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Arabinoxylans (AX) are gelling polysaccharides with potential applications as colon-targeted biomaterials. Nevertheless, the fermentation of highly cross-linked AX particles (AXP) by colonic bacteria and the effect of its fermentation supernatants on the proliferation of human colon cancer cells have not been investigated so far. In this study, electrosprayed AXP were fermented by Bifidobacterium longum , Bifidobacterium adolescentis , and Bacteroides ovatus . The effect of AXP fermentation supernatant (AXP-fs) on the inhibition of the human colon cancer cell line Caco-2 proliferation was investigated. AXP presented a mean diameter of 533 µm, a spherical shape, and a cross-linking content (dimers and trimers of ferulic acid) of 1.65 µg/mg polysaccharide. After 48 h of bacteria exposure, AXP were only partly fermented, probably due to polymeric network steric hindrance that limits the access of bacterial enzymes to the polysaccharide target sites. AXP partial fermentation was evidenced by a moderate short-chain fatty acid production (SCFA) (23 mM) and a collapsed and disintegrated microstructure revealed by scanning electron microscopy. AXP-fs exerted slight inhibition of Caco-2 cell proliferation (11%), which could be attributed to the SCFA generated during partly polysaccharide fermentation. These findings indicate that electrosprayed AXP are a slow-fermentable biomaterial presenting slight anti-cancer properties and potential application in colon cancer prevention.

Pectin from sugar beet (Beta vulgaris L.) (SBP) was extracted from a sugar beet waste (SBW) registering a 4.4% (w/w) yield. SBP presented a weight-average molar mass of 459 kDa, galacturonic acid content of 52.2%, and a low esterification degree (30%). The macromolecular characteristics of SBP revealed a flexible and extended coil chain conformation. The main neutral sugars in SBP were galactose (20.7%), mannose (5.0%), and arabinose (3.60%) while ferulic acid (FA) content was 2.1 µg·mg−1 sample. FA remained in the SBP chain mainly in RG I region even after suffering both, industrial processing and harsh weathering conditions. Consequently, SBP formed covalent gels induced by laccase. Covalent cross-linking content (dimers and trimer of FA) was 0.97 mg·g−1 SBP. The 8-5′, 5-5′, and 8-O-4′ dimers of FA isomers proportions were 75, 17, and 8%, respectively. SBP gels at 4% (w/v ) registered storage (G′) and loss (G″) moduli final values of 44 and 0.66 Pa, respectively. SBP gels were soft and adhesive according to texture profile analysis. Scanning electron microscopy analysis of SBP lyophilized gels revealed an imperfect honeycomb-like structure with 4.5 ± 1.4 µm average cavities diameter.

Background Prolamins are the endosperm storage proteins of cereal grains. Currently, the agri-food industry generates large quantities of by-products, among which are those generated from wet-milling, such as Gluten Meals (GM), dry-milling, such as the Distillers Dried Grains with Solubles (DDGS) and Brewer's Spent Grain (BSG). These by-products are important biopolymer sources such as prolamins. The prolamins have low nutritional value, however can be are useful for obtaining micro- and nanomaterials Scope and approach The main objective of this review was to make known the techniques of obtaining and its main applications in micro- and nanotechnology of prolamins obtained from cereal, and the purpose of this investigation was to promote the use of prolamins obtained from cereal by-products. Key findings and conclusions The prolamins can be obtained of by-products cereals and due to their economic importance and high productivity, the main cereals that generate these types of by-products are wheat and corn, in addition to sorghum, which is experiencing an increasing boom. The conformational structure of prolamins render them feasible for producing various micro- and nanomaterials, particles and fibers. These micro- and nanomaterials are of interest in the food industry and medicine for protection of bioactive compounds, pickering emulsions stabilized, drug delivery system and controlled release fertilizer. There is more evidence on nanomaterials that micromaterials that have been obtained from prolamins: from 2014 and up to date, around 247 investigations have been published dealing with the obtention of nanoparticles and nanofibers, of which only 2.0% corresponds to materials obtained from cereals by-products. Therefore, future prolamin research in nanotechnology from the by-products of cereals is necessary, with the purpose of increase added value and decreasing environmental contamination.

Ferulated polysaccharides such as pectin and arabinoxylan form covalent gels which are attractive for drug delivery or cell immobilization. Saccharomyces boulardii is a probiotic yeast known for providing humans with health benefits; however, its application is limited by viability loss under environmental stress. In this study, ferulated pectin from sugar beet solid waste (SBWP) and ferulated arabinoxylan from maize bioethanol waste (AX) were used to form a covalent mixed gel, which was in turn used to entrap S. boulardii (2.08 × 108 cells/mL) in microbeads using electrospray. SBWP presented a low degree of esterification (30%), which allowed gelation through Ca2+, making it possible to reduce microbead aggregation and coalescence by curing the particles in a 2% CaCl2 cross-linking solution. SBWP/AX and SBWP/AX+ S. boulardii microbeads presented a diameter of 214 and 344 µm, respectively, and a covalent cross-linking content (dimers di-FA and trimer tri-FA of ferulic acid) of 1.15 mg/g polysaccharide. The 8-5’, 8-O-4’and 5-5’di-FA isomers proportions were 79%, 18%, and 3%, respectively. Confocal laser scanning microscopy images of propidium iodide-stained yeasts confirmed cell viability before and after microbeads preparation by electrospray. SBWP/AX capability to entrap S. boulardii would represent an alternative for probiotic immobilization in tailored biomaterials and an opportunity for sustainable waste upcycling to value-added products.

