Search

This research evaluates the potential use of ultraviolet C light (UV-C) as a decontamination method for powdered foods, particularly of refined flour. This technology's lethal effectiveness was evaluated on Salmonella enterica subsp. Enterica serotype Typhimurium and Lactobacillus plantarum in wheat flour, and in laboratory liquid media of different a w and turbidities to evaluate the action mechanisms of UV-C light in powdered products. Initial results showed a large variability of lethality in flour, obtaining between 0.2 and 3.0 log 10 cycles of inactivation. Results obtained in laboratory media and SEM analysis of contaminated flour indicated that the variability was due to a shadow effect on the efficacy of UV-C light and not due to the low water a w of the flour or starch content. Based on these conclusions, a 2-m vertical tunnel with twelve 480 W UV-C lamps was designed to treat flour by forming a continuous cloud of dust (0.05–2.4 kg/h). Inactivation levels of 4.0 to 1.7 log 10 cycles of the population of L. plantarum in flour were achieved at flow rates of 0.2 and 2.4 kg/h respectively, with a maximum residence time of 4 s. Industrial relevance This investigation demonstrated the lethal efficacy of the application of UV–C light to inactivate microorganisms, both pathogenic and spoilage, present in flour. 4-log10 cycles of inactivation of both Salmonella Typhimurium and Lactobacillus plantarum were inactivated with UV-C treatments. A UV-C facility was built up which enabled to treat flour in continuous conditions creating a cloud of dust with treatments of 4 s and lethalities of 4-log10 reductions. [ABSTRACT FROM AUTHOR]

The UV–C resistance of yeasts ( Saccharomyces cerevisiae , Saccharomyces bayanus , Zygosaccharomyces bailii , Dekkera anomala and Dekkera bruxellensis ) commonly involved in juice spoilage was investigated. Saccharomyces spp. showed the greatest UV resistance and yeast inactivation decreased with absorptivity of the medium. To improve the UV lethal effect on yeasts in juice, UV treatment was combined with heat (UV–H) (45–60 °C). The inactivation of S. cerevisiae by UV–H treatments between 52.5 and 57.5 °C was greater than use of both technologies individually, suggesting a synergistic effect. Modeling of inactivation data found that a combination of UV–C light with mild temperatures (50–60 °C) produced a 5-log 10 reduction of S. cerevisiae in clarified apple juice with lower UV doses (up to a 89.3% of reduction at 57.5 °C) and treatment times (up to 63% of reduction at 52.5 °C) than those needed for UV treatments or heat alone. Industrial relevance This investigation demonstrated the lethal efficacy of the combination of UV–C radiation and heat to improve the inactivation of spoilage yeasts in juice. Combined UV–H treatments synergistically increased yeast inactivation, with this approach being less effective than for bacteria. In any case, UV–H at mild temperatures would be an alternative to heat pasteurization treatments, enabling the inactivation of pathogenic bacteria and reducing the concentration of spoilage microorganisms like yeasts, obtaining a safe and stable product at lower temperatures. [ABSTRACT FROM AUTHOR]

Abstract: The influence of pulsed electric field (PEF) treatment on the extraction by pressing of total polyphenols and flavonoids (naringin and hesperin) from orange peel was investigated. A treatment time of 60μs (20 pulses of 3μs) achieved the highest cell disintegration index (Zp) at the different electric field strengths tested. After 30min of pressurization at 5bars, the total polyphenol extraction yield (TPEY) increased 20%, 129%, 153% and 159% for orange peel PEF treated at 1, 3, 5 and 7kV/cm, respectively. A PEF treatment of 5kV/cm to the orange peels increased the quantity of naringin and hesperidin in the extract of 100g of orange peels from 1 to 3.1mg/100g of fresh weigh (fw) orange peel and from 1.3 to 4.6mg100g fw orange peel respectively. Compared to the untreated sample, PEF treatments of 1, 3, 5 and 7kV/cm increased the antioxidant activity of the extract 51%, 94%, 148% and 192%, respectively. The results of this investigation demonstrate the potential of PEF as a gentle technology to improve the extraction by pressing of polyphenols from fresh orange peel. This procedure enhances the antioxidant capacity of the extracts, reduces extraction times and does not require using organic solvents. Industrial relevance: Processing of orange fruits to obtain fresh juice or citrus-based drinks generates very large amounts of byproduct wastes, such as peels that are a rich source of polyphenols mainly flavonoids. Extraction of these compounds from orange peels is a crucial step for use of these compounds in the food and pharmaceutical industries as antioxidants. PEF-assisted extraction by pressing of polyphenols from fresh orange peels stands as an economical and environmentally friendly alternative to conventional extraction methods which require the product to be dried, use large amounts of organic solvents and need long extraction times. [Copyright &y& Elsevier]

Pulsed electric field (PEF) is a food processing technology based on the phenomenon of electroporation for the inactivation of microorganisms with main advantage the minimal effect on the quality (nutritional, functional, and sensorial) characteristics of the food products. Despite the plethora of research literature on PEF-processed food safety, PEF's industrial application as an alternative of classical pasteurization is limited and mainly at industrial level is focused on high acid-liquid food products. Thus, the thorough assessment of the antimicrobial efficiency of PEF, coupled with the meticulous identification of key microbial resistance mechanisms is scientifically imperative. These efforts are essential for refining the process and exploring potential enhancements through synergistic integration and combination with other methods or/and hurdles. On this basis this manuscript aims to critically review and summarise: a) the antimicrobial mechanism of action, b) the microbial inactivation efficiency, and c) the effect of PEF at a microbial genomic/transcriptomic level. Evaluating the effectiveness of inactivation and understanding the underlying resistance mechanisms can help on strategies to optimize PEF-mediated decontamination practices, and thereby enhancing the overall process efficiency. • PEF leads to inactivation of microorganisms due to the electroporation. • Microbial inactivation efficiency of PEF is dependent on the microbial characteristics, food product propetries and PEF parameters. • Insufficient PEF treatments can generate sub-lethally injured cells that potentially can raise food safety issues. • Transcriptomic, proteomic and metabolomic studies can help in optimization of PEF processing. [ABSTRACT FROM AUTHOR]

The effect of pulsed electric fields (PEF) and thermal treatments on the inactivation of the population of 40 strains of 4 model microorganisms (Escherichia coli , Listeria monocytogenes , Lactiplantibacillus plantarum , Saccharomyces cerevisiae) were investigated. Microbial samples of McIlvaine buffer pH 7.0 were subjected to pulses with electric field strength 20 kV/cm and total specific energies (88, 136, and 184 kJ/kg). Depending on the species and strain, microorganisms exhibited various resistances. PEF microbial resistance and strain variability data were correlated to the total specific energy used. E. coli strains showed statistical log 10 inactivation differences under the 88 and 136 kJ/kg but not under the 184 kJ/kg PEF treatment. In contrast, L. monocytogenes strains showed statistical log 10 inactivation differences only under the 184 kJ/kg treatment. L. monocytogenes L6 strain was identified as the most resistant strain at PEF treatment (184 kJ/kg). This result was in accordance with the resistance under thermal treatment (62.8 °C, 30 min). The identification of target microorganisms related to their resistance in one or more technologies can help at establishing treatment conditions that reassure food safety. Data obtained in this research show that species and strain behaviours vary and are dependent on the technology and the applied treatment conditions. Thus, the resistance exhibited by microorganisms of public health importance may be dependent on the used technology and the applied treatment. • Strain variability resistance under PEF treatments is strain and species dependent. • Strain variability resistance under PEF treatments is total specific energy dependent. • L. monocytogenes is identified as the most resistant microorganism to all PEF conditions compared to E. coli, L. plantarum and S. cerevisiae at pH 7.0. • L. monocytogenes L6 strain is identified as the most resistant strain to PEF and thermal treatments. [ABSTRACT FROM AUTHOR]

The brewing industry produces significant volumes of spent brewer's yeast (SBY), which presents an intriguing opportunity for valorization. This study aims to optimize the extraction of various compounds of interest from electroporated SBY located both in the cytoplasm (amino acids, glutathione and proteins) and in the cell walls (mannoproteins). The optimization of the extraction time, temperature and pH, allowed obtaining an extract rich in glutathione of 2.31 ± 0.15 mg/g dw after 1 h of incubation (pH 8; 30 °C) and, a second extract rich in amino acids (155.74 ± 7.83 mg/g dw) and proteins (331.70 ± 15.64 mg/g dw) after a second incubation (37 °C, 47 h) of the biomass. To achieve comprehensive valorization of SBY, the exhausted yeast biomass was incubated with lyticase to extract mannoproteins from the cell wall. This study showcases the efficacy of a multiple response function in optimizing valuable compound extraction from electroporated SBY, aligning with circularity principles. [Display omitted] • PEF-assisted sequential extraction is proposed for revalorization of SBY. • Extraction of compounds from electroporated SBY has been optimized. • Extract rich in glutathione obtained after incubation for 1 h at pH 8 and 30 °C. • Extract rich in amino acids and proteins after incubation for 47 h at pH 8 and 37 °C. • Cell -wall mannoproteins extracted was obtained from exhausted SBY. [ABSTRACT FROM AUTHOR]

Market globalization and changes in purchasing habits pose a challenge to the fishery industry because of the short shelf life of fish products. In view of this scenario, it would be very helpful if tools capable of predicting the shelf-life of fish could be developed. Thus, the objective of this study was to employ a modelling approach capable of predicting the evolution of the microbiota of hake fillets packaged under a modified atmosphere (MAP) rich in CO 2 (50% CO 2 / 50% N 2) when stored at temperatures ranging between 1 and 10 °C. Growth curves of ten microbial groups were obtained at four different temperatures and fitted with the Baranyi model. Photobacterium showed high growth rates in hake fillets (0.99 days−1 at 4 °C), similar to those of Shewanella , lactic acid bacteria, and non-specific microbial groups investigated, and significantly higher than those of Pseudomonas. Furthermore, no lag phase was observed for Photobacterium regardless of the temperature investigated. On the other hand, Enterobacteriaceae and moulds and yeasts displayed low growth fitness, and their counts increased by <1.5–2 Log 10 cycles along the incubation period regardless of storage temperature. The influence of storage temperature on growth parameters (λ, μ max and Y end) was subsequently studied, and secondary models were developed for the eight most relevant microbial groups. All of the final equations developed in this study showed R2 values ≥0.90, and RMSE values ≤0.50. In addition, results obtained in this investigation strongly suggest that Photobacterium would be the main responsible microorganism for the spoilage of hake fillets stored under MAP conditions (50% CO 2 /50% N 2) along the entire range of temperatures investigated (1–10 °C). Unlabelled Image • The influence of temperature on microbial growth in MAP hake fillets was studied. • Primary and secondary models for different microbial groups have been developed. • Photobacterium , Shewanella and lactic acid bacteria showed the higher growth rates. • Photobacterium displayed the shortest lag phase among the microbial groups studied. • Photobacterium would be the main cause of the spoilage of MAP hake fillets. [ABSTRACT FROM AUTHOR]

Abstract The potential of PEF for triggering autolysis of Saccharomyces cerevisiae and accelerating the release of mannoproteins during aging on the lees of Chardonnay wine was evaluated. Release of mannoproteins in Chardonnay wine increased drastically in samples containing PEF-treated (5 and 10 kV/cm, 75 μs) yeasts. No mannoprotein release was observed in the first seven days of aging on the lees in wine containing untreated yeast; however, after the same time interval, the concentration of those compounds increased by 40 and 60% in wines containing yeast treated by PEF at 5 and 10 kV/cm, respectively. After 30 days of incubation, the mannoprotein concentration in wines containing yeast treated under the most intense PEF conditions reached the maximum value. Control cells, on the other hand, required six months to reach that maximum level. Chromatic characteristics, total polyphenol index, total volatile acidity, pH, ethanol, and CIELAB parameters of the wine were not affected during aging on the lees with untreated and PEF-treated yeast. On the other hand, the capability of the mannoproteins released from yeast treated by PEF for decreasing wine turbidity, foaming, and interacting with tannins was similar to that of those released from untreated yeast; the differences observed were a consequence of the varying concentration of mannoproteins. The result obtained demonstrates that PEF permits the acceleration of the aging-on-lees step while avoiding or reducing the problems associated with it. To achieve this effect, intense treatment is not required. Therefore, wineries could process lees by using the most economical PEF devices on the market. Graphical abstract Unlabelled Image Highlights • S. cerevisiae mannoprotein release in Chardonnay wine is accelerated by PEF. • Aging on the lees with yeast treated by PEF did not negatively affect wine properties. • PEF treatment did not affect the functional properties of released mannoproteins. [ABSTRACT FROM AUTHOR]

The aim of this study was to demonstrate the potential of PEF for inducing autolysis of R. glutinis , with the purpose of designing a more efficient and ecofriendly carotenoid extraction process: an extraction from fresh biomass, using cheaper, non-toxic, environmental-friendly solvents. Propidium iodide uptake and release of intracellular components revealed the irreversible electroporation of R. glutinis by PEF. Flow cytometry measurements detected morphological changes in PEF-treated R. glutinis cells during incubation caused by the autolysis triggering effect of electroporation. After submitting the fresh biomass to a PEF treatment (15 kV/cm, 150 μs) that irreversibly electroporated more than the 90% of the cells, ethanol proved ineffective for extracting carotenoids from fresh biomass of R. glutinis . However, after incubating the PEF-treated fresh biomass for 24 h at 20 °C in a pH 7 buffer, ca. 240 μg/g d.w. of carotenoids were recovered after 1 h of extraction in ethanol. The highest amount of carotenoids extracted (375 μg/g d.w.) from the PEF-treated cells of R. glutinis was obtained after having incubated them at 25 °C for 24 h in a medium of pH 8.0. The improvement in carotenoid extraction by incubating the R. glutinis cells after PEF treatment seems to be caused by PEF-triggered autolysis, which tends to disrupt the association of carotenoids with other molecules present in the cytoplasm, and causes a degradation of the cell wall. [ABSTRACT FROM AUTHOR]

