Improved extractability of carotenoids from tomato peels as side benefits of PEF treatment of tomato fruit for more energy-efficient steam-assisted peeling

The combination of steam blanching (SB) with Pulsed Electric Fields (PEF) treatments of whole tomatoes, in addition to reducing the energy required for tomato peeling, can significantly contribute to the recovery of carotenoids from the peels. In this work, PEF (0.25-0-75 kV/cm, 1 kJ/kg) and SB (1 min at 50–70 °C), as pre-treatment prior to hand peeling, were investigated to assess their ability, separately and in combination, to induce the cell permeabilization of tomato peels, and hence to improve the carotenoids extraction in acetone (4 h at 25 °C). PEF and SB, by inducing significant damages at the cuticular level, caused the increase of the yield in total carotenoids (up to 188% for PEF and 189% for SB) and antioxidant power (up to 372% for PEF and 305% for SB) with respect to the peels from untreated tomatoes. The application of a combined treatment (PEF + SB) significantly increased the carotenoid content and the antioxidant power of the extracts, with a synergistic effect observed already at 60 °C (37.9 mg/100 g fresh weight tomato peels). HPLC analyses revealed that lycopene was the main carotenoid extracted and that neither PEF nor SB caused any selective release or degradation of lycopene. Results obtained from this study demonstrate that the integration of PEF in the processing line of tomato fruits prior to SB contributes to the valorization of tomato processing by-products

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

Modeling microbial inactivation by high-pressure homogenization with a machine learning approach

This study leverages machine learning to create advanced predictive models for microbial inactivation during high-pressure homogenization (HPH). Unlike conventional models, which often focus solely on operating conditions, these models integrate additional factors, such as homogenizer-specific hydrodynamics, liquid media properties, and microorganism-specific characteristics. These factors are typically omitted in conventional models due to their wide variability across studies and the challenge of transforming them into a limited set of quantifiable variables. For instance, the influence of variations in homogenization valve geometry or changes in fluid viscosity are rarely incorporated, despite their significant impact on HPH outcomes. Through a comprehensive meta-analysis of literature data and the incorporation of dimensionless number to cluster diverse independent operating variables, various models, including artificial neural network (ANN) and random forest (RF), are trained and tested. While RF models exhibit faster runtimes without sacrificing performance compared to neural networks, a hybrid model was also devised to enhance prediction accuracy. This hybrid approach integrates RFs with the empirical Weibull model, linking microbial inactivation with applied pressure and the number of HPH passes. Notably, the hybrid model outperforms others, aligning well with expected inactivation trends. Challenges persist, such as the need for additional data and the inclusion of more relevant variables, underscoring the study's significance in advancing our comprehension of HPH's impact on microbial inactivation, thereby bolstering food safety and prolonging shelf-life

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

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

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