International audience; Maize by-product from the bioethanol industry (distiller’s dried grains with solubles, DDGS) is a source of ferulated arabinoxylan (AX), which is a health-promoting polysaccharide. In the present study, AX from DDGS was fermented by a representative colonic bacterial mixture (Bifidobacterium longum, Bifidobacterium adolescentis, and Bacteroides ovatus), and the effect of the fermented AX (AX-f) on the proliferation of the cell line Caco-2 was investigated. AX was efficiently metabolized by these bacteria, as evidenced by a decrease in the polysaccharide molecular weight from 209 kDa to < 50 kDa in AX-f, the release of ferulic acid (FA) from polysaccharide chains (1.14 µg/mg AX-f), and the short-chain fatty acids (SCFA) production (277 µmol/50 mg AX). AX-f inhibited the proliferation of Caco-2 cells by 80–40% using concentrations from 125–1000 µg/mL. This dose-dependent inverse effect was attributed to the increased viscosity of the media due to the polysaccharide concentration. The results suggest that the AX-f dose range and the SCFA and free FA production are key determinants of antiproliferative activity. Using the same polysaccharide concentrations, non-fermented AX only inhibited the Caco-2 cells proliferation by 8%. These findings highlight the potential of AX recovered from the maize bioethanol industry as an antiproliferative agent once fermented by colonic bacteria

In vivo evaluation of arabinoxylans (AX) microspheres showed to protect insulin from degradation in the upper gastrointestinal tract and carrier insulin to colon. Insulin-loaded AX microspheres (50 UI/kg) decreased blood glucose level by 39% in diabetic rats with a maximum effect at 18 h post-administration, indicating that insulin remains bioactive. The continuous administration (4 days) of insulin-loaded AX microspheres improved the polyuria and increased the production of short-chain fatty acids, as well as Bifidobacterium and Bacteroides in diabetic rats compared to untreated diabetic rats. AX microspheres are a potential microbiota-activated carrier for colon-specific drug delivery and could be useful as a complementary treatment for diabetes.

Stenocereus thurberi is an endemic species in northwestern Mexico. It produces colorful fruits called pitayas that have an edible pulp. They have phytochemical compounds associated with biological activities. Ultrafiltration is a widely used method for the clarification of fruit juices and the recovery of phytochemicals. However, its effect has not been extensively studied in extracts. Therefore, the objective of this work is to study the effect of the ultrafiltration of pitaya extract (Stenocereus thurberi) on its phytochemical content, antioxidant capacity, and identification of phenolic compounds by UPLC-DAD-MS, providing greater knowledge about the pitaya. In this study, two extracts were analyzed, the unclarified extract (UE) and the clarified extract (CE). The antioxidant capacity was higher in the CE with 15.93 &plusmn, 0.42 mM TE/g, DPPH and 18.37 &plusmn, 0.016 mM TE/g, ABTS. The UPLC-MS analysis indicated the decrease in phenolic compounds in the CE and the presence of gallic acid and resorcinol, compounds that had not been identified in other species of Stenocereus spp. The correlation analysis indicated that all the phytochemicals present in the pitaya contribute significantly to the antioxidant capacity. The ultrafiltration process could be a viable option to improve the biological activity of the natural extracts.

Sulfated polysaccharides were extracted from Navicula sp. cultivated at three wavelengths: white (WSPN), red (RSPN) and blue (BSPN) with yield rates of 3.4, 3.9 and 4.4 (% w / w dry biomass basis) respectively. Analysis of these polysaccharides using gas chromatography showed that they contain glucose, galactose, rhamnose, xylose and mannose as main neutral sugars. The amount of rhamnose was higher in WSPN. The molecular weight ( Mw ) value was 17, 107 and 108 kDa for WSPN, BSPN and RSPN, respectively. The sulfate content in WSPN was higher (0.40% w/w ) than in the BSPN and RSPN. The polysaccharides recovered from Navicula sp. presented antioxidant activity, which could be related to the molecular structural characteristics such as Mw and sulfate content. The scavenging activity was higher in WSPN (DPPH 49% and ABTS + 68 μmol Trolox/g), than in the BSPN and RSPN samples. The WSPN possess a high antioxidant capability, thus this sulfated polysaccharide might be a potential antioxidant for biotechnological applications.