This study investigated the PEF-resistance of Saccharomyces bayanus , Brettanomyces bruxellensis, Lactobacillus plantarum , and Oenococus oeni in must or wine under continuous PEF processing. Results showed the capacity of PEF to achieve 3.0-log 10 -cycles (CFU/mL) of inactivation of all the microorganisms under moderate conditions (< 155 kJ/kg). Developed tertiary models accurately predicted the effect of PEF parameters on microbial inactivation, and Monte Carlo simulation considered the variability of factors and the maximum assumable microbial load in the final treated product. Results showed that PEF-treatments at 15 kV/cm and 129 or 153 kJ/kg would ensure the adequate decontamination (< 10 CFU/mL) of spoilage microorganism in must or wine, respectively. PEF technology has been shown to achieve adequate levels of microbial inactivation (3-log 10) in must and wine under industrial applicable processing parameters, making it a suitable alternative to SO 2 or sterilizing filtration for microbial control in winemaking. Reductions of 3-log 10 CFU/mL of must and wine microbiota were found by continuous flow PEF-processing at 15 to 25 kV/cm and 175 to 148 kJ/kg, parameters applicable at industrial scale at 1 ton/h. • Weibull distribution model successfully predicted microbiota inactivation by PEF. • Must and wine microbiota were reduced by 3-log 10 CFU/mL at 15 kV/cm and 155 kJ/kg. • Bacteria strains were more PEFresistant (> 1.2-fold) than yeasts in wine and must. • Scalable PEF-parameters guarantee 90% probability of zero spoilage (< 10 CFU/mL). [ABSTRACT FROM AUTHOR]

Thinned fruits are agricultural by-products which nowadays have few economic or environmental benefits. However, previous studies have revealed that these immature fruits have a large amount of antioxidant compounds. The aim of this study was to evaluate whether pulsed electric fields (PEF) might be a suitable green technology for enhancing the extraction of phenols, flavonoids and antioxidant compounds from fresh thinned peaches, thus reducing the use of methanol. Moreover, response surface methodology has been used to determine the optimal PEF treatment conditions, observing that the solvent is the main factor. The highest amounts of bioactive compounds were extracted using 80% methanol and no PEF. Methanol combined with PEF produced a negative effect on the extraction yield. However, the use of water as a solvent increased the amount of total bioactive compounds and individual phenols (chlorogenic acid, coumaric acid and neochlorogenic acid). Thus, PEF-assisted extraction of bioactive compounds from thinned peach fruits using water as a solvent is an alternative to conventional extraction methods which require dried products, large amounts of organic solvents and long extraction times. [ABSTRACT FROM AUTHOR]

The aim of the present study was to analyze the impact of ozone processing technology on the stability of fungal pigments produced by Talaromyces spp. suspended in a buffer of pH 6 and a beverage model system (BMS). Both samples were ozonated by different ozone levels (0.031 to 0.064 mg/min/mL) and processing times (0 to 10 min). The impact of these processing variables on color degradation parameters was studied. Significant changes in pigmented extract and pigmented beverage model system (BMS) were observed. Ozone concentration and treatment time demonstrated to be critical factors in the color degradation of fungal pigments. First-order kinetic models adequately described the degradation pattern of pigments during ozonation. Degradation rate constants ranged from 0.127 to 0.206 in the buffer and from 0.068 to 0.119 in the BMS. The CIE L * a * b * parameters also confirmed the degradation behavior during ozonation process. Results from this study indicated that color stability of microbial pigments is affected by ozone processing conditions, thus, this quality aspect should be considered before applying this type of colorants in food products processed with ozone. Industrial relevance Natural colorants sources are required to meet the recent growing demands by the food industry due to consumers concerns of using synthetic pigments. Microbial pigments are of increasing interest as a result of the high yields that can be produced by microorganisms. Recently, Talaromyces spp. has gained attention as a good pigment producer strain. However, the application of these pigments in food manufacturing will depend on their stability to food processing (thermal and non-thermal). Accordingly, this work aimed to determinate if the colorants produced by Talaromyces spp. are applicable given their stability under ozone pasteurization. Results indicated that fungal pigments exposed to ozone could be considered as a potential natural ingredient to replace the color loss of some fruit juice processed under ozone technology. These results are promising for future applications in the food sector. [ABSTRACT FROM AUTHOR]

