Eduardo Puértolas

Pulsed electric fields inactivation of wine spoilage yeast and bacteria.

The use of the pulsed electric fields technology (PEF) as an alternative system of microbiological control in wineries was evaluated. The PEF resistance of different wine spoilage microorganisms such as Dekkera anomala, Dekkera bruxellensis, Lactobacillus hilgardii and Lactobacillus plantarum in both must and wine was investigated by applying treatments ranging from 16 to 31 kV/cm and from 10 to 350 kJ/kg at 24 degrees C. The non-exponential kinetics of inactivation by PEF of these microorganisms in both products has been described by mathematical equations based on the Weibull distribution. An optimum treatment of 186 kJ/kg at 29 kV/cm has been established which permitted to reduce the 99.9% of the spoilage flora of must and wine, limiting the risk of alteration of these products by microorganisms of genera Brettanomyces and Lactobacillus.

Pulsed-electric-field-assisted extraction of anthocyanins from purple-fleshed potato.

The influence of pulsed electric field (PEF) treatment on the anthocyanin extraction yield (AEY) from purple-fleshed potato (PFP) at different extraction times (60-480 min) 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 3.4 kV/cm and 105 μs (35 pulses of 3 μs) resulted in the highest cell disintegration index (Z(p)=1) at the lowest specific energy requirements (8.92 kJ/kg). This PEF treatment increased the AEY, the effect being higher at lower extraction temperature with water as solvent. After 480 min at 40°C, the AEY obtained for the untreated sample using 96% ethanol as the solvent (63.9 mg/100 g fw) was similar to that obtained in the PEF-treated sample using water (65.8 mg/100 g fw). Therefore, PEF was possible with water, a more environmental-friendly solvent than ethanol, without decreasing the AEY from PFP.

A New Crocodylian from the Late Maastrichtian of Spain: Implications for the Initial Radiation of Crocodyloids

Background The earliest crocodylians are known primarily from the Late Cretaceous of North America and Europe. The representatives of Gavialoidea and Alligatoroidea are known in the Late Cretaceous of both continents, yet the biogeographic origins of Crocodyloidea are poorly understood. Up to now, only one representative of this clade has been known from the Late Cretaceous, the basal crocodyloid Prodiplocynodon from the Maastrichtian of North America. Methodology/Principal Findings The fossil studied is a skull collected from sandstones in the lower part of the Tremp Formation, in Chron C30n, dated at −67.6 to 65.5 Ma (late Maastrichtian), in Arén (Huesca, Spain). It is located in a continuous section that contains the K/P boundary, in which the dinosaur faunas closest to the K/P boundary in Europe have been described, including Arenysaurus ardevoli and Blasisaurus canudoi. Phylogenetic analysis places the new taxon, Arenysuchus gascabadiolorum, at the base of Crocodyloidea. Conclusions/Significance The new taxon is the oldest crocodyloid representative in Eurasia. Crocodyloidea had previously only been known from the Palaeogene onwards in this part of Laurasia. Phylogenetically, Arenysuchus gascabadiolorum is situated at the base of the first radiation of crocodyloids that occurred in the late Maastrichtian, shedding light on this part of the cladogram. The presence of basal crocodyloids at the end of the Cretaceous both in North America and Europe provides new evidence of the faunal exchange via the Thulean Land Bridge during the Maastrichtian.

Olive oil pilot-production assisted by pulsed electric field: Impact on extraction yield, chemical parameters and sensory properties

The impact of the use of pulsed electric field (PEF) technology on Arroniz olive oil production in terms of extraction yield and chemical and sensory quality has been studied at pilot scale in an industrial oil mill. The application of a PEF treatment (2 kV/cm; 11.25 kJ/kg) to the olive paste significantly increased the extraction yield by 13.3%, with respect to a control. Furthermore, olive oil obtained by PEF showed total phenolic content, total phytosterols and total tocopherols significantly higher than control (11.5%, 9.9% and 15.0%, respectively). The use of PEF had no negative effects on general chemical and sensory characteristics of the olive oil, maintaining the highest quality according to EU legal standards (EVOO; extra virgin olive oil). Therefore, PEF could be an appropriate technology to improve olive oil yield and produce EVOO enriched in human-health-related compounds, such as polyphenols, phytosterols and tocopherols.

Defining treatment conditions for pulsed electric field pasteurization of apple juice

The influence of temperature and the presence of N(α)-lauroyl ethylester (ethyl lauroyl arginate, LAE) on the inactivation caused by continuous pulsed electric field treatments (PEF) in Escherichia coli O157:H7 suspended in apple juice have been investigated to define treatment conditions applicable at industrial scale that promote an equivalent safety level when compared with thermal processing. In the range of experimental conditions investigated (outlet temperature: 20-40 °C, electric field strength: 20-30 kV, treatment time: 5-125 μs) at outlet temperatures equal or lower than 55±1 °C, the inactivation of E. coli O157:H7 treated in apple juice ranged from 0.4 to 3.6 Log₁₀ cycles reduction and treated in apple juice supplemented with LAE (50 ppm) ranged from 0.9 to 6.7 Log₁₀ cycles reduction. An empirical mathematical model was developed to estimate the treatment time and total specific energy input to obtain 5 Log₁₀ cycles reduction in the population of E. coli O157:H7 suspended in apple juice supplemented with 50 ppm of LAE at different electric field strengths and inlet temperatures. Treatment conditions established for E. coli O157:H7 were validated with other PEF resistant Gram-positive (Listeria monocytogenes, and Staphylococcus aureus) and Gram-negative (Salmonella enterica serovar Typhimurium) strains. When the treatment was applied to the apple juice, a treatment of 25 kV/cm for 63 μs corresponding with an outlet temperature of 65 °C and input energy of 125 kJ/kg was required to achieve more than 5 Log₁₀ cycles in the four strains investigated. The addition of LAE reduced the treatment time required to obtain an equivalent inactivation (>5 Log₁₀ cycles) in the four microorganisms to 38.4 μs, the outlet temperature to 55 °C, and the input energy to 83.2 kJ/kg.