Large volumes of fruit and vegetable production are lost during postharvest handling due to attacks by necrotrophic fungi. One of the promising alternatives proposed for the control of postharvest diseases is the induction of natural defense responses, which can be activated by recognizing molecules present in pathogens, such as chitin. Chitin is one of the most important components of the fungal cell wall and is recognized through plant membrane receptors. These receptors belong to the receptor-like kinase (RLK) family, which possesses a transmembrane domain and/or receptor-like protein (RLP) that requires binding to another RLK receptor to recognize chitin. In addition, these receptors have extracellular LysM motifs that participate in the perception of chitin oligosaccharides. These receptors have been widely studied in Arabidopsis thaliana (A. thaliana) and Oryza sativa (O. sativa); however, it is not clear how the molecular recognition and plant defense mechanisms of chitin oligosaccharides occur in other plant species or fruits. This review includes recent findings on the molecular recognition of chitin oligosaccharides and how they activate defense mechanisms in plants. In addition, we highlight some of the current advances in chitin perception in horticultural crops.

A novel edible film and coating with antagonistic yeast in arabinoxylan (AX) matrix was prepared and its effects on preserving against fungus infection on limes were investigated. The effect of yeast cell incorporation of developed films was evaluated in terms of viability, biocontrol activity and barrier properties. Furthermore, the application of AX as bioactive coatings was investigated in order to evaluate their efficacy to preserve postharvest quality and prevent or cure infection by Penicillium italicum during storage. Results revealed AX as a matrix compatible with D. hansenii and able to maintain more than 97% viability of the initial inoculum at temperatures tested, films with antagonistic yeast are capable to inhibit the growth of P. italicum in vitro. Presence of yeast did not change water vapor permeability on films. Viability of yeasts was preserved on coated limes on 100%. Preventive application of treatments was more effective than curative applications in the control of blue mold decay. Yeast added coatings were effective at reducing weight loss and had no effect on limes color. This study demonstrates the potential application of bioactive AX coatings with D. hansenii as an alternative of postharvest disease management.

Changes in the solubility of corn proteins occurring during traditional nixtamalization and extrusion processes used to produce tortillas were studied using size exclusion chromatography, SDS-PAGE and the Dumas method to measure 50% propanol-insoluble protein. Size exclusion chromatography (HPL-SEC) studies furthered the understanding of protein solubility changes during both processes. Extrusion caused more protein aggregation in tortilla intermediate and final products than traditional nixtamalization. Mixing during extrusion and in the intermediate step of masa production in the traditional nixtamalization process was critical in reducing protein solubility. Baking tortillas also considerably reduced the protein solubility for the traditional nixtamalization process. Baking produced aggregation that could not be disrupted with a reducing agent.

Sugar beet is a potential source of pectin, competitive with traditional sources, that has recently acquired great relevance for its interesting covalent gelling and applications in food and biomedical industries. Pectins from three Sugar beet (Beta vulgaris L.) commercial cultivars (Cadet, Coronado large, and SV MEI) were grown under irrigated desertic conditions and the influence of cultivar, on pectin yield, composition, physicochemical and gelling characteristics was investigated. The composition and chemical properties of pectin from the three cultivars were in general, statistically different, especially in the Syngenta Cadet cultivar, presenting higher protein (10.3%), neutral sugars (21.6%), galacturonic acid (55%) and ferulic acid (5.5 mg/g) content, which are important parameters for gel formation. All pectins gelled via oxidative coupling and the main ferulic acid dimers found were 8-5&prime, and 8-O-4&prime, Pectin from Cadet cultivar formed gels with higher hardness (6.65 N) and adhesiveness (12.2 N) values than the other two varieties. The results indicate that pectin composition is affected by the sugar beet cultivars reported herein, especially in ferulic acid content, which confer the covalent gelling capability. Sugar beet cultivars grown under desert conditions could be a source of gelling ferulated pectins for the food industry, as valuable as those obtained in temperate conditions.

Arabinoxylans (AX) gels at 4% (w/v) were prepared using laccase (LAX gels) or peroxidase (PAX gels), and their cross-linking, rheological, structural, and spectroscopic characteristics were investigated. LAX gels presented lower amount of 5,5′-diferulic acid (11%), smaller mesh size (128 nm), and higher hardness (37 N) and elasticity (430 Pa) than the PAX gels (28%, 197 nm, 7 N, and 120 Pa, respectively). Microscopy of the LAX gels showed linked strands, while the system was less connected in the PAX gels. The Raman band at 2895 cm(−1) of the LAX and PAX gels was less intense, indicating enhanced hydrogen bonding compared to that of AX. This decrease was less dramatic for the PAX gels. The greater content of 5,5′-diferulic acid in PAX gels could favor intrachain bonds, affecting their rheological, structural, and spectroscopic characteristics. Laccase may be a better option than peroxidase for AX gelation intended for food and biotechnological applications.

