Kelly A. Ross

Isolation and characterization of lignins extracted from flax shives using pressurized aqueous ethanol.

High-molecular weight lignins (HML) and low-molecular weight lignins (LML) were extracted from flax shives using pressurized 30% aqueous ethanol, and isolated by precipitation and ultrafiltration. The isolated lignin samples and two commercial lignins were assayed for monolignol content and functional groups, solubility assays, thermal analysis using differential scanning calorimetry (DSC), size exclusion chromatography (SEC), and Fourier transform infrared spectroscopy (FT-IR). The highest yield of HML was 13.5 g/100 g of flax shives, and this was about six times higher than the LML yield. SEC of lignin samples revealed that the molecular weights of HML and LML are about 30,000 and 8749 Da, respectively. The DSC results of HML show that this lignin has a glass transition temperature near 160 degrees C. HML contains fewer carboxyl groups and more phenolic hydroxyl groups than LML. The higher molecular weight and higher thermal stability of HML makes it an excellent candidate for industrial applications.

Characteristics of Lignin from Flax Shives as Affected by Extraction Conditions

Lignin, a polyphenolic molecule, is a major constituent of flax shives. This polyphenolic molecular structure renders lignin a potential source of a variety of commercially viable products such as fine chemicals. This work compares the performance of different lignin isolation methods. Lignin from flax shive was isolated using both conventional alkaline extraction method and a novel experimental pressurized low polarity water (PLPW) extraction process. The lignin yields and chemical composition of the lignin fractions were determined. The conventional alkali treatment with 1.25 M NaOH, heated at 80 °C for 5 h, extracted 92 g lignin per kg flax shives, while lignin yields from the PLPW extracts ranged from 27 to 241 g lignin per kg flax shives. The purity and monomeric composition of the lignins obtained from the different extraction conditions was assessed via UV spectroscopy and alkaline nitrobenzene oxidation. Lignin obtained from conventional alkali treatment with 1.25 M NaOH, heated at 80 °C for 5 h was of low purity and exhibited the lowest yields of nitrobenzene oxidation products. With respect to alkali assisted PLPW extractions, temperature created an opposing effect on lignin yield and nitrobenzene oxidation products. More lignin was extracted as temperature increased, yet the yield of nitrobenzene oxidation products decreased. The low yield of nitrobenzene oxidation products may be attributed to either the formation of condensed structures or the selective dissolution of condensed structures of lignin during the pressurized alkaline high temperature treatment. Analytical pyrolysis, using pyroprobe GC-MS, was used to investigate the molecular composition of the lignin samples. The total yield of pyrolysis lignin products was 13.3, 64.7, and 30.5% for the 1.25 M NaOH extracted lignin, alkaline assisted PLPW extracted lignin, and the unprocessed flax shives, respectively. Key lignin derived compounds such as guaiacol, 4-vinyl guaiacol, 4-methyl guaiacol, syringol, eugenol, isoeugenol, catechol, homocatechol, and vanillin were detected in all of the samples.

Thermogenesis-triggered seed dispersal in dwarf mistletoe

Lodgepole pine dwarf mistletoe (DM), Arceuthobium americanum, is a parasitic flowering plant and forest pathogen in North America. Seed dispersal in DM occurs by explosive discharge. Notably, slight warming of ripe DM fruit in the laboratory can trigger explosions. Previously, we showed that alternative oxidase, a protein involved in endogenous heat production (thermogenesis) in plants, is present in DM fruit. These observations have led us to investigate if thermogenesis induces discharge. Here, infrared thermographs reveal that ripe DM fruits display an anomalous increase in surface temperature by an average of 2.1±0.8 °C over an average time of 103±29 s (n=9, 95% confidence interval) before dehiscence. Furthermore, both non-isothermal and isothermal modulated differential scanning calorimetry consistently show an exothermic event (~1 J g−1) in the non-reversible heat flow just prior to discharge. These results support thermogenesis-triggered seed discharge, never before observed in any plant.

Characterization of Water Extractable Crude Polysaccharides from Cherry, Raspberry, and Ginseng Berry Fruits: Chemical Composition and Bioactivity

Water extractable crude polysaccharides from three sweet cherry varieties, raspberries, and ginseng berry pulp were evaluated for their chemical composition, structural features, molecular weight, and bioactive properties. The yields of the crude polysaccharides isolated from cherries, raspberries, and ginseng berry pulp ranged from 0.79 to 0.18% on a dry weight fruit basis. All of the crude polysaccharides contained protein, phenolic compounds, and uronic acid. Each crude polysaccharide contained the sugar monomers: rhamnose, arabinose, xylose, mannose, galactose, and glucose. Of the water extractable polysaccharides obtained from the mature fruits, the crude polysaccharides from the raspberries had the highest molecular weight while the crude polysaccharides from the ginseng berry pulp had the smallest molecular weight. Results from Fourier transform infrared spectroscopy suggested that the crude polysaccharides contained a monosaccharide with six carbon atoms in a D-glucopyranose ring and a protein component. The crude polysaccharides from cherries, raspberries, and ginseng berry pulp were shown to possess antioxidant activity as determined with the ferric reducing antioxidant power and the 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. The effect of crude polysaccharides on: (1) caspase 3 activation, which was determined using a hypoxia/reoxygenation model, and (2) immunostimulation, which was determined by evaluating the inflammatory mediator response, were examined. Only crude polysaccharides obtained from certain varieties of sweet cherries inhibited caspase 3 activation in a dose-dependent manner, while only the crude polysaccharides obtained from ginseng berry pulp stimulated immune function. Crude polysaccharides present in small fruits do possess bioactivities that may enhance human health.