Inactivation kinetics of pulsed electric field-resistant strains of Listeria monocytogenes and Staphylococcus aureus in media of different pH

A study of the effect of pulsed electric fields (PEF) on the inactivation of Listeria monocytogenes STCC 5672 and Staphylococcus aureus STCC 4459 in McIlvaine buffer covering a range from pH 3.5 to 7.0 was conducted. Mathematical models based on the Weibull distribution were developed to describe the influence of the electric field strength, treatment time and pH of the treatment medium on the lethality of both Gram positive pathogenic bacteria after PEF treatments. Both microorganisms were more sensitive to PEF in media of low pH, although the influence of the pH on the PEF resistance was more significant in S. aureus. In the best cases scenario, the highest inactivation levels achieved were 3.3 and 6.1 log(10) cycles for L. monocytogenes and S. aureus respectively in pH 3.5 after 500 micros of 35 kV/cm. Based on these results and those observed in literature, L. monocytogenes STCC 5672 at any pH investigated has been shown as one of the most PEF resistant microorganism. Therefore, this microorganism should be considered as a possible target microorganism to define process criterion for PEF pasteurization.

Changes in phenolic compounds of Aragon red wines during alcoholic fermentation.

Changes in the principal phenolic compounds during the maceration-fermentation process of Garnacha, Merlot and Syrah grapes cultivated in Aragón region (northeast of Spain) have been investigated. While Garnacha is a traditional grape variety cultivated in this region, Merlot and Syrah have been introduced recently. During fermentation, Syrah showed the highest concentration in anthocyanins, flavan-3-ols and flavonols (802.7 ± 0.5 mg/L, 74.7 ± 2.4 mg/L and 37.1 ± 1.5 mg/L at the end of fermentation, respectively). Unexpectedly, Garnacha, a variety with lower phenolic content, showed the highest amount of hydroxycinnamic acids (83.1 ± 5.6 mg/L at the end of fermentation). The overall results also indicated that the evolution during maceration-fermentation process of the different phenolic compounds and their concentrations were influenced by the varietal factor.

Application of Pulsed Electric Field Treatment for Food Waste Recovery Operations

Food industry is generating annually huge quantities of by-products and waste, which are generally considered as problem, as their disposal is associated with environmental and health related issues. During the last decade, numerous research groups and industries have been interested in valorizing these by-products by extracting valuable compounds and incorporating them generally in food and/or cosmetic products, which enhances the profitability of the process. Conventional extraction methods (i.e., maceration, thermal extraction) are exten- sively used for such purposes and showed high yields in many cases. However, the need to replace toxic organic solvents, shortening the extraction time, and reducing the energy consumption has incited the researchers to develop and evaluate alternative methods (i.e., electrotechnologies, high pressure processing, ultrasound- and microwave-assisted extractions), which are more environmental friendly and cost effective. Among electrotechnologies, pulsed electric fields (PEF) technology has been widely evaluated for the extraction of high-added value compounds from waste and by-products, showing promising results, com- pared to conventional methods. This chapter describes the features of PEF as well as its use as sustainable and green recovery technology of valuable compounds from food by-products.

Chapter 11 – Emerging extraction

Traditional extraction methods include usually high temperature treatment (more than 100°C) with the subsequent risk of thermal denaturation or transformation of the target molecules. Moreover, these techniques are very time-consuming and require relatively large quantities of solvents. On the other hand, the use of environmentally friendly technologies has led researchers and the food industry to develop new alternative processes that can extract valuable compounds from different sources and food wastes of different origin. This chapter describes the potential use of emerging technologies such as ultrasound-assisted extraction (UAE), laser ablation, pulsed electric fields (PEF), high voltage electrical discharge (HVED), and membrane-assisted extraction. The latest methodologies comply with the concepts of green chemistry and sustainability within the food industry.

Aplicación industrial de los pulsos eléctricos de alto voltaje para la pasteurización de alimentos: revisión de su viabilidad técnica y comercial

En las últimas décadas, la industria alimentaria ha experimentado un importante avance tecnológico que se refleja en el desarrollo de nuevas técnicas y procesos de elaboración. Especialmente han cobrado particular importancia aquellas tecnologías que permiten obtener alimentos seguros, alterando mínimamente sus características sensoriales y/o disminuyendo los costes de producción. Una de las tecnologías emergentes más prometedoras, que pretende conseguir estos objetivos, son los pulsos eléctricos de alto voltaje (PEAV). El objetivo de este trabajo es revisar la viabilidad de la aplicación industrial de los PEAV para la pasteurización de alimentos líquidos desde un enfoque técnico, ambiental, económico y comercial. Se recogen los principales avances y datos publicados al respecto, así como los desafíos existentes para la implantación de esta tecnología en la industria alimentaria.