1,720,973 research outputs found
Break-up and recoalescence phenomena induced by high pressure homogenization: effect of the homogenization valve geometry
No full textNovel Edible Coating Containing Essential Oil Nanoemulsions to Prolong the Shelf Life of Vegetable Products
No full textEdible coatings are considered an environmentally friendly technology, able to extend the shelf-life of fruit and vegetables. In the present work, a novel approach to the preservation of vegetable products is proposed, through the development of edible coatings, containing nanoemulsified natural antimicrobial compounds. Modified chitosan was initially selected as film-forming biopolymer, owing to its inherent antimicrobial activity.
Different essential oil nanoemulsions, with variable composition, mean droplet size and surface charge, containing lemon, mandarin, oregano or clove essential oils, were developed to maximize in vitro the interaction with the modified chitosan coating and promote the resulting antimicrobial activity. The combined use of nanoemulsified lemon essential oil with modified chitosan resulted in the remarkable increase in antimicrobial activity, with respect to other essential oils. Therefore, this formulation, comprising 0.05%wt modified chitosan and 0.1%wt nanoemulsified lemon essential oil, was further tested in product for the stabilization of a leaf vegetable, such as rucola, during a shelf-life, consisting of storage at 4 degrees C for 3 d and then at 8 degrees C for a total of 21 d. Microbial viability as well as colour and texture changes were monitored during the shelf-life.
The obtained results showed that the incorporation of nanoencapsulated lemon essential oil into the modified chitosan coating prolonged the shelf life of rucola leaves from 3 to 7 d, in comparison to the untreated sample. Moreover, the modified chitosan containing the nanoemulsified antimicrobial caused a significantly longer shelf-life also in comparison to a coating made of modified chitosan or essential oil alone. In conclusion, thanks to this novel treatment it is possible to prolong the shelf life of delicate leaf vegetables to about 10 - 14 d, without causing any significant alteration of the organoleptic properties of the product, preventing the loss of firmness and colour changes and preserving palatability during storage
Nanoemulsion-based delivery systems
No full textOil-in-water (O/W) nanoemulsions are exceptional carriers for a wide range of industrial applications, and for several bioactive compounds in functional foods and additives, promoting their homogeneous dispersion in the end product, as well as protecting them from interaction with other ingredients, and from degradation during end product transformation, storage, and preparation. This chapter describes the main features of O/W nanoemulsions for the delivery of bioactive compounds, giving insights on their methods of fabrication, especially from the perspective of industrial applications. In addition, this chapter provides recent examples of O/W nanoemulsions designed and developed for the encapsulation of different classes of payload compounds with diverse functionalities, ranging from the antimicrobial activity of essential oils, to the health-beneficial properties of polyphenols, carotenoids, vitamins, and lipids, as well as organoleptic features of flavors
Antimicrobial edible films and coatings based on modified chitosan containing essential oil nanoemulsions
No full textThe interest towards the use of edible films and coatings in food preservation has been sustained in the recent years by the development of active biopolymeric matrices incorporating natural antimicrobial compounds, in replacement of synthetic additives.
In this work, we present our recent activities addressed to the development and optimization of edible films and coatings based on modified chitosan containing different types of essential oil nanoemulsions. The essential oil nanoemulsions have been formulated to maximize the antimicrobial activity, developing significant synergies with the intrinsic antimicrobial properties of modified chitosan and its barrier properties, while preserving the desired material characteristics, and in particular transparency and hydrophobicity.
The developed antimicrobial films and coatings have been tested in vitro (disk inhibition zone) and in product (broccoli florets and green beans) against different microorganisms of interest for food preservation, such as Escherichia coli, Listeria innocua, and Listeria monocytogenes.
In addition, this work discusses also the possible synergies and technological drawbacks of the combination of the antimicrobial edible films and coatings with non-thermal preservation technologies, such as high intensity pulsed light and high hydrostatic pressure, in view of food microbiological stabilization during its shelf life, as well as of the impact on product color and texture.
Results showed that emulsion formulations significantly affected the intrinsic antimicrobial activity of edible films and coatings. However, also the interaction of the nanoemulsions structure with the modified chitosan matrix impacted film properties and resulting bactericidal action. In addition, in comparison to the use of pure essential oils, the encapsulation into nanoemulsions also fostered the production of more homogeneous films with better appearance.
