Search

The increasing world population, impact of food production on climate change, and ongoing issues with diet-related diseases (e.g., malnutrition and obesity) are global major challenges. Recent advances in how food structure impacts the extent and kinetics of uptake of nutrients and its consequent effects on the physiological outcomes are beginning to shift our understanding of nutrition. This understanding is important to designing future foods that provide optimum nutrient bioavailability and deliver healthy outcomes. We discuss perspectives and scientific challenges in understanding the complex relationship between food structure/matrix modification during the digestion process and the absorption of nutrients as well as designing food structures with more sustainable materials.

Plants store triacylglycerols in the form of oil bodies (OBs) as an energy source for germination and subsequent seedling growth. The interfacial biomaterials from these OBs are called OB membrane materials (OBMMs) and have several applications in foods, e.g., as emulsifiers. OBMMs are preferred, compared with their synthetic counterparts, in food applications as emulsifiers because they are natural, i.e., suitable for clean label, and may stabilize bioactive components during storage. This review focuses mainly on the extraction technologies for plant OBMMs, the functionality of these materials, and the interaction of OB membranes with other food components. Different sources of OBs are evaluated and the challenges during the extraction and use of these OBMMs for food applications are addressed.

Plants store triacylglycerides in organelles called oil bodies, which are important fuel sources for germination. Oil bodies consist of a lipid core surrounded by an interfacial single layer membrane of phospholipids and proteins. Oleosins are highly conserved plant proteins that are important for oil body formation, solubilising the triacylglycerides, stabilising oil bodies, and playing a role in mobilising the fuel during the germination process. The domain structure of oleosins is well established, with N- and C-terminal domains that are hydrophilic flanking a long hydrophobic domain that is proposed to protrude into the triacylglyceride core of the oil body. However, beyond this general understanding, little molecular level detail on the structure is available and what is known is disputed. This lack of knowledge limits our understanding of oleosin function and concomitantly our ability to engineer them. Here, we review the state of play in the literature regarding oleosin structure and function, and provide some examples of how oleosins can be used in commercial settings.

Milk has been shown to contain a specific fraction of extracellular particles that are reported to resist digestion and are purposefully packaged with lipids, proteins, and nucleic acids to exert specific biological effects. These findings suggest that these particles may have a role in the quality of infant nutrition, particularly in the early phase of life when many of the foundations of an infant’s potential for health and overall wellness are established. However, much of the current research focuses on human or cow milk only, and there is a knowledge gap in how milk from other species, which may be more commonly consumed in different regions, could also have these reported biological effects. Our review provides a summary of the studies into the extracellular particle fraction of milk from a wider range of ruminants and pseudo-ruminants, focusing on how this fraction is isolated and characterised, the stability and uptake of the fraction, and the reported biological effects of these fractions in a range of model systems. As the individual composition of milk from different species is known to differ, we propose that the extracellular particle fraction of milk from non-traditional and minority species may also have important and distinct biological properties that warrant further study.

The gastric digestion behaviours of blended protein beverages containing different ratios of casein, whey protein and soya protein that were heat-treated at 60 °C or 80 °C were investigated using an in vitro dynamic human gastric simulator. All beverages showed protein aggregation and curd formation under gastric conditions; the extent of protein aggregation/curd formation was dependent on the protein composition of the beverage. The beverages with high proportions of milk proteins showed a greater degree of curd formation during gastric digestion, due to the coagulation of casein micelles. These beverages also showed a lower rate of protein emptying from the stomach. Increasing the relative proportion of soya protein in the beverage increased the rate of protein emptying, because of changes in the curd structure caused by the interactions of soya protein with casein micelles. There was a relatively small effect of heating to 80 °C on the protein emptying rate and the protein content of the clot. The results suggest that protein beverages with different protein compositions could be developed to provide controlled delivery of proteins and amino acids.

