Immobilization of Natural Antimicrobial Compounds on Food-Grade Supports as a New Strategy to Preserve Fruit-Derived Foods.

The use of natural antimicrobials in the food industry is being proposed as an eco-friendly postharvest technology to preserve fruit-derived foods. In this context, this systematic review aims to describe and discuss the application of naturally occurring antimicrobial compounds in the processing of fruit-derived foods by the PRISMA methodology. In a first step, the use of free natural antimicrobials was investigated as an approach to identify the main families of bioactive compounds employed as food preservatives and the current limitations of this dosage form. Then, the use of immobilized antimicrobials, in an innovative dosage form, was studied by distinguishing two main applications: addition to the food matrix as preservatives or use during processing as technological aids. Having identified the different examples of the immobilization of natural antimicrobial compounds on food-grade supports, the mechanisms of immobilization were studied in detail to provide synthesis and characterization guidelines for future developments. Finally, the contribution of this new technology to decarbonization and energy efficiency of the fruit-derived processing sector and circular economy is discussed in this review.

Gated Organonanoclays for Large Biomolecules: Controlled Release Triggered by Surfactant Stimulus.

The low toxicity and high adsorption capacities of clay minerals make them attractive for controlled delivery applications. However, the number of controlled-release studies in the literature using clay minerals is still scarce. In this work, three different clays from the smectite group (Kunipia F, montmorillonite; Sumecton SA, saponite; and Sumecton SWN, hectorite) were successfully loaded with rhodamine B dye and functionalized with oleic acid as a gatekeeper to produce organonanoclays for active and controlled payload-release. Moreover, hematin and cyanocobalamin have also been encapsulated in hectorite gated clay. These organonanoclays were able to confine the entrapped cargos in an aqueous environment, and effectively release them in the presence of surfactants (as bile salts). A controlled delivery of 49 ± 6 µg hematin/mg solid and 32.7 ± 1.5 µg cyanocobalamin/mg solid was reached. The cargo release profiles of all of the organonanoclays were adjusted to three different release-kinetic models, demonstrating the Korsmeyer-Peppas model with release dependence on (i) the organic-inorganic hybrid system, and (ii) the nature of loaded molecules and their interaction with the support. Furthermore, in vitro cell viability assays were carried out with Caco-2 cells, demonstrating that the organonanoclays are well tolerated by cells at particle concentrations of ca. 50 µg/mL.

Automatic and non-targeted analysis of the volatile profile of natural and alkalized cocoa powders using SBSE-GC-MS and chemometrics.

A total of 56 key volatile compounds present in natural and alkalized cocoa powders have been rapidly evaluated using a non-target approach using stir bar sorptive extraction gas chromatography mass spectrometry (SBSE-GC-MS) coupled to Parallel Factor Analysis 2 (PARAFAC2) automated in PARADISe. Principal component analysis (PCA) explained 80% of the variability of the concentration, in four PCs, which revealed specific groups of volatile characteristics. Partial least squares discriminant analysis (PLS-DA) helped to identify volatile compounds that were correlated to the different degrees of alkalization. Dynamics between compounds such as the acetophenone increasing and toluene and furfural decreasing in medium and strongly alkalized cocoas allowed its differentiation from natural cocoa samples. Thus, the proposed comprehensive analysis is a useful tool for understanding volatiles, e.g., for the quality control of cocoa powders with significant time and costs savings.

Nanotechnology in the agri-food sector: Consumer perceptions.

The purpose of this work was to evaluate Spanish consumers' opinions on using nanotechnology in food processing and packaging. For this purpose, a literature review was carried out in the main research database to determine the most widespread uses of nanotechnology in the food industry and the most promising developments. Of all the nanotechnology uses in food, five areas of application were identified: developing new ingredients or additives, formulating new antimicrobial systems, and designing new processing methods, sensors and packaging with nanostructured materials. Subsequently, a consumers' opinion study was carried out by means of a survey, in which the opinions and purchase intention of a representative product of all five categories were evaluated, as well as the neophobia level to new food technologies. All the products obtained positive evaluations, and the applications in which nanotechnology did not form part of food were generally better valued than those in which it did form part. The respondents had a medium neophobia level, with an average score of 4.59 (out of 7 points), being consumers with more knowledge about new technologies the least neophobic and those who gave products higher scores. This study provides relevant information for using nanotechnology in the food processing and packaging sector.

