Integral valorisation of walnut shells based on a three-step sequential delignification.

Walnut kernels represent no more than 50-60% of the total weight of the fruit, so the sum of walnut shells generated every year is immense. Nonetheless, these shells could be further valorised for the extraction of their main constituents following a biorefinery scheme. Hence, the objective of this work was an integral valorisation of walnut shells, which involved a sequential organosolv delignification (200 °C, 90 min, 70/30 v/v EtOH/H2O, LSR 6:1) and several posterior non-isothermal hydrothermal treatments (180, 195 and 210 °C, LSR 8:1). Moreover, the spent solids after the aforementioned treatments were evaluated as possible sources of cellulose nanocrystals. The results showed that the sequential organosolv delignifications presented relative lignin yields up to 60%, which leaded to lignins that just differed on their molecular weight distributions. The hydrothermal treatments were efficient for the removal of still present hemicelluloses (14.7-71.8%), and permitted a successful cellulose nanocrystal obtaining whereas the spent solid from the delignification stages did not. Thus, this study presented an innovative strategy for the integral valorisation of walnut shells.

Recent advances in food products fortification with anthocyanins.

Anthocyanins are polyphenolic compounds belonging to the group of flavonoids in charge of providing red, purple, and blue colourations to different parts of trees and plants, such as leaves, flowers, fruits, roots, and stems. These substances have potential health benefits due to characteristics such as antioxidant and anti-inflammatory properties, which could be leveraged in the food industry. However, the use and handling of anthocyanins are conditioned due to the low stability of these molecules. For this reason, the application of adequate extraction, purification and stabilization techniques is required for its subsequent management. In this regards, green extraction methods and novel stabilization techniques are of particular interest in the utilization of these biocompounds. This review provides in-depth information about the extraction, purification, and stabilization of anthocyanins from different plant sources. Additionally, this work highlights the potential use of anthocyanins in the food industry for the formulation of different fortified foods and beverages, which could have beneficial health effects. Green technologies, are a promising tool to recover extracts rich in anthocyanins from different vegetable matrices, including by-products. The extracts obtained can be easily used in the fortification of baked foods, dairy products, and different beverages.

Edible Mushrooms as Functional Ingredients for Development of Healthier and More Sustainable Muscle Foods: A Flexitarian Approach.

Consumers are increasingly interested in nutritious, safe and healthy muscle food products with reduced salt and fat that benefit their well-being. Hence, food processors are constantly in search of natural bioactive ingredients that offer health benefits beyond their nutritive values without affecting the quality of the products. Mushrooms are considered as next-generation healthy food components. Owing to their low content of fat, high-quality proteins, dietary fibre and the presence of nutraceuticals, they are ideally preferred in formulation of low-caloric functional foods. There is a growing trend to fortify muscle food with edible mushrooms to harness their goodness in terms of nutritive, bioactive and therapeutic values. The incorporation of mushrooms in muscle foods assumes significance, as it is favourably accepted by consumers because of its fibrous structure that mimics the texture with meat analogues offering unique taste and umami flavour. This review outlines the current knowledge in the literature about the nutritional richness, functional bioactive compounds and medicinal values of mushrooms offering various health benefits. Furthermore, the effects of functional ingredients of mushrooms in improving the quality and sensory attributes of nutritionally superior and next-generation healthier muscle food products are also highlighted in this paper.

Traditional plants from Asteraceae family as potential candidates for functional food industry.

Traditional plants have been used in the treatment of disease and pain due to their beneficial properties such as antioxidant, antiinflammation, analgesic, and antibiotic activities. The Asteraceae family is one of the most common groups of plants used in folk medicine. The species Achillea millefolium, Arnica montana, Bellis perennis, Calendula officinalis, Chamaemelum nobile, Eupatorium cannabinum, Helichrysum stoechas, and Taraxacum officinale have been used in different remedies in Northwest Spain. Besides health benefits, some of them like C. nobile and H. stoechas are already employed in cooking and culinary uses, including cocktails, desserts, and savory dishes. This study aimed to review the current information on nutritive and beneficial properties and bioactive compounds of these plants, which are not mainly used as foods but are possible candidates for this purpose. The report highlights their current uses and suitability for the development of new functional food industrial applications. Phenolic compounds, essential oils, and sesquiterpene lactones are some of the most important compounds, being related to different bioactivities. Hence, they could be interesting for the development of new functional foods.

Hydrothermal treatments of walnut shells: A potential pretreatment for subsequent product obtaining.