Consumers with gluten-related disorders require gluten-free (GF) foods to avoid an immune response. Alternative to the use of non-gluten containing grains to prepare GF bread, the gluten reactivity has been greatly reduced using a proline specific cleavage enzyme, however, the gluten functionality was lost. The aim of this study was to evaluate the effect of adding an amaranth flour blend (AFB) to enzymatically modified wheat-flour proteins on dough functionality and to evaluate the immunoreactivity and acceptability of the prepared bread. First, wheat flour (20% w/v, substrate) was hydrolyzed using 8.4 U mg−1 protein Aspergillus niger prolyl-endopeptidase (AnPEP) for 8 h at 40 °C under constant agitation. Four types of breads were prepared with the same formulation except for the type of flour (14% w.b.): wheat flour (WF), WF-AFB unmodified not incubated, WF-AFB unmodified incubated and WF-AFB modified. The protein composition and free thiols were analyzed before and after amaranth addition, and the flour and bread proteins were run using SDS-PAGE and immune-detected in blots with IgA from celiac disease patients. The immunoreactive gluten content, specific volume and bread acceptability were evaluated. The polymeric proteins and free thiol groups of WF decreased after AnPEP treatment. The electrophoretic patterns of the modified flour and bread proteins were different and the IgA-immunodetection in blots was highly reduced, particularly for the higher molecular weight subunits. The addition of AFB to the modified wheat flour prepared using AnPEP improved the dough functionality by increasing the thiol groups and allowed the preparation of a sensorially acceptable bread with only 60 mg kg−1 immunoreactive gluten.

Due to their porous structure, aqueous environment and dietary fiber nature arabinoxylan (AX) gels could have potential applications for colon-specific therapeutic molecule delivery. In addition, prebiotic and health related effects of AX have been previously demonstrated. It has been also reported that cross-linked AX can be degraded by bacteria from the intestinal microbiota. However, AX gels have not been abundantly studied as carrier systems and there is no information available concerning their capability to entrap cells. In this regard, probiotic bacteria such as Bifidobacterium longum have been the focus of intense research activity lately. The objective of this research was to investigate the entrapment of probiotic B. longum in AX gels. AX solution at 2% (w/v) containing B. longum (1 × 107 CFU/cm) formed gels induced by laccase as cross-linking agent. The entrapment of B. longum decreased gel elasticity from 31 to 23 Pa, probably by affecting the physical interactions taking place between WEAX chains. Images of AX gels containing B. longum viewed under a scanning electron microscope show the gel network with the bacterial cells entrapped inside. The microstructure of these gels resembles that of an imperfect honeycomb. The results suggest that AX gels can be potential candidates for the entrapment of probiotics.

The grafting of fruits and vegetables influences fruit quality. The aim of the present work was to assess the effect of the rootstock and the scion on the antioxidant activity and the content in vitamin C, total phenols, lycopene and β-carotene of bell pepper. The cultivars Fascinato and Jeanette were used as scion and Terrano was used as rootstock. Four harvests in the production cycle of the vegetable were analyzed in a cultivation system under shading nets. The results indicate statistical differences in the content of these bioactive compounds between the varieties, between grafting and not grafting and between sampling dates (p ≤ 0.05). The vitamin C content, β-carotene, and antioxidant capacity proved significantly higher in Fascinato than in Janette. On average, grafting increased β-carotene and vitamin C concentrations and improved the antioxidant capacity, but had no influence on the total phenol or lycopene contents. It is concluded that grafting to the rootstock Terrano improves the nutritional quality of the fruit produced in both varieties of bell pepper studied.

Maize is a major source of food in Mexico. In order to improve its nutritional value, maize kernel is exposed to an alkali treatment that generates large volumes of waste water containing gelling arabinoxylan. The purpose of the present study was to evaluate the capability of maize waste water arabinoxylans (MWAX) to encapsulate probiotics. The rheological, structural, and microstructural characteristics of this bio-based material were also investigated. MWAX gels at 10% (w/v) were able to encapsulate Bifidobacterium as probiotic model. The MWAX gel containing 1 × 107 CFU/mL of probiotics presented a storage (G′) and loss (G″) moduli of 50 and 11 Pa, respectively. The average mesh size of the MWAX gel was around 11 times smaller than the Bifidobacterium cell magnitude. MWAX gels with or without probiotics were studied using scanning electron microscopy. The interior of the Bifidobacterium loaded gels was composed of a pore-like network of MWAX through which probiotics were distributed. The probiotic encapsulating MWAX gels appeared to be less porous than the empty gels. MWAX capability to encapsulate Bifidobacterium may be important in designing probiotic encapsulating biodegradable gels and could represent an opportunity in sustainable food waste management and utilization through upcycling to value-added products.

IATE Axe 1: Fractionnement des Agro ressources : bases structurales et physicochimiques ; procédés de broyage, extraction et de séparationIATE Axe 2: Structuration sous contraintes des agropolymères et réactivité des poudres; The oxidative gelation of maize bran arabinoxylans (MBAX) using a peroxidase/H2O2 system as a free radical-generating agent was investigated. The peroxidase/H2O2 system led to the formation of dimers and trimer of ferulic acid as covalent cross-link structures in the MBAX network. MBAX gels at 4% (w/v) presented a storage modulus of 180 Pa. The structural parameters of MBAX gels were calculated from swelling experiments. MBAX gels presented a molecular weight between two cross-links (Mc), a cross-linking density (ρc) and a mesh size (x) of 49 × 103 g/mol, 30 × 10−6 mol/cm3 and 193 nm, respectively.

