Production of antioxidants by non-isothermal autohydrolysis of lignocellulosic wastes

Effect of addition of wheat bran hydrolysate on bread properties

Although the addition of bran to bread makes it healthier and more functional, it brings with it some technological problems. One way to eliminate these problems is hydrothermal pretreatment of wheat bran. In this study, five different ratios (10%, 20%, 30%, 50%, and 100%) of hydrolysates from hydrothermal pretreatment of wheat bran (150°C, 30 min) were substituted with dough-kneading water during dough kneading for bread making. The physical, chemical, functional, textural and important starch fractions of the bread produced were determined. The addition of hydrolysate in different amounts to the dough-kneading water resulted in similar physical properties (height, specific volume, and crust color) as the control bread. While the addition of hydrolysate decreased the hardness of the breads, it positively improved important starch fractions (increasing the amount of slowly digestible starch and decreasing the amount of rapidly digestible starch). It also increased antioxidant capacity (iron (III) reducing antioxidant power, ABTS, and DPPH (2,2-diphenyl-1-picrylhydrazyl) and reduced the starch hydrolysis index of the bread. It was shown that the hydrolysate obtained after the hydrothermal treatment of bran could be used in bread making to satisfy the demand for products preferred by consumers from both health and sensory points of view.

Green solvents extraction-based detoxification to enhance the enzymatic hydrolysis of steam-exploded lignocellulosic biomass and recover bioactive compounds

A novel strategy for pre-treated biomass detoxification combining emerging green solvents and low environmental impact extraction technologies was evaluated. Steam-exploded biomass was subjected to microwave-assisted or orbital shaking extraction using bio-based or eutectic solvents. The extracted biomass was enzymatically hydrolysed. The potential of this detoxification methodology was studied in terms of phenolic inhibitors extraction and sugar production improvement. The effect of adding a post-extraction water washing step before hydrolysis was also evaluated. Excellent results were achieved when steam-exploded biomass was subjected to the microwave-assisted extraction combined with the washing step. The highest sugar production was achieved when ethyl lactate was used as extraction agent (49.80 ± 3.10 g total sugar/L) over the control (30.43 ± 0.34 g total sugar/L). Results suggested that a detoxification step based on green solvents would be a promising option to extract phenolic inhibitors, which can be revalorized as antioxidants, and improve the sugar production from the extracted pre-treated biomass.

Current Options in the Valorisation of Vine Pruning Residue for the Production of Biofuels, Biopolymers, Antioxidants, and Bio-Composites following the Concept of Biorefinery: A Review

Europe is considered the largest producer of wine worldwide, showing a high market potential. Several wastes are generated at the different stages of the wine production process, namely, vine pruning, stalks, and grape marc. Typically, these residues are not used and are commonly discarded. Portugal generates annually approximately 178 thousand metric tons of wine production waste. In this context, the interest in redirecting the use of these residues has increased due to overproduction, great availability, and low costs. The utilization of these lignocellulosic biomasses derived from the wine industry would economically benefit the producers, while mitigating impacts on the environment. These by-products can be submitted to pre-treatments (physical, chemical, and biological) for the separation of different compounds with high industrial interest, reducing the waste of agro-industrial activities and increasing industrial profitability. Particularly, vine-pruning residue, besides being a source of sugar, has high nutritional value and may serve as a source of phenolic compounds. These compounds can be obtained by bioconversion, following a concept of biorefinery. In this framework, the current routes of the valorisation of the pruning residues will be addressed and put into a circular economy context.

