1,721,086 research outputs found
SUSTAINABLE VALORIZATION OF AGRI-FOOD RESIDUES BY HIGH PRESSURE HOMOGENIZATION PROCESSING TO UNLOCK HIGH-ADDED VALUE INTRACELLULAR COMPONENTS
No full textResidues from agri-food industry, including both by-products and wastes, often represent an environmental burden, either in terms of the impact of their use in low-added value products, or of their disposal. However, they also represent an opportunity to bring economic and social benefits, because still rich in valuable intracellular compounds, which can be efficiently valorized if adequately recovered.
The present work addresses the use of wet milling by High Pressure Homogenization (HPH), as an efficient process to unlock high-added value intracellular components from plant-based agri-food residues through the mechanical disruption of vegetable cells. HPH processing has been tested in the valorization of different agri-food residues, such as tomato peels, coffee residues, and rice bran, primarily to increase the bioaccessibility of antioxidant compounds. The vegetable matrices were suspended in water, pre-milled and screened at 600 micron. Subsequently, the vegetable suspensions were processed by HPH, at pressures ranging between 100 and 200 MPa and for 1 - 5 passes.
The results show that HPH processing causes a statistically significant increase in both supernatant antioxidant activity (related to the antioxidant compounds released in the aqueous phase upon HPH processing) and surface antioxidant activity (related to the antioxidant still bonded to the surface of cell debris). However, HPH-processed suspensions exhibited also other interesting features, suggesting their possible use not only as functional ingredients but also as thickening agents or stabilizers: (a) the content of soluble protein significantly increased, with a consequent higher surface activity of the vegetable suspension; (b) the fine cell debris resulting from the mechanical disruption of vegetable cells caused a measurable increase in the viscosity of the suspension.In conclusion, HPH processing of agri-food residues enables to unlock the high-added values components still remaining in the vegetable cells using a purely physical process and water as solvent, contributing to pursue the concepts of sustainable valorization and total use of the residue
Essential oil nanoemulsions as antimicrobial agents in food
Full text linkThe crescent interest in the use of essential oils (EOs) as natural antimicrobials and preservatives in the food industry has been driven in the last years by the growing consumers' demand for natural products with improved microbial safety, and fresh-like organoleptic properties. Nanoemulsions efficiently contribute to support the use of EOs in foods by increasing their dispersibility in the food areas where microorganisms grow and proliferate, by reducing the impact on the quality attributes of the product, as well as by enhancing their antimicrobial activity. Understanding how nanoemulsions intervene on the mass transfer of EOs to the cell membrane and on the mechanism of antimicrobial action will support the engineering of more effective delivery systems and foster the application of EOs in real food systems. This review focuses on the enabling contribution of nanoemulsions to the use of EOs as natural preservative agents in food, (a) specifically addressing the formulation and fabrication of stable EO nanoemulsions, (b) critically analyzing the reported antimicrobial activity data, both in vitro and in product, to infer the impact of the delivery system on the mechanisms of action of EOs, as well as (c) discussing the regulatory issues associated with their use in food systems
Effect of Nanoemulsion Formulation on Permeation of Essential Oils Through Biological Membranes
No full textThe encapsulation of essential oils in nanoemulsions represents an effective approach not only to disperse them in the aqueous systems where microorganisms proliferate but also to enhance their permeability through biological membranes.
In this work, different food-grade emulsifiers, such as whey proteins, lecithin, Tween 80, alginate or zein, were tested in the preparation of carvacrol nanoemulsions in water. In order to prevent the occurrence of instability phenomena associated with Ostwald ripening, carvacrol was mixed at different ratios with peanut oil or medium chain triglycerides. The high-pressure homogenization method (200 MPa, three passes, using an orifice valve) was used to reduce the droplet size in the nanometric range.
The nanoemulsions were tested for their stability over time at varying the main formulation parameters, and then carvacrol permeability across dialysis membranes was investigated, using a Franz cell assembly.
The results showed that, in order to prevent droplet coalescence due to Ostwald ripening, the minimum ripening inhibitor oil-carvacrol ratio in the dispersed oil phase should be 3:1.
In addition, despite comparable droplet sizes (< 150 nm), the nanoemulsions stabilized by lecithin or whey proteins enabled a higher carvacrol diffusion through the cellulose membranes, which was one order of magnitude higher than Tween 80-based systems
Structuring Vegetable Oils Through the Formation of Capillary Suspensions: Comparison of Wheat Middlings and Pure Cellulose Processed by High-pressure Homogenization
No full textReducing the intake of harmful trans-fats and saturated fats in the diet, by replacing detrimental fats with healthier oils, without affecting the organoleptic properties of the food product, represent a formidable challenge for the scientific community. In this scenario, this work explores a possible strategy for structuring sunflower oil by investigating the formation of capillary suspensions using wheat middlings (WM) and pure cellulose (CL) as a structuring solid fraction. High-pressure homogenization (HPH), a purely mechanical cell disruption technology, was directly applied to oil suspensions of WM or CL. Subsequently, the addition under high-shear mixing (HSM) of different amounts of an immiscible secondary fluid, water, to the oil suspensions, led to WM and CL particles bridging and network formation, through the development of attractive capillary forces among the particles. The effect of water and particles characteristics on the rheological behavior of the oil suspensions was investigated. The presence of water caused initially an increase in viscosity and then a decrease, as water concentration exceeded a critical value, with an inversion from a continuous oil phase to a continuous aqueous phase. Moreover, the oxidative stability of the capillary suspensions was evaluated, during accelerated aging.