The growth of six Trichoderma spp. warm-weather strains (WWS) and temperate-weather strains (TWS) was determined by microcalorimetry at different temperatures from 10 to 35 °C. The metabolic heat production ( p ) and the apparent activation energy ( E a ) were calculated. Significant differences among the strains were noted between 20 and 30 °C. The optimal growth temperature was 30 °C for strains TC74, T359, T479, and Th and was 35 °C for TC74M and T397. The p values were from 18 to 28 mW g −1 dry weight of mycelium and 11–16 mW g −1 of dry weight of mycelium for the WWS and TWS, respectively. The highest and lowest E a values were observed for T479 (98 kJ mol −1 ) and Th (34 kJ mol −1 ), respectively. For WWS, the p value at the highest growth was directly related to antibiosis, and the E a values were directly correlated to sclerotium parasitism. Both p and E a were inversely related to sclerotium parasitism and pathogen growth inhibition, respectively. By contrast, the p value for TWS at maximal growth was inversely related to antibiosis while the E a was directly related. Microcalorimetry was used to detect minute differences in metabolism heat among the Trichoderma strains, providing a rapid and accurate way to yield reproducible data.

This work presents the fabrication and characterization of electro-sprayed core-shell particles that were composed of maize bran arabinoxylans (MBAX) with insulin in the core, and maize wastewater arabinoxylans (MWAX) with Bifidobacterium in the shell. Two concentrations of MBAX (3 and 6% w/v) and MWAX (6 and 10% w/v) were evaluated. The particles fabricated with MBAX at 6% (w/v) in the core and MWAX at 10% (w/v) in the shell were more stable, presented spherical shape and no aggregation being therefore selected to be loaded with insulin and probiotics. These particles presented a size of 2.9 mm. Scanning electron microscopy analysis of the particle cross section revealed the presence of both, a smooth (shell) and a porous (core) microstructure. Confocal laser scanning microscopy confirmed the core-shell structure of the particles and the viability of the probiotic entrapped. Gastrointestinal simulation strongly suggests that these particles are not degraded in the stomach and small intestine and that 76% of the carried insulin is released in colon. These results indicate that insulin and Bifidobacterium encapsulation by tetraaxial electro spraying can be a feasible and adequate technique to produce arabinoxylan capsules containing both insulin and probiotics. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46411.

This research documented the metabolic changes associated with the use of budbreak promoter sprays in vineyards. The objective was to evaluate metabolic heat production (Rq) and respiratory ( R C O 2 ) rates and water content of Vitis vinifera L. cv. ‘Flame Seedless’ buds during dormancy, and after spraying with the budbreak promoter, hydrogen cyanamide (H2CN2), assessing its effect on the developmental response of buds through several phenological phases in the vineyard. The study was conducted in the winter from November 24, 2005 to February 8, 2006 using isothermal calorimetry at 25 °C. Phenological stages monitored were dormant bud, swollen bud, half-inch green, first-flat leaf and second-flat leaf. On December 23, when 97 chilling units had accumulated, H2CN2 (0.82 M divided into two applications of 0.47 and 0.35 M) was applied and compared with untreated controls. Metabolic heat rates significantly (p ≤ 0.05) increased from endodormant buds to the half-inch green stage, from 2 to 33 μW mg−1 dry weight (dw). This occurred from November 24 to January 15. Bud respiration rate showed a similar pattern, increasing from 3.7 to 346 nmoles CO2 s−1 mg−1 dw, and bud water content increased from 2.2 to 5.6 mg mg−1 dw. In a 27-day period after spraying, treated vines reached 50% budbreak, while controls reached only 7%. Phenological development was heterogeneous due to insufficient chilling, as well as to low temperatures following H2CN2 application. Changes in Rq and R C O 2 were detected 12 days in advance compared with changes in bud hydration.

Isothermal calorimetry was used to evaluate the effect of budbreaking agents (BBA) on metabolic rates Rq and R C O 2 , metabolic efficiency ( R q / R C O 2 ) and specific growth rate (RSG·ΔHB) in apple flower buds during late winter. Three BBA were tested (hydrogen cyanamide, HC at 1.0% (v/v); thidiazuron (1-phenyl-3-(1,2,3-thiadiazol-5-yl)urea), TDZ at 0.3% (v/v) and mineral oil, MO at 1% (v/v)). Water was used as a control. BBA application was performed at two Rq rates (4.8 and 5.3 μW mg−1 dw, corresponding to 30 and 15 days before budbreak, approximately). Rq, R C O 2 , R q / R C O 2 and RSG·ΔHB were measured during 18 days at 3 day intervals under forcing conditions. Budbreak percentage was scored at the end of the experiment. Significant differences in the calorimetric parameters (p ≤ 0.05) were found between BBA treatment and BBA application date. The highest Rq (11.4 μW mg−1 dw), R C O 2 (32.2 mmol CO2 mg−1 dw), RSG·ΔHB (2.8 μW mg−1 dw) and budbreak percentage (95%) values were found for HC treated buds when application was performed 15 days before budbreak. These samples showed the lowest R q / R C O 2 value (368 kJ mol−1) confirming an increase in bud metabolic efficiency. These results indicate that HC is an effective BBA to overcome blooming problems associated with insufficient winter chilling on apples.