Most of the dietary lipids found in food are in the form of triacylglycerols (TAGs), cholesterol, and phospholipids, with TAGs often representing more than 95% of the total lipids. In natural foods (e.g., meat, fish, dairy, and nuts), they are often a part of structures in which the lipid particles are coated with a solubilizing layer or multilayer of membrane phospholipids and proteins. In processed foods, lipids are extracted from animal or plant materials and are then incorporated within the food matrix in the form of emulsions (e.g., yoghurt, cheese, spreads, salad dressings, ice creams, confectionery products, and chocolate). Breaking down the surrounding structures and releasing the lipid droplets from the food matrix affect the rate of lipid digestibility and the bioavailability of fatty acids at the point of utilization in the human body. The consumption of long-chain n-3 polyunsaturated fatty acids (LCn-3PUFAs) has been related to important health benefits, and understanding the different factors affecting their bioavailability from foods becomes critical. The structures of the lipids and matrices also play an important role in the rates of digestion, absorption, and bioavailability of LCn-3PUFA-rich lipids. Limited studies on the relationship between structure and lipid digestibility in natural and fabricated LCn-3PUFA-enriched foods have been carried out. This chapter focuses on the impact of food structures and matrices on lipid digestion and absorption, with a particular focus on LCn-3PUFA-containing model emulsion systems and food products.

Nut-based products may aid low-glycaemic dietary strategies that are important for diabetes prevention in populations at increased risk of dysglycaemia, such as Asian Chinese. This randomised cross-over trial assessed the postprandial glycaemic response (0–120 min) of a higher-protein nut-based (HP-NB) snack formulation, in bar format (1009 kJ, Nutrient Profiling Score, NPS, −2), when compared with an iso-energetic higher-carbohydrate (CHO) cereal-based bar (HC-CB, 985 kJ, NPS +3). It also assessed the ability to suppress glucose response to a typical CHO-rich food (white bread, WB), when co-ingested. Ten overweight prediabetic Chinese adults (mean, sd: age 47⋅9, 15⋅7 years; BMI 25⋅5, 1⋅6 kg/m2), with total body fat plus ectopic pancreas and liver fat quantified using dual-energy X-ray absorptiometry and magnetic resonance imaging and spectroscopy, received the five meal treatments in random order: HP-NB, HC-CB, HP-NB + WB (50 g available CHO), HC-CB + WB and WB only. Compared with HC-CB, HP-NB induced a significantly lower 30–120 min glucose response (P < 0⋅05), with an approximately 10-fold lower incremental area under the glucose curve (iAUC0–120; P < 0⋅001). HP-NB also attenuated glucose response by approximately 25 % when co-ingested with WB (P < 0⋅05). Half of the cohort had elevated pancreas and/or liver fat, with 13–21 % greater suppression of iAUC0–120 glucose in the low v. high organ fat subgroups across all five treatments. A nut-based snack product may be a healthier alternative to an energy equivalent cereal-based product with evidence of both a lower postprandial glycaemic response and modulation of CHO-induced hyperglycaemia even in high-risk, overweight, pre-diabetic adults.

In this work, we sought to incorporate coenzyme Q10-loaded nanoemulsions into a food system and to understand the impact of food digestion on the in vivo bioavailability of this bioactive compound. We selected octenyl succinic anhydride modified starch as emulsifier to prepare the nanoemulsions (with approximately 200 nm droplet diameter) after comparing with two other food-grade surfactants (whey protein isolate and lecithin) in terms of their colloidal stability during simulated gastrointestinal digestion. The change in ζ-potential revealed that the initial emulsifier might be partially replaced by bile salts under intestinal conditions, and the mixed micelles formed after digestion showed an apparent permeability coefficient of 4.79 × 10−6 cm/s in a rat intestinal epithelial cell line, without compromising the trans-epithelial electrical resistance. In a second step, a high protein beverage that incorporated the coenzyme Q10-loaded nanoemulsion was developed in a food pilot plant. The beverage had a particle size of D4,3 = 18 μm and D3,2 = 2.5 μm, corresponding to its different components. The changes in particle morphology and size distribution were analysed to understand the behaviour of this beverage during simulated gastrointestinal digestion. When coenzyme Q10 was encapsulated into the nanoemulsions and the beverage, its bioavailability in vivo increased 1.8- and 2.8-fold respectively, compared with coenzyme Q10 dissolved in oil. The higher coenzyme Q10 bioavailability in the beverage was probably because of a significantly higher level of lipolytic activity found for beverage than for nanoemulsions during gastrointestinal digestion. These results show the potential of using natural food materials to generate formulations to improve the bioavailability of bioactive compounds. More importantly, we highlight the influence of food digestion (i.e. lipolysis) on the absorption of hydrophobic bioactive components and suggest that food systems can be utilised as a dosage form to further enhance oral bioavailability.