Walnuts are nowadays widely consumed. Since the edible part of walnuts does not account more than 50-60% of their total weight, the total amount of shells produced annually is huge. However, as walnut shells are part of lignocellulosic biomass, they could be valorised via a biorefinery approach in order to extract their diverse constituents. For this reason, the aim of this work was to valorise walnut shells by a biorefinery scheme. The latest involved multiple microwave assisted and conventional hydrothermal treatments for the subsequent valorisation of oligosaccharides. Then, an organosolv delignification of the solid that permitted the maximum oligosaccharide yield was performed, in order to isolate the lignin. Finally, it was treated for cellulose nanocrystal obtaining. The results showed, on the one hand, that the hydrothermal treatments leaded to xyloligossacharide-rich liquors (1-17 g/L). On the other hand, the organosolv delignification resulted into the extraction of a highly pure lignin (93.6%) and a weight average molecular weight of 7000 Da. Moreover, the solid from the delignification treatment was suitable for a successful nanocrystal production. The extracted fractions could be employed in many applications and could be considered renewable precursors for new materials and chemicals. Hence, the proposed biorefinery scheme would allow an integral valorisation of currently undervalued walnut shells.

Influence of the heating mechanism during the aqueous processing of vine shoots for the obtaining of hemicellulosic oligosaccharides.

This work deals with the revalorization of an important winery residue such as the vine shoots by the obtaining of oligosaccharides with potential prebiotic activity. The manufacture of these added-value products was performed by an autohydrolysis treatment assisted with microwaves to make the process less time consuming and more environmentally friendly. The influence of the reaction time (0-40 min) and the temperature (140-200) on the production of oligosaccharides during the microwave-assisted autohydrolysis was evaluated. The highest concentration of oligosaccharides (168.3 g/Kg oven-dried vines shoots) was achieved during the treatment carried out at 180 °C for 20 min. To assess the benefits of the assistance of the autohydrolysis treatment with the microwaves a conventionally heated treatment was performed using conditions (180 °C for 15 min) that provoked similar effects on the solubilisation of the hemicellulosic fraction. This treatment permitted the obtaining of 203.5 g oligosaccharides/Kg oven-dried vines shoots using 61.0% more of the time needed to carry out the microwaves-assisted autohydrolysis. Although the microwave-assisted treatment permitted the manufacture of a lower amount of oligosaccharides, only consumed 28.8% of the energy needed to perform the conventionally heated treatment. The oligosaccharides manufactured by the two treatments were substituted xyloglucans with different polymerization and acetylation degrees, which due to their potential prebiotic activity could be highly appreciated by pharmaceuticals and food industries. Thus, this work demonstrated the environmental sustainability of the microwave-assisted autohydrolysis for the revalorisation of the vine shoots.

Valorization of by-products from olive oil industry and added-value applications for innovative functional foods.

BACKGROUND: In the last years, the consumption of olive oil has experienced a sharp rise due to its organoleptic and healthy properties and with this the wastes and by-products derived from the olive production and the olive oil industry have also increased causing important environmental and economic issues. However, the high content in bioactive compounds of these wastes and by-products makes that its recovery is both a great challenge and an excellent opportunity for the olive oil sector. AIM OF THE REVIEW: This review encompasses the more outstanding aspects related to the advances achieved until date in the olive oil by-products valorisation and added-value applications for innovative functional foods. CONCLUSION: Taking into account the information reported in this manuscript, the development of a multiproduct biorefinery in cascade using eco-friendly technologies interchangable seems a suitable stratety to obtaining high added value compounds from olive oil by-products with applications in the field of innovative functional foods. In addition, this would allow an integral valorization of these residues enhancing the profitability of the olive oil industry. On the other hand, the biocompounds fom olive oil by-products have been described by their interesting bioactivities with beneficial properties for the consumers' health; therefore, their incorporation into the formulation of functional foods opens new possibilities in the field of innovative foods. Future perspective: Despite the studies descibed in the literature, more research on the healthy properties of the recovered compounds and their interactions with food components is key to allow their reintegration in the food chain and therefore, the removal of the olive oil by-products.

Value-Added Compound Recovery from Invasive Forest for Biofunctional Applications: Eucalyptus Species as a Case Study.

From ancient times, the medicinal properties of the different Eucalyptus species are well known. In fact, plants from this family have been used in folk medicine as antiseptics, and to treat different ailments of the upper respiratory tract such as sinus congestion, common cold, or influenza. Moreover, other biological activities were described for Eucalyptus species such as antioxidant and antimicrobial properties. In the last few decades, numerous investigations revealed that the compounds responsible for these properties are secondary metabolites that belonging to the group of phenolic compounds and are present in different parts of the plants such as leaves, bark, wood, fruits, and stumps. The increasing demand for natural compounds that can substitute synthetic antioxidants and the increase in resistance to traditional antibiotics have boosted the intense search for renewable natural sources containing substances with such bioactivities, as well as greener extraction technologies and avant-garde analytical methods for the identification of the target molecules. The literature data used in this paper were collected via Scopus (2001-2020) using the following search terms: Eucalyptus, extraction methods, phenolic compounds, and biological activities. This review collects the main studies related to the recovery of value-added compounds from different Eucalyptus species, as well as their biofunctional applications.