This paper assesses the application of pulsed electric fields (PEF) to the fresh biomass of Artrhospira platensis in order to enhance the extraction of C-phycocyanin into aqueous media. Electroporation of A. platensis depended on both electric field strength and treatment duration. The minimum electric field intensity for detecting C-phycocyanin in the extraction medium was 15 kV/cm after the application of a treatment time 150 μs (50 pulses of 3 μs). However higher electric field strength were required when shorter treatment times were applied. Response surface methodology was used in order to investigate the influence of electric field strength (15–25 kV/cm), treatment time (60–150 μs), and temperature of application of PEF (10–40 °C) on C-phycocyanin extraction yield (PEY). The increment of the temperature PEF treatment reduced the electric field strength and the treatment time required to obtain a given PEY and, consequently decreased the total specific energy delivered by the treatment. For example, the increment of temperature from 10 °C to 40 °C permitted to reduce the electric field strength required to extract 100 mg/g d w of C-phycocyanin from 25 to 18 kV/cm, and the specific energy input from 106.7 to 67.5 kJ/Kg. Results obtained in this investigation demonstrated PEF's potential for selectively extraction C-phycocyanin from fresh A. platensis biomass. The purity of the C-phycocyanin extract obtained from the electroporated cells was higher than that obtained using other techniques based on the cell complete destruction. [ABSTRACT FROM AUTHOR]

[Display omitted] • Under industrial scale PEF conditions, 5.0 log cycles of yeast were inactivated. • Moderate PEF-treatments sublethally damaged yeast population. • PEF effect for yeast decontamination was equivalent to the use of 20 ppm of SO 2. • Chardonnay wine treated by PEF was microbiologically stable for at least 4 months. • PEF did not have negative effects on the quality parameters of Chardonnay wine. The use of sulfites (SO 2) for microbial control in the winemaking process is currently being questioned due to its potential toxicity. Pulsed Electric Fields (PEF) are capable of inactivating microorganisms at low temperatures, thus avoiding the negative effects of heat on food properties. In this study, the capacity of PEF technology for the decontamination of yeasts involved in the fermentation process of Chardonnay wine from a winery was evaluated. PEF treatments at 15 kV/cm of low (65 µs, 35 kJ/kg) and higher intensity (177 µs 97 kJ/kg) were selected for evaluating the microbial stability, physicochemical and volatile composition of wine. Even with the least intense PEF-treatment, Chardonnay wine remained yeast-free during 4 months of storage without sulfites. PEF-treatments did not affect the wine's oenological parameters or its aroma during storage. This study, therefore, reveals the potential of PEF technology as an alternative to sulfites for the microbiological stabilization of wine. [ABSTRACT FROM AUTHOR]

The influence of the electric field intensity and pulse width on the improvement of total polyphenol index (TPI) and colour intensity (CI) during extraction in an ethanolic solution (30%) and during fermentation-maceration has been investigated in different grape varieties: Grenache from two harvesting times, Syrah and Tempranillo. The aim of this study was to develop a procedure to establish the PEF treatment conditions that cause enough permeabilization in the skin cells of different grape varieties to obtain a significant improvement in the vinification process in terms of increment on the polyphenol content or reduction of maceration time. Results obtained in this investigation indicate that extraction of polyphenols in a solution of ethanol (30%) for 2 h could be a suitable procedure to know if the PEF technology is effective for improving extraction of polyphenols from the grapes during vinification and to determine the most suitable PEF treatment conditions to obtain this objective. Improvement in the extraction during vinification only was observed with those grapes and under treatment conditions in which the improvement of the polyphenol extraction was higher than 40%. Other interesting observation from this research is the highest efficacy of PEF when treatments of the same duration are applied using longer pulses. Therefore, in a continuous process, where the flow processed is determined by the frequency applied by the PEF generator, it is possible to increase the processing capacity of the PEF installation. Industrial relevance Benefits from PEF treatment of the grapes before the maceration step in the vinification process have been demonstrated. Nevertheless, the characteristics of the grapes may change in different vintages and grape varieties. Therefore, it is of high importance to be able to determine the optimum PEF conditions in order to obtain the desired benefit during the vinification. The rapid method developed permits to determine PEF process parameters before the application of the PEF treatment with the objective of facilitating the phenolic extraction and therefore, reducing the maceration time. In these cases, it would be possible to remove the skins from the rest of the wine earlier, and therefore, increase the processing capacity of the winery. [ABSTRACT FROM AUTHOR]

