Dependence of the Ripeness Stage on the Antioxidant and Antimicrobial Properties of Walnut (Juglans regia L.) Green Husk Extracts from Industrial By-Products.

Walnut green husk (WGH) is a waste generated by the walnut (Juglans regia L.) harvest industry. It represents a natural source of polyphenols, compounds with antioxidant and antimicrobial activities, but their activity could be dependent on the ripeness stage of the raw material. In this study, the effect of the different ripeness stages-open (OH) and closed (CH) husks-on the antioxidant and antimicrobial properties of WGH extracts were analyzed, emphasizing the influence of the extracts in inhibiting Escherichia coli growth. The ripeness stage of WGH significantly affected the antioxidant activity of the extracts. This was attributed to the different polyphenol profiles related to the mechanical stress when the husk opened compared to the closed sample. The antimicrobial activity showed inhibition of E. coli growth. OH-extracts at 96 µg/mL caused the lowest specific growth rate (µmax = 0.003 h-1) and the greatest inhibition percentage (I = 93%) compared to CH-extract (µmax = 0.01 h-1; I = 69%). The obtained results showed the potential of the walnut green husk, principally open husk, as an economical source of antioxidant and antimicrobial agents with potential use in the food industry.

Active food additive based on encapsulated yerba mate (Ilex paraguariensis) extract: effect of drying methods on the oxidative stability of a real food matrix (mayonnaise).

The drying process used to obtain active food additives is critical to ensure its functionality. In this study, freeze- and spray-drying techniques were evaluated for encapsulation of extracts with antioxidant activity from yerba mate (Ilex paraguariensis), using maltodextrin (MD) as wall material. Additionally, the oxidative stability in a real food matrix (mayonnaise) was assessed. Both MD addition and drying methods affected the physical properties [moisture content, water activity (aW)] and oxidative stability. MD addition diminished moisture content and prevented polyphenol compounds from degradation. The spray-dried powders displayed the lowest moisture content (1.6 ± 0.3% bs), the highest polyphenol content (135.4 mg GAE/g pure extract), and oxidative stability than the freeze-dried samples. The antioxidant capacity of the encapsulated powder subjected to spray-drying increased the oxidative stability of the mayonnaise (258 ± 32 min) more than the other assayed system (165 ± 5 min). Therefore, a natural spray-dried antioxidant food additive was obtained with potential use in the food industry.

Chitosan-Based Nanoparticles for Intracellular Delivery of ISAV Fusion Protein cDNA into Melanoma Cells: A Path to Develop Oncolytic Anticancer Therapies.

Oncolytic virus therapy has been tested against cancer in preclinical models and clinical assays. Current evidence shows that viruses induce cytopathic effects associated with fusogenic protein-mediated syncytium formation and immunogenic cell death of eukaryotic cells. We have previously demonstrated that tumor cell bodies generated from cells expressing the fusogenic protein of the infectious salmon anemia virus (ISAV-F) enhance crosspriming and display prophylactic antitumor activity against melanoma tumors. In this work, we evaluated the effects of the expression of ISAV-F on the B16 melanoma model, both in vitro and in vivo, using chitosan nanoparticles as transfection vehicle. We confirmed that the transfection of B16 tumor cells with chitosan nanoparticles (NP-ISAV) allows the expression of a fusogenically active ISAV-F protein and decreases cell viability because of syncytium formation in vitro. However, the in vivo transfection induces a delay in tumor growth, without inducing changes on the lymphoid populations in the tumor and the spleen. Altogether, our observations show that expression of ISAV fusion protein using chitosan nanoparticles induces cell fusion in melanoma cells and slight antitumor response.

Encapsulation of Vitamins A and E as Spray-Dried Additives for the Feed Industry.

Encapsulated fat-soluble powders containing vitamin A (VA) and E (VE) were prepared as a feasible additive for extruded feed products. The effect of the encapsulating agents (Capsul-CAP®, sodium caseinate-SC) in combination with Tween 80 (TW) as an emulsifier and maltodextrin (MD) as a wall material on the physicochemical properties of emulsions and powders was evaluated. First, nanoemulsions containing MD:CAP:TW:VA/VE and MD:SC:TW:VA/VE were prepared and characterized. Then, powders were obtained by means of spray-drying and analyzed in terms of the product yield, encapsulation efficiency, moisture content, porosity, surface morphology, chemical structure, and thermal properties and thermo-oxidative/thermal stability. Results showed that although nanoemulsions were obtained for all the compositions, homogeneous microcapsules were found after the drying process. High product yield and encapsulation efficiency were obtained, and the presence of the vitamins was corroborated. The characteristics of the powders were mainly influenced by the encapsulating agent used and also by the type of vitamin. In general, the microcapsules remained thermally stable up to 170 °C and, therefore, the proposed encapsulation systems for vitamins A and E were suitable for the preparation of additives for the feed manufacturing through the extrusion process.