Multiproduct biorefinery based on almond shells: Impact of the delignification stage on the manufacture of valuable products.

In this work, an integral valorisation of almond shells through a biorefinery approach was studied. The three main components of almond shells were extracted, isolated and characterised. The autohydrolysis process permitted the extraction of the hemicellulosic fraction obtaining a liquor rich in xylooligosaccharides (22.12 g/L). Then, two different delignification processes, alkaline and organosolv treatments, were proposed to obtain a very high purity lignin (≈90%) which could be further valorised for a wide variety of applications. The valorisation of the high cellulosic content of the delignified solids was carried out using two different methods. On the one hand, producing cellulose nanocrystals and on the other hand obtaining glucose by an enzymatic hydrolysis as well as a spent solid mainly composed by lignin (≈78 wt%). Thus, the proposed biorefinery approach could contribute to a circular economy as all the main components of the almond shells could be revalorised by environmentally friendly procedures.

Comparative study of biorefinery processes for the valorization of fast-growing Paulownia wood.

In this work, valorization of Paulownia wood (PW) was proposed following several process configurations for biofuels and value-added compounds production. Firstly, autohydrolysis and ethanol-organosolv strategies were assessed separately for the fractionation of PW to enhance the enzymatic digestibility of cellulose. A third strategy focused on a sequential process (autohydrolysis and organosolv) was explored. Two temperatures were selected for the first stage of the combined process. High concentration of oligosaccharides (26.29 g/L) and high concentration of degradation products (17.21 g/L) were obtained at 210 and 230 °C, respectively. The solids obtained from both pretreatments were subjected to organosolv delignification (200 °C, 3 h and 50% ethanol) achieving delignification of 58 and 30% for the autohydrolyzed biomass at 210 °C and 230 °C, respectively. The combined process resulted in susceptible biomass able to produce 64 g/L of ethanol. Therefore, the strategies explored in this work open the possibility to build a refinery around Paulownia wood.

Pomegranate Peel as Suitable Source of High-Added Value Bioactives: Tailored Functionalized Meat Products.

In the last few years, the consumer's concern with the relationship between health and diet has led to the search of foods with functional properties beyond the nutritional. In this framework, the consumption of pomegranate has increased due to their sensorial attributes and remarkable amounts of bioactive compounds, which generate, at the same time, huge amounts of by-products. A search in the Scopus database for the last 10 years has revealed the rising interest in pomegranate peel (PP), the main residue from this fruit. The meat industry is a food sector that has had to search for new alternatives to substitute the use of synthetic preservatives by new natural additives, to extend the self-life and keep the quality attributes of their processed products. This review sets out the main bioactivities of PP extracts, and their incorporation in meat products is elaborated. PP is a good source of bioactive compounds, including phenolic acids, flavonoids and hydrolyzable tannins, which have beneficial health effects. It can be concluded that the reformulation of meat products with PP extracts is a suitable strategy for enhancing their technological characteristics, in addition to conferring functional properties that make them healthier and potentially more acceptable for the consumer.

Valorization of horse chestnut burs to produce simultaneously valuable compounds under a green integrated biorefinery approach.

A biorefinery scheme for the valorization of horse chestnut biowastes (a municipal solid waste) into added value bioactive compounds is proposed in this work. The bur fraction of horse chestnut was evaluated as a novel and cheap renewable feedstock to obtain valuable compounds suitable for their use in industrial applications. The integrated valorization scheme comprised an initial hydroethanolic extraction of antioxidant compounds (optimized through surface response methodology), the alkaline delignification of the exhausted solid to obtain a lignin-enriched fraction, and the enzymatic digestibility of the remaining cellulose fraction to produce fermentable sugars. In addition, the structural characterization of the extract by FT-IR and TGA was performed, and the analysis by UPLC-DAD-ESI-MS allowed the tentative identification of eleven antioxidant phenolic compounds. The application of this multiproduct valorization approach led to the production of 13 kg antioxidant extracted compounds, 33.2 kg lignin and 14.5 kg glucose per each 100 kg of horse chestnut burs, which demonstrates the great potential of this residue as a biorefinery substrate.