Several studies have demonstrated the feasibility of pulsed electric fields (PEF) for different applications in food industry. PEF technology is therefore a valuable tool that can improve functionality, extractability, and recovery of nutritionally valuable compounds as well as the bioavailability of micronutrients and components in a diverse variety of foods. Additionally, other studies have shown the potential of PEF treatments to reduce food processing contaminants and pesticides. This opens the doors to new PEF applications in the food industry. This review focused on some of the most renowned traditional and emerging PEF applications for improvement of osmotic dehydration, extraction by solvent diffusion, or by pressing, as well as drying and freezing processes. The impact of PEF on different products of biological origin including plant tissues, suspension of cells, by-products and wastes will be analyzed in detail. In addition, recent examples of PEF-assisted biorefinery application will be presented, and finally, the main aspects of PEF-assisted cold pasteurization of liquid foods will also be described. [ABSTRACT FROM AUTHOR]

Influence of the of temperature of biomass (10–40 °C) treated by pulsed electric fields (PEFs) at different intensities (10–25 kV/cm) on electroporation of the microalgae Chlorella vulgaris and on the extraction of lutein was investigated. The occurrence of reversible and irreversible electroporation increased with electric field strength and medium treatment temperature. On the other hand, increasing temperature increased the sensitivity of C. vulgaris cells to irreversible electroporation. Response surface methodology was used to identify optimal PEF treatment conditions for enhancing lutein extraction yield (LEY) from fresh C. vulgaris biomass. Considering the cultivation temperature of C. vulgaris (25–30 °C) and the low increase in the LEY when the PEF treatments were applied at temperatures above 30 °C, a treatment of 25 kV/cm–100 μs at 25–30 °C increased the LEY around 3.5–4.2-fold in comparison with the control, resulting in the most suitable treatment conditions for maximizing the lutein extraction at the lowest energy cost. Industrial relevance In recent years, industrial interest in microalgae as source of bioproducts such as natural additives or active ingredients for food and cosmetic formulations has arisen. However, there are still several obstacles to fully take advantage, such as the ability to successfully extract these compounds from the cell biomass. Electroporation of microalgae by PEF-technology could be an alternative to conventional cell disruption techniques. Therefore, identifying critical factors affecting the enhancement of bioproduct extraction from microalgae is necessary to establish PEF as a true option. [ABSTRACT FROM AUTHOR]

Thermal effects can strongly influence the impact of pulsed electric field (PEF) treatment on enzyme inactivation. Most of the kinetic models found in literature, do not distinguish between PEF and thermal effects. A batch PEF treatment chamber with temperature control was used in order to allow performance of PEF treatments at quasi-isothermal conditions. An empirical model describing the PEF polyphenoloxidase (PPO) inactivation as a function of the electric field strength, temperature, treatment time, residence time and synergistic effects of electric field strength and temperature was developed. Experimental data showed that PPO was not inactivated by PEF treatments at temperatures below 55°C and thermal inactivation seems to be significant at temperatures between 59 and 67°C. However, PPO activity decreased down to 60% when PEF treatments were applied at temperatures in the range of 55 to 59°C. The synergistic effect of PEF and temperature was described by a kinetic model at different treatment temperatures. Industrial relevance: Kinetic models to describe the inactivation of enzymes as a function of PEF parameters, such as electric field strength and treatment time have already been developed. However, these models do not consider the temperature as a variable within the kinetic model. In the present study, a kinetic model was developed, which includes the synergistic effect between temperature and electric field strength. This allows quantifying the PPO inactivation under different processing temperatures and may serve as a base to set up experimental trials whereas a certain temperature is desired. [ABSTRACT FROM AUTHOR]

Abstract: The influence of pulsed electric field (PEF) treatment on the anthocyanin extraction yield (AEY) from purple-fleshed potato (PFP) at different extraction times (60–480min) and temperatures (10–40°C) using water and ethanol (48% and 96%) as solvents has been investigated. Response surface methodology was used to determine optimal PEF treatment and optimise anthocyanin extraction. A PEF treatment of 3.4kV/cm and 105μs (35 pulses of 3μs) resulted in the highest cell disintegration index (Zp =1) at the lowest specific energy requirements (8.92kJ/kg). This PEF treatment increased the AEY, the effect being higher at lower extraction temperature with water as solvent. After 480min at 40°C, the AEY obtained for the untreated sample using 96% ethanol as the solvent (63.9mg/100g fw) was similar to that obtained in the PEF-treated sample using water (65.8mg/100g fw). Therefore, PEF was possible with water, a more environmental-friendly solvent than ethanol, without decreasing the AEY from PFP. [Copyright &y& Elsevier]