Implementation of Auto-Hydrolysis Process for the Recovery of Antioxidants and Cellulose from Wheat Straw

Wheat straw is an easily affordable, cost-effective and natural source of antioxidants and cellulose, but its full potential is not yet utilized. In the present investigation, an auto-hydrolytic process was applied to recover both antioxidant phenolic compounds and cellulose from wheat straw. Two three-step acid/alkaline fractionation processes were applied differing for the first step: a conventional mild acid hydrolysis or an auto-hydrolysis. The liquors from the first step were analyzed for the recovery of antioxidants, while the final residues from the whole process were analyzed for cellulose yield and purity. The auto-hydrolysis process led to a higher yield in antioxidants but also in sugars (glucose and xylose) and sugar degradation products (5-HMF, 5-MF, furfural) than the acid hydrolysis process. The overall cellulose recovery (about 45% g/100 gcellulose wheat straw dm) and purity was comparable in the two processes; therefore, the auto-hydrolysis-based process could be recommended as a potentially more environmentally friendly process to recover antioxidants and cellulose from wheat straw for different applications. Finally, a first study on the optimization of hydrolysis step was provided from the point of view of improving the cellulose yield, monitoring the sugars release during both the acid hydrolysis and the auto-hydrolysis process.

Optimizing the extraction of phenolic antioxidants from chestnut shells by subcritical water extraction using response surface methodology

The objective of this study was to evaluate the optimal Subcritical Water Extraction (SWE) conditions of antioxidants and polyphenols from chestnut shells using Response Surface Methodology (RSM). A central composite design (CCD) was conducted to analyse the time (6-30 min) and temperature (51-249 °C) effects in antioxidant activity (ABTS, DPPH and FRAP) and Total Phenolic Compounds (TPC). TPC ranged from 315.21 to 496.80 mg gallic acid equivalents (GAE)/g DW; the DPPH from 549.23 to 1125.68 mg Trolox equivalents (TE)/g DW; ABTS varied between 631.16 and 965.45 mg ascorbic acid equivalents (AAE)/g DW and FRAP from 2793.95 to 11393.97 mg ferrous sulphate equivalents (FSE)/g DW. The optimal extraction conditions were 30 min/220 °C, revealing excelling scavenging efficiencies against HOCl (IC₅₀ = 0.79 µg/mL) and O₂^- (IC₅₀ = 12.92 µg/mL) without toxicity on intestinal cells (0.1 µg/mL). The phenolic composition revealed high amounts of pyrogallol and protocatechuic acid. SWE can be a useful extraction technique for the recovery of polyphenolics from chestnut shells.

Integrated biorefinery approach to valorize winery waste: A review from waste to energy perspectives

The ever-increasing environmental crisis, depleting natural resources, and uncertainties in fossil fuel availability have rekindled researchers' attention to develop green and environmentally friendlier strategies. In this context, a biorefinery approach with a zero-waste theme has stepped-up as the method of choice for sustainable production of an array of industrially important products to address bio-economy challenges. Grape winery results in substantial quantities of solid organic and effluent waste, which epitomizes an increasing concentration of pollution problems with direct damage to human health, economy and nature. From the perspective of integrated biorefinery and circular economy, winery waste could be exploited for multiple purpose value-added products before using the biomass for energy security. This review covers state-of-the-art biorefinery opportunities beyond traditional methods as a solution to overcome many current challenges such as waste minimization in grape leaves, stems, seeds, pomace, wine lees, vinasse etc. and the biosynthesis of various high-value bioproducts viz., phenolic compounds, hydroxybenzoic acids, hydroxycinnamic acids, flavonoids, tartaric acids, lignocellulosic substrates etc.. The critical discussion on the valorization of winery waste (solid, liquid, or gaseous) and life cycle assessment was deployed to find a sustainable solution with value added energy products in an integrated biorefinery approach, keeping the environment and circular economy in the background.

Comparative assessment of solvents and lignocellulolytic enzymes affiliated extraction of polyphenols from the various lignocellulosic agro-residues: identification and their antioxidant properties

The present investigation was aimed to utilize lignocellulosic agro-residues and compare the extraction of polyphenols utilizing lignocellulolytic enzymes secreted by Sphingobacterium sp. ksn and with that of the solvents (ethanol, methanol) affiliated methods. The maximum amount of polyphenols, flavonoids and tannins were 94.29, 11.36, and 79.21 g 100 g^-1 respectively, found in the extracts obtained by enzymes affiliated extraction of coffee cherry husk (CCH). The phenolics namely, gallic acid, caffeic acid, coumaric acid, 1-hydroxybenzoic acid, 2,5-dihydroxybenzoic acid, p-hydroxybenzaldehyde were commonly found whereas syringic acid, quercetin, kaempferol, and epicatechin were hardly found in the extracts of agro-residues. The extracts of CCH shown maximum antioxidant properties for DPPH, ABTS, and FRAP. The present study reports that the affiliation of enzymes for the extraction of polyphenols from agro-residues is more efficient than that of the solvents affiliation and CCH as the good source of polyphenols.