Alginate edible films containing microencapsulated lemongrass oil or citral: effect of encapsulating agent and storage time on physical and antimicrobial properties.

Active edible films have been proposed as an alternative to extend shelf life of fresh foods. Most essential oils have antimicrobial properties; however, storage conditions could reduce their activity. To avoid this effect the essential oil (EO) can be microencapsulated prior to film casting. The aim of this study was to determine the effects of the type of encapsulating agent (EA), type of EO and storage time on physical properties and antimicrobial activity of alginate-based films against Escherichia coli ATCC 25922. Trehalose (TH), Capsul® (CAP) and Tween 20 (Tw20) were used as EA. Lemongrass essential oil (LMO) and citral were used as active agents. The results showed that the type of EA affected the stability of the film forming-emulsions as well as the changes in opacity and colour of the films during storage but not the antimicrobial activity of them. Both microencapsulated EOs showed a prolonged release from the alginate films during the 28 days of storage. Trehalose was selected to encapsulate both active compounds because the films made with this microencapsulated EA showed the greatest physical stability and the lowest color variation among all the films studied.

Edible antimicrobial films based on microencapsulated lemongrass oil.

Edible films and coatings have been proposed as viable alternatives for the preservation of fresh food such as fruit, meat, fish and cheese. They can be designed to contain natural antioxidants, vitamins and antimicrobials in order to extend shelf life of the product keeping the natural sensorial properties. Essential oils have been targeted as potential active principles for edible films and coatings given their well-recognized antioxidant, antimicrobial and sensory properties. In the present work, lemongrass oil (LMO) microcapsules were prepared by the emulsification-separation method using sodium caseinate as wall material. Microcapsules had an average size of 22 µm and contained over 51 % oil in their nucleus. The release kinetics of the LMO components was studied for both, microcapsules and microcapsule containing films. Experimental data for the controlled release of LMO components showed good correlation with Peppas and Weibull models. The effect of the alginate matrix on the release parameters of the mathematical models could be detected by the modification of the b constant of the Weibull equation which changed from 0.167 for the microcapsules to 0.351 for the films. Films containing LMO at concentrations of 1250, 2500 and 5000 ppm were able to inhibit growth of Escherichia coli ATCC 25922 and Listeria monocytogenes ISP 65-08 in liquid cultures. A possible future application of these films for shelf life extension of fresh food is discussed.

Design of an antioxidant powder additive based on carvacrol encapsulated into a multilayer chitosan-alginate-maltodextrin emulsion.

Carvacrol has demonstrated antioxidant activity; however, its high volatility and low water solubility limit its direct application in food matrices. Then, an effective encapsulation system is required to protect it. This study aimed to design and characterize a carvacrol-based additive encapsulated in a spray-dried multilayer emulsion based on chitosan/sodium alginate/maltodextrin. Spray-drying temperature of 120 °C and 3 %(w/w) maltodextrin content maximized both encapsulation efficiency (~97 %) and loading capacity (~53 %). The powder's antioxidant properties were evaluated in two food simulant media: water (SiW) and water-ethanol (SiD). The highest antioxidant activity was observed in SiW for both ABTS•+ (8.2 ± 0.3mgEAG/g) and FRAP (4.1 ± 0.2mgEAG/g) methods because of the reduced release of carvacrol in SiD vs. SiW, as supported by micro- and macrostructural observations by SAXS and microscopy, respectively. An increase from 143 to 157 °C attributable to carvacrol protection and Tg = 44.4 °C (> ambient) were obtained by TGA and DSC, respectively. FT-IR confirmed intermolecular interactions (e.g. -COO- and -NH3+) as well as H-bonding formation. High water solubility (81 ± 3 %), low hygroscopicity (8.8 ± 0.2 %(w/w), poor flowability (CI:45 ± 4), and high cohesiveness (HR:1.8 ± 0.1) between particles were achieved, leading to a powdered antioxidant additive with high potential for applications which required avoiding/reducing oxidation on hydrophilic and hydrophobic food products.

Development and Characterization of a Natural Antioxidant Additive in Powder Based on Polyphenols Extracted from Agro-Industrial Wastes (Walnut Green Husk): Effect of Chickpea Protein Concentration as an Encapsulating Agent during Storage.

