake, Scots pine bark and willow.

Inter-laboratory evaluation of SEC-post-column calcofluor for determination of the weight-average molar mass of cereal ß-glucan.

Even though size exclusion chromatography (SEC) with post column addition of calcofluor (SEC-calcofluor) has been used for the determination of cereal ß-glucan molar mass in foods for many years, there is a lack of systematic evaluation of the method. To address this issue a set of suitable ß-glucan standards were generated by preparative SEC and their molar mass characteristics were determined by analytical multi-detection SEC (refractive index (RI), light scattering). Each standard was then analysed by SEC-calcofluor at three different labs. As a direct comparison, the analyses were repeated with a RI detector. For SEC-calcofluor accurate measurements of weight average molar mass (Mw) can be made for ß-glucan populations within 10-500×10(3)g/mol. Above this molar mass threshold there is an increasing tendency for underestimation of Mw. Precipitation of some ß-glucan-calcofluor complexes may have delayed their transport into the detector.

Analysis of beers from an 1840s' shipwreck.

Two bottles of beer from an about 170-year-old shipwreck (M1 Fö 403.3) near the Åland Islands in the Baltic Sea were analyzed. Hop components and their degradation compounds showed that the bottles contained two different beers, one more strongly hopped than the other. The hops used contained higher levels of ß-acids than modern varieties and were added before the worts were boiled, converting α-acids to iso-α-acids and ß-acids to hulupones. High levels of organic acids, carbonyl compounds, and glucose indicated extensive bacterial and enzyme activity during aging. However, concentrations of yeast-derived flavor compounds were similar to those of modern beers, except that 3-methylbutyl acetate was unusually low in both beers and 2-phenylethanol and possibly 2-phenylethyl acetate were unusually high in one beer. Concentrations of phenolic compounds were similar to those in modern lagers and ales.

Supercritical water treatment for cello-oligosaccharide production from microcrystalline cellulose.

Microcrystalline cellulose was treated in supercritical water at 380 °C and at a pressure of 250 bar for 0.2, 0.4, and 0.6s. The yield of the ambient-water-insoluble precipitate and its average molar mass decreased with an extended treatment time. The highest yield of 42 wt% for DP2-9 cello-oligosaccharides was achieved after the 0.4s treatment. The reaction products included also 11 wt% ambient-water-insoluble precipitate with a DP(w) of 16, and 6.1 wt% monomeric sugars, and 37 wt% unidentified degradation products. Oligo- and monosaccharide-derived dehydration and retro-aldol fragmentation products were analyzed via a combination of HPAEC-PAD-MS, ESI-MS/MS, and GC-MS techniques. The total amount of degradation products increased with treatment time, and fragmented (glucosyl(n)-erythrose, glucosyl(n)-glycolaldehyde), and dehydrated (glucosyl(n)-levoglucosan) were identified as the main oligomeric degradation products from the cello-oligosaccharides.

Hydrolysis of konjac glucomannan by Trichoderma reesei mannanase and endoglucanases Cel7B and Cel5A for the production of glucomannooligosaccharides.

In this paper we describe the enzymatic hydrolysis of konjac glucomannan for the production of glucomannooligosaccharides using purified Trichoderma reesei mannanase, endoglucanases EGI (Tr Cel7b) and EGII (Tr Cel5a). Hydrolysis with each of the three enzymes produced a different pattern of oligosaccharides. Mannanase was the most selective of the three enzymes in the hydrolysis of konjac mannan and over 99% of the formed oligosaccharides had mannose as their reducing end pyranosyl unit. Tr Cel5A hydrolysate shared similarities with mannanase and Tr Cel7B hydrolysates and the enzyme had the lowest substrate specificity of the studied enzymes. The hydrolysate of Tr Cel7B contained a series of oligosaccharides with non-reducing end mannose (M) and reducing end glucose (G) (MG, MMG, MMMG, and MMMMG). These oligosaccharides were isolated from the hydrolysate by size exclusion chromatography in relatively high purity (86-95%) and total yield (23% of substrate). The isolated oligosaccharides were characterized using acid hydrolysis and HPAEC-PAD (carbohydrate composition), HPLC-RI and HPAEC-MS (to determine the DP of purified oligosaccharides), enzymatic hydrolysis (determination of non-reducing end carbohydrate) and NMR (both 1D and 2D, to verify structure and purity of purified compounds). Hydrolysis of konjac mannan with a specific enzyme, such as T. reesei Cel7B or mannanase, followed by fractionation with SEC offers the possibility to produce glucomannooligosaccharides with defined structure. The isolated oligosaccharides can be utilised as analytical standards, for determination of bioactivity of oligosaccharides with defined structure or as substrates for defining substrate specificity of novel carbohydrate hydrolyzing enzymes.