Effect of the Application of Ultrasound to Homogenize Milk and the Subsequent Pasteurization by Pulsed Electric Field, High Hydrostatic Pressure, and Microwaves.

The efficacy of applying ultrasound (US) as a system to homogenize emulsions has been widely demonstrated. However, research has not yet shown whether the effect achieved by homogenizing milk with US is modified by subsequent pasteurization treatments that use new processing technologies such as pulsed electric fields (PEF), microwaves (MW), and high hydrostatic pressure (HPP). The aim of this study was, therefore, to optimize the application of US for milk homogenization and to evaluate the effect of PEF, HPP, and MW pasteurization treatments on the sensorial, rheological, and microbiological properties of milk throughout its shelf life. To homogenize whole milk, a continuous US system (20 kHz, 0.204 kJ/mL, 100%, 40 °C) was used, and different ultrasonic intensities (0.25, 0.5, and 1.0 kJ/mL) were evaluated. The optimal ultrasonic treatment was selected on the basis of fat globule size distribution and pasteurization treatments by MW (5800 W, 1.8 L/min), PEF (120 kJ/kg, 20 kV/cm) and HPP (600 MPa, 2 min, 10 °C) was applied. The ultrasound intensity that achieved the highest reduction in fat globule size (0.22 ± 0.02 µm) and the most homogeneous distribution was 1.0 kJ/mL. Fat globule size was smaller than in commercial milk (82% of volume < 0.5 µm for US milk versus 97% of volume < 1.2 µm for commercial milk). That size was maintained after the application of the different pasteurization treatments, and the resulting milk had better emulsion stability than commercial milk. After 28 days of storage, no differences in viscosity (4.4-4.9 mPa s) were observed. HPP pasteurization had the greatest impact on color, leading to higher yellowness values than commercial milk. Microbial counts did not vary significantly after 28 days of storage, with counts below 102 CFU/mL for samples incubated at 15 °C and at 37 °C. In summary, the homogenization of milk obtained by US was not affected by subsequent pasteurization processes, regardless of the technology applied (MW, PEF, or HPP). Further research is needed to evaluate these procedures' effect on milk's nutritional and functional properties.

Evaluation of Pulsed Electric Fields (PEF) Parameters in the Inactivation of Anisakis Larvae in Saline Solution and Hake Meat.

Larvae of the nematode family Anisakidae are capable of causing parasitic infections in humans associated with the consumption of fishery products, leading to intestinal syndromes and allergic reactions. Anisakidae larvae are widely distributed geographically, with rates of parasitism close to 100% in certain fish species. Methods need to be established for their inactivation and elimination, especially in fishery products that are to be consumed raw, pickled, or salted, or which have been insufficiently treated to kill the parasite. Many strategies are currently available (such as freezing and heat treatment), but further ones, such as pulsed electric fields (PEF), have hardly been investigated until now. This study focuses on the experimental evaluation of the efficacy of PEF in the inactivation of Anisakis spp. larvae in terms of electric field strength, specific energy, and pulse width, as well as on the evaluation of the quality of fish samples after PEF treatment. Results show that viability of Anisakis was highly dependent on field strength and specific energy. Pulse width exerted a considerable influence at the lowest field strengths tested (1 kV/cm). Central composite design helped to define a PEF treatment of 3 kV/cm and 50 kJ/kg as the one capable of inactivating almost 100% of Anisakis present in pieces of hake, while affecting the investigated quality parameters (moisture, water holding capacity, and cooking loss) to a lesser extent than freezing and thawing. These results show that PEF could serve as an alternative to traditional freezing processes for the inactivation of Anisakis in fish.

Pulsed electric field increases the extraction yield of extra virgin olive oil without loss of its biological properties.

Introduction: Pulsed electric field (PEF) has been used for improving extraction of extra virgin olive oil (EVOO). However, the biological changes induced by the consumption of pulsed electric field-obtained extra virgin olive oil (PEFEVOO) have not been studied yet. Materials and methods: EVOO oils from Empeltre variety were prepared by standard (STD) cold pressure method involving crushing of the olives, malaxation and decanting and by this procedure including an additional step of PEF treatment. Chemical analyses of EVOO oils were done. Male and female Apoe-deficient mice received diets differing in both EVOOs for 12 weeks, and their plasma, aortas and livers were analyzed. Results: PEF application resulted in a 17% increase in the oil yield and minimal changes in chemical composition regarding phytosterols, phenolic compounds and microRNA. Only in females mice consuming PEF EVOO, a decreased plasma total cholesterol was observed, without significant changes in atherosclerosis and liver steatosis. Conclusion: PEF technology applied to EVOO extