Lignin/Carbohydrate Complex Isolated from Posidonia oceanica Sea Balls (Egagropili): Characterization and Antioxidant Reinforcement of Protein-Based Films

A lignin fraction (LF) was extracted from the sea balls of Posidonia oceanica (egagropili) and extensively dialyzed and characterized by FT-IR and NMR analyses. LF resulted water soluble and exhibited a brownish-to-black color with the highest absorbance in the range of 250-400 nm, attributed to the chromophore functional groups present in the phenylpropane-based polymer. LF high-performance size exclusion chromatography analysis showed a highly represented (98.77%) species of 34.75 kDa molecular weight with a polydispersity index of 1.10 and an intrinsic viscosity of 0.15. Quantitative analysis of carbohydrates indicated that they represented 28.3% of the dry weight of the untreated egagropili fibers and 72.5% of that of LF. In particular, eight different monosaccharides were detected (fucose, arabinose, rhamnose, galactose, glucose, xylose, glucosamine and glucuronic acid), glucuronic acid (46.6%) and rhamnose (29.6%) being the most present monosaccharides in the LF. Almost all the phenol content of LF (113.85 ± 5.87 mg gallic acid eq/g of extract) was water soluble, whereas around 22% of it consisted of flavonoids and only 10% of the flavonoids consisted of anthocyanins. Therefore, LF isolated from egagropili lignocellulosic material could be defined as a water-soluble lignin/carbohydrate complex (LCC) formed by a phenol polymeric chain covalently bound to hemicellulose fragments. LCC exhibited a remarkable antioxidant activity that remained quite stable during 6 months and could be easily incorporated into a protein-based film and released from the latter overtime. These findings suggest egagropili LCC as a suitable candidate as an antioxidant additive for the reinforcement of packaging of foods with high susceptibility to be deteriorated in aerobic conditions

Biorefining of seed oil cakes as industrial co-streams for production of innovative bioplastics. A review

Background: Numerous different seeds are utilized for edible oil extraction and seed by-products following oil extraction, known as seed oil cakes, represent roughly 50% of the original seed weight. Since seed oil cakes are rich in fibers, proteins and secondary metabolites, they are considered as promising candidates to be raw material to be consumed in a biorefinery for the production of high-value added products according to circular economy paradigms. Several studies have been performed on the potential uses of seed oil cakes derived from different plant species. Scope and approach: This review, resulting from a collection of experimental results by databases, as well as by topic and keyword search, summarizes the current use of most seed oil cakes so far utilized, as well as that of additional four seed cakes obtained from plants having an economically significant relevance due to their food, nutraceutical or pharmaceutical properties: sesame (Sesamum indicum L.), hemp (Cannabis sativa), cardoon (Cynara cardunculus) and black cumin (Nigella sativa). Various attempts have been done to convert their protein content into a renewable source for producing biodegradable and edible plastics, potentially attractive mainly for food and agricultural industries, as substitutes of the highly polluting petroleum-based plastics. Key findings and conclusions: Seed oil cakes are generally used as animal feed supplementation, plant fertilizer or soil compost due to their high protein, carbohydrate and nitrogen contents. More recently, novel exploitations of the seed oil cakes are under study, such as the production of biofuels and bioplastics. Therefore, seed oil cakes may represent an attractive feedstock for the development of biorefineries through the edible or not edible oil production

Sustainable Exploitation of Posidonia oceanica Sea Balls (Egagropili): A Review

: Posidonia oceanica (L.) Delile is the main seagrass plant in the Mediterranean basin that forms huge underwater meadows. Its leaves, when decomposed, are transported to the coasts, where they create huge banquettes that protect the beaches from sea erosion. Its roots and rhizome fragments, instead, aggregate into fibrous sea balls, called egagropili, that are shaped and accumulated by the waves along the shoreline. Their presence on the beach is generally disliked by tourists, and, thus, local communities commonly treat them as waste to remove and discard. Posidonia oceanica egagropili might represent a vegetable lignocellulose biomass to be valorized as a renewable substrate to produce added value molecules in biotechnological processes, as bio-absorbents in environmental decontamination, to prepare new bioplastics and biocomposites, or as insulating and reinforcement materials for construction and building. In this review, the structural characteristics, and the biological role of Posidonia oceanica egagropili are described, as well as their applications in different fields as reported in scientific papers published in recent years

A biorefinery approach for the conversion of Cynara cardunculus biomass to active films

Cardoon (Cynara cardunculus), an herbaceous perennial plant able to grow with high productivity in dry and hot regions, as well as in unproductive soils, was used as a biomass source for the production of both bioactive compounds derived from leaves and proteins extracted from seeds. Naviglio® technology was found as an efficient method to obtain a cardoon leaf extract (CLE) characterized by high phenol content and oxygen scavenging activity. On the other hand, cardoon proteins (CPs) were demonstrated to give rise to handleable greenish films endowed with promising mechanical and barrier properties in the presence of glycerol used as plasticizer. Hence, the CLE was used to functionalize the films that were further characterized. Film microstructure observed by SEM revealed a good compatibility among CPs and CLE, showing a uniform distribution of the leaf extract components throughout the film network that reflected, in turn, an improvement in the mechanical and barrier properties of the obtained material. In addition, the CLE containing films exhibited higher hydrophobicity, as indicated by the contact angle measurement and by the evaluation of water solubility and swelling degree experiments. Finally, CLE-containing films showed a marked antioxidant activity, highlighting the potential of Cynara cardunculus to be exploited as a biorefinery where different low-value renewable biomass materials are turned in several higher value bio-based products

Surface activity of protein extracts from seed oil by-products and wettability of developed bioplastics