International audience; Arabinoxylan gels with different cross-linking densities, swelling ratios, and rheological properties were obtained by increasing the concentration of arabinoxylan from 4 to 6% (w/v) during oxidative gelation by laccase. The degradation of these covalently cross-linked gels by a mixture of two Bifidobacterium strains (Bifidobacterium longum and Bifidobacterium adolescentis) was investigated. The kinetics of the evolution of structural morphology of the arabinoxylan gel, the carbohydrate utilization profiles and the bacterial production of short-acid fatty acid (SCFA) were measured. Scanning electron microscopy analysis of the degraded gels showed multiple cavity structures resulting from the bacterial action. The total SCFA decreased when the degree of cross-linking increased in the gels. A slower fermentation of arabinoxylan chains was obtained for arabinoxylan gels with more dense network structures. These results suggest that the differences in the structural features and properties studied in this work affect the degradation time of the arabinoxylan gels.

Many studies have reported that the exposure of microalgae cultures to red light increases the production of carbohydrates, while blue light promotes the production of protein. There are several studies about Navicula, however there are few, if any, studies of the combined effects of wavelength and light intensity on the biochemical composition of this genus In this study we evaluated the combined effect of three wavelengths: white (400-750nm), blue (430-480nm), and red (650-750nm), at two light intensities (50 and100 μmol/m2/sec) on the growth and biochemical composition of Navicula sp. cultured on a laboratory scale. The experiment was carried out under controlled conditions utilizing a factorial design 2x3 (light intensity and wavelength) with white light as the control. The cell concentration was measured daily. Dry biomass of filtered cells was incinerated at 450ºC in a muffle oven. The biochemical content was measured using micro methods. The cell concentration was higher with white light at both intensities (291,875 and 90,938 cells/mL at 50 and100 μmol photon/m2/sec, respectively). Microalgae grown under blue wavelengths at 100 μmol photon/m2/sec had the highest dry biomass (1607 pg/cell). The highest percentage of protein was obtained under the blue light (22.83%), carbohydrates under the white light (4.13) and lipids under the red light (35.25%) all these results were observed under the low light intensity (50 μmol photon/m2/sec). The highest cell concentration and growth rate was observed under the low light intensity the largest proportions of which were proteins produced under the blue light. Lipid composition was not affected by light intensity or wavelength.

In the present study, wheat water extractable arabinoxylans (WEAX) were isolated and characterized, and their capability to form covalently cross-linked films in presence of Debaryomyces hansenii was evaluated. WEAX presented an arabinose to xylose ratio of 0.60, a ferulic acid and diferulic acid content of 2.1 and 0.04 µg∙mg(-1) WEAX, respectively and a Fourier Transform Infra-Red (FT-IR) spectrum typical of WEAX. The intrinsic viscosity and viscosimetric molecular weight values for WEAX were 3.6 dL∙g(-1) and 440 kDa, respectively. The gelation of WEAX (1% w/v) with and without D. hansenii (1 × 10(7) CFU∙cm(-2)) was rheologically investigated by small amplitude oscillatory shear. The entrapment of D. hansenii decreased gel elasticity from 1.4 to 0.3 Pa, probably by affecting the physical interactions between WEAX chains. Covalently cross-linked WEAX films containing D. hansenii were prepared by casting. Scanning electron microscopy images show that WEAX films containing D. hansenii were porous and consisted of granular-like and fibre microstructures. Average tensile strength, elongation at break and Young's modulus values dropped when D. hansenii was present in the film. Covalently cross-lined WEAX containing D. hansenii could be a suitable as a functional entrapping film.

Solutions (1 % w/v) of water-extractable arabinoxylans (WEAX) from wheat were mixed with ovalbumin solutions at different concentrations in order to obtain different protein/polysaccharide ratios (0, 0.6, 2.5, 5.0, 7.5 and 10.0). These mixtures were oxidized by a laccase (Pycnoporus cinnabarinus). The kinetics of gelation was monitored by rheological measurements of the storage modulus (G') and loss modulus (G) at 25°C during 2 h. In the different ovalbumin/WEAX mixtures, WEAX cross-linking occurred as shown by an increase in G'. However, final G' decreased as a function of protein concentration from 17.2 Pa (WEAX) to 7.1 Pa (ovalbumin/WEAX=10), following a sigmoidal relationship. Ovalbumin is probably entrapped in a WEAX covalent network, which explains the changes in rheological properties, but it does not participate in the network formation. Ferulic acid oxidation and diferulic acid formation was delayed at ovalbumin/WEAX=5.0 until 40 min but not at the end of gelation. In the same mixture SH groups from ovalbumin oxidized more rapidly than the protein alone. Ovalbumin via SH groups are probably responsible for the FA oxidation delay and the weaker WEAX gel formed by blocking the enzymatically formed free radicals.

