Production of xylo-oligosaccharides (XOS) of tailored degree of polymerization from acetylated xylans through modelling of enzymatic hydrolysis.

Xylo-oligosaccharides (XOS) are emerging prebiotics that have recently been gained a great interest in the market of functional foods. Since their beneficial activity strictly depends on their chemical structure and on their degree of polymerization (DP), in this work an enzymatic method was developed to produce XOS with variable and modellable DPs, involving a combination of a commercial endo-ß-1,4-xylanase M3 from Trichoderma longibrachiatum and a deacetylase, using a commercial acetylated standard xylan as substrate. A Design of Experiment (DoE) was developed and through the variation of some hydrolysis conditions, some experiments allowed to obtain significant amounts of XOS with DP 7-10, up to 11%, despite XOS with DP 2-4 were always the most abundant (60-96% of total XOS). The most impacting parameter on the XOS distribution was the order of addition of the xylanase and deacetylating enzyme, while pH showed to have a great influence on the total yield. The method was also tested on an acetylated xylan extracted from grape stalks, structurally similar to the commercial standard xylan. The model was found to work in a very similar way also on the non-purified xylan sample, allowing the manipulation of enzymatic hydrolysis on a low-cost by-product, with the potential to obtain on a large scale XOS with high added value and with a specific DP, depending on the final application.

Making the reuse of agro-industrial wastes a reality for starch-based packaging sector: A storage case study of carrot cake and cherry tomatoes.

Cassava inner bark (CIB) and grape stalks (GS), residues from agro-industrial activities, were applied in the development of biodegradable foams by thermocompression. The samples produced with untreated stalks (sample GSWT) and with stalks only physically treated (sample GSP) presented good mechanical strength (2.1 MPa and 2.5 MPa, respectively) and low water absorption capacity (58% and 56% at 90 min, respectively). Therefore, these samples were selected for the storage of carrot cake and cherry tomatoes. Compared with the cakes stored in the supermarket packaging, there were no significant moisture content differences of the cakes stored in the biodegradable packaging developed by the formulation with the GSP sample (25% and 23%, respectively). The cakes' hardness increased up to 88% when stored in S + CIB + GSWT foam. More interesting, it was observed that the biodegradable packaging is more suitable for the storage of cherry tomatoes than the supermarket ones once the firmness of this product was maintained during storage (initial firmness of 5.4 N and final firmness of 5.3 N after 15 days in S + CIB packaging). Thus, biodegradable packaging developed from agro-industrial residues (CIB and GS) can be considered environmentally-friendly and promising materials to preserve the quality and freshness of carrot cake and cherry tomatoes.

Effects of Dietary Incorporation of Grape Stalks Untreated and Fungi-Treated in Growing Rabbits: A Preliminary Study.

This study aimed to evaluate the effect of the incorporation of untreated grape stalks (UGS) and fungi-treated grape stalks (Lentinula edodes, TGS) in rabbits' diets. The control group was fed with a control diet without grape stalks (C), two experimental groups were fed on diets with 5% and 10% incorporation of UGS (5UGS and 10UGS), and two with 5% and 10% incorporation of TGS (5TGS and 10TGS). Rabbits fed with TGS diets showed higher daily weight gain (p = 0.034), feed conversion rate (p = 0.002), carcass weight (p = 0.038), and reference carcass weight (p = 0.03) when compared to the control diet. Moreover, animals fed with TGS diets showed an increase in the caecum (p = 0.015) and small intestine (p = 0.021) lengths and in the total volatile fatty acid content (p = 0.005) compared to animals fed UGS diets. Blood triglyceride levels were lower in animals fed with TGS diets compared to UGS (p = 0.005) and C (p ≤ 0.001) diets (12% and 19% lower, respectively), and a trend to lower cholesterol levels was observed (p = 0.071). Meat from rabbits fed with TGS diets had higher levels of linoleic acid, γ-linolenic, ∑ω-6, ∑PUFA, and ∑PUFA/∑SFA ratio compared to rabbits fed with the C diet. Results indicated that grape stalks (UGS and TGS) could be effectively used as an alternative raw material in rabbits' diets without compromising animal performance.

Techno-economic evaluation and life cycle assessment of a biorefinery using winery waste streams for the production of succinic acid and value-added co-products.