During the last decade, major scientific advances on understanding the mechanisms of lipid digestion and metabolism have been made, with a view to addressing health issues (such as obesity) associated with overconsumption of lipid-rich and sucrose-rich foods. As lipids in common foods exist in the form of emulsions, the structuring of emulsions has been one the main strategies for controlling the rate of lipid digestion and absorption, at least from a colloid science viewpoint. Modulating the kinetics of lipid digestion and absorption offers interesting possibilities for developing foods that can provide control of postprandial lipaemia and control the release of lipophilic compounds. Food emulsions can be designed to achieve considerable differences in the kinetics of lipid digestion but most research has been applied to relatively simple model systems and in in vitro digestion models. Further research to translate this knowledge into more complex food systems and to validate the results in human studies is required. One promising approach to delay/control lipid digestion is to alter the stomach emptying rate of lipids, which is largely affected by interactions of emulsion droplets with the food matrices. Food matrices with different responses to the gastric environment and with different interactions between oil droplets and the food matrix can be designed to influence lipid digestion. This review focuses on key scientific advances made during the last decade on understanding the physicochemical and structural modifications of emulsified lipids, mainly from a biophysical science perspective. The review specifically explores different approaches by which the structure and stability of emulsions may be altered to achieve specific lipid digestion kinetics.

The formation, characterization, photo-protective properties and release profiles of folic acid-loaded nanolaminated films were investigated by UV-visible spectroscopy, FTIR, Raman and SEM microscopy. Food-grade alginate/chitosan nanolaminates were obtained by the layer-by-layer technique and folic acid (FA) was incorporated by post-diffusion. The FA concentration of loading solutions and immersion time significantly affected the FA content in nanolaminates. The maximum FA loading was reached using FA solutions at 10 mg/mL for 30 min (54.4 μg/cm2), or 12.5 mg/mL for 120 min (≈70 μg/cm2). Nanolaminates containing FA were more stable under ultraviolet light exposure than non-encapsulated FA. The rate and concentration of FA released from nanolaminates were greater at buffer pH 7 than at pH 3, which might play a key role in the delivery and bioavailability of nutraceuticals. These results provide important information for the design of nanolaminates containing hydrophilic active compounds for food applications. This research was supported by the Ministerio de Ciencia e Innovación throughout the projects AGL2009-11475 and MINECO ALG2012-35635. Author Acevedo-Fani also thanks to the University of Lleida for the pre-doctoral grant.

This study examined the impact of the dynamic gastric digestion of two iso-caloric dairy gels containing curcumin nanoemulsion (D3,2 = 0.187 μm) on the intestinal lipid digestion and the bioaccessibility of curcumin. The residence time in the stomach and the release of oil together with solubilized curcumin were influenced by the type of gel structure. The rennet gel restructured and became denser because of the action of pepsin and the low pH, thus slowing the outflow of both protein and oil from the gel. In contrast, the acid gel experienced rapid protein disintegration under gastric conditions and most of the chyme was emptied out of the stomach within 2 h. Similarly, the content of curcumin-enriched oil in the digesta of the acid gel was higher than that in the digesta of the rennet gel, in which the oil droplets appeared to be embedded in the gelled particles. The size of the oil droplets within the emptied gastric digesta of both gels was not significantly impacted during digestion. The rate of free fatty acid release and the concentration of curcumin during intestinal digestion were linked with the compositional profile of the gastric digesta, whereas the bioaccessibility of curcumin (85–91%) was influenced by the gel type and the gastric disintegration of the gels. This study demonstrates the influence of different gel structures on the bioaccessibility of curcumin, which could be further used to design therapeutic dairy products with health benefits.