Characterization of Pilot Scale Processed Canadian Organic Cranberry (Vaccinium macrocarpon) and Blueberry (Vaccinium angustifolium) Juice Pressing Residues and Phenolic-Enriched Extractives

ABSTRACT This work examined the processing yields, physico-chemical characteristics, and bioactive properties of Canadian organic cranberry and blueberry pomace and phenolic-enriched extractives. The ethanol extracts from each berry contained three to four times the soluble solids and sugar contents compared to the pomace. The lipid content of organic cranberry pomace (4.44%), cranberry ethanol extractives (3.86%), and blueberry ethanol extractives (4.44%) were significantly lower than the lipid content of the organic blueberry pomace (5.42%). The organic blueberry pomace showed higher protein content (8.41%) than organic cranberry pomace (5.76%); however, both organic cranberry and blueberry ethanol extracts showed similarly low protein contents. Significant differences were observed in the mineral and elemental contents of both pomaces and their extractives. Total phenolics, tartaric esters, flavonols, anthocyanins, and antioxidant activities were increased by two to three times in both organic cranberry and blueberry ethanol extracts compared to their respective pomaces. The major anthocyanins detected in organic blueberry pomace and ethanol extracts were peonidin 3-glucoside, malvidin 3-galactoside, malvidin 3-glucoside, and cyanidin 3-arabinoside. Peonidin 3-galactoside, cyanidin 3-galactoside, cyanidin 3-arabinoside, and peonidin 3-arabinside were the major anthocyanins in the organic cranberry and ethanol extacts. Results indicated that cranberry and blueberry pomace could be used to develop bioactives with antioxidant activity for potential health benefit and/or bioenergy production.

Influence of variety, storage, and simulated gastrointestinal digestion on chemical composition and bioactivity of polysaccharides from sweet cherry and apple tree fruits

Abstract This work examined the effect of extraction regime (hot water vs. simulated in vitro gastrointestinal digestion) and postharvest storage on the chemical composition, molecular weight, and bioactive properties of polysaccharides obtained from sweet cherries (Lapins and Staccato varieties) and apples (Gala and Fuji varieties). The yields of the polysaccharides isolated from cherries and apples ranged from 0.2 to 2.4% on a dry weight fruit basis. All of the isolated polysaccharides contained protein, phenolic compounds, and uronic acid. All polysaccharides contained the sugar monomers: rhamnose, arabinose, xylose, mannose, galactose, and glucose. Also, all of the polysaccharides obtained using the different extraction regimes were shown to possess antioxidant activity as determined with the ferric reducing antioxidant power and the 2,2-azinobis (3-ethyl-benzothiazoline-6-sulfonic acid) (ABTS) radical scavenging assays. Only the polysaccharides isolated from the cherry and apples after simulated in vitro gastrointestinal digestion showed appreciable α-glucosidase inhibition activity, with polysaccharides obtained from Staccato cherries showing nearly 90% of the inhibition of α-glucosidase as achieved with the positive control acarbose. This work shows that bioactive polysaccharides are available and/or can be isolated during digestion which supports the concept that fruit polysaccharides play a role in enhancing human health.

The chemical composition, antioxidant activity and α-glucosidase inhibitory activity of water-extractable polysaccharide conjugates from northern Manitoba lingonberry

Abstract Lingonberry (Vaccinium vitis-idaea L.) is a small northern fruit that has been harvested historically by native North Americans and Northern Europeans. These berries have been traditionally consumed as food and for medicinal use. Lingonberries are reported to be rich in vitamin C, benzoic acid, and anthocyanins, which have been implicated in health benefits associated with the consumption of lingonberries. We hypothesized that water-extractable polysaccharides, conjugated with proteins and/or phenolics may also serve as bioactive compounds with potential health benefits in northern Manitoba lingonberries. A hot water extraction was used to obtain water-extractable polysaccharides from lingonberries and the water-extractable polysaccharides were fractionated into water-eluted/neutral and NaCl-eluted/acidic fractions using chromatography. The water-extractable polysaccharides were evaluated for their chemical composition and structural features. The antioxidant activity (FRAP and ABTS assays) and potential of the polysaccharides to serve as α-glucosidase inhibitors were determined. The chemical composition and structural features of the water-extractable polysaccharides were influenced by fraction. The water-extractable polysaccharides and fractions all possessed antioxidant activity, while only the water-extractable polysaccharide conjugates and NaCl-eluted/acidic fraction demonstrated appreciable α-glucosidase inhibition. This work provides novel information indicating that water-extractable polysaccharide conjugates isolated from northern Manitoba lingonberry demonstrate bioactivity.

Author Correction: Thermogenesis-triggered seed dispersal in dwarf mistletoe

This corrects the article DOI: 10.1038/ncomms7262.