The polysaccharide composition of yellow passion fruit rind cell wall: chemical and macromolecular features of extracted pectins and hemicellulosic polysaccharides

BACKGROUND: Yellow passion fruit (Passiflora edulis var. flavicarpa Degener) is one of the main sources of juice production in tropical regions, the extraction of which generates large amounts of rind and seeds as by‐products. In a view to valorize rinds as a possible fiber source, the whole polysaccharide composition is first investigated. RESULTS: Cell wall material, from rinds, consists of ～80% (w/w) non‐starchy polysaccharides, of which 42% is cellulose, 25% pectic substances and 12% hemicelluloses. Fractional extraction of non‐starchy polysaccharides from cell wall material showed that the degree of methyl esterification, intrinsic viscosity and weight‐average molecular mass of extracted pectins range widely from 5 to 40, from 170 to 580 mL g^?1 and from 58 000 to 105 000 g mol^?1, respectively. Likewise, the intrinsic viscosity and weight‐average molecular mass of extracted hemicellulosic polysaccharides range from 40 to 55 mL g^?1 and from 21 000 to 48 000 g mol^?1, respectively. Chromatographic fractionation of hemicellulosic fractions and glycosyl linkage analysis substantiate the presence of ～90% (w/w) of xyloglucans and 10% (w/w) of glucomannans of the whole fraction. CONCLUSION: The cell wall material, obtained from yellow passion fruit rinds, contains high amounts of non‐starchy polysaccharides. Cellulose appears to be the predominant polysaccharide, thus denoting a potential insoluble fiber source. Copyright © 2008 Society of Chemical Industry     

Cell Wall Composition of Olives

Cell walls of olives (Olea europaea L.), Hojiblanca and Manzanilla, were isolated and fractionated into polysaccharides, and compositions compared. Pectic and hemicellulosic fractions were purified by ion exchange and gel filtration chromatography, and neutral sugar and uronic acid composition determined. Differences occurred between cultivars and seasons: Manzanilla had higher pectic polysaccharides and lower xylans. Hojiblanca showed similar but lesser differences. Arabinans were the main neutral pectic polysaccharides with arabinose > 80%. Homogalacturonans and rhamnogalacturonans were > 50% of the acidic pectic fractions. Degree of esterification and molecular weights were related to extracting solvent. Xyloglucans and galactoglucomannans were neutral hemicelluloses with molecular weights ? 260 kD. Glucuronoarabinoxylans had higher molecular weights (up to 400 kD). Acidic xylans were important in the pulp.     

Extraction of pectic polysaccharides from sugar‐beet cell walls

Previous methods of extracting pectin from sugar‐beet have used pulp as the starting material. As the temperature and pressure of the pulping process may modify the architecture of the cell wall, we have adapted a relatively non‐disruptive method to characterise cell wall material (CWM) isolated directly from the sugar‐beet. Cell walls from mature sugar‐beets (Beta vulgaris L Aztec) were sequentially extracted four times with imidazole and twice with sodium carbonate to produce six heterogeneous pectic polysaccharide extracts, and with KOH to produce a hemicellulosic extract which was predominantly xylans. Heterogeneity of the extracted pectins was indicated by differences in FTIR spectra, uronic acid content, % methyl esterification, % feruloylation, % acetylation, molecular weight distribution and neutral sugar composition. The highest proportion of feruloyl esters was found in polysaccharides solubilised by the second sodium carbonate extraction. Anion exchange chromatography of these polysaccharides gave three fractions, one of which contained most of the feruloyl ester. These results indicate that feruloyl esters are not randomly distributed among the different pectic polysaccharides in the sugar‐beet cell wall, and that esterification is likely to be dependent on the local sugar sequence or conformation. © 2000 Society of Chemical Industry     

Characterisation of Rosa Mosqueta seeds: cell wall polysaccharide composition and light microscopy observations