Green sustainable process to revalorize purple corn cobs within a biorefinery frame: Co-production of bioactive extracts.

Purple corn (Zea mays L.) is used for the preparation of traditional drinks and desserts, generating great quantities of residues. The scarce information about purple corn cob (PCC) is encouraging an interest in exploring its potential as a valuable source of bioactive compounds with benefits for human health. In this study, a green method based on hydrothermal processing was used for the simultaneous extraction of oligosaccharides and phenolic compounds from PCC. For this purpose, the effects of three factors (time, temperature and pH) on the oligosaccharide content (OSC), total phenolic content (TPC), total flavonoid content (TFC), total anthocyanin content (TAC), as well as on the antioxidant activity measured with three different methods (DPPH, ABTS and FRAP) were evaluated. The bioactive extract obtained under optimal conditions presented a high content of bioactive compounds exhibiting a notable antioxidant capacity and moderate inhibitory activities towards xanthine oxidase. This extract was also structurally characterized by FTIR, HPAEC-DAD, MALDI-TOF-MS and TGA, and the HPLC-ESI-MS analysis led to the tentative identification of 15 antioxidant phenolic compounds. Thus, this research demonstrated that this residue from the food industry has a high potential for obtaining several bioactive compounds that can be utilized as multi-functional ingredients in the food and pharmaceutical industries.

Tomato as Potential Source of Natural Additives for Meat Industry. A Review.

Tomato industry produces huge amounts of by-products that represent an environmental and economic problem. However, these by-products contain multiple bioactive compounds, which would make them a renewable source for obtaining natural antioxidants and colourants (carotenoids). This is in line with the preferences of the current consumer who demands more natural and healthy products. However, the lipophilic character of carotenoids means that their extraction must be carried out using toxic organic solvents. To overcome environmental and health problems of organic solvents, the application of supercritical fluid extraction (SFE) for the extraction of lipophilic compounds such as lycopene was used successfully, achieving yields similar to those obtained with conventional techniques. Nonetheless, the extraction conditions must be carefully selected, to obtain high yields and at the same time maintain a high antioxidant capacity. On the other hand, the use of tomato and tomato extracts as natural additives in meat products are reduced in comparison with other natural antioxidant/colourant extracts. However, different researches conclude that the use of tomato improved nutritional quality, reduced lipid oxidation and increased stability during the shelf-life period of meat products, while retaining or increasing sensory properties and overall acceptability, which converts tomato by-products into a promising source of natural additives.

Innovative Green Technologies of Intensification for Valorization of Seafood and Their by-Products.

The activities linked to the fishing sector generate substantial quantities of by-products, which are often discarded or used as low-value ingredients in animal feed. However, these marine by-products are a prominent potential good source of bioactive compounds, with important functional properties that can be isolated or up-concentrated, giving them an added value in higher end markets, as for instance nutraceuticals and cosmetics. This valorization of fish by-products has been boosted by the increasing awareness of consumers regarding the relationship between diet and health, demanding new fish products with enhanced nutritional and functional properties. To obtain fish by-product-derived biocompounds with good, functional and acceptable organoleptic properties, the selection of appropriate extraction methods for each bioactive ingredient is of the outmost importance. In this regard, over the last years, innovative alternative technologies of intensification, such as ultrasound-assisted extraction (UAE) and supercritical fluid extraction (SFE), have become an alternative to the conventional methods in the isolation of valuable compounds from fish and shellfish by-products. Innovative green technologies present great advantages to traditional methods, preserving and even enhancing the quality and the extraction efficiency, as well as minimizing functional properties' losses of the bioactive compounds extracted from marine by-products. Besides their biological activities, bioactive compounds obtained by innovative alternative technologies can enhance several technological properties of food matrices, enabling their use as ingredients in novel foods. This review is focusing on analyzing the principles and the use of UAE and SFE as emerging technologies to valorize seafoods and their by-products.

Production and characterization of lignin and cellulose fractions obtained from pretreated vine shoots by microwave assisted alkali treatment.

This work deals with the optimization of the second stage of a biorefinery scheme to separate simultaneously cellulose and lignin from hydrothermally pre-treated vine shoots. For this, the suitability of the microwave-assisted alkaline delignification was assessed and optimized through a Box-Wilson experimental design. The optimum conditions (150 °C, 6 wt% NaOH, 30 min) allowed maximizing the lignin removal (82 wt%) and minimizing the loss of the cellulose (35 wt%) present in the pre-treated vine shoots. A thorough characterization of the two fractions obtained at optimum conditions was performed: the cellulose rich solid was analyzed by XRD and FTIR and the lignin was subjected to HPSEC, Py/GC-MS, 13C- and 1H NMR. This purposed second stage would allow performing an integral biorefinery with low energy requirements and environmentally friendly conditions. This approach aligns with the circular economy and the zero waste production philosophies, promoting the sustainable development.

Vine shoots as new source for the manufacture of prebiotic oligosaccharides.

Vine shoots were subjected to a hydrothermal treatment to cause the selective solubilisation of the hemicelluloses. The hemicelluloses solubilisation products were refined by a sequential processing with nanofiltration and ion exchange obtaining a refined product with a purity of 99%. A depth chemical and structural characterization of the purified oligosaccharide mixture from vine shoots was performed for the first time by HPLC, FTIR, HPAEC-PAD, MALDI-TOF and UPLC-DAD-ESI-MS. The characterization showed the presence of oligosaccharide mixtures with a wide polymerization degree (DP = 2-17) and a rich substitution pattern. Moreover, the thermal behaviour of the mixture was evaluated by TGA in order to obtain information about the thermal and storage conditions during its incorporation into processed functional foods. The thermal and acid stability of the obtained oligosaccharides was also evaluated corroborating their resistance to the digestive conditions. The assessment of the prebiotic activity of the digested mixture was carried out by in vitro fermentability with faecal inocula from human volunteers by the monitoring of short chain fatty acids production and the population dynamic of bifidobacteria by FISH.

Valorisation of olive agro-industrial by-products as a source of bioactive compounds.

A large amount of olive-derived biomass is generated yearly in Spain, which could be used as a potential source of bioactive compounds. The present work evaluates the recovery of natural antioxidants from olive tree pruning (OTP) and olive mill leaves (OML). For this purpose, the effect of different solvents on the total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activity was evaluated. The solvent was found to have a significant effect (p < 0.05) on the TPC, TFC, and the DPPH, ABTS, and FRAP activity, affording similar results for the extracts from the two by-products. The extracts obtained using 50% ethanol showed high TPC (23.85 and 27.54 mg GAE/gdw for OTP and OML, respectively) and TFC (52.82 and 52.39 mg RE/gdw for OTP and OML, respectively). Also, the OTP and OML extracts exhibited notable antioxidant activity as measured by the ABTS method (45.96 and 42.71 mg TE/gdw, respectively). Using pyrolysis-gas chromatography/mass spectrometry, 30 bioactive compounds were detected in both extracts. Additionally, UPLC-DAD-ESI-MS allowed the identification of 15 compounds in the samples. Furthermore, the antioxidant extracts were found to inhibit the growth of several food pathogenic bacteria. This research demonstrates that these by-products from olive grove farming are a good source of antioxidant compounds with antibacterial properties, which have potential applications in the food and pharmaceutical industries.

Hydrothermal treatment of chestnut shells (Castanea sativa) to produce oligosaccharides and antioxidant compounds.

Hydrothermal treatment is an environmentally friendly technology that allows the solubilisation of hemicellulosic oligosaccharides with potential for their use as prebiotics. The purpose of this study was to solubilize oligosaccharides and antioxidant compounds from chestnut shells by a hydrothermal processing. The highest content of oligosaccharides (18.3 g/L), with a relatively low level of monosaccharides (2.4 g/L) and degradation products (0.5 g/L) was obtained at 180 °C (severity of 3.08). In addition, the liquors presented a high content of phenolic and flavonoid compounds with good antioxidant properties. The GC-MS revealed that the most abundant phenolic compound was pyrogallol (13.2%). The molecular weight distribution of the solubilization products showed that a 26.5% presented an apparent Mw of 6077 g/mol and a 73.5% presented an apparent Mw of 586 g/mol with a high polydispersity index. MALDI-TOF, FTIR, and TGA analyses revealed structural information of these compounds and their thermal stability.

Comparative environmental Life Cycle Assessment of integral revalorization of vine shoots from a biorefinery perspective.

The use of vine shoots as feedstock in biorefining activities to obtain bioproducts under efficient and optimized conditions could be crucial to make future high added value compounds and processes more sustainable. In this study, five different potential valorization scenarios from vine shoots differing on diverse extraction and delignification steps were assessed from an environmental perspective using the Life Cycle Assessment methodology to identify the most sustainable biorefining route. The main findings from this study reported that an increment on the number of valorization steps involved higher energy and chemical requirements deriving on worse environmental profiles. Scenarios incorporating fermentation of the glucose liquors or organosolv delignification performed the worst profiles. Autohydrolysis, concentration and freeze drying and enzymatic hydrolysis were the main responsible stages of the environmental burdens. Further research should be focused on optimizing chemicals and electricity requirements to develop greener systems.