Secreted Enzyme-Responsive System for Controlled Antifungal Agent Release.

Essential oil components (EOCs) such as eugenol play a significant role in plant antimicrobial defense. Due to the volatility and general reactivity of these molecules, plants have evolved smart systems for their storage and release, which are key prerequisites for their efficient use. In this study, biomimetic systems for the controlled release of eugenol, inspired by natural plant defense mechanisms, were prepared and their antifungal activity is described. Delivery and antifungal studies of mesoporous silica nanoparticles (MSN) loaded with eugenol and capped with different saccharide gates-starch, maltodextrin, maltose and glucose-against fungus Aspergillus niger-were performed. The maltodextrin- and maltose-capped systems show very low eugenol release in the absence of the fungus Aspergillus niger but high cargo delivery in its presence. The anchored saccharides are degraded by exogenous enzymes, resulting in eugenol release and efficient inhibition of fungal growth.

Changes in cocoa properties induced by the alkalization process: A review.

Alkalization, also known as "Dutching," is an optional, but very useful, step taken in the production chain of cocoa to darken its color, modify its taste, and increase natural cocoa solubility. Over the years, various attempts have been made to design new and more effective alkalization methods. Moreover, different authors have attempted to elucidate the impact of alkalization on the physicochemical, nutritional, functional, microbiological, and sensory characteristics of alkalized cocoa. The aim of this review is to provide a clear guide about not only the conditions that can be applied to alkalize cocoa, but also the reported effects of alkalization on the nutritional, functional, microbiological, and sensory characteristics of cocoa. The first part of this review describes different cocoa alkalization systems and how they can be tuned to induce specific changes in cocoa properties. The second part is a holistic analysis of the effects of the alkalization process on different cocoa features, performed by emphasizing the biochemistry behind all these transformations.

Roadmap of cocoa quality and authenticity control in the industry: A review of conventional and alternative methods.

Cocoa (Theobroma cacao L.) and its derivatives are appreciated for their aroma, color, and healthy properties, and are commodities of high economic value worldwide. Wide ranges of conventional methods have been used for years to guarantee cocoa quality. Recently, however, demand for global cocoa and the requirements of sensory, functional, and safety cocoa attributes have changed. On the one hand, society and health authorities are increasingly demanding new more accurate quality control tests, including not only the analysis of physicochemical and sensory parameters, but also determinations of functional compounds and contaminants (some of which come in trace quantities). On the other hand, increased production forces industries to seek quality control techniques based on fast, nondestructive online methods. Finally, an increase in global cocoa demand and a consequent rise in prices can lead to future cases of fraud. For this reason, new analytes, technologies, and ways to analyze data are being researched, developed, and implemented into research or quality laboratories to control cocoa quality and authenticity. The main advances made in destructive techniques focus on developing new and more sensitive methods such as chromatographic analysis to detect metabolites and contaminants in trace quantities. These methods are used to assess cocoa quality; study new functional properties; control cocoa authenticity; or detect frequent emerging frauds. Regarding nondestructive methods, spectroscopy is the most explored technique, which is conducted within the near infrared range, and also within the medium infrared range to a lesser extent. It is applied mainly in the postharvest stage of cocoa beans to analyze different biochemical parameters or to assess the authenticity of cocoa and its derivatives.

New Oleic Acid-Capped Mesoporous Silica Particles as Surfactant-Responsive Delivery Systems.