The combination of the coating application with high hydrostatic pressure resulted as the most promising approach, causing a significant microbial reduction over the entire storage period analyzed, owing to the development of a significant synergism of antimicrobial effects; however, it also had a strong impact on product firmness. In contrast, the combination of the coating application with high intensity pulsed light exhibited a slight antagonistic effect, and had a slight detrimental impact on color properties.
This work hence contributes to promote the incorporation of nanoemulsions of essential oils in edible films and coatings for integrated food preservation strategies
Rheological and interfacial properties at the equilibrium of almond gum tree exudate (Prunus dulcis) in comparison with gum arabic
No full textAlmond gum contains an arabinogalactan-type polysaccharide, which plays an important role in defining its interfacial and rheological properties. In this study, rheological and interfacial properties of almond gum and gum arabic aqueous dispersions were comparatively investigated. The interfacial tension of almond gum and gum arabic aqueous dispersions was measured using the pendant drop method in hexadecane. The asymptotic interfacial tension values for almond gum were significantly lower than the corresponding values measured for gum arabic, especially at high concentration. Rheological properties were characterized by steady and oscillatory tests using a coaxial geometry. Almond gum flow curves exhibited a shear thinning non-Newtonian behavior with a tendency to a Newtonian plateau at low shear rate, while gum arabic flow curves exhibited such behavior only at high shear rate. The influence of temperature (5-50 °C) on the flow curves was studied at 4% (m/m) gum concentration and the Newtonian viscosities at infinite and at zero shear rate, for gum arabic and almond gum, respectively, were accurately fitted by an Arrhenius-type equation. The dynamic properties of the two gum dispersions were also studied. Both gum dispersions exhibited viscoelastic properties, with the viscous component being predominant in a wider range of concentrations for almond gum, while for gum arabic the elastic component being higher than the elastic one especially at higher concentrations.The rheological and interfacial tension properties of almond gum suggest that it may represent a possible substitute of gum arabic in different food applications
Cellular antioxidant activity of resveratrol encapsulated in nanoscale lipid-based delivery systems
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Effect of Emulsifier Type and Disruption Chamber Geometry on the Fabrication of Food Nanoemulsions by High Pressure Homogenization
No full textProduction of food nanoemulsions by high pressure homogenization (HPH) is investigated, focusing on the effect on droplet nanonization of emulsifier type and concentration, as well as of the geometry of the homogenization chamber. Several food-grade emulsifiers were characterized, in comparison with artificial ones, in terms of their interfacial and dynamic properties, by pendant drop measurements. The kinetics of the emulsification process was determined by dynamic light scattering measurements on the emulsions produced at different pressure levels (70-280 MPa) and number of HPH passes, in four different homogenization chamber geometries. The results show that the kinetic parameters of the emulsification process can be primarily correlated with the interfacial and dynamic properties of the emulsifiers, while the fluid-dynamics regime establishing in the homogenization chamber contributes only to a lesser extent. Nevertheless, the correct design of the homogenization chamber may help in obtaining uniform fluid-dynamic conditions, which ensure a narrow droplet size distribution
Nanoencapsulation of essential oils to enhance their antimicrobial activity in foods
No full textThis work focuses on the encapsulation of essential oils into nanometric delivery systems for incorporation into fruit juices, in order to enhance their antimicrobial activity while minimizing the impact on the quality attributes of the final product. A terpenes mixture and d-limonene were encapsulated into nanoemulsions based on food-grade ingredients, prepared by high pressure homogenization at 300 MPa.
The effect of the delivery systems on the antimicrobial activity of terpenes was investigated by determining the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for three different classes of microorganisms (Lactobacillus delbrueckii, Saccharomyces cerevisiae, Escherichia coli). The increase of the antimicrobial activity resulted to depend on the formulation and mean diameter of the delivery systems as well as on the microorganisms class. Additionally, GC–MS analysis revealed that high intensity processing for nanoemulsion production may affect the chemical stability of several active compounds.
The application of the most efficient antimicrobial nanocapsules was tested in pear and orange juices inoculated with L. delbrueckii. Due to the higher antimicrobial activity of the nanoencapsulated compounds, lower antimicrobial concentrations are required for a bactericidal action under accelerated aging at 32 °C, with a minimal alteration of the organoleptic properties of the juice
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