Foods are composed of a wide variety of biopolymers (e.g. proteins and polysaccharides) that interact during processing and formulation, resulting in the development of the different structures and physical characteristics of food products. Although a wealth of information on protein‒polysaccharide interactions in model food systems is available, there is a considerable challenge in understanding the nature and implications of these interactions in the environment of the human digestive tract. Several liquid foods containing complex mixtures of biopolymers have been shown to undergo major re-structuring and phase changes during gastric digestion, and these re-structured entities may influence some of the physiological processes. This review brings together some of the current knowledge on biopolymer interactions and gastric digestive physiology, with emphasis on the intragastric structuring of liquid food systems. Major emphasis is placed on gastric processing, as critical interactions and structure formation and disintegration occur in the stomach region. The potential impact of the gastric re-structuring of liquid foods on the rate of delivery of nutrients is discussed, where appropriate. The gastric digestion behaviour of selected natural colloidal dispersions (plant-based and bovine milk), including the mechanisms of protein‒protein interactions and gastric re-structuring, are discussed. Understanding the relationship between gastric re-structuring and the rates of nutrient digestion will be vital for developing future foods with specific health attributes.

Edible coatings are used to preserve food quality but may serve to immobilize active ingredients on the food surface. Nanoemulsions are effective systems for encapsulating lipophilic active ingredients since the reduction of droplet size increases their solubility, stability and may enhance their biological activity. Therefore, this review aims to highlight the most important aspects in designing food nanoemulsions for active substances delivery and the recent advances in their application as edible coatings. Up to date, research studies confirm that nanoemulsion-based edible coatings can enhance the transport of antimicrobial substances to solid foods extending their shelf life. However, future studies should be oriented to assess the impact of nanoemulsions on the organoleptic properties of coated foods and their potential toxicity.

The aim of this study was to develop a β-carotene-enriched tertiary emulsion (lactoferrin/alginate/ε-poly-L-lysine). Then, its physical stability as well as β-carotene content under external stresses (temperature, pH and ionic strength changes) was evaluated. Furthermore, lipid digestibility and β-carotene bioaccessibility of primary, secondary and tertiary emulsions were determined. Tertiary emulsion underwent a substantial particle size increase up to 13 μm after extreme temperatures, acidic conditions and with salt addition. However, small particle size (0.41 μm) and negative ζ-potential (-43.4 mV) was observed at basic pH. In addition, β-carotene content in tertiary emulsions decreased only 40% when emulsions were subjected at temperatures ≤70ºC, in acidic conditions and below 0.3M NaCl. After in vitro digestion, tertiary emulsion presented higher lipid digestibility (83.59±11.81%) and β-carotene bioaccessibility (70.10±5.26%) compared with primary and secondary emulsions. This study provides knowledge to understand the behaviour of β-carotene-loaded tertiary emulsions under different conditions, valuable for further application in foodstuffs. This work was supported by the Fondo Europeo de Desarrollo Regional (FEDER) and Ministerio de Economía y Competitividad (project AGL2015-65975-R). Ariadna Gasa Falcon thanks the Agencia de Gestio d’Ajuts Universitaris I de Recerca (AGAUR) from the catalan government (Spain), for the pre-doctoral grant.