The utilisation of enzymes for the extraction of vegetable oils from seeds has been a topic of growing interest in recent years. Knowledge of the cell wall polysaccharide composition is important to select the enzyme(s) necessary for the most effective degradation of the cell walls. The purpose of the present work is to characterise the seeds of Rosa Mosqueta (Rosa aff rubiginosa) by light microscopy (where several differential staining methods were applied to analyse the seed structure) and by the isolation of cell wall polysaccharide extracts. The mature seed of Rosa Mosqueta has a very thick and structurally complex seed coat comprising heavily lignified tissue. The embryo has two cell layers of remaining endosperm tissue (indicating that this is an exalbuminous seed), two voluminous cotyledons that contain the oil, and bundles of provascular tissues distributed perpendicularly to the transverse axis of the embryo. The major non‐cellulosic polysaccharides from the non‐lignified tissues are glucuronoxylans and pectic polysaccharides; glucans are also present in small amounts. The major non‐cellulosic polysaccharides from the lignified tissues are glucuronoxylans. Concerning the use of enzymes for oil extraction, microscopy and cell wall polysaccharide analysis showed that the use of pectic enzymes followed by a xylanase or a cellulase should be explored. © 2000 Society of Chemical Industry     

Ripening‐related changes in the cell walls of olive (Olea europaea L.) pulp of two consecutive harvests

Olive fruits, harvested in two consecutive seasons at green, cherry and black stages, were used to study compositional changes in the cell walls during ripening. Ripening‐related changes in both harvests were characterised mainly by an increase in the solubilisation of pectic and hemicellulosic polysaccharides, an increase in the relative amount of arabinose in pectic polysaccharides and a decrease in the degree of methylesterification of pectic polysaccharides. Further to degrading processes, the data obtained suggest the synthesis of new polysaccharides. The analysis of olive cell wall phenolics showed mainly the presence of p‐coumaric acid, which increased in one harvest, whereas in the other the values did not differ. The samples of the second harvest, although presenting green, cherry and black colours, had less distinct ripening characteristics than those of the previous harvest. Different activity levels of polyphenol oxidase, polygalacturonase and pectin methylesterase might have contributed to the differences observed between the two harvests. The results showed the distinct extension of ripening‐related changes in the cell walls of the two harvests, indicating that the olive colour, although characteristic of the stage of ripening, cannot be strictly used for its evaluation and definition. Copyright © 2006 Society of Chemical Industry     

Developmental and ripening-related effects on the cell wall of apricot (Prunus armeniaca) fruit

Alcohol-insoluble residues (AIRs) were prepared from apricots at six stages during development/ripening on the tree. To investigate the changes in cell wall polymers, and in particular those affecting pectic polysaccharides, the AIR preparations were sequentially extracted with water, cyclohexane-trans-1,2-diamine-N,N,N′,N′-tetraacetate (CDTA) and Na₂CO₃. A significant proportion of initially Na₂CO₃-soluble pectic polysaccharides became water- and CDTA-soluble during the ripening process. In terms of composition, a significant decrease in galactose and uronic acid content was detected in all the extractions, whereas the percentage of arabinose increased in both water and CDTA-soluble polymers but decreased in the Na₂CO₃-extracted polysaccharides. The ability of pectic polysaccharides to cross-link was diminished during ripening due to an overall increase in the concentration of Na⁺ or K⁺ associated with the AIRs. This was accompanied by a decrease in the amounts of Ca²⁺ and Mg²⁺. The decrease in pectic galactans and the inhibition of pectin cross-linking detected within the pectic backbone are probably linked to the softening process observed during apricot ripening. © 1998 SCI.     

MALDI-based identification of stable hazelnut protein derived tryptic marker peptides

Food allergy is an important health problem especially in industrialised countries. Tree nuts, among which are hazelnuts (Corylus avellana), are typically causing serious and life-threatening symptoms in sensitive subjects. Hazelnut is used as a food ingredient in pastry, confectionary products, ice cream and meat products, therefore undeclared hazelnut can be often present as a cross-contaminant representing a threat for allergic consumers. Mass spectrometric techniques are used for the detection of food allergens in processed foods, but limited information regarding stable tryptic peptide markers for hazelnut is available. The aim of this study was to detect stable peptide markers from modified hazelnut protein through the Maillard reaction and oxidation in a buffered solution. Peptides ³⁹⁵Gly-Arg⁴⁰³ from Cor a 11 and ²⁰⁹Gln-Arg²¹⁷, ³⁵¹Ile-Arg³⁶³, ⁴⁶⁴Ala-Arg⁴⁷⁸ and ⁴⁰¹Val-Arg⁴¹⁷ from Cor a 9 hazelnut allergens proved to be the most stable and could be detected and confirmed with high scores in most of the modified samples. The identified peptides can be further used as analytical targets for the development of more robust quantitative methods for hazelnut detection in processed foods.     