This study presents techno-economic evaluation and life cycle assessment of a novel biorefinery using the three main waste streams generated by wineries for the production of bio-based succinic acid (SA), crude phenolic-rich extract, grape-seed oil, calcium tartrate and crude tannin-rich extract. Process design has been employed for the estimation of material and energy balances and the sizing of unit operations. The Minimum Selling Price of succinic acid production within a winery waste biorefinery ranges from $1.23-2.76/kgSA depending on the market price and the potential end-uses of the extracted fractions. The Global Warming Potential and the Abiotic Depletion Potential of winery waste valorisation through the proposed biorefinery are 1.47 kg CO2-eq per kg dry waste and 25.2 MJ per kg dry waste, respectively. Biorefining of winery waste could lead to the development of a sustainable and novel bioeconomy business model with new market opportunities and efficient waste management.

Biocomposites: could agroindustrial wastes be used as reinforcements in polymers?

The use of agricultural by-products in the production of biocomposite materials is of growing interest worldwide. Mechanical properties and degradation temperature of a biocomposite depend strongly on the characteristics of the selected reinforcement. The present study focuses on the characterization of three lignocellulosic agro-industrial wastes: olive wet husk (OWH), olive pits (OP) and grape stalks (GS), generated by industries of Cuyo region in Argentina. Such characterization comprises proximate analysis, lignocellulosic composition, functional groups, crystalline phases, mineralogical and elemental composition, and thermal properties. The results obtained are of relevance for understanding the final properties of the biocomposites that will be prepared with these lignocellulosic particles, and will allow to determine which of them is the most appropriate for a specific application. This work suggests that OP could have better interfacial interaction with a polymeric matrix.

Batch and Flow Ultrasound-Assisted Extraction of Grape Stalks: Process Intensification Design up to a Multi-Kilo Scale.

Nowadays, approximately 1 billion kg/y of grape stalks, with a remarkable polyphenols content, are produced worldwide. In this paper, the extraction process intensification of polyphenols in water was achieved under ultrasound-assisted recovery, focusing on kinetics and scaling-up factors. Immersion and cup-horn systems were exploited as acoustic cavitation sources, and the total phenolic content (TPC) was chosen to assess the process efficiency. The kinetics were evaluated by Peleg's hyperbolic model, and the effect of both the initial feedstock granulometry and ultrasound size-reduction were determined. The results were compared with conventional extraction methods (data analysis by ANOVA). The best polyphenols yield was obtained after 45 min of sonication, giving between 29.71 and 31.89 mg/g (gallic acid equivalents over the dry matter). The extracts were characterized using HPLC-DAD, UPLC-ESI-MS/MS, DPPH• assay (2,2-diphenyl-1-picrylhydrazyl), TEAC assay (Trolox equivalent antioxidant capacity), and proanthocyanidin content determination. The flow-mode extraction procedure of grape stalks (2 kg) was carried out in a 15 L reactor. A semi-industrial decanter unit and a bag-filter were the keys units of the downstream operations. The resulting particle-free solution underwent nanofiltration on a membrane pilot skid, providing a final polyphenols-enriched stream concentrated up to 355.91%, as shown by the antioxidant activity and TPC.

Pretreatment of Grape Stalks by Fungi: Effect on Bioactive Compounds, Fiber Composition, Saccharification Kinetics and Monosaccharides Ratio.

Grape stalks, an inedible lignocellulosic residue from winemaking and agro-industrial grape juice production, can be valorized as a source of bioactive compounds and as feedstock for the saccharification and bioconversion of soluble sugars. Solid-state fermentation (SSF) by six white-rot fungi was applied as pretreatment. Fiber composition, free radical scavenging activity, four ligninolytic, and three hydrolytic enzyme activities were determined. Saccharification kinetics, yield, and productivity were evaluated and complemented with scanning electron microscopy (SEM), high performance liquid chromatography (HPLC) quantification of monosaccharides, and principal component analysis (PCA). After SSF, the biomass exhibited a drastic free radical scavenging activity decrease and the main enzymes produced were manganese-dependent peroxidase and xylanase. Scanning electron microscopy revealed the erosion of cell walls, and PCA exhibited a negative correlation between saccharification, and neutral detergent fiber and acid detergent lignin. Phlebia rufa pretreated biomass gave the highest sugars yield and productivity, representing a nearly three-fold increase compared to untreated samples. Also, monosaccharides quantification revealed that the 1:1 ratio of glucose to the sum of xylose plus galactose changes to the value of 2:1 after pretreatment. In this work, and for the first time, P. rufa proved to be an effective pretreatment of grape stalks for the saccharification and further bioconversion into value-added chemicals. In addition, lignocellulolytic enzymes were also produced through SSF.