Abstract: This paper evaluates the physicochemical and functional properties of liquid whole egg (LWE) processed by alternative treatments based on the application of Pulsed Electric Fields (25kV/cm, 75kJ/kg) followed by heat (52°C/3.5min, 55°C/2min or 60°C/1min) in the presence of 2% triethyl citrate (LWE-TC-PEF-HT), and by current heat pasteurization treatments of 60°C/3.5min or 64°C/2.5min (LWE-HT). LWE-TC-PEF-HT showed a more similar color to the raw LWE (R-LWE), and a foaming and emulsifying capacity 48% and 26% higher than LWE-HT, respectively. Designed treatments even improved by 17 and 9% foaming and emulsifying capacities of R-LWE, respectively, and kept similar texture gelling properties. Considering that the designed processes are lethally equivalent to heat pasteurization treatments but keep better LWE functional properties, the successive application of PEF and heat in the presence of triethyl citrate could be very promising alternatives to the recommended heat pasteurization treatments. [Copyright &y& Elsevier]

Abstract: This paper evaluates the possibilities of a high hydrostatic pressure (HHP) combined process as an alternative to liquid whole egg (LWE) heat pasteurization. In a first step, HHP boundary conditions with a certain impact on LWE viscosity were established. Secondly, the lethality of HHP at those boundary conditions, alone or combined with temperature or triethyl citrate – E1505 – (TC) followed by heat, on the inactivation of Listeria innocua BGA 3532 (Listeria genus surrogate) and Escherichia coli K12 (Salmonella Enteritidis surrogate in liquid egg) was investigated. HHP treatments that increased viscosity less than current heat pasteurization of 60°C/3.5′ (20% increment in viscosity), reduced 1.5 and 0.6 Log10 the population of E. coli and L. innocua, respectively. These results indicated that HHP technology at 20°C was unsuitable for LWE pasteurization without affecting its physical properties. HHP applied at 4 or 50°C increased lethality but insufficiently to assure LWE safety. The addition of 2% TC resulted in a synergistic lethal effect of HHP at 20 or 4°C, reducing the heat resistance of both microorganisms. Combined processes based on the successive application of HHP at 20°C (300MPa/3′) and heat (52°C/3.5′ or 55°C/2′) to LWE with 2% TC reduced more than 5 Log10 in E. coli and L. innocua with better physic-chemical and functional properties than the ultrapasteurization heat treatment (71°C/1.5′). Industrial relevance: A new alternative to heat pasteurization is proposed in this investigation. The successive application of low intensity treatments of high hydrostatic pressure (300MPa/3min) followed by heat (52°C/3.5min or 55°C/2min) to liquid whole egg (LWE) in presence of 2% triethyl citrate would offer LWE with the same microbial safety level than the industrially treated at 71°C/1.5min but with quality properties similar to fresh LWE. [Copyright &y& Elsevier]

Abstract: The influence of the application of a continuous pulsed electric fields treatment (PEF treatment) to grape pomace on the evolution of colour and phenolic content of Cabernet Sauvignon red wines has been investigated. Wine from grape treated by PEF presented at the end of alcoholic fermentation higher colour intensity (CI), total polyphenol index (TPI) and total anthocyanic content (TAC) than control wine. This effect was observed even although maceration time for PEF wine was 48h shorter than for control. Differences remained during malolactic fermentation and maturation. After 4months of aging in bottle, CI, TPI and TAC of PEF wine were 38%, 22% and 11% higher respectively than the control. HPLC phenolic profiles of wines were qualitatively similar, without detecting a selective effect on any phenol. No significant differences in sensory attributes between wines were detected. Results indicate that PEF is a promising technology in red winemaking for reducing the maceration time and increasing colour and phenolic extraction. [Copyright &y& Elsevier]