Image Analysis Techniques for Automated Hazelnut Peeling Determination

According to FAO statistics, in 2000, Italy was the second largest hazelnut (Corylus avellana, L. 1753) producer in the world. The price of the stock depends on the nut quality (kernel/nut ratio, nut and seed defect, percentage of peeling, and taste panel scores). The evaluation of peeling efficiency after toasting is generally conducted by trained operators in sight on 100 kernels. This work tests two alternative objective methods of after toasting peeling evaluation based on image analysis. Eleven hazelnut cultivars were analyzed and results were compared with the ones assessed by trained operators. Images were analyzed with two statistical approaches: fixed values of RGB thresholding and trained K Nearest Neighbors (KNN). Root mean squared error (RMSE), estimating the comparison between operators and the two image analysis-based techniques, shows better results for KNN (6.6) with respect to fixed threshold (15.9).     

Effect of pretreatment with microwaves on mechanical extraction yield and quality of vegetable oil from Chilean hazelnuts (Gevuina avellana Mol)

The effect of microwave (MW) radiation on hazelnut seed (Gevuina avellana Mol) was studied as a substrate pretreatment prior to oil extraction by pressing. Samples were MW-treated at a frequency of 2450 MHz using a microwave oven. Six MW pretreatments were established, combining two potencies (400 W and 600 W) and three times of pretreatment (120, 180 and 240 s). Extraction oil yield increased with MW pretreatments of hazelnut seed with respect to untreated seeds, as a control. Conditions of 400 W and 240 s were selected (45.3% of extraction oil yield). Observations under light microscopy showed that the microstructure of treated samples to 400 W and 240 s, was modified comparing with that of untreated samples, thereby improving the extraction efficiency. The quality characteristics (e.g. acid value, peroxide value), oil composition (e.g. fatty acids, α-tocotrienol content) and oil oxidative stability (e.g. induction time) were measured. These results were compared to those of an untreated oil sample. MW pretreatment had a positive effect on oxidative oil stability (induction time of 23.9 h) with respect to untreated oil (8.8 h).

Industrial relevance

Chilean hazelnut (Gevuina avellana Mol) is the southernmost Macadamieae species of the family Proteaceae that grows mainly in the southern part of Chile and Argentina. The oil is composed mainly of unsaturated fatty acids, which represent 93% of the total. Its main components are oleic and palmitoleic acids, which represent 70% fatty acids. Conventional vegetable oil extraction is carried out by pressing or solvent extraction. Solvent oil extraction is the most efficient method; however, its application presents some industrial disadvantages such as plant security problems, emissions of volatile organic compounds into atmosphere, high operation costs and poor quality products caused by high processing temperatures. Mechanical pressing oil extraction is technically less extensive and less labor-intensive than the extraction solvent method . The safety and simplicity of the whole process is advantageous over the more efficient solvent extraction equipment. Furthermore, materials pressed out generally have better preserved native properties, end products are free of chemicals and it is a safer process. However, extraction by just pressing the seeds is relatively inefficient. It is advisable to research new methodologies for pretreating substrates that also allow for better retention and availability of desirable plant metabolites. Within these pretreatments, the radiation microwave is included. There is not much information in the literature about the application of microwave radiation as a pretreatment for Chilean hazelnut and its effect on the microstructure of the substrate, extraction yield and quality of oil. The aim of the present study was to investigate the impact of pretreatment by microwave radiation prior to the oil extraction by pressing on the microstructure, recovery of oils and oil quality of Chilean hazelnut seeds (G. avellana Mol).     