A new delivery microdevice, based on hydrophobic oleic acid-capped mesoporous silica particles and able to payload release in the presence of surfactants, has been developed. The oleic acid functionalization confers to the system a high hydrophobic character, which avoids cargo release unless surfactant molecules are present. The performance of this oleic-acid capped microdevice in the presence of different surfactants is presented and its zero-release operation in the absence of surfactants is demonstrated.

Double Drug Delivery Using Capped Mesoporous Silica Microparticles for the Effective Treatment of Inflammatory Bowel Disease.

Silica mesoporous microparticles loaded with both rhodamine B fluorophore (S1) or hydrocortisone (S2), and capped with an olsalazine derivative, are prepared and fully characterized. Suspensions of S1 and S2 in water at an acidic and a neutral pH show negligible dye/drug release, yet a notable delivery took place when the reducing agent sodium dithionite is added because of hydrolysis of an azo bond in the capping ensemble. Additionally, olsalazine fragmentation induced 5-aminosalicylic acid (5-ASA) release. In vitro digestion models show that S1 and S2 solids are suitable systems to specifically release a pharmaceutical agent in the colon. In vivo pharmacokinetic studies in rats show a preferential rhodamine B release from S1 in the colon. Moreover, a model of ulcerative colitis is induced in rats by oral administration of 2,4,6-trinitrobenzenesulfonic acid (TNBS) solutions, which was also used to prove the efficacy of S2 for colitis treatment. The specific delivery of hydrocortisone and 5-ASA from S2 material to the colon tissue in injured rats markedly lowers the colon/body weight ratio and the clinical activity score. Histological studies showed a remarkable reduction in inflammation, as well as an intensive regeneration of the affected tissues.

Anchoring Gated Mesoporous Silica Particles to Ethylene Vinyl Alcohol Films for Smart Packaging Applications.

This work is a proof of concept for the design of active packaging materials based on the anchorage of gated mesoporous silica particles with a pH triggering mechanism to a packaging film surface. Mesoporous silica micro- and nanoparticles were loaded with rhodamine B and functionalized with N-(3-trimethoxysilylpropyl)diethylenetriamine. This simple system allows regulation of cargo delivery as a function of the pH of the environment. In parallel, poly(ethylene-co-vinyl alcohol) films, EVOH 32 and EVOH 44, were ultraviolet (UV) irradiated to convert hydroxyl moieties of the polymer chains into ⁻COOH functional groups. The highest COOH surface concentration was obtained for EVOH 32 after 15 min of UV irradiation. Anchoring of the gated mesoporous particles to the films was carried out successfully at pH 3 and pH 5. Mesoporous particles were distributed homogeneously throughout the film surface and in greater concentration for the EVOH 32 films. Films with the anchored particles were exposed to two liquid media simulating acidic food and neutral food. The films released the cargo at neutral pH but kept the dye locked at acidic pH. The best results were obtained for EVOH 32 irradiated for 15 min, treated for particle attachment at pH 3, and with mesoporous silica nanoparticles. This opens the possibility of designing active materials loaded with antimicrobials, antioxidants, or aromatic compounds, which are released when the pH of the product approaches neutrality, as occurs, for instance, with the release of biogenic amines from fresh food products.

Sistemas de encapsulación y liberación controlada basados en el uso de puertas moleculares / Encapsulation and controlled delivery systems based on molecular gates

Las partículas mesoporosas de sílice (PMS) son estructuras de dióxido de silicio organizadas de manera que se crean poros entre 2 y 50 nm. El alto volumen de poros y su superficie interna, convierten a las PMS en excelentes soportes para la encapsulación de moléculas bioactivas. Además, la posibilidad de incluir moléculas con función de puerta molecular en su superficie externa permite el diseño de sistemas inteligentes de liberación. Las PMS con puerta molecular muestran "liberación cero" de la molécula encapsulada, pero tras la aplicación de un estímulo externo específico son capaces de liberar su carga como respuesta específica a dicho estímulo. En este artículo se describen las características de las PMS usadas en la encapsulación de compuestos bioactivos, las puertas moleculares más importantes para crear sistemas de liberación controlada y ejemplos de aplicación de PMS para la encapsulación de ingredientes alimenticios y nutracéuticos. Estas aplicaciones incluyen la modulación de la bioaccesibilidad de ingredientes alimenticios o nutracéuticos, así como la protección de su estabilidad frente a la degradación por agentes externos