Rutin is a dietary flavonoid and a potent antioxidant with clinically relevant functions. Hence, rutin-enriched food products can be used as functional foods. However, rutin has low bioavailability because of its low water solubility, poor stability and limited membrane permeability. We previously reported a casein‒rutin co-precipitate that significantly increased water solubility, compared with commercially available rutin powders. This work investigated the gastrointestinal behaviour of a yoghurt enriched with casein‒rutin co-precipitate (RuYO) and an unfortified yoghurt combined with powdered rutin in a vegetable-based capsule (CtYO + Ru). A semi-dynamic in vitro digestion protocol was followed; the gastric phase was simulated in a human gastric simulator. The physical properties and rutin content of digesta samples were determined at different digestion times. The solids retention of RuYO and CtYO + Ru in the gastric phase decreased with increasing digestion time, confirming that gastric emptying occurred at a constant rate. Confocal microscopy indicated that the protein network was increasingly hydrolysed during gastric digestion. The release and stability of rutin during the digestion of RuYO were dramatically different from those of CtYO + Ru. Although a significant amount of the flavonoid remained in the insoluble fraction during gastric digestion, it was more stable in RuYO than in CtYO + Ru (total cumulative recoveries of 98% and 61% respectively). Similarly, rutin degradation was lower in RuYO in the intestinal phase (total cumulative recovery: RuYO, 26%; CtYO + Ru, 17%). Overall, yoghurt fortified with rutin‒casein co-precipitate gives better in vitro rutin bioaccessibility than the same yoghurt co-digested with a rutin supplement capsule.

Edible films including active ingredients can be used as an alternative to preserve food products. Essential oils (EOs) exhibit antimicrobial activity against pathogenic microorganisms but their low water solubility limits the application in foods. To improve water dispersion and protect EOs from degradation, nano-sized emulsions emerge as a viable alternative. Nanoemulsions containing EOs and polysaccharides could be used to form edible films with functional properties. This study was focused on the evaluation of physical, mechanical and antimicrobial properties of alginate-based edible films formed from nanoemulsions of EOs. Nanoemulsions containing thyme (TH-EO), lemongrass (LG-EO) or sage (SG-EO) oil as dispersed phase and sodium alginate solution as continuous phase were prepared. The average droplet size of nanoemulsions was reduced after the microfluidization treatment exhibiting multimodal size distributions. The zeta-potentials of nanoemulsions were between 41 mV and 70 mV depending on the type of EO used. The lowest whiteness index was found in SG-EO nanoemulsions, whereas those containing TH-EO showed the highest value. Films formed from SG-EO nanoemulsions exhibited higher transparency, water vapor resistance and flexibility than films formed from TH-EO or LG-EO. Edible films containing TH-EO were those with the strongest antimicrobial effect against inoculated Escherichia coli, achieving up to 4.71 Log reductions after 12 h. Results obtained in the present work evidence the suitability of using nanoemulsions with active ingredients for the formation of edible films, with different physical and functional properties. (C) 2015 Elsevier Ltd. All rights reserved This research was supported by the Ministerio de Ciencia e Innovación (Spain) throughout projects ALG2009-11475 and ALG2012-35635. Author Acevedo-Fani also thanks to the University of Lleida for the pre-doctoral grant. Author Martín-Belloso acknowledges to the Institució Catalana de Recerca I Estudis Avançats (ICREA) for the Academia 2008 Award.