Abstract: A systematic study about the influence of pulsed electric fields (PEF) and other operating parameters on betanine extraction from red beetroots has been carried out in this investigation. Thin disks of red beetroots were subjected to PEF at different intensities (number of pulses and field strengths), and the release of betanine into media of different pH and at different temperatures was determined. The influence of mechanical pressing after PEF treatments on betanine extraction was also investigated. The use of extracting media having pH 3.5 and temperatures of 30°C gave the highest yields and rates for betanine extraction from PEF treated samples. When subjected to 5 pulses of 2μs at 7kV/cm, the samples released about 90% of total betanine in 300min, a rate that is fivefold quicker than the non-PEF-treated samples. Pressing the samples during the extraction process at all pressures investigated further reduced the extracting time. A general mathematical expression was developed to determine the percentage of betanine extracted from red beetroots treated at different electric field strengths (1–9kV/cm), and then pressed (0–14kg/cm2). Based on this equation, a treatment of 5 pulses at 7kV/cm (2.5kJ/kg) and 10kg/cm2 at room temperature permitted the extraction of 90% of the total red colouring in 35min. [Copyright &y& Elsevier]

Phenolic compounds extracted from the solid parts of the grapes during the maceration-fermentation stage define many of the sensory attributes of red wine such as color, bitterness or astringency. The effect of moderate a PEF treatment (M-PEF) (5 kV·cm−1, 8.8 kJ·kg−1) and an intense PEF treatment (I-PEF) (5 kV·cm−1, 52.9 kJ·kg−1) on the reduction of maceration time during vinification of Caladoc and Grenache grapes was investigated. In both grape varieties, M-PEF treatment combined with 4 days of maceration was the most effective treatment in achieving high anthocyanin content, color intensity and total phenol index at the end of fermentation. The I-PEF treatment promoted a rapid release of anthocyanins and phenolic compounds, along with a fast increment in the color intensity of the must after 24 h of maceration. Although the color intensity and anthocyanin content decreased significantly throughout fermentation when grape pomace was removed after 24 h, these parameters were similar, after 3 months of bottling, in the case of Caladoc and slightly lower in Grenache than the control wine, for which maceration was extended for 10 days. Therefore, results obtained in this investigation are the first to demonstrate the potential of I-PEF for the reduction of maceration time to 24 h in red winemaking. • PEF of high specific energy permits reducing red winemaking maceration to 24 h. • A fast increment of wine color intensity was promoted after few hours of maceration. • PEF could result an alternative to maceration techniques based on grape heating. [ABSTRACT FROM AUTHOR]

Application to different electric field strengths (E) and specific energies (W) with the pulsed electric fields (PEF) technology on the rate of extraction of phenolic compounds during maceration/fermentation of Grenache grapes was studied. A response surface model between the total polyphenol index extraction rate (TPI) and the E and W of the PEF treatments was established, which permitted the determination of PEF processing conditions to achieve a certain TPI. To achieve a TPI of 50, treatments ranged from high intensity and short time (8 kV·cm−1 and 45 μs) to low intensity and long time (1 kV·cm−1 and 2800 μs) applying an optimum W of 4 kJ·kg−1 in all cases. The application of these PEF treatments reduced maceration time by a rate of 25 to 37% with respect to the untreated grape. Quality characteristics (color intensity, tannins, and total anthocyanins) were neither affected after fermentation nor after 12 months aging in bottles. • Treatments at 4 kV·cm−1 have the best relationship between extractions polyphenols compound/energy used. • An optimal PEF treatment permitted to reduce the maceration several days during vinification. • The polyphenol extraction depended on the electric field intensities, specific energies and the number of pulses applied. [ABSTRACT FROM AUTHOR]

• Permeabilization efficiency of H. pluvialis cells depended on growth conditions. • Pulsed electric field followed by incubation efficiently extracts astaxanthin. • PEF triggers an intracellular enzymatic process facilitating the extraction. The Nordic microalgal strain Haematococcus pluvialis was exposed to various stress conditions to induce astaxanthin accumulation. Highest carotenoid content (19.1 mg·g−1 dw) was achieved in nitrogen-free culture medium at a high light intensity. The efficiency of Pulsed Electric Field (PEF) pre-treatment of stressed fresh biomass of H. pluvialis followed by incubation in the growth medium was compared to classical disruption methods (bead-beating, freezing-thawing, thermal treatment or ultrasound) for the subsequent extraction of astaxanthin in ethanol. N-starved cells treated with PEF followed by aqueous incubation for 6 h resulted in extraction of 96% (18.3 mg car ·g dw −1) of the total carotenoid content compared to 80% (15.3 mg car ·g dw −1) using other physical methods. The proportion of free forms of astaxanthin was higher in PEF-treated samples compared to mechanical disruption, suggesting PEF triggering an esterase activity. PEF pre-treatment of the cells followed by incubation in growth medium improved astaxanthin extraction in the eco-friendly solvent ethanol. [ABSTRACT FROM AUTHOR]