Development of biodegradable starch-based foams incorporated with grape stalks for food packaging.

Biodegradable cassava starch-based foams incorporated with grape stalks were obtained by thermal expansion. The morphology (SEM), chemical structure (FTIR), crystallinity (XRD), and biodegradability of the foams were evaluated. An applicability test was performed in the storage of food. SEM images showed no residue agglomerations and cell structure generally observed in materials obtained by thermal expansion; FTIR analysis verified interactions of foam components. XRD analysis showed native cassava starch characteristic peaks and the loss of crystallinity after the expansion process, with the formation of an amorphous material. Foams were completely biodegraded after 7 weeks, demonstrating that, for the experimental conditions used, the interactions between the starch and the grape stalks did not generate recalcitrant compounds or structural alterations that would impair foam degradation. Furthermore, the foams added with grape stalks presented good properties in the applicability test, showing a promising application in the storage of foods with low moisture content.

Impact of mesophilic co-composting conditions on the quality of substrates produced from winery waste activated sludge and grape stalks: Lab-scale and pilot-scale studies.

In this study, different amounts of a mixture of winery waste activated sludge and grape stalks were co-composted for 8 weeks, at lab-scale under different temperatures and aeration rates, and at pilot-scale. None of the experiments showed the occurrence of a thermophilic stage, even when the composting temperature was kept at 34 °C, which might suggest biological suppression by the acclimated mesophilic microorganisms ubiquitous to the winery waste activated sludge. The composted substrates were fully characterized by physicochemical analysis, plant growth tests and germination indexes using parsley (Petroselinum crispum) seedlings and seeds. Surprisingly, despite the higher volume reduction at lab-scale, it was the initial mixture and the mixture composted outdoors which presented the best horticultural qualities, with seedling survival rates of 88.9% and 87.0% and modified germination indexes of 54% and 161%, respectively. These findings shed some light on previous contradictory results and allow the development of new recycling strategies.

Wine industry by-product: Full polyphenolic characterization of grape stalks.

In this research work grape stalk samples from the Douro region were analyzed concerning polyphenolic composition. Different solid-liquid extraction conditions were tested for reaching the optimal parameters to obtain higher amounts of polyphenols. In general, the best conditions comprise the use of a mixture of acetone/ethanol/water (1:1:1) at room temperature during 20 min, using a pre-wash treatment with deionized water. The polyphenolic extractions with acetone are generally more effective than without acetone. Total phenolic determination (Folin-Ciocalteu), antioxidant capacity (DPPH/FRAP) and more accurate methods such as HPLC-DAD and HPLC-ESI-MS were performed. An intensive polyphenolic characterization (including a possible identification of a new polyphenol) and compound quantification was achieved. A comparative study between these two analysis approaches was accomplished, which allowed to conclude that the Folin-Ciocalteu and DPPH/FRAP determinations do not always allow a direct correspondence between high phenolic content or antioxidant/reducing capacity and real high polyphenolic content on crude polyphenolic extracts.

Evaluation of a hybrid anaerobic biofilm reactor treating winery effluents and using grape stalks as biofilm carrier.

Wine production processes generate large amount of both winery wastewater and solid wastes. Furthermore, working periods, volumes and pollution loads greatly vary over the year. Therefore, it is recommended to develop a low-cost treatment technology for the treatment of winery effluents taking into account the variation of the organic loading rate (OLR). Accordingly, we have investigated the sequential operation of an anaerobic biofilm reactor treating winery effluents and using grape stalks (GSs) as biofilm carrier with an OLR ranging from 0.65 to 27 gCOD/L/d. The result showed that, during the start-up with wastewater influent, the chemical oxygen demand (COD) removal rate ranged from 83% to 93% and was about 91% at the end of the start-up period that lasted for 40 days. After 3 months of inactivity period of the reactor (no influent feeding), we have succeeded in restarting-up the reactor in only 15 days with a COD removal of 82% and a low concentration of volatile fatty acids (1 g/L), which confirms the robustness of the reactor. As a consequence, GSs can be used as an efficient carrier support, allowing a fast reactor start-up, while the biofilm conserves its activity during a non-feeding period. The proposed hybrid reactor thus permits to treat both winery effluents and GSs.