Mesoporous silica particles (MSP) are structures of silicon dioxide arranged so that they are able to create pores between 2 and 50 nm. The high volume of pores and the internal surface of the MSP make them excellent supports for the encapsulation of bioactive molecules. In addition, the possibility of including molecules acting as molecular gate onto their outer surface allows the design of smart delivery systems. Gated-MSP show "zero release" of the encapsulated molecule, but after the application of a specific external stimulus, the cargo is released as a specific response to the stimulus. This article describes the features of the MSP used in the encapsulation of bioactive compounds, the most important molecular gates to create controlled release systems, as well as examples of application of MSP for the encapsulation and controlled release of food ingredients and nutraceuticals. These applications include the modulation of the bioaccessibility of food ingredients or nutraceuticals as well as the protection of their stability against external agents degradation

[Encapsulation and controlled delivery systems based on molecular gates]. / Sistemas de encapsulación y liberación controlada basados en el uso de puertas moleculares.

Mesoporous silica particles (MSP) are structures of silicon dioxide arranged so that they are able to create pores between 2 and 50 nm. The high volume of pores and the internal surface of the MSP make them excellent supports for the encapsulation of bioactive molecules. In addition, the possibility of including molecules acting as molecular gate onto their outer surface allows the design of smart delivery systems. Gated-MSP show "zero release" of the encapsulated molecule, but after the application of a specific external stimulus, the cargo is released as a specific response to the stimulus. This article describes the features of the MSP used in the encapsulation of bioactive compounds, the most important molecular gates to create controlled release systems, as well as examples of application of MSP for the encapsulation and controlled release of food ingredients and nutraceuticals. These applications include the modulation of the bioaccessibility of food ingredients or nutraceuticals as well as the protection of their stability against external agents degradation.

Las partículas mesoporosas de sílice (PMS) son estructuras de dióxido de silicio organizadas de manera que se crean poros entre 2 y 50 nm. El alto volumen de poros y su superficie interna, convierten a las PMS en excelentes soportes para la encapsulación de moléculas bioactivas. Además, la posibilidad de incluir moléculas con función de puerta molecular en su superficie externa permite el diseño de sistemas inteligentes de liberación. Las PMS con puerta molecular muestran "liberación cero" de la molécula encapsulada, pero tras la aplicación de un estímulo externo específico son capaces de liberar su carga como respuesta específica a dicho estímulo.En este artículo se describen las características de las PMS usadas en la encapsulación de compuestos bioactivos, las puertas moleculares más importantes para crear sistemas de liberación controlada y ejemplos de aplicación de PMS para la encapsulación de ingredientes alimenticios y nutracéuticos. Estas aplicaciones incluyen la modulación de la bioaccesibilidad de ingredientes alimenticios o nutracéuticos, así como la protección de su estabilidad frente a la degradación por agentes externos.

Improving the Antimicrobial Power of Low-Effective Antimicrobial Molecules Through Nanotechnology.

The objective of this work was on the one hand to assess the antibacterial activity of amines anchored to the external surface of mesoporous silica particles against Listeria monocytogenes in comparison with the same dose of free amines as well. It was also our aim to elucidate the mechanism of action of the new antimicrobial device. The suitability of silica nanoparticles to anchor, concentrate and improve the antimicrobial power of polyamines against L. monocytogenes has been demonstrated in a saline solution and in a food matrix. Moreover, through microscope observations it has been possible to determine that the attractive binding forces between the positive amine corona on the surface of nanoparticles and the negatively charged bacteria membrane provoke a disruption of the cell membrane. The surface concentration of amines on the surface of the nanoparticles is so effective that immobilized-amines were 100 times more effective in killing L. monocytogenes bacteria than the same amount of free polyamines. This novel approach for the creation of antimicrobial nanodevices opens the possibility to put in value the antimicrobial power of natural molecules that have been discarded because of its low antimicrobial power. PRACTICAL APPLICATION: Consumers demand for high-quality products, free from chemical preservatives, with an extended shelf-life. In this study, a really powerful antimicrobial agent based on a nanomaterial functionalized with a non-antimicrobial organic molecule was developed as a proof of concept. Following this approach it could be possible to develop a new generation of natural and removable antimicrobials based on their anchoring to functional surfaces for food, agricultural or medical purposes.