The alternate deposition of oppositely charged materials (layer-by-layer technique) is an effective approach to functionalize materials. Biopolymer-based nanolaminates obtained by the layer-by-layer technique can also be used to change the surface properties of food products or food contact materials. However, the final properties of nanolaminates may be affected by the conditions of the adsorbing solutions. The objective of this study was to form and characterize the physicochemical properties of nanolaminates assembled from alginate and chitosan solutions. The effect of pH, ionic strength and polysaccharide concentration on the properties of the adsorbing solutions was also evaluated. The ζ-potential, viscosity and whiteness index of the solutions were assessed before the assembly. Alginate/chitosan nanolaminates were characterized in terms of UV-visible spectroscopy, surface ζ-potential, contact angle, DSC analysis and SEM. The absorbance increased as a function of the number of polysaccharide layers on the substrate, suggesting an increase in the mass adsorbed. The surface ζ-potential of nanolaminates changed depending on the last polysaccharide deposited. Alginate layers were negatively charged, whereas chitosan layers were positively charged. Contact angles obtained in alginate layers were ≈ 10°, being mostly hydrophilic. Chitosan layers showed higher contact angle values (80°), indicating a more hydrophobic behavior. Microscopic examinations revealed the presence densely packed structures that corresponded to alginate/chitosan nanolaminates, having an estimated thickness of 700 nm. The results obtained in this work lay the basis for the rational design of polysaccharide-based nanolaminates in the food sector. This research was supported by the Ministerio de Ciencia e Innovación (Spain) (project AGL2009-11475). Author Acevedo-Fani also thanks to the University of Lleida for the pre-doctoral grant.

Interfacial deposition of biopolymer layers on oil droplets may be a suitable strategy for increasing the emulsion stability and protection of functional ingredients. Resveratrol is a naturally occurring phenolic compound with numerous health-promoting properties, but its usage is still restricted due to its poor water solubility and high chemical instability. The aim of this study was to formulate single-layer (lactoferrin) and multilayer (lactoferrin/alginate and lactoferrin/alginate/-poly-l-lysine) emulsions containing resveratrol and to study the emulsions stability and antioxidant activity during storage. All primary (single-layer) emulsions had average droplet diameters below 300 nm and -potentials strongly positive, allowing the electrostatic deposition of another layer of anionic biopolymer, such as alginate. Secondary (multilayer) emulsions were highly unstable at low alginate concentrations, which was attributed to the bridging flocculation. At higher alginate concentrations, secondary emulsions were rather stable. Tertiary emulsions containing either low or high -poly-l-lysine concentrations presented flocculation, but formulations with 0.0036% (w/w) were fairly stable. The antioxidant activity of all resveratrol-loaded emulsions did not significantly change during storage, whereas it decreased in non-encapsulated resveratrol oil from the third week onwards. This study provides useful information for the design of delivery systems for resveratrol with relevance in food applications., This research was supported by the Ministerio de Ciencia e Innovación (Spain) throughout the projects AGL2009-11475 and ALG2012-35635, and by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit and COMPETE 2020 (POCI-01-0145-FEDER-006684), Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124- FEDER-027462) and FCT Strategic Project of UID/BIO/04469/2013 unit. The authors also thank the Project “BioInd - Biotechnology and Bioengineering for improved Industrial and Agro-Food processes, REF. NORTE-07-0124-FEDER-000028” Co-funded by the Programa Operacional Regional do Norte (ON.2 e O Novo Norte), QREN, FEDER. The author A. Acevedo-Fani thanks the University of Lleida for the pre-doctoral grant. The author H. D. Silva, (SFRH/BD/81288/2011) is the recipient of a fellowship from the Fundação para a Ciência e Tecnologia (FCT, Portugal). The authors would like to acknowledge to Rui Fernandes from IBMC, University of Porto, for assistance in taking the TEM microphotographs., info:eu-repo/semantics/publishedVersion

