Wood hemicelluloses as effective wall materials for spray-dried microcapsulation of polyunsaturated fatty acid-rich oils.

The most commonly-used and effective wall materials (WMs) for spray-dried microencapsulation of bioactive compounds are either costly, or derived from unsustainable sources, which lead to an increasing demand for alternatives derived from sustainable and natural sources, with low calories and low cost. Wood hemicelluloses obtained from by-products of forest industries appear to be attractive alternatives as they have been reported to have good emulsifying properties, low viscosity at high concentrations, high heat stability and low heat transfer. Here, we investigated the applicability of spruce galactoglucomannans (GGM) and birch glucuronoxylans (GX), to encapsulate flaxseed oil (FO, polyunsaturated fatty acid-rich plant based oil) by spray drying; and the results were compared to those of the highly effective WM, gum Arabic (GA). It was found that depending on solid ratios of WM:FO (1:1, 3:1 and 5:1), encapsulation efficiency of GGM was 88-96%, and GX was 63-98%. At the same encapsulation ratio, both GGM and GX had higher encapsulation efficiency than GA (49-92%) due to their ability to produce feed emulsions with a smaller oil droplet size and higher physical stability. In addition, the presence of phenolic residues in GGM and GX powders enabled them to have a greater ability to protect oil from oxidation during spray drying than GA. Physiochemical properties of encapsulated powders including thermal properties, morphology, molecular structure, particle size and water adsorption intake are also investigated. The study has explored a new value-added proposition for wood hemicelluloses which can be used as effective WMs in the production of microcapsules of polyunsaturated fatty acid-rich oils for healthy and functional products in food, pharmaceutical and cosmetic industries.

Polysaccharides as wall materials in spray-dried microencapsulation of bioactive compounds: Physicochemical properties and characterization.

Natural bioactive compounds (BCs) are types of chemicals found in plants and certain foods that promote good health, however they are sensitive to processing and environmental conditions. Microencapsulation by spray drying is a widely used and cost-effective approach to create a coating layer to surround and protect BCs and control their release, enabling the production of high functional products/ingredients with extended shelf life. In this process, wall materials determine protection efficiency, and physical properties, bioavailability, and storage stability of microencapsulated products. Therefore, an understanding of physicochemical properties of wall materials is essential for the successful and effective spray-dried microencapsulation process. Typically, polysaccharide-based wall materials are generated from more sustainable sources and have a wider range of physicochemical properties and applications compared to their protein-based counterparts. In this review, we highlight the essential physicochemical properties of polysaccharide-based wall materials for spray-dried microencapsulation of BCs including solubility, thermal stability, and emulsifying properties, rheological and film forming properties. We provide further insight into possibilities for the chemical structure modification of native wall materials and their controlled release behaviors. Finally, we summarize the most recent studies involving polysaccharide biopolymers as wall materials and/or emulsifiers in spray-dried microencapsulation of BCs.

Glucose-Functionalized Silver Nanoparticles as a Potential New Therapy Agent Targeting Hormone-Resistant Prostate Cancer cells.

Purpose: Silver nanoparticles (AgNPs) have shown great potential as anticancer agents, namely in therapies' resistant forms of cancer. The progression of prostate cancer (PCa) to resistant forms of the disease (castration-resistant PCa, CRPC) is associated with poor prognosis and life quality, with current limited therapeutic options. CRPC is characterized by a high glucose consumption, which poses as an opportunity to direct AgNPs to these cancer cells. Thus, this study explores the effect of glucose functionalization of AgNPs in PCa and CRPC cell lines (LNCaP, Du-145 and PC-3). Methods: AgNPs were synthesized, further functionalized, and their physical and chemical composition was characterized both in water and in culture medium, through UV-visible spectrum, dynamic light scattering (DLS), transmission electron microscopy (TEM) and Fourier-transform infrared spectroscopy (FTIR). Their effect was assessed in the cell lines regarding AgNPs' entering pathway, cellular proliferation capacity, ROS production, mitochondrial membrane depolarization, cell cycle analysis and apoptosis evaluation. Results: AgNPs displayed an average size of 61nm and moderate monodispersity with a slight increase after functionalization, and a round shape. These characteristics remained stable when redispersed in culture medium. Both AgNPs and G-AgNPs were cytotoxic only to CRPC cells and not to hormone-sensitive ones and their effect was higher after functionalization showing the potential of glucose to favor AgNPs' uptake by cancer cells. Entering through endocytosis and being encapsulated in lysosomes, the NPs increased the ROS, inducing mitochondrial damage, and arresting cell cycle in S Phase, therefore blocking proliferation, and inducing apoptosis. Conclusion: The nanoparticles synthesized in the present study revealed good characteristics and stability for administration to cancer cells. Their uptake through endocytosis leads to promising cytotoxic effects towards CRPC cells, revealing the potential of G-AgNPs as a future therapeutic approach to improve the management of patients with PCa resistant to hormone therapy or metastatic disease.