Smart gated magnetic silica mesoporous particles for targeted colon drug delivery: New approaches for inflammatory bowel diseases treatment.

Magnetic mesoporous silica microparticles were loaded with safranin O (S1) and with hydrocortisone (S2) and the outer surface functionalized with a bulky azo derivative bearing urea moieties. Aqueous suspensions of both solids at pH 7.4 showed negligible payload release whereas a marked delivery was observed in the presence of sodium dithionite due to the rupture of the azo bonds. Besides, a moderate cargo release was observed at acidic pH due to the hydrolysis of the urea bonds that linked the azo derivative onto the external surface of the inorganic scaffolds. In vitro digestion models showed that S1 and S2 microparticles could be used for the controlled release of payload in the reducing colon environment (in which azoreductase enzymes are present). On the other hand, in vivo pharmacokinetic studies in rats showed that safranine O release from S1 microparticles was concentrated in colon. The performance of S2 microparticles for the treatment of colitis in rats (induced by oral administration of a 2,4,6-trinitrobenzenesulfonic acid solution) was tested. The controlled release of hydrocortisone from S2 in the colon of injured rats induced marked reduction in colon/body weight ratio and in clinical activity score. Also, histological studies showed a marked decrease in inflammation followed by intensive regeneration and almost normal mucosal structure of the individuals treated with S2. Besides, the use of a magnetic belt increased the therapeutic performances of S2 due to an enhanced retention time of the particles in the colon.

Enhanced antimicrobial activity of essential oil components immobilized on silica particles.

The antimicrobial activity of essential oils components (EOCs) is well-known. However, their high volatility and powerful aroma limit their application in the formulation of a wide range of food products. In this context, the antimicrobial activity of carvacrol, eugenol, thymol and vanillin grafted onto the surface of three silica supports with different morphologies, textural properties and chemical reactivities (fumed silica, amorphous silica and MCM-41) was evaluated herein. Materials characterization revealed a good immobilization yield and all the devices showed a micro-scale particle size. Sensory evaluation revealed that sensory perception of EOCs decreases after covalent immobilization. Moreover, immobilization greatly enhanced the antimicrobial activity of the essential oil components against Listeria innocua and Escherichia coli compared to free components. The incorporation of EOCs immobilized on silica particles into pasteurized milk inoculated with L. innocua demonstrated their effectiveness not only for in vitro conditions, but also in a real food system.

Protection of folic acid through encapsulation in mesoporous silica particles included in fruit juices.

Folic acid (FA) is a synthetic vitamin commonly used for food fortification. However, its vulnerability to processing and storage implies loss of efficiency, which would induce over-fortification by processors to obtain a minimum dose upon consumption. Recent studies have indicated potential adverse effects of FA overdoses, and FA protection during processing and storage could lead to more accurate fortification. In addition, sustained vitamin release after consumption would help improve its metabolism. The objective of this work was to study controlled FA delivery and stability in fruit juices to reduce potential over-fortification risks by using gated mesoporous silica particles (MSPs). The obtained results indicated that FA encapsulation in MSPs significantly improved its stability and contributed to controlled release after consumption by modifying vitamin bioaccessibility. These results confirmed the suitability of MSPs as support for controlled release and protection of bioactive molecules in food matrices in different food production and storage stages.

Protective effect of mesoporous silica particles on encapsulated folates.