Cauliflower (Brassica oleracea L), globe artichoke (Cynara scolymus) and chicory witloof (Cichorium intybus) processing by-products as sources of dietary fibre

By-products arising from vegetable processing activities have been assessed in relation to their potential application as sources of dietary fibre supplements in refined foods. Sources used were fresh cauliflower, globe artichoke and chicory witloof. Non-starch polysaccharide (NSP) content and composition of selected parts of each plant source have been measured from alcohol insoluble residues (AIR) and by fibre analysis, complemented by methylation analysis to characterise structural features of component polysaccharides. Results indicate that cauliflower upper stem NSP was similar to the floret (∽25 g kg⁻¹ fresh weight) and each was rich in pectic polysaccharides. Cauliflower lower stem was enriched in NSP (∽66 g kg⁻¹) due mainly to cellulose and xylan deposition, which resulted in a proportionate decrease in pectic polysaccharides. Artichoke stem (∽38 g NSP kg⁻¹) was similar to the receptacle (∽34 g NSP kg⁻¹) but bracts were heavily lignified. Chicory root and leaf bud were each rich in pectic polysaccharides but NSP content was much higher in the root (∽46 g kg⁻¹) than the leaf (∽8 g kg⁻¹). Results indicate that processing by-products, eg cauliflower upper stem, artichoke stem and chicory root, could prove useful as sources of pectic polysaccharide-rich supplements. However, polysaccharide composition and glycosidic linkage pattern also identified important structural differences between sources. The importance of ‘fibre type’ when considering development of food supplements is discussed. © 1998 SCI.     

Effect of Cooking and Pre-Cooking on Cell-Wall Chemistry in Relation to Firmness of Carrot Tissues

The aim of this work was to investigate heat-induced changes in cell wall polysaccharides of carrot in relation to texture. Discs of fresh carrot (Daucus carota cv Amstrong) tissue were subjected to cooking (100°C, 20 min), with or without a pre-cooking treatment (50°C, 30 min). Alcohol-insoluble residues were prepared from the tissues and were extracted sequentially with water, NaCl, CDTA, Na₂CO₃ and 0·5 M KOH to leave a residue. These were analysed for their carbohydrate compositions, their degree of methyl esterification and the molecular size of selected soluble polysaccharides. Cooking caused tissues to soften. This involved cell separation, an increase in water- and salt-soluble, high-molecular-weight pectic polysaccharides and a concomitant decrease in the pectic polymers in all wall extracts and the residue. Pre-cooking prior to cooking enhanced cell–cell adhesion and reduced the extent of softening. This was accompanied by a general reduction in the degree of methylesterification of cell-wall pectic polymers, and a decrease in the cooking-induced modification to all pectic fractions. The firming effect of pre-cooking could be reversed by extracting the precooked+cooked tissue with CDTA, a chelating agent. The role of Ca²⁺ cross-linked polymers and pre-cooking in the enhancement of firmness are discussed. © 1997 SCI.     

Non-starch polysaccharides from sunflower (Helianthus annuus) meal and palm-kernel (Elaeis guineensis) meal—investigation of the structure of major polysaccharides

For the identification and characterisation of major non-starch polysaccharides from sunflower (Helianthus annuus L) meal and palm-kernel (Elaeis guineensis Jacq) meal, extracts obtained by sequential alkaline extraction and delignification of the corresponding cell wall materials were subfractionated by graded ethanol precipitation and size-exclusion and adsorption chromatography. Determination of the sugar and glycosidic linkage composition of extracts and subfractions and intact cell wall materials allowed the identification and quantification of a variety of polysaccharides. In sunflower meal, cellulose (42% of total non-starch polysaccharides), pectic polysaccharides (24%), (4-O-methyl)-glucuronoxylans with 8-11% uronic acid substitution (24%), (gluco)mannans (5%) and fucoxyloglucans (4.5%) were encountered. Major polysaccharides in palm-kernel meal were linear mannans with very low galactose substitution (78% of total non-starch polysaccharides), followed by cellulose (12%) and small amounts of (4-O-methyl)-glucuronoxylans and arabinoxylans (3% each).     