Gut microbiota can utilize prebiotic birch glucuronoxylan in production of short-chain fatty acids in rats.

Birch-derived glucuronoxylan (GX)-rich hemicellulose extract is an abundantly available by-product of the forest industry. It has multifunctional food stabilizing properties, and is rich in fiber and polyphenols. Here, we studied its effects on colonic metabolism and gut microbiota in healthy rats. Male and female Wistar rats (n = 42) were fed AIN-93G-based diets with 10% (w/w) of either cellulose (control), a polyphenol and GX-rich extract (GXpoly), or a highly purified GX-rich extract (pureGX) for four weeks. Both the GXpoly and pureGX diets resulted in changes on the gut microbiota, especially in a higher abundance of Bifidobacteriaceae than the cellulose containing diet (p < 0.001). This coincided with higher concentrations of microbial metabolites in the luminal contents of the GX-fed than control rats, such as total short-chain fatty acids (SCFAs) (p < 0.001), acetate (p < 0.001), and N-nitroso compounds (NOCs) (p = 0.001). The difference in the concentration of NOCs was not seen when adjusted with fecal weight. GX supplementation supported the normal growth of the rats. Our results indicate that GXpoly and pureGX can favorably affect colonic metabolism and the gut microbiota. They have high potential to be used as prebiotic stabilizers to support more ecologically sustainable food production.

Colloidal features of softwood galactoglucomannans-rich extract.

Development of a sustainable bioeconomy requires valorization of renewable resources, such as wood hemicelluloses. The intra- and inter-molecular association of hemicelluloses within themselves or with other wood components can result in complex macromolecular features. These features exhibit functionality as hydrocolloids, however macromolecular characterization of these heterogeneous materials are challenging using conventional techniques such as size-exclusion chromatography. We studied galactoglucomannans (GGM) -rich softwood extracts at two grades of purity-as crude extract and after ethanol-precipitation. Asymmetrical flow field-flow fractionation (AF4) was optimized and utilized to fractionate size classes in GGM extracts, and subsequent characterization was performed with light scattering and microscopy techniques. Both GGM extracts contained polysaccharides of around 10,000 g/mol molar mass, and colloidal assemblies and/or particles in sub-micron size range. The optimized AF4 method facilitates the characterization of complex biomass-derived carbohydrates without pre-fractionation, and provides valuable understanding of their unique macromolecular features for their future application in food, pharmaceuticals, and cosmetics.

Effects of Enzymatic Hydrolysis of Fava Bean Protein Isolate by Alcalase on the Physical and Oxidative Stability of Oil-in-Water Emulsions.

Fava bean protein isolate (FBPI) was hydrolyzed by Alcalase with different degrees of hydrolysis (DHs), and the role of hydrolysates in oil-in-water (O/W) emulsion stability was investigated. Four emulsions, DH0, DH4, DH9, and DH15, were prepared by 1% (w/v) FBPI hydrolysates with different DHs (0% as the control and 4, 9, and 15%) and 5% (w/v) purified rapeseed oil. The emulsions were monitored for physical and oxidative stability at 37 °C for 7 days. DH4 and DH0 exhibited better physical stability than DH9 and DH15, indicated by droplet size, morphology, and Turbiscan stability index. More importantly, FBPI hydrolysates with DH of 4% most effectively inhibited lipid oxidation (i.e., formation of conjugated dienes and hexanal) while maintaining protein oxidative stability compared to the native and extensively hydrolyzed FBPI. Higher DHs (9 and 15%) induced unduly decreased surface hydrophobicity and increased surface load, which might negatively affect the emulsifying activity. FBPI hydrolysates with DH of 4% had suitable molecular weight for better interfacial layer stability, increased surface net charge for more repulsive electrostatic force, and increased hydrophobicity for better adsorption at the interface and, therefore, may serve as potential natural emulsifiers to maintain both physical and oxidative stability of O/W emulsions.

Safety considerations of plant polysaccharides for food use: a case study on phenolic-rich softwood galactoglucomannan extract.

A growing population and concern over the sufficiency of natural resources for feeding this population have motivated researchers and industries to search for alternative and complementary sources of food ingredients and additives. Numerous plant species and parts of plants are explored as raw materials for food production. An interesting example is wood; to date, only a few wood-based additives or ingredients are authorized for food use. Wood hemicelluloses, such as softwood galactoglucomannans (GGM), constitute an abundant bioresource that shows a high potential functionality in edible materials. Spruce GGM acts as a multi-functional emulsion stabilizer, and it could be used in various processed food products, replacing less effective, conventional emulsifiers. Before new materials can be released into the food market, their safety must be evaluated, according to the Novel Food regulation. This review focuses on the safety aspects that must be considered before polysaccharide- and phenolic-rich plant extracts can be awarded the status of authorized food ingredients. In this review, GGM is presented as a case study and examples are given of plant-based polysaccharides that are already authorized for food purposes. The legislation regarding Novel Food ingredients in Europe is also briefly reviewed.