Nanoemulsion-based edible coatings containing oregano essential oil (OEO) as antimicrobial were applied onto low-fat cut cheese to extend its shelf life. Nanoemulsions formulation was 2.0% (w/w) sodium alginate, 0.5% (w/w) mandarin fiber, 2.5% (w/w) Tween 80 and 1.5%, 2.0% or 2.5% (w/w) of OEO. Particle size, ζ-potential, apparent viscosity and whiteness index of nanoemulsions were assessed. Water vapor resistance of coatings was evaluated as well as their antimicrobial efficiency against inoculated Staphylococcus aureus and native microbiota growth during refrigerated storage. Headspace gases were measured as an indicator of bacterial activity and sensory alterations such as color and texture of cheese pieces were studied. Coatings with at least 2.0% (w/w) OEO decreased Staphylococcus aureus population from 6.0 to 4.6 log CFU/g after 15 days. Coated-cheese pieces containing 2.5% (w/w) OEO inhibited psychrophilic bacteria or molds and yeasts growth during 6 or 24 days of storage, respectively. Consequently, the atmosphere into the sealed tracks was stabilized and the outward appearance of cheese pieces was preserved. Thus, the present work evidences the feasibility of using mandarin fiber with high nutritional properties and sodium alginate acting as texturizing agents, to form OEO-loaded coatings onto low-fat cut cheese in order to extend its shelf life. This study was supported by the Ministry of Science and Innovation (Spain) throughout project AGL2009-11475 and by the MINECO (Spain) throughout project AGL2012-35635. Authors María Artiga-Artigas and Alejandra Acevedo-Fani thank the University of Lleida for their pre-doctoral fellowship.

Background: Nowadays, consumers are increasingly demanding high-quality, safe and healthy food products. Nanostructured emulsions and nanolaminates may have the potential to protect and transport lipophilic and hydrophilic active compounds commonly incorporated to food products, such as natural antimicrobials and nutraceuticals, while protecting or even enhancing their functional properties. Scope and approach: This review deals with the most important aspects concerning to the use of nanostructured emulsions and nanolaminates as delivery systems of active ingredients, including the advantages and challenges of incorporating plant-derived antimicrobials and nutraceuticals in foods, relevant factors affecting the formation of these nanostructures, fabrication methods, their advantages as delivery systems, and the current trends in food applications. In addition, concerns regarding the potential toxicity of nanomaterials are also discussed. Key findings and conclusions: The successful production of nanostructured emulsions and nanolaminates depends on several physicochemical factors that should be controlled in order to reach stable systems. Research evidences that nanostructured emulsions and nanolaminates are able to improve the delivery and biological activity of encapsulated active compounds. Antimicrobial and bioactive nanostructured emulsions and nanolaminates exhibit some promising advantages in food preservation and may represent a new strategy to produce functional foods. However, the knowledge in this area is still limited. The potential toxicological effects of nanostructured delivery systems are a current concern. Therefore, future investigations should be directed towards more comprehensive studies to shed light on the formation, physicochemical stability, functional performance, interactions with food matrices and toxicity of nanostructured delivery systems before their commercialization. This research work was supported by the Ministry of Science and Innovation (Spain) [ALG2009-11475, ALG2012-35635, ALG2015-65975-R]. Also, author Acevedo-Fani thanks to the University of Lleida for the pre-doctoral grant.

The aim of this work was to study the influence of biopolymer (alginate, ALG; chitosan, CHI) charge on the formation of multilayer nanofilms by the layer-by-layer (LbL) technique. The electrical charge of ALG and CHI (high, medium, or low) was modulated by adjusting the pH of biopolymer solutions. The amount of biopolymer deposited in multilayers depended on the charge of ALG and CHI solutions. The lower the charge the higher the deposition rate due to the higher number of biopolymer molecules needed to neutralize the previous layer. Medium and low charge biopolymers led to a drastic change in the wettability of multilayers, with ALG layers being strongly hydrophilic and CHI layers strongly hydrophobic. The surface ζ-potential alternatively changed from negative to positive using ALG or CHI. This effect was more pronounced using highly charged biopolymers. Results obtained in this study evidenced that the multilayers properties can be tuned by controlling the biopolymer electrical charge. This research was supported by the Ministerio de Ciencia e Innovacion (Spain) throughout projects ALG2009-11475. A.A.- ́ F. also thanks to the University of Lleida for the predoctoral grant. O.M.-B. acknowledges the Institució Catalana de Recerca i Estudis Avançats (ICREA) for the Academia 2008 Award.