Wheat bran arabinoxylan (WBAX) gels entrapping standard model proteins at different mass ratios were formed. The entrapment of protein affected the gel elasticity and viscosity values, which decreased from 177 to 138 Pa. The presence of protein did not modify the covalent cross-links content of the gel. The distribution of protein through the network was investigated by confocal laser scanning microscopy. In mixed gels, protein aggregates forming clusters were detected at protein/polysaccharide ratios higher than 0.25. These clusters were not homogeneously distributed, suggesting that WBAX and protein are located in two different phases. The apparent diffusion coefficient (Dm) of proteins during release from mixed gels was investigated for mass ratios of 0.06 and 0.12. For insulin, Dm increased significantly from 2.64 × 10−7 to 3.20 × 10−7 cm2/s as the mass ratio augmented from 0.06 to 0.12. No significant difference was found for Dm values of ovalbumin and bovine serum albumin released from the mixed gels. The results indicate that homogeneous protein/WBAX gels can be formed at low mass ratios, allowing the estimation of Dm by using an analytical solution of the second Fick’s law.

Arabinoxylans are polysaccharides constituted of a linear backbone of xylose in which arabinose substituents are attached, some ferulic acid esterifies arabinose. Arabinoxylan can form covalent gels by oxidative coupling of ferulic acid. Arabinoxylan gels could have potential applications for colon-specific biomolecules delivery due to their macroporous structure, and their aqueous environment and their dietary fiber nature. Lycopene has received increasing attention for its possible role in the prevention of colon cancer. It has been previously reported that arabinoxylan gels could be formed in presence of lycopene with no detriment on the lycopene antioxidant activity. The objective of this research was to investigate the in vitro degradation of arabinoxylan gels (AX gels) by two human colon bacterial species (Bacteroides ovatus and Bifidobacterium longum). Bacterial counts (CFU ml-1) and metabolic heat production (p) followed a similar pattern with a high response during the first 24 h at 37 °C. A regression model related CFU ml-1 and p (r2= 0.98). These results show that AX gels could be carriers for lycopene delivery in colon due structure degradation by gut microbiota.

The laccase induced gelation of maize bran arabinoxylans at 2.5% (w/v) in the presence of insulin or beta-lactoglobulin at 0.1% (w/v) was investigated. Insulin and beta-lacto-globulin did not modify either the gel elasticity (9 Pa) or the cross-links content (0.03 and 0.015 microg di- and triferulic acids/mg arabinoxylan, respectively). The protein release capability of the gel was also investigated. The rate of protein release from gels was dependent on the protein molecular weight. The apparent diffusion coefficient was 0.99 x 10(-7) and 0.79 x 10(-7) cm(2)/s for insulin (5 kDa) and beta-lactoglobulin (18 kDa), respectively. The results suggest that maize bran arabinoxylan gels can be potential candidates for the controlled release of proteins.

The enzymatic gelation of wheat water-extractable arabinoxylan (WEAX) in presence of ovalbumin (Ov) at different concentrations was investigated by rheological measurements and di and triferulic acid (di-FA, tri-FA) cross-links content determination. Ov added in a 10-fold amount of arabinoxylan (AX) did not modify the di-FA and tri-FA contents of the gel but decreased gel elasticity ( G ′) from 41 to 11 Pa probably by affecting the physical interactions taking place between AX chains. The WEAX cross-linking process did not affect Ov, which was only entrapped in a phase-separated Ov–WEAX gel. The rate of Ov release from gels was dependent on its Ov content. The apparent Ov diffusion coefficient ( D m ) increased from 1.5 to 4.2×10 −7 cm 2 /s with Ov/AX ratio changing from 1 to 10. The results suggest that WEAX gels can be potential candidates for the entrapment and controlled release of proteins.

Flame Seedless grapes were sprayed with N-(2-chloro-4-pyridyl)-N-phenylurea (CPPU) at 0, 2.5, and 5.0 ppm to develop rachis resistant to browning and dehydration. Rachis polyphenol oxidase (PPO) activity was determined during cluster development. Cluster components were weighed at commercial (CM), and physiological maturity (PM). PPO activity, rachis color changes (L* and a*), and cluster weight loss were evaluated at 0 °C for 8, 16, 32, and 56 days. CPPU-treated rachis had a decrease of 36% in PPO activity and a week delay in peak activity. At PM, dry weight of CPPU-treated rachis increased by 3 g. Postharvest rachis PPO activity declined with CPPU application, and color changes followed the same pattern for CM and PM. After 32 days of storage, L* and a* in lateral branches were significantly superior in CPPU treatments. Weight losses below 2.1% were significantly lowest in CPPU-treated clusters for 16 days of storage regardless of cluster maturity. Keywords: Polyphenol oxidase; table grapes; rachis, dar...