Grape stalks as substrate for white rot fungi, lignocellulolytic enzyme production and dye decolorization / Uso del escobajo como sustrato para el crecimiento de hongos de la pudrición blanca, la producción de enzimas ligninolíticas y la decoloración de tinturas

The aim of this work was to evaluate the potential of grape stalks, an agroindustrial waste, for growth and lignocellulolytic enzyme production via solid-state fermentation, using the following three white rot fungi: Trametes trogii, Stereum hirsutum and Coriolus antarcticus. The decolorization of several dyes by the above mentioned cultures was also investigated. Similar values of dry weight loss of the substrate were measured after 60 days (33-43 %). C. antarcticus produced the highest laccase and Mn-peroxldase activities (33.0 and 1.6 U/g dry solid). The maximum endoglucanase production was measured in S. hirsutum cultures (10.4 U/g), while the endoxylanase peak corresponded to T. trogii (14.6 U/g). The C. antarcticus/grape stalk system seems potentially competitive in bioremediation of textile processing effluents, attaining percentages of decolorization of 93, 86, 82, 82, 77, and 58 % for indigo carmine, malachite green, azure B, remazol brilliant blue R, crystal violet and xylidine, respectively, in 5 h.

El objetivo de este trabajo fue evaluar el potencial del escobajo, un residuo agroindustrial, como sustrato para el crecimiento y la producción de enzimas lignocelulósicas de tres hongos causantes de pudrición blanca en la madera: Trametes trogii, Stereum hirsutum y Coriolus antarcticus. Para ello se utilizaron técnicas de fermentación en estado sólido. También se ensayó la decoloración de colorantes industriales sobre estos cultivos. La pérdida de peso seco del sustrato fue similar después del día 60 (33-43 %). C. antarcticus produjo las mayores actividades de lacasa y Mn-peroxidasa (33,0 y 1,6 U/g peso seco). La mayor actividad endoglucanasa fue medida en cultivos de S. hirsutum (10,4 U/g), y la mayor actividad endoxilanasa en T. trogii (14,6 U/g). El sistema C. antarcticus/escobap mostró un importante potencial para su aplicación en la biorremediación de efluentes textiles, con porcentajes de decoloración de 93, 86, 82, 82, 77 y 58 % para índigo carmín, verde de malaquita, azure B, azul R brillante de remazol, cristal violeta y xilidina, respectivamente, en 5 h.

Grape stalks as substrate for white rot fungi, lignocellulolytic enzyme production and dye decolorization / Uso del escobajo como sustrato para el crecimiento de hongos de la pudrición blanca, la producción de enzimas ligninolíticas y la decoloración de tinturas

The aim of this work was to evaluate the potential of grape stalks, an agroindustrial waste, for growth and lignocellulolytic enzyme production via solid-state fermentation, using the following three white rot fungi: Trametes trogii, Stereum hirsutum and Coriolus antarcticus. The decolorization of several dyes by the above mentioned cultures was also investigated. Similar values of dry weight loss of the substrate were measured after 60 days (33-43 %). C. antarcticus produced the highest laccase and Mn-peroxldase activities (33.0 and 1.6 U/g dry solid). The maximum endoglucanase production was measured in S. hirsutum cultures (10.4 U/g), while the endoxylanase peak corresponded to T. trogii (14.6 U/g). The C. antarcticus/grape stalk system seems potentially competitive in bioremediation of textile processing effluents, attaining percentages of decolorization of 93, 86, 82, 82, 77, and 58 % for indigo carmine, malachite green, azure B, remazol brilliant blue R, crystal violet and xylidine, respectively, in 5 h.(AU)

El objetivo de este trabajo fue evaluar el potencial del escobajo, un residuo agroindustrial, como sustrato para el crecimiento y la producción de enzimas lignocelulósicas de tres hongos causantes de pudrición blanca en la madera: Trametes trogii, Stereum hirsutum y Coriolus antarcticus. Para ello se utilizaron técnicas de fermentación en estado sólido. También se ensayó la decoloración de colorantes industriales sobre estos cultivos. La pérdida de peso seco del sustrato fue similar después del día 60 (33-43 %). C. antarcticus produjo las mayores actividades de lacasa y Mn-peroxidasa (33,0 y 1,6 U/g peso seco). La mayor actividad endoglucanasa fue medida en cultivos de S. hirsutum (10,4 U/g), y la mayor actividad endoxilanasa en T. trogii (14,6 U/g). El sistema C. antarcticus/escobap mostró un importante potencial para su aplicación en la biorremediación de efluentes textiles, con porcentajes de decoloración de 93, 86, 82, 82, 77 y 58 % para índigo carmín, verde de malaquita, azure B, azul R brillante de remazol, cristal violeta y xilidina, respectivamente, en 5 h.(AU)