Revalorisation of vine trimming wastes using Lactobacillus acidophilus and Debaryomyces hansenii

BACKGROUND: Mild acid treatments of vine‐shoot trimmings result in the hydrolysis of hemicellulosic sugars that can be utilised by Lactobacillus acidophilus CECT‐4179 (ATCC 832) and Debaryomyces hansenii NRRL Y‐7426 as carbon sources to obtain food additives. Since the high content of glucose in these hydrolysates reduces the effective bioconversion of xylose into xylitol by D. hansenii, the use of Lactobacillus acidophilus, one of the main probiotic species, allows this problem to be solved by the selective consumption of glucose. In order to use both sugars (glucose and xylose), hemicellulosic vine‐shoot trimming hydrolysates can be sequentially fermented by both micro‐organisms. RESULTS: It was found that, in the first step, L. acidophilus generated almost exclusively lactic acid (32.7 g of lactic acid L^?1, Q_LA = 1.363 g L^?1 h^?1, Y_LA/S = 0.72 g g^?1) by homofermentative degradation of sugars (mainly glucose), and in the second step, the remaining hemicellulosic sugars were transformed primarily into xylitol by Debaryomyces hansenii (31.3 g of xylitol L^?1, Q_Xylitol = 0.708 g L^?1 h^?1, Y_Xylitol/S = 0.66 g g^?1). Furthermore, L. acidophilus proved to be a strong cell‐bounded biosurfactant producer. Cell extracts were able to reduce the surface tension (ST) of PBS in 18 mN m^?1 units. Lactobacillus acidophilus cells showed no difference in viability before or after PBS extraction of biosurfactants, achieving values of 0.9 × 10⁹ colony‐forming units (CFU) mL^?1 in both cases. CONCLUSIONS: These results have made a serious contribution to the re‐evaluation of a useless and pollutant residue, producing a wide range of natural food additives. Copyright © 2008 Society of Chemical Industry     

Differentiation of Crude Lipopolysaccharides from Escherichia coli Strains Using Fourier Transform Infrared Spectroscopy and Chemometrics

Crude phenol‐phase extracts containing bacterial lipopolysaccharides (LPS) from 5 strains of Escherichia coli were investigated to differentiate the strains using Fourier transform infrared (FTIR) spectroscopy and multivariate statistical analysis. The strains used were E. coli K12, E. coli DH5α, E. coli O157:H7, E. coli O157:H12, and E. coli O157:H19. LPS‐containing extracts were isolated from each E. coli strain using a hot phenol‐water extraction procedure. The extracts were 1st analyzed by deoxycholic acid‐polyacrylamide gel electrophoresis and visualized by silver‐staining. Analysis of the extracts from E. coli K12 and E. coli DH5α showed rough‐type LPS on the lower half of the gel, whereas E. coli O157:H7, E. coli O157:H12, and E. coli O157:H19 yielded abundant smooth LPS (high‐molecular‐weight LPS that include the O‐polysaccharides). Spectra (4000 cm^‐1 to 700 cm^‐1) of crude E. coli LPS extracts and intact cells were collected using a FTIR spectrometer. Spectral data were compressed by principle component analysis and analyzed using canonical variate analysis (CVA) of 4000 cm^‐1 to 700 cm^‐1 or 1200 cm^‐1 to 900 cm^‐1 spectral regions. CVA showed better separation between strains using LPS extracts than intact cells in the 1200 cm^‐1 to 900 cm^‐1 spectral region. The same separation trend was found using Mahalanobis distances that quantified spectral differences between the E. coli strains, providing 80% and >95% correct classifications of intact cells and LPS extracts, respectively. This article is the first to report the successful differentiation of E. coli strains at a serotype level using FTIR spectra of bacterial phenol‐phase extracts (crude LPS preparations).     

Cell wall compositions of raw and cooked corms of taro (Colocasia esculenta)

The monosaccharide compositions of parenchyma cell walls of raw and cooked corms of taro, Colocasia esculenta cv Tausala Pink, were determined. The cell wall constituents were sequentially extracted using CDTA, Na₂CO₃, 1 M KOH, 4 M KOH and water to leave a final residue (α‐cellulose). The monosaccharide compositions of the cell walls and cell wall fractions from the raw and cooked corms were consistent with the presence in these cell walls of large amounts of cellulose and pectic polysaccharides. The monosaccharide composition of the cell walls of the raw corms resembled the monosaccharide compositions of primary cell walls of other non‐commelinoid monocotyledons and dicotyledons. Cooking of the corms resulted in alteration of the cell walls, with solubilisation of pectic polysaccharides occurring earlier in the sequential fractionation and possibly changes in the extractability of xyloglucans and/or xylans. © 2000 Society of Chemical Industry     