Although extensive work has been reported on winegrapes (Vitis vinifera L.) regarding canopy structure, management and microclimate on berry ripening and composition, scarce information has been devoted to this issue in tablegrapes. Canopy microclimate, photosynthesis and other physiological traits were determined in three year old ‘Perlette’ vines trained on a T-trellis, in Sonora, México. In the undivided commercial T-trellis UTT) vine canopy, the photosynthetic photon flux densities (PPFD) reaching external, middle and internal leaf layers were 1922, 53 and 34 μmol m-2 s-1, respectively. In the same order, net photosynthesis (Pn) rates were 19.0, 1.7 and 1.0 μmol CO2 m-2 s-1, while chlorophyll contents were 1.9, 1.7 and 1.0 mg mL-1. No differences in total protein content were found between leaf layers, but significant differences in rubisco specific activity were found among external, middle and internal leaves, reaching 1.07, 0.65 and 0.25 μmol min-1 mg-1, respectively. Four training systems were compared against a commercial undivided T-trellis (UTT): Slanted pergola (Pergola), a specifically designed system (CIAD), Lyre (Lyre) and a divided T-trellis (Divided). Significant differences in PPFD on Lyre, Pergola, CIAD, Divided and UTT yielded 2192, 2076, 1900, 885 and 711 μmol m-2 s-1. At véraison, Pn in Pergola, CIAD, Lyre, Divided and UTT was 12.7, 11, 12.5, 10.5 and 5.1 μmol CO2 m-2 s-1, respectively. Five days after harvest, Pn showed a decrease in all training systems, particularly in UTT which showed only 3.7 μmol CO2 m-2 s-1. Stomatal resistance at véraison and postharvest was highest in UTT with 4.2 and 6.8 s cm-1 for both periods. Total soluble solids by 27 April were 15.7 °Brix for CIAD, while for UTT was only 12.1 °Brix. A week later, CIAD, Lyre, Pergola and Divided reported 16.3, 15.9, 15.5 and 15.2 °Brix, while UTT reached only 13.1 °Brix. Thus by dividing canopies and applying canopy management techniques the harvest date in the early season seedless grapes can be advanced, by increasing light harvest, photosynthetic rate and berry sugar accumulation.

Table grapes grown in the Sonoran Desert of Mexico are mostly an export commodity directed to early season markets. In order to define the effect on canopy management on light use and berry ripening, `Perlette' vines planted along eastwest rows (typical in such a region) were trained under four systems: slanted pergolas (SP), CIAD, lyre (LY), and T-trellis with open canopies (TTOC). They were compared with traditional closed-canopy T-trellis (TT). Variables evaluated were photosynthetic active radiation (PAR), photosynthesis (PH), stomatal resistance (SR), chlorophyll content (CC), and berry total soluble solids (TSS). At harvest, PAR values for LY, SP, CIAD, TTOD, and TT were 2192, 2076, 1900, 885, and 771 μmol·m-2·s-1, respectively. In the same order, PH at veraison was 12.5, 12.7, 11.0, 10.5, and 5.1 μmol CO2/m2 per s, while in recently harvest vines it decreased to 9, 9, 8.1, 5.1, and 3.7 μmol CO2/m2 per s. SR at veraison was 3.4, 2.6, 2.8, 3.9, and 4.2 s/cm, but, after harvest it was 2.5, 3.5, 2.3, .2.9, and 6.8 s/cm. No significant differences in CC were found among treatments. TSS on 27 Apr. reached 14.9, 15.3, 15.7, 14.5, and 12.2 °Brix; on 29 Apr. they increased to 15.9, 15.5, 16.3, 15.1, and 13.1 °Brix. Based on the above, we demonstrated that canopy management and sunlight cropping represent a useful tool to advance table grape ripening, thus allowing an early harvest and therefore access to the high prices typical of early season markets.

Chilling exposure is important in apple buds to overcome dormancy. The objective of this work was to determine the effect of different chilling treatments on apple bud calorimetric responses. One-year-old Golden Delicious trees were kept in a controlled temperature chamber at 48C for up to 1600 h. At 200 h intervals, five trees were transferred to forcing conditions at 258C. Isothermal calorimetry was used to determine metabolic activity (q), respiration rate (RCO2 ), respiration efficiency (q/ RCO2 ) and specific growth rate (RSG DHB) in vegetative buds. DSC was used to estimate activation energy (Ea). Calorimetric assays were performed at 0, 15 and 30 days at forcing conditions and budbreak was recorded. No significant differences (p0.05) in the above respiration parameters were found between chilling treatments during cold storage and immediately when the trees were transferred to growing conditions (0 days at 258C). Also, the lowest values registered for q (2.5 mW mg/ dw) and RCO2 (8 mmol CO2 mg/dw) were found during the above two periods. However, after 15 and 30 days at forcing conditions, buds increased their metabolism at a slow, but significant pace, as a direct function of chilling exposure time. After 15 days under forcing treatments q increased from 2.5 to 4 m Wm g ˇ1 dw, RCO2 from 9 to 13.5 mmol CO2 mg ˇ1 dw and RSG DHB from 1 to 2.5. After 30 days, these responses kept increasing, q from 2.5 to 5 m Wm g ˇ1 dw, RCO2 rose from 10 to 17 mmol CO2 mg ˇ1 dw and RSG DHB from 2 to 3. On both periods (15 and 30 day), highest values were found after chilling exposures more than 1000 h at 48C, which coincides with an increased budbreak of 12%. No consistent pattern was observed in q/RCO2 , regardless of exposure to forcing conditions. Cumulative chilling resulted in decreasing Ea of 29.8 and 33.3 J mol ˇ1 K after forcing for 15 and 30 days, respectively. In general, dormant vegetative apple buds increased their calorimetric responses after forcing for 15 and 30 days, but this was significant only when chilling equaled or exceeded 1000 h. Calorimetric parameters agree with information available elsewhere on chilling requirements for this variety # 2000 Elsevier Science B.V. All rights reserved.