Application of hull, bur and leaf chestnut extracts on the shelf-life of beef patties stored under MAP: Evaluation of their impact on physicochemical properties, lipid oxidation, antioxidant, and antimicrobial potential

The impact of chestnut extracts (Castanea sativa) from leaf, bur and hull at different concentrations on the shelf-life of beef patties during 18 days of refrigerated storage at (2 ± 1 °C) was studied and compared to control and synthetic antioxidant (BHT) samples. Total phenolics and in vitro antioxidant capacity of extracts were evaluated by using DPPH, FRAP, reducing power and oil accelerated oxidation test (peroxide value, conjugated dienes, p-anisidine and fatty acid profile). The microbial spoilage, colour parameters, lipid oxidation and sensorial properties were used to assess antioxidant activity in beef patties. The highest total phenolic content was found in bur extracts (43.68 ± 2.05 g/100 g lyophilized extract). In addition, bur extracts showed the strongest antioxidant activity in all in vitro assays. None of the evaluated extracts showed antimicrobial activity. The addition of hull extracts at 500 and 1000 ppm resulted in the highest (P < .05) metmyoglobin reduction in the surface of beef patties compared to control and the others batches after 15 days of storage. However, leaf extract at 1000 ppm was the most effective in inhibiting lipid oxidation. Overall, for all extracts evaluated, the increase in the concentration of chestnuts extracts improved the desired effect, hence our findings suggest the possibility of using chestnuts extracts (preferable a mixture from the different parts of the chestnut byproducts) rather than synthetic antioxidants. Finally, sensorial analysis did not show any detrimental effect from a sensory point of view, after the addition of chestnuts extracts, thus indicating a potential to develop chestnut extracts as food ingredients.

Addressing Facts and Gaps in the Phenolics Chemistry of Winery By-Products

Grape and wine phenolics display a noticeable structural diversity, encompassing distinct compounds ranging from simple molecules to oligomers, as well as polymers usually designated as tannins. Since these compounds contribute critically to the organoleptic properties of wines, their analysis and quantification are of primordial importance for winery industry operators. Besides, the occurrence of these compounds has been also extensively described in winery residues, which have been pointed as a valuable source of bioactive phytochemicals presenting potential for the development of new added value products that could fit the current market demands. Therefore, the cumulative knowledge generated during the last decades has allowed the identification of the most promising compounds displaying interesting biological functions, as well as the chemical features responsible for the observed bioactivities. In this regard, the present review explores the scope of the existing knowledge, concerning the compounds found in these winery by-products, as well as the chemical features presumably responsible for the biological functions already identified. Moreover, the present work will hopefully pave the way for further actions to develop new powerful applications to these materials, thus, contributing to more sustainable valorization procedures and the development of newly obtained compounds with enhanced biological properties.

A multifunctional extract from corn steep liquor: antioxidant and surfactant activities

In the last few years the awareness of consumers and institutions about the impact that our industrial processes has on health and the environment has increased, demanding more natural products. In this work, a multifunctional bioactive extract with surfactant and antioxidant properties, composed mainly of C16 and C18 fatty acids, and phenolic compounds (vanillic acid, p-coumaric acid, ferulic acid, sinapic acid and quercetin) was obtained from corn steep liquor (CSL). Different liquid-liquid extraction protocols were evaluated obtaining a natural extract, which was able to reduce the surface tension of water by more than 30 units, showing antioxidant activity with an EC50 of 8.51 mg mL(-1) and a yield of 6.85 g of extract per kg of CSL. Additionally, it was observed that after liquid-liquid extraction with chloroform, the aqueous phase can be subjected to a hydrothermal treatment, followed by extraction with ethyl acetate, in order to obtain another extract (24.7 g of extract per kg of CSL) with a higher antioxidant capacity (EC50 of 4.02 mg mL(-1)). In this case the antioxidant extract is composed of protocatechuic acid, vanillic acid, caffeic acid, epicatechin, p-coumaric acid, ferulic acid, sinapic acid and quercetin.