Developing a powder-form natural antioxidant additive involves utilizing polyphenols extracted from agro-industrial wastes (walnut green husk). This research explores chickpea proteins (CPP) as an emergent encapsulating agent to enhance the stability and shelf life of the antioxidant additive. This study aims to develop a natural antioxidant powder additive based on polyphenols obtained from walnut green husks encapsulated by chickpea protein (5%, 7.5%, and 10% w/v) to evaluate their effect under storage at relative humidities (33 and 75% RH). The physicochemical and structural properties analysis indicated that better results were obtained by increasing the protein concentration. This demonstrates the protective effect of CPP on the phenolic compounds and that it is potentially non-toxic. The results suggest that the optimal conditions for storing the antioxidant powder, focusing on antioxidant activity and powder color, involve low relative humidities (33%) and high protein concentration (10%). This research will contribute to demonstrating chickpea protein as an emerging encapsulating agent and the importance of the cytotoxic analysis of extracts obtained from agroindustrial wastes.

Structural and Physicochemical Characterization of Extracted Proteins Fractions from Chickpea (Cicer arietinum L.) as a Potential Food Ingredient to Replace Ovalbumin in Foams and Emulsions.

Chickpeas are the third most abundant legume crop worldwide, having a high protein content (14.9-24.6%) with interesting technological properties, thus representing a sustainable alternative to animal proteins. In this study, the surface and structural properties of total (TE) and sequential (ALB, GLO, and GLU) protein fractions isolated from defatted chickpea flour were evaluated and compared with an animal protein, ovalbumin (OVO). Differences in their physicochemical properties were evidenced when comparing TE with ALB, GLO, and GLU fractions. In addition, using a simple and low-cost extraction method it was obtained a high protein yield (82 ± 4%) with a significant content of essential and hydrophobic amino acids. Chickpea proteins presented improved interfacial and surface behavior compared to OVO, where GLO showed the most significant effects, correlated with its secondary structure and associated with its flexibility and higher surface hydrophobicity. Therefore, chickpea proteins have improved surface properties compared to OVO, evidencing their potential use as foam and/or emulsion stabilizers in food formulations for the replacement of animal proteins.

State diagram of salmon (Salmo salar) gelatin films.

BACKGROUND: A state diagram presents different physical states of a biomaterial as a function of solid content and temperature. Despite their technological interest, little information is available on protein systems such as gelatin/water mixtures. The objective of this work was to develop state diagrams of salmon gelatin (SG) and bovine gelatin (BG) in order to determine maximal freeze concentration parameters (T'(g) , T'(m) and X(s') ) and to relate possible differences to their biochemical characteristics. RESULTS: Biochemical characterisation of SG showed lower molecular weight and iminoacid concentration compared with BG. Likewise, the glass transition temperature (T(g) ) was lower for SG at X(s) > 0.8, which was associated with its lower molecular weight. Unexpectedly, the depression of freezing temperature (T(f) ) was greater for SG at X(s) > 0.1, which was associated with its higher ash content. Isothermal annealing produced effective values of T'(g) ≈ - 52 °C, T'(m) ≈ - 46 °C and X'(s) ≈ 0.6 for both gelatins. Interestingly, the enthalpy change associated with T'(m) (ΔH T m) was significantly higher for SG than for BG after annealing, indicating a higher proportion of ice present at about - 50 °C. CONCLUSION: Maximal freeze concentration parameters were similar between the two gelatins, though differences in biochemical properties were evident. The results show that there are likely different ways of interaction of SG and BG with water.

Study of the effect of the addition of plasticizers on the physical properties of biodegradable films based on kefiran for potential application as food packaging.

Spectroscopies analysis indicated that kefiran contains branched hexasaccharide repeating units. Neat kefiran films, 2 and 5% w/w of glycerol, d-glucitol, d-galactitol, d-mannitol, and d-limonene were incorporated as plasticizers. Neat and plasticized kefiran films were characterized by physical, thermal, mechanical, optical, and water solubilization properties. Neat kefiran had a glass transition temperature (Tg) of -20 ± 2 °C and, with the addition of plasticizers between -15 to -17 ± 2 °C. The values were close to the neat kefiran, and the results could be attributed to a lower amount of plasticizer used. The solubility of the glycerol plasticized films increases by 33% and decreased with the concentration of other plasticizers in comparison with the neat kefiran. d-glucitol and d-galactitol decreased the microhardness and Young's Modulus of films around 30% and 74% respectively, obtaining more flexible kefiran films. Kefiran based films could find applications as potential materials in the food-packaging industry.

Chitosan-Based Delivery of Avian Reovirus Fusogenic Protein p10 Gene: In Vitro and In Vivo Studies towards a New Vaccine against Melanoma.