Antioxidative activities of grape (Vitis vinifera) seed extracts obtained from different varieties grown in Turkey

In this study, total phenolic contents and antioxidant activities of grape seed extracts obtained from twelve different grape seeds from common varieties grown in Turkey were determined. Grape seeds were extracted with 70% acetone and extraction yield of grape seed were calculated. The total phenolic content of grape seed extracts were determined by the Folin‐Ciocalteu procedure and ranged from 33 945 to 58 730 mg per 100 g extract as gallic acid equivalent. Antioxidant activities of grape seed extracts with two different free radical scavenging methods, ABTS [2,2/‐azinobis (3‐ethylbenzothiazoneline‐6‐sulfonic acid)] and DPPH (2,2‐diphenyl‐picrylhydrazyl) assays, using Trolox equivalent as standards, were investigated. Grape seed extracts exhibited antioxidant activities 2.46–4.14 and 3.55–5.76 [Trolox equivalent antioxidant capacities (TEAC) mg^?1 extracts] in ABTS and DPPH assays, respectively. Compared with varieties, Muskule extracts exhibited the lowest total phenolic content, TEAC_ABTS and TEAC_DPPH value while Narince extracts had the highest total phenolic content and TEAC_DPPH value, and Alphonse Lavalleé had the highest TEAC_ABTS value. Total phenolic content showed that there is a significant correlation with TEAC_DPPH (r = 0.7974, P ≤ 0.001) and TEAC_ABTS values (r = 0.4860, P ≤ 0.05).     

An explorative study on the cell wall polysaccharides in the pulp and peel of dragon fruits (Hylocereus spp.)

The pectic and hemicellulosic cell wall polysaccharides from the pulp and the peel of white-flesh and red-flesh dragon fruits (Hylocereus spp.) were isolated and compared in terms of degree of methoxylation (DM), solubility properties (relative content of uronic acids and neutral sugars in different fractions), neutral sugar composition, molar mass distribution, and affinity toward some specific anti-pectin antibodies. Hereto, the alcohol-insoluble residues were extracted and sequentially fractionated using hot water, a chelating agent, sodium carbonate, and potassium hydroxide solutions to obtain different pectin fractions and a hemicellulose fraction. Chemical analyses were used to characterize these polysaccharide fractions. The results show that cell wall polysaccharides of the pulp and especially of the peel from white-flesh and red-flesh dragon fruits contain significant amounts of pectic substances that are lowly methyl-esterified. The cell wall polysaccharides of the peel as well as those of the pulp contain high amounts (38–47 %) of loosely bound (water-soluble) pectic substances. In the water-soluble fraction (WSF) of the peel samples, uronic acids are the predominant monomers. On the contrary, rhamnogalacturonan-I type neutral sugars, and especially arabinose and galactose, contribute equally, as compared to uronic acid, to the WSF of the pulp samples. Despite the low average DM value of pulp and peel pectin, pectic substances in both samples showed affinity for antibodies with different specificities indicating that a wide range of epitopes, including long blocks of unesterified galacturonic acids (GalA) residues as well as (short) blocks of esterified GalA residues, is present. No large differences between the pectic substances among the different dragon fruit varieties were observed.     

Fermentation characteristics of polysaccharide fractions extracted from the cell walls of soya bean cotyledons

