High-pressure homogenization for the recovery of value-added compounds from vegetable matrices

High-pressure homogenization (HPH) has been recently reported to be an effective mechanical cell disruption technology to unlock the intracellular compounds, tightly entrapped in vegetable tissues, using only water as an extraction medium. In this work, HPH was used to promote the recovery of the bioactive compounds contained in white and black sesame seeds (Sesamum indicum). Aqueous suspensions (10% w/w) of the seeds, obtained by high-shear mixing (HSM) for 5 min at 20000 rpm, were treated by HPH at 100 MPa or 140 MPa for up to 10 passes and different temperatures (25 and 50 °C). The HPH treatment caused a considerable cell deagglomeration and fragmentation effect, as shown by the decrease in the size distribution of the suspended particles. At the same time, the HPH treatment also significantly increased, more than twofold, the polyphenolic content and antioxidant activity of the aqueous extracts, in comparison to HSH. Remarkably, a significant decrease (-20%) in antioxidant activity was observed during HPH processing at a higher temperature, likely due to the degradation of thermolabile compounds. Higher operating pressures increased the antioxidant activity of the aqueous extracts but caused also the increased release of polyphenol oxidases, which induced a higher degradation of the antioxidant activity of the extracts over time in comparison with samples processed at lower pressure. However, spray drying of the HPH-treated suspensions, without any further treatment or additive, resulted in the efficient stabilization of the extracts

Changing the vision in smart food design utilizing the next generation of nanometric delivery systems for bioactive compounds

In modern foods, the delivery systems for bioactive compounds play a fundamental role in health promotion, wellbeing, and disease prevention through diet. Nanotechnology has secured a fundamental role in the fabrication of delivery systems with the capability of modulating the in-product and in-body behavior for augmenting bioavailability and activity of bioactive compounds. Structured nanoemulsions and nanoparticles, liposomes, and niosomes can be designed to improve bioactives preservation after ingestion, mucoadhesion, as well as of their release and pathophysiological relevance. In the future, it is expected that the delivery systems will also contribute to augment the effcacy of the bioactive compounds, for example by improving the intestinal absorption and delivery in the bloodstream, as well as promoting the formation of additional bioactive metabolites by regulating the transformations taking place during digestion and the interaction with the intestinal microbiota

Infusione di oli essenziali in alimenti solidi attraverso l’incapsulamento in nanoemulsioni

L’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

A multistep surface mechanism for ethane oxidative dehydrogenation on Pt- and Pt/Sn-coated monoliths

A computational study of ethane oxidative dehydrogenation to ethylene on Pt- and Pt/Sn-coated monoliths is presented as an improvement to previous kinetic models in reproducing experimental findings over a wide range of feed conditions. The multistep surface mechanism containing 20 reversible reactions among 11 surface species is based on published reaction steps for hydrogen and methane oxidation combined with lumped steps for ethane surface chemistry and coupled with an established homogeneous mechanism to form the detailed chemistry model. Simulation results at 1 atm are in good agreement with experimental data obtained on Pt at variable C2H6/ O2 and C2H6/O2/H2 ratios and predict experimentally observed phenomena such as ignition temperatures and homogeneous ethylene formation. The model is also used to predict Pt monolith performance over an industrially relevant range of space velocities (0.7-3.4 x 1e5 h-1) and pressures (1-10 atm). Furthermore, the Pt mechanism is extended to a Pt/Sn catalyst by changing two parameters in the H and CO oxidation steps, and agreement with experiments is obtained with and without H2 addition

Effect of formulation on properties, stability, carvacrol release and antimicrobial activity of carvacrol emulsions

The structural design of essential oil emulsions can be exploited to modulate their antimicrobial activity, through the effect that the main formulation parameters (oil phase composition and type of emulsifier) have on the release of encapsulated antimicrobial compounds. In this work, different emulsions containing carvacrol, selected as model essential oil component, were characterized in terms of emulsions size, stability, and carvacrol release and solubilization, determined in Franz cells, and tested for minimum inhibitory and microbicidal concentration against P. fluorescens, S. epidermidis, and S. cerevisiae. The results showed that carvacrol fraction in the oil phase significantly affected oil viscosity, density, and O/W interfacial tension. Carvacrol solubilization in the aqueous phase, in equilibrium with the oil mixture, increased with the concentration of carvacrol in the oil phase and with the presence of an emulsifier/stabilizer in the aqueous phase. However, when encapsulated in emulsions carvacrol solubilization exhibited a weak dependence on carvacrol fraction in oil phase because part of the emulsifier/stabilizer was adsorbed at the O/W interface. Higher carvacrol solubilization was observed for WPM Pickering emulsions, followed by WPI and T80 emulsions. The antimicrobial activity was proportional to carvacrol solubilization, suggesting that emulsion droplets act as micrometric tanks for carvacrol, which is steadily released over time in the aqueous phase. The high carvacrol solubilization in the aqueous phase at higher carvacrol fractions in the oil phase (≥75% w/w) was also responsible for lower T80 and WPI emulsion stability because of coalescence, whereas all WPM emulsions exhibited signs of flocculation

Cellulose Isolation from Tomato Pomace Pretreated by High-Pressure Homogenization

This work proposes a biorefinery approach for the utilization of agri-food residues, such as tomato pomace (TP), through combining chemical hydrolysis with high-pressure homogenization (HPH), aiming to achieve the isolation of cellulose with tailored morphological properties from underused lignocellulose feedstocks, along with the valorization of the value-added compounds contained in the biomass. Cellulose was isolated from TP using sequential chemical hydrolysis in combination with mechanical pretreatment through HPH. The chemical and structural features of cellulose isolated from TP pretreated by HPH were compared with cellulose isolated from untreated TP through light scattering for particle size distribution, optical and scanning electron microscopy, and Fourier-transform infrared spectroscopy (FT-IR) analysis. HPH pretreatment (80 MPa, 10 passes) not only promoted a slight increase in the yield of cellulose extraction (+9%) but contributed to directly obtaining defibrillated cellulose particles, characterized by smaller irregular domains containing elongated needle-like fibers. Moreover, the selected mild chemical process produced side streams rich in bioactive molecules, evaluated in terms of total phenols and reducing activity. The liquors recovered from acid hydrolysis of TP exhibited a higher biological activity than those obtained through a conventional extraction (80% v/v acetone, 25◦C, 24 h at 180 rpm)

The use of nanocellulose in edible coatings for the preservation of perishable fruits and vegetables

The usage of edible coatings (ECs) represents an emerging approach for extending the shelf life of highly perishable foods, such as fresh and fresh-cut fruits and vegetables. This review addresses, in particular, the use of reinforcing agents in film-forming solutions to tailor the physi-cochemical, mechanical and antimicrobial properties of composite coatings. In this scenario, this review summarizes the available data on the various forms of nanocellulose (NC) typically used in ECs, focusing on the impact of their origin and chemical or physical treatments on their structural properties (morphology and shape, dimension and crystallinity) and their functionality. Moreover, this review also describes the deposition techniques of composite ECs, with details on the food engineering principles in the application methods and formulation optimization. The critical analysis of the recent advances in NC-based ECs contributes to a better understanding of the impact of the incorporation of complex nanoparticles in polymeric matrices on the enhancement of coating properties, as well as on the increase of shelf life and the quality of fruits and vegetables