Mesoporous silica particles (MSPs) are considered suitable supports to design gated materials for the encapsulation of bioactive molecules. Folates are essential micronutrients which are sensitive to external agents that provoke nutritional deficiencies. Folates encapsulation in MSPs to prevent degradation and to allow their controlled delivery is a promising strategy. Nevertheless, no information exists about the protective effect of MSPs encapsulation to prevent their degradation. In this work, 5-formyltetrahydrofolate (FO) and folic acid (FA) were entrapped in MSPs functionalized with polyamines, which acted as pH-dependent molecular gates. The stability of free and entrapped vitamins after acidic pH, high temperature and light exposure was studied. The results showed the degradation of FO after high temperature and acidic pH, whereas entrapped FO displayed enhanced stability. Free FA was degraded by light, but MSPs stabilized the vitamin. The obtained results point toward the potential use of MSPs as candidates to enhance stability and to improve the bioavailability of functional biomolecules.

Encapsulation of folic acid in different silica porous supports: A comparative study.

Although folic acid is essential to numerous bodily functions, recent research indicates that a massive exposition to the vitamin could be a double-edged sword. In this study, the capacity of different caped mesoporous silica particles (i.e. Hollow Silica Shells, MCM-41, SBA-15 and UVM-7) to dose FA during its passage through the gastrointestinal tract has been evaluated. Results confirmed that the four capped materials were capable to hinder the delivery of FA at low pH (i.e. stomach) as well as able to deliver great amounts of the vitamin at neutral pH (i.e. intestine). Nevertheless, the encapsulation efficiency and the deliver kinetics differed among supports. While supports with large pore entrance exhibited an initial fast release, MCM-41, showed a sustained release along the time. This correlation between textural properties and release kinetics for each of the supports reveals the importance of a proper support selection as a strategy to control the delivery of active molecules.

Mesoporous Silica-Based Supports for the Controlled and Targeted Release of Bioactive Molecules in the Gastrointestinal Tract.

Mesoporous silica particles (MSPs) have attracted increasing interest as supports in the design of controlled delivery materials. Besides their excellent properties as loading supports (that is, large surface area and pore volume), the modification of their external surface with molecular/supramolecular ensembles allows the design of gated MSPs. Delivery systems based on gated MSPs show "zero delivery" until an adequate stimulus is present and triggers gate opening and the cargo is released. Encapsulation of bioactive molecules in gated MSPs may improve biological stability, facilitate component handling, mask unpleasant sensorial properties, and modulate the bioaccessibility of target molecules along the gastrointestinal tract. These properties make gated MSPs excellent candidates for encapsulating bioactive molecules and their subsequent utilization in the formulation of functional foods. This text highlights the most significant endogenous triggering stimuli that might be applied to design these site-specific delivery systems, as well as the strategies to develop them. Given the novelty of using MSPs in the food sector, the benefits and current potential limitations of employing MSPs in human food have been identified and discussed.

Antifungal effect of essential oil components against Aspergillus niger when loaded into silica mesoporous supports.

BACKGROUND: Essential oil components (EOCs) are known for their antifungal properties; however, their high volatility limits their application as antimicrobial agents. Strategies used for controlling the volatility of EOCs include encapsulation or loading into porous materials. This study evaluated the in vitro antifungal activity of selected EOCs (carvacrol, cinnamaldehyde, eugenol and thymol) against the fungus Aspergillus niger when loaded into MCM-41 and ß-cyclodextrin (ß-CD). RESULTS: Carvacrol and thymol in Mobil Composition of Matter No. 41 (MCM-41) displayed remarkable enhanced antifungal properties in comparison to the pure or ß-CD-encapsulated EOCs. In fact, carvacrol and thymol were able to maintain antifungal activity and inhibit fungal growth for 30 days, suggesting better applicability of these EOCs as natural preservatives. CONCLUSIONS: The sustained antifungal effect of EOCs encapsulated into silica mesoporous supports was described.