Full‐fat soya beans were separated into hulls and cotyledons. After separation the cell wall fraction was extracted from the cotyledons. These purified cell walls were sequentially extracted with 0.05 M cyclohexane‐trans‐1,2‐diamine‐N,N,N ′,N ′‐tetraacetate (CDTA) + 0.05 M NH₄ oxalate (extract 1), 0.05 M NaOH (extract 2), 1 M KOH (extract 3) and 4 M KOH (extract 4) to fractionate the cell wall into its polysaccharide fractions. The extraction procedure was designed to first extract the pectic fraction (extracts 1 and 2), after which more hemicellulose was extracted in subsequent steps (extracts 3 and 4). In addition to the polysaccharides solubilised during extraction, the residues after each extraction step were collected. Extracts and residues were analysed for their fermentation characteristics using an in vitro gas production procedure. Fermentability of the sequential extracts increased for each subsequent extraction step, as witnessed by an increasing rate of fermentation (from 2.2 to 10.0% h⁻¹) and decreasing half‐time of gas production (from 56.0 to 18.7 h). Fermentability of the residues increased after pectins had been removed in the first two extraction steps, as witnessed by a shorter half‐time of gas production (from 47.0 to 29.7 h). Fermentability was similar for residues 2 and 3, but decreased again for residue 4, which was deemed to consist mainly of cellulose. The different cell wall sugars were degraded at different rates, with a rapid rate of degradation for galactose and arabinose, an intermediate rate for xylose and uronic acids and a slow rate for glucose. The sugar degradation rates for extract 1 had a similar ranking. These results are discussed in light of the concept that pectins determine the pore size of the cell wall matrix (Carpita NC and Gibeant DM, Planta J 3 : 1–30 (1993) and the model of the cell wall architecture of legumes of Hatfield (Hatfield RD, in Forage Cell Wall Structure and Digestibility, Ed by Jung HG, Buxton DR, Hatfield RD and Ralph J. American Society of Agronomy/Crop Science Society of America/Soil Science Society of America, Madison, WI, pp 285–313 (1993)). © 2000 Society of Chemical Industry     

Polysaccharides from Sesamum indicum meal: Isolation and structural features

Defatted Sesamum indicum seed cake was extracted, following two separate sequences, and the effects of extraction medium on yield and composition of the extracts were compared. Polysaccharides extracted sequentially with dilute acid and alkali represented 250 mg/g of defatted meal. The isolated polymers contained arabinan, rhamnogalacturonan I (RG I) and arabinogalactan proteins. Polysaccharides extracted during chlorite treatment and with dilute alkali had a higher proportion of rhamnose, suggesting a more branched variety of polymer. Three extracts, which were further characterized by size exclusion chromatography, gave two overlapping peaks. Structural characterisation of hemicellulosic polysaccharides, isolated with KOH, using specific enzyme hydrolysis, ion exchange chromatography (HPAEC) and matrix assisted laser desorption ionisation-time-of-flight (MALDI-TOF) mass spectroscopy, showed that sesame meal xyloglucan (XG) contained XXXG, XXFG and XXLG, and XLLG (named according to Fry et al., 1993) as the major building sub-units in the ratio of 1:0.9:0.3. Hydrolysis with endo-β-(1 → 4)-d-xylanase and analysis of the xylan derived oligosaccharides showed the presence of monomeric xylose (40%), xylobiose (46%) and acidic xylan oligosaccharides containing 4-O-methyl-d-glucuronic acid residues (14%).     

Changes of bioactive components in berry seed oils during supercritical CO2 extraction

The objective of the work was to elucidate the chemical composition of fractions of oil extracts obtained during the supercritical extraction on a semi‐industrial scale from strawberry (Fragaria x ananassa Duch.), chokeberry [Aronia melanocarpa (Michx.)], and raspberry (Rubus idaeus L.) seeds from industrial press cake. The oil extracts differed in terms of their content of bioactive components: carotenoids, tocopherols, chlorophylls, and fatty acids. Raspberry seed oil was the richest source of tocopherols (620.1–2166.7 mg kg^?1) and α‐linolenic acid (above 37%). Chokeberry seed oil had the highest content of linoleic acid (above 70%), and α‐tocopherol (166.0–1104.8 mg kg^?1). Strawberry oil was characterized by the highest content of chlorophylls and α‐linolenic acid (above 30%). It was showed that the oil fraction collected at the beginning of extraction is characterized by a high acid value, which requires purification steps to be used for food purposes.

Practical applications

Strawberry, raspberry, and chokeberry by‐products left over from the production of concentrated juice are a valuable source of oils rich in n‐3 and n‐6 polyunsaturated fatty acids, tocopherols, and carotenoids. The research showed that the fractionation of extracts in the course of supercritical extraction leads to oils with varying amounts of different bioactive compounds, and thus to products with potentially wide applications. Seeds oils have high potential utility as a source of unconventional oil for cosmetic and pharmaceutical sectors and biodiesel. Their targeted utilization may be exploited for economic, environmental and health benefits.