Bioactive packaging using antioxidant extracts for the prevention of microbial food-spoilage

Bioactive food packaging is an innovative approach for the prevention of the growth of food-spoilage microorganisms.

Castanea sativa by-products: a review on added value and sustainable application

Castanea sativa Mill. is a species of the family Fagaceae abundant in south Europe and Asia. The fruits (chestnut) are an added value resource in producing countries. Chestnut economic value is increasing not only for nutritional qualities but also for the beneficial health effects related with its consumption. During chestnut processing, a large amount of waste material is generated namely inner shell, outer shell and leaves. Studies on chestnut by-products revealed a good profile of bioactive compounds with antioxidant, anticarcinogenic and cardioprotective properties. These agro-industrial wastes, after valorisation, can be used by other industries, such as pharmaceutical, food or cosmetics, generating more profits, reducing pollution costs and improving social, economic and environmental sustainability. The purpose of this review is to provide knowledge about the type of chestnut by-products produced, the studies concerning its chemical composition and biological activity, and also to discuss other possible applications of these materials.

Industrial robust yeast isolates with great potential for fermentation of lignocellulosic biomass

The search of robust microorganisms is essential to design sustainable processes of second generation bioethanol. Yeast strains isolated from industrial environments are generally recognised to present an increased stress tolerance but no specific information is available on their tolerance towards inhibitors that come from the pretreatment of lignocellulosic materials. In this work, a strategy for the selection of different yeasts using hydrothermal hydrolysate from Eucalyptus globulus wood, containing different concentrations of inhibitors, was developed. Ten Saccharomyces cerevisiae and four Kluyveromyces marxianus strains isolated from industrial environments and four laboratory background strains were evaluated. Interestingly, a correlation between final ethanol titer and percentage of furfural detoxification was observed. The results presented here highlight industrial distillery environments as a remarkable source of efficient yeast strains for lignocellulosic fermentation processes. Selected strains were able to resourcefully degrade furfural and HMF inhibitors, producing 0.8g ethanol/Lh corresponding to 94% of the theoretical yield.

Erythrocytes and cell line-based assays to evaluate the cytoprotective activity of antioxidant components obtained from natural sources

Oxidative stress can damage cellular components including DNA, proteins or lipids, and may cause several skin diseases. To protect from this damage and addressing consumer's appeal to natural products, antioxidants obtained from algal and vegetal extracts are being proposed as antioxidants to be incorporated into formulations. Thus, the development of reliable, quick and economic in vitro methods to study the cytoactivity of these products is a meaningful requirement. A combination of erythrocyte and cell line-based assays was performed on two extracts from Sargassum muticum, one from Ulva lactuca, and one from Castanea sativa. Antioxidant properties were assessed in erythrocytes by the TBARS and AAPH assays, and cytotoxicity and antioxidant cytoprotection were assessed in HaCaT and 3T3 cells by the MTT assay. The extracts showed no antioxidant activity on the TBARS assay, whereas their antioxidant capacity in the AAPH assay was demonstrated. On the cytotoxicity assays, extracts showed low toxicity, with IC50 values higher than 200μg/mL. C. sativa extract showed the most favourable antioxidant properties on the antioxidant cytoprotection assays; while S. muticum and U. lactuca extracts showed a slight antioxidant activity. This battery of methods was useful to characterise the biological antioxidant properties of these natural extracts.