The proposed approach not only does not suffer the presence of water, but significantly improves the oxidation stability with respect to the pure oil
Understanding the effect of formulation on functionality of modified chitosan films containing carvacrol nanoemulsions
No full textThe interest towards the use of films and coatings in food preservation has been reinforced in the recent years by the development of biopolymeric matrices incorporating essential oil as antimicrobial barriers in food as an alternative to synthetic additives.
This work has therefore been addressed to investigate the effect of composition parameters on antimicrobial activity and properties of films based on modified chitosan containing different types of carvacrol nanoemulsions. Specifically, response surface methodology, applied for the concentration of biopolymer and carvacrol nanoemulsion in the film forming dispersions to maximize the antimicrobial activity against two model microorganisms, Escherichia coli and Listeria innocua, as well as surface hydrophobicity, was used to determine the optimum conditions for comparison of most promising systems.
Results showed that emulsion formulations had a significant effect on the intrinsic antimicrobial activity, but also that their interaction with the modified chitosan matrix affected film properties and resulting bactericidal action. The two most active emulsion formulations, based on a combination of polysorbate 20 and glycerol monooleate, and on whey protein isolates, respectively, when incorporated in modified chitosan films significantly increased the inhibition zone against E. coli and L. innocua from 7.2-7.4 mm (modified chitosan alone) to 13.4-16.1 mm, while still ensuring surface hydrophobicity of the film. In comparison to the use of pure carvacrol, the encapsulation into nanoemulsions also fostered the production of more homogeneous films with better appearance
Taste masking of bitter polyphenolic compounds by rational design of nanostructured lipid particles
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
Infusione di oli essenziali in alimenti solidi attraverso l’incapsulamento in nanoemulsioni
No full textL’utilizzo di oli essenziali (EO) come antimicrobici naturale ne richiede il loro incapsulamento in sistemi compatibili con gli alimenti, come le nanoemulsioni. Questo lavoro studia gli aspetti fondamentali dell’infusione di nanoemulsioni di carvacrolo in prodotti vegetali solidi per stabilizzarli microbiologicamente. Le cinetiche di infusione sono determinate mediante l'analisi delle micrografie in fluorescenza ottenute da campioni di zucchine esposti ad emulsioni di diversa composizione e dimensione. I risultati chiaramente evidenziano che la velocità di infusione delle nanoemulsioni nella struttura vegetale è principalmente funzione della loro dimensione, piuttosto che della composizione. Inoltre, l'attività antimicrobica misurata contro E. coli, inoculato nelle zucchine, risulta essere ben correlabile con le cinetiche di infusione nelle matrici vegetali, con la massima inattivazione raggiunta per nanoemulsioni subcellulari
Applications of Pulsed Electric Field Treatments for the Enhancement of Mass Transfer from Vegetable Tissue
No full textIn the last decades, several non-thermal technologies have been proposed as alternative to the traditional ones to improve the competitiveness of the food industry. The key to success was identified in offering to food industries the opportunity to improve food quality, to introduce new foods in the market, and to optimize the processing procedures while reducing energy costs. Pulsed electric fields (PEF) showed the potential to be one of the most promising novel technologies to reach these objectives.
The application of PEF as a pretreatment of permeabilization of vegetable and animal tissue to enhance the efficiency of mass transfer of water or of valuable compounds from biological matrices demonstrated its efficiency in drying, extraction, and diffusion processes.
This article reviews the basic mechanisms of electroporation of plant tissues, discusses the methods of detection of electrically
induced cell damage, and analyses the influence of process parameters on the efficiency of the treatment.
Furthermore, this article focuses on the applications of PEF, its advantages, and energy costs in different fields of food processing, such as juice expression, drying, and extraction, with special emphasis on the relevance of PEF to the winemaking industry
Estrazione di succo di mirtillo mediante pressatura assistita da PEF
No full textPEF treatments of different electric field intensity (E=0-7 kV/cm) and
total specific energy (WT=0-20 kJ/kg) were applied during the pressing process
(0.35-1.65 bar) to enhance the expression of fresh and thawed blueberry juice.
Results demonstrate that PEF treatment is able to induce the permeabilization of
blueberry tissues. The higher is the intensity of the applied electric field, the
lower is the energy required to obtain the desired degree of cell membrane
disintegration. The application of a PEF treatment of moderate intensity (E=1
kV/cm, WT=12 kJ/kg) in combination with pressures below 1 bar allows to obtain
higher extraction yields (up to 75%) and the production of juices with a higher
content of polyphenols and antioxidant activity than those achievable with a
conventional pressing process
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