Reovirus is known to have an anticancer effect in both the preclinical and clinical assays. Current evidence suggests that the reovirus-mediated impact on tumor growth depends on the activation of specific antitumor immune responses. A feasible explanation for the oncolytic effects and immune system activation is through the expression of the fusogenic reovirus protein. In this work, we evaluated the in vivo antitumor effects of the expression of fusogenic protein p10 of avian reovirus (ARV-p10). We used chitosan nanoparticles (CH-NPs) as a vehicle for the ARV-p10 DNA in murine B16 melanoma models both in vitro and in vivo. We confirmed that ARV-p10 delivery through a chitosan-based formulation (ARV-p10 CH-NPs) was capable of inducing cell fusion in cultured melanoma cells, showing a mild cytotoxic effect. Interestingly, intratumor injection of ARV-p10 CH-NPs delayed tumor growth, without changing lymphoid populations in the tumor tissue and spleen. The injection of chitosan nanoparticles (CH-NPs) also delayed tumor growth, suggesting the nanoparticle itself would attack tumor cells. In conclusion, we proved that in vitro ARV-p10 protein expression using CH-NPs in murine melanoma cells induces a cytotoxic effect associated with its cell fusion. Further studies are necessary for establishing a protocol for efficient in vivo DNA delivery of fusion proteins to produce an antitumoral effect.

Non-enzymatic browning kinetics in sucrose-glycine aqueous and dehydrated model systems in presence of MgCl2.

The development of non-enzymatic browning in the presence of MgCl2 was evaluated in liquid and dehydrated sucrose-glycine model systems, in relation to interactions of the salt with water and/or with sucrose. In both systems, browning was accelerated by the presence of MgCl2 because of the increased sugar hydrolysis (ten times faster) and the reduction of water mobility (1H NMR T2 relaxation times) caused by this salt (between 6 and 14% lower), counteracting the inhibitory effect of water on the Maillard reaction. MgCl2 also provoked a 40% reduction on the fluorophores quantum yield, responsible also of the fluctuations observed in the fluorescence development as a function of time after 50 h at 70 °C. Molecular and supramolecular effects of the presence of MgCl2 have been observed on the Maillard reaction kinetics. These results are of high technological interest when strategies to control the Maillard reaction rate are required for a particular application.

Quality Parameters of Six Cultivars of Blueberry Using Computer Vision.

Background. Blueberries are considered an important source of health benefits. This work studied six blueberry cultivars: "Duke," "Brigitta", "Elliott", "Centurion", "Star," and "Jewel", measuring quality parameters such as °Brix, pH, moisture content using standard techniques and shape, color, and fungal presence obtained by computer vision. The storage conditions were time (0-21 days), temperature (4 and 15°C), and relative humidity (75 and 90%). Results. Significant differences (P < 0.05) were detected between fresh cultivars in pH, °Brix, shape, and color. However, the main parameters which changed depending on storage conditions, increasing at higher temperature, were color (from blue to red) and fungal presence (from 0 to 15%), both detected using computer vision, which is important to determine a shelf life of 14 days for all cultivars. Similar behavior during storage was obtained for all cultivars. Conclusion. Computer vision proved to be a reliable and simple method to objectively determine blueberry decay during storage that can be used as an alternative approach to currently used subjective measurements.

Multi-level approach for the analysis of water effects in corn flakes.

The purpose of this work was to analyze the effect of water on thermal transitions, mechanical properties, and molecular mobility in corn flakes (CF), and their relationships. Commercial common (CCF) and sugar-frosted (SCF) corn flakes were studied in a water content (wc) range from 5 to 20 (% dry basis). The slope of (1)H NMR spin-spin relaxation time T 2* (determined by FID) versus temperature plot changed close to T g. Compression force showed a maximum at wc of ca. 12 and 16% (db) for SCF and CCF, respectively. (1)H NMR complemented DSC data in determining the temperature dependence of water and solid mobility, in order to assess quality of laminated corn products. The results of the present work indicate that while the compression force showed a maximum value as a function of water content, T g values determined by DSC or by spin-spin relaxation decreased progressively with increasing water content.

Fluorescence from the maillard reaction and its potential applications in food science.

The chemistry of the Maillard reaction involves a complex set of steps, and its interpretation represents a challenge in basic and applied aspects of Food Science. Fluorescent compounds have been recognized as important early markers of the reaction in food products since 1942. However, the recent advances in the characterization of fluorophores' development were observed in biological and biomedical areas. The in vivo non-enzymatic glycosylation of proteins produces biological effects, promoting health deterioration. The characteristic fluorescence of advanced glycosylation end products (AGEs) is similar to that of Maillard food products and represents an indicator of the level of AGE-modified proteins, but the structure of the fluorescent groups is, typically, unknown. Application of fluorescence measurement is considered a potential tool for addressing key problems of food deterioration as an early marker or index of the damage of biomolecules. Fluorophores may be precursors of the brown pigments and/or end products. A general scheme of the Maillard reaction is proposed in this article, incorporating the pool concept. A correct interpretation of the effect of environmental and compositional conditions and their influences on the reaction kinetics may help to define the meaning of fluorescence development for each particular system.