Induction of laccase activity in the white rot fungus Pleurotus ostreatus using water polluted with wheat straw extracts

The purpose of this work was to explore the use of polluted water effluents from wheat straw using industries as inducers of lignocellulolytic enzymatic activities in cultures of white rot basidiomycetes. For this purpose, we studied the effect of a wheat straw water extract on the evolution of the laccase activity recovered from submerged cultures of Pleurotus ostreatus made in different media and under various culture conditions. Our results demonstrated an accumulative induction effect in all the cultures and conditions tested. This induction is parallel to changes in the laccase electrophoretic profiles recovered from the culture supernatants. The isoenzyme that appeared to be mainly responsible for the laccase activity under these conditions was laccase 10, as confirmed by sequencing the induced protein. These results support the idea of using wheat straw effluents as inducers in liquid cultures of P. ostreatus mycelia for the production of ligninolytic enzymatic cocktails.

Solvent extraction of antioxidants from steam exploded sugarcane bagasse and enzymatic convertibility of the solid fraction

Solvent extraction of steam exploded lignocellulosic biomass may be a potential way to obtain antioxidative extracts and to enhance the enzymatic convertibility of the solid residue. Boiling solvent extraction (BSE) showed higher solid and phenolic yields than room temperature extraction. Solubilities of phenolics and sugars were higher in anhydrous ethanol (AE) and deionized water (DW) than in ethyl acetate under each individual extraction condition. The antioxidant activities of the AE and DW extract obtained under BSE were better than those of 10mM vitamin C. Conversion of the solid fractions into reducing sugar using Celluclast 1.5L and Novozym 188 after AE and DW extraction was 95.13% and 92.97%, respectively, higher than that obtained with SESB (88.95%).

Autohydrolysis and organosolv process for recovery of hemicelluloses, phenolic compounds and lignin from grape stalks

A combination of two environment-friend processes for hemicelluloses and lignin recovery from red grape stalks were investigated: an autohydrolysis pretreatment at 180°C for 30 min followed by a non-catalysed ethanol organosolv step at 180°C for 90 min. Hemicelluloses were precipitated by ethanol addition to autohydrolysis liquor, while lignin was tentatively precipitated by acidification of liquors from both the processes. Results suggest that stalks hemicelluloses can be easily hydrolysed requiring a milder treatment to reduce sugar degradation, while the organosolv process did not give a consistent delignification. Autohydrolysis allowed a recovery of 2% (on stalks d.m.) of total phenols in the liquor. Organosolv liquor had a higher concentration of phenols (corresponding to 0.72% of stalks d.m.) which almost completely precipitated with lignin.

Valorization of winery waste vs. the costs of not recycling

Wine production generates huge amounts of waste. Before the 1990s, the most economical option for waste removal was the payment of a disposal fee usually being of around 3000 Euros. However, in recent years the disposal fee and fines for unauthorized discharges have increased considerably, often reaching 30,000-40,000 Euros, and a prison sentence is sometimes also imposed. Some environmental friendly technologies have been proposed for the valorization of winery waste products. Fermentation of grape marc, trimming vine shoot or vinification lees has been reported to produce lactic acid, biosurfactants, xylitol, ethanol and other compounds. Furthermore, grape marc and seeds are rich in phenolic compounds, which have antioxidants properties, and vinasse contains tartaric acid that can be extracted and commercialized. Companies must therefore invest in new technologies to decrease the impact of agro-industrial residues on the environment and to establish new processes that will provide additional sources of income.

Purified phenolics from hydrothermal treatments of biomass: ability to protect sunflower bulk oil and model food emulsions from oxidation

The phenolic fractions released during hydrothermal treatment of selected feedstocks (corn cobs, eucalypt wood chips, almond shells, chestnut burs, and white grape pomace) were selectively recovered by extraction with ethyl acetate and washed with ethanol/water solutions. The crude extracts were purified by a relatively simple adsorption technique using a commercial polymeric, nonionic resin. Utilization of 96% ethanol as eluting agent resulted in 47.0-72.6% phenolic desorption, yielding refined products containing 49-60% w/w phenolics (corresponding to 30-58% enrichment with respect to the crude extracts). The refined extracts produced from grape pomace and from chestnut burs were suitable for protecting bulk oil and oil-in-water and water-in-oil emulsions. A synergistic action with bovine serum albumin in the emulsions was observed.