Ana C. Pinheiro

Chitosan/fucoidan multilayer nanocapsules as a vehicle for controlled release of bioactive compounds.

Hollow multilayer nanocapsules were successfully prepared through layer-by-layer assembly of two bioactive polysaccharides, chitosan and fucoidan. The stepwise adsorption of 10 chitosan/fucoidan layers and the consequent formation of a multilayer film on polystyrene nanoparticles (used as templates) were followed through ζ-potential measurement and the removal of the polystyrene core was confirmed by FTIR analysis. The chitosan/fucoidan nanocapsules morphology and size were evaluated by SEM and TEM, which showed that after the core removal, the nanocapsules maintained their spherical shape and a decrease of size occurred. A cationic bioactive compound, poly-L-lysine (PLL), was chosen to evaluate the loading and release behaviour of the nanocapsules. The chitosan/fucoidan nanocapsules showed a good capacity for the encapsulation and loading of PLL, which shows to be influenced by the initial PLL concentration and the method of encapsulation used. The results of fitting the linear superimposition model to the experimental data of PLL release suggest an anomalous behaviour, with one main polymer relaxation. The PLL release was found to be pH-dependent: at pH 2 relaxation is the governing phenomenon and at pH 7 Ficks diffusion is the main mechanism of PLL release. Chitosan/fucoidan nanocapsules is a promising delivery system for water soluble bioactive compounds, such as PLL, showing a great potential of application in food and pharmaceutical industries.

Design of Bio-nanosystems for Oral Delivery of Functional Compounds

Nanotechnology has been referred to as one of the most interesting topics in food technology due to the potentialities of its use by food industry. This calls for studying the behavior of nanosystems as carriers of biological and functional compounds aiming at their utilization for delivery, controlled release and protection of such compounds during food processing and oral ingestion. This review highlights the principles of design and production of bio-nanosystems for oral delivery and their behavior within the human gastrointestinal (GI) tract, while providing an insight into the application of reverse engineering approach to the design of those bio-nanosystems. Nanocapsules, nanohydrogels, lipid-based and multilayer nanosystems are discussed (in terms of their main ingredients, production techniques, predominant forces and properties) and some examples of possible food applications are given. Phenomena occurring in in vitro digestion models are presented, mainly using examples related to the utilization of lipid-based nanosystems and their physicochemical behavior throughout the GI tract. Furthermore, it is shown how a reverse engineering approach, through two main steps, can be used to design bio-nanosystems for food applications, and finally a last section is presented to discuss future trends and consumer perception on food nanotechnology.

Hollow chitosan/alginate nanocapsules for bioactive compound delivery

This work aimed at the development of biodegradable nanocapsules as carriers of two bioactive compounds, 5-aminosalycilic acid and glycomacropeptide. Nanocapsules were produced through layer-by-layer (LbL) deposition of chitosan (CH) and alginate (ALG) layers on polystyrene nanoparticles. The bioactive compounds were incorporated on the third layer of the nanocapsules being its encapsulation efficiency and release behaviour evaluated. The LbL deposition process, stability, morphology and size of the multilayer nanocapsules were monitored by means of zeta potential and transmission electron microscopy (TEM). The bioactive compounds release from the CH/ALG nanocapsules was successfully described by a mathematical model (linear superimposition model - LSM), which allowed concluding that bioactive compounds release is due to both Brownian motion and the polymer relaxation of the CH/ALG layers. Final results demonstrated that the synthesized LbL hollow nanocapsules presented spherical morphology and a good capacity to encapsulate different bioactive compounds, being the best results obtained for the system containing 5-aminosalycilic acid (with an encapsulation efficiency of approximately 70%). CH/ALG multilayer nanocapsules could be a promising carrier of bioactive compounds for applications in food and pharmaceutical industries.

Edible bio-based nanostructures: delivery, absorption and potential toxicity

The development of bio-based nanostructures as nanocarriers of bioactive compounds to specific body sites has been presented as a hot topic in food, pharmaceutical and nanotechnology fields. Food and pharmaceutical industries seek to explore the huge potential of these nanostructures, once they can be entirely composed of biocompatible and non-toxic materials. At the same time, they allow the incorporation of lipophilic and hydrophilic bioactive compounds protecting them against degradation, maintaining its active and functional performance. Nevertheless, the physicochemical properties of such structures (e.g., size and charge) could change significantly their behavior in the gastrointestinal (GI) tract. The main challenges in the development of these nanostructures are the proper characterization and understanding of the processes occurring at their surface, when in contact with living systems. This is crucial to understand their delivery and absorption behavior as well as to recognize potential toxicological effects. This review will provide an insight into the recent innovations and challenges in the field of delivery via GI tract using bio-based nanostructures. Also, an overview of the approaches followed to ensure an effective deliver (e.g., avoiding physiological barriers) and to enhance stability and absorptive intestinal uptake of bioactive compounds will be provided. Information about nanostructures’ potential toxicity and a concise description of the in vitro and in vivo toxicity studies will also be given.