Protein concentrates, extracted from the by-products of Hemp (Cannabis sativa), Cardoon (Cynara cardunculus), and Argan (Argania spinosa L.) oilseeds after oil extraction, were utilized to produce sustainable and eco-friendly protein-based bioplastics. The surface wettability and roughness of these bioplastics were investigated due to the pivotal role of these parameters in their application in food packaging sector. Advancing contact angle value revealed that Argan protein-based bioplastic is the most hydrophobic (θ > 90°) while Cardoon protein-based film is the most hydrophilic (θ 45 mN m−1) at both pHs, while Argan and Hemp proteins displayed lower values than Cardoon, especially at pH 12 (<40 mN m−1), indicative of higher surface activity. Finally, Argan protein adsorbed more irreversibly, followed by Hemp protein while Cardoon protein provides the largest partial desorption from the surface. Combined analysis of the data features a correlation between the higher advancing contact angle of Hemp protein-based bioplastic and higher hydrophobicity, less swelling, faster adsorption kinetics, lower surface tension and more irreversible adsorption of protein. These apply for Hemp and Cardoon protein concentrates and their driven bioplastics while the presence of free oil in Argan protein concentrate and its bioplastic hinders the correlation between different phenomena. The new interconnections highlighted between film properties and surface adsorption could potentially be employed in food packaging and coating technology

Valorisation of posidonia oceanica sea balls (Egagropili) as a potential source of reinforcement agents in protein-based biocomposites

Nanocrystalline cellulose (NC) and a lignin-containing fraction (LF) were obtained from egagropili, the so called sea balls produced from rhizome and stem fragments of Posidonia oceanica that accumulate in large amounts along the coastal beaches in the form of tightly packed and dry materials of various dimensions. Both egagropili fractions have been shown to be able to improve the physicochemical properties of biodegradable films prepared from protein concentrates derived from hemp oilseed cakes. These materials, manufactured with a biodegradable industrial by-product and grafted with equally biodegradable waste-derived additives, exhibited an acceptable resistance with a still high flexibility, as well as they showed an effective barrier activity against water vapor and gases (O2 and CO2). Furthermore, both NC and LF decreased film moisture content, swelling ability and solubility, thus indicating that both additives were able to improve water resistance of the hydrocolloid films. The exploitation of egagropili, actually considered only an undesirable waste to be disposed, as a renewable source of reinforcing agents to blend with different kinds of polymers is suggested

Manufacture of active multilayer films made of functionalized pectin coated by polyhydroxyalkanoates: A fully renewable approach to active food packaging

Biodegradable active packaging, i.e. materials able to promote food preservation while avoiding plastic waste accumulation are expecting to play a key role fsor the manufacture of new generation materials. Bioactive films composed of citrus pectin (CP) added with extracts from spent coffee grounds (SCGs) were herein developed. To address the limitations of pectin-based materials, i.e. hydrophilicity and poor water barrier properties, an active multilayer film was prepared by coating the functionalized pectin by a two-steps dipping into polyhydroxyalkanoates (PHA) solutions characterized by different monomeric compositions. The PHA coating affected the stiffness of the film and its opacity, while improving its hydrophobicity and water vapor permeability. The dipping procedure did not compromise the stability of the bioactive compounds, rather it allowed to preserve their antioxidant and antimicrobial activities for longer times in comparison with uncoated functionalized film. Further, the multilayer material functionalized with extracts was able to delay the carotenoid degradation in mashed carrots likely because of the increased film opacity conferred by both phenols (caffeoylquinic acid isomers including chlorogenic acid) found in SCGs and PHAs layer suggesting that the new material may be used to extend the food shelf-life and potentially to enhance product health credentials

Potential use of glycerol- and/or spermidine-plasticized secalin films as leaf surface coatings for sustainable plant disease management

The effects of spermidine (SPD) on the properties of both secalin (SCL)-based film-forming solutions (FFSs) and their resultant films were studied in the absence or presence of glycerol (GLY) used as primary plasticizer. The average size of SCL particles significantly increased with the increase of SPD concentration, mainly in the presence of GLY, while the negative zeta potential values parallely decreased suggesting a greater stability of the FFSs containing SPD concentrations lower than 1.0 mM. In addition, the decreased contact angle value, compared to water and ethanol solution, indicated that SCL FFSs were highly hydrophobic and that it might be spreaded easily on hydrophobic biological surfaces. SPD could replace GLY in obtaining handleable, homogeneous and performing SCL-based films. The film tensile strength and the Young's module strongly increased in the absence of GLY, reaching values higher than 5 times with respect to controls, whereas elongation at break value of GLY-plasticized films containing 5.0 mM SPD was twice of that of the films prepared without SPD. Conversely, the film moisture content, water solubility and swelling ratio progressively decreased, both in the presence and absence of GLY, up to a SPD concentration of 1.0 mM, whereas the film contact angle increased, confirming the enhancement of its hydrophobicity determined by SPD incorporation. SPD also increased the film barrier properties to gases and water vapor, while the presence of GLY hindered these effects. Finally, SEM analysis of the cross-sections of the SPD containing films showed heterogeneous microstructures, whereas their surfaces appeared rougher than those of the control films. Preliminary experiments carried out by Rosa chinensis Jacq. leaf coating suggest the potential use of SCL-based FFSs spraying in plant disease control. High spreading of the SCL-based FFSs on the entire leaf surfaces, both in the presence and absence of Bordeaux mixture tested as agrochemical, was observed, and the SEM images showed the formation of an evident coating of the leaves. Therefore, these findings suggest the possibility to coat the leaf surface also in vivo with different SCL-based FFSs, giving rise to films possessing tailored functional properties and able to carry and release different agrochemicals