Advances in Food Nanotechnology

Abstract The use of nanotechnology in the food industry offers many potential benefits for consumers and manufacturers. The dimension and physico-chemical properties of materials at the nanoscale allow their inclusion in several food processes and applications showing great advantages when compared with micro- and macroscale alternatives. The benefits of applying nanotechnology have been driving the development of new and high performance materials for the food sector in areas, such as: encapsulation of compounds (using bio-based nanostructures), food safety (i.e., detection of contaminants and microorganisms and removal of chemicals from foods), and food processing (i.e., nanofiltration and enzyme immobilization). The increasing number of publications and patents shows the fast growth of this topic in the agro-food industry, which is confirmed by the significant number of companies using nanotechnology in the development of their products. Also, the acceptance of the consumers for nanotechnology-based products is of utmost importance: this will dictate if they will/should be in the market or not. This chapter addresses these issues aiming at providing an integrated perspective to reader, foreseeing that, in the next few years, government organizations, academia, and industry will need to work together to increase the acceptance of nanotechnology-based products.

Probiotic-loaded microcapsule system for human in situ folate production: Encapsulation and system validation

This study focused on the use of a new system, an alginate|Ɛ-poly-l-lysine|alginate|chitosan microcapsule (APACM), able to immobilize a folate-producing probiotic, Lactococcus lactis ssp. cremoris (LLC), which provides a new approach to the utilization of capsules and probiotics for in situ production of vitamins. LLC is able to produce 95.25±26μg·L-1 of folate, during 10h, and was encapsulated in the APACM. APACM proved its capacity to protect LLC against the harsh conditions of a simulated digestion maintaining a viable concentration of 6logCFU·mL-1of LLC. A nutrients exchange capacity test, was performed using Lactobacillus plantarum UM7, a high lactic acid producer was used here to avoid false negative results. The production and release of 2g·L-1 of lactic acid was achieved through encapsulation of L. plantarum, after 20h. The adhesion of APACM to epithelial cells was also quantified, yielding 38% and 33% of capsules adhered to HT-29 cells and Caco-2 cells, respectively.

Lactoferrin-based nanoparticles as a vehicle for iron in food applications: development and release profile

This study aims at developing and characterizing bovine lactoferrin (bLf) nanoparticles as an iron carrier. bLf nanoparticles were characterized in terms of size, polydispersity index (PdI), electric charge (ζ-potential), morphology, structure and stability over time. Subsequently, iron release experiments were performed at different pH values (2.0 and 7.0) at 37°C, in order to understand the release mechanism. bLf (0.2%, w/v) nanoparticles were successfully produced by thermal gelation (75°C for 20min). bLf nanoparticles with 35mM FeCl3 showed an iron binding efficiency value of approximately 20%. The nanoparticles were stable (i.e. no significant variation of size and PdI of the nanoparticles) for 76days at 4°C and showed to be stable between 4 and 60°C and pH2 and 11. Release experiments at pH2 showed that iron release could be described by the linear superposition model (explained by Fick and relaxation phenomenon). On the contrary, the release mechanism at pH7 cannot be described by either Fick or polymer relaxation behaviour. In general, results suggested that bLf nanoparticles could be used as an iron delivery system for future food applications.

Downscale fermentation for xylooligosaccharides production by recombinant Bacillus subtilis 3610

The global demand of prebiotics such as xylooligosaccharides (XOS) has been growing over the years, motivating the search for different production processes with increased efficiency. In this study, a cloned Bacillus subtilis 3610, containing the xylanase gene xyn2 of Trichoderma reesei coupled with an endogenous secretion tag, was selected for XOS production through direct fermentation of beechwood xylan. A mixture of XOS with a degree of polymerization ranging from 4 to 6 was obtained, presenting high stability after a static in vitro digestion (98.5 ± 0.2%). The maximum production yield expressed as total XOS per amount of xylan (306 ± 4 mg/g) was achieved after 8 h of fermentation operating under one-time impulse fed-batch. The optimal conditions found were pH 6.0 and 42.5 °C, using 2.5 g/L of initial concentration of xylan increased up to 5.0 g/L at 3 h. Xylopentaose was the major oligosaccharide produced, representing 47% of the total production yield.

Characterization of Particle Properties in Nanoemulsions

Ana C. Pinheiro acknowledges the Foundation for Science and Technology (FCT) for her fellowship (SFRH/BPD/101181/2014). This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the project PTDC/AGR-TEC/5215/2014, of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684), and BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte 2020 - Programa Operacional Regional do Norte.

Electric Field Processing: Novel Perspectives on Allergenicity of Milk Proteins

Milk proteins are being widely used in formulated foods as a result of their excellent technological, functional, and biological properties. However, the most representative proteins from casein and whey fractions are also recognized as major allergens and responsible for the prevalence of cows milk protein allergy in childhood. Electroheating technologies based on thermal processing of food as a result of application of moderate electric fields, also known by ohmic heating (OH) or Joule effect, are establishing a solid foothold in the food industry. Currently, the influence of OH on allergenic aspects of milk proteins is under debate but still undisclosed. The occurrence of electrical effects on the protein structure and its function has already been reported; thus, the impact of OH over allergenicity should not be overlooked. On the basis of these recent findings, it is then relevant to speculate about the impact of this emergent technology on the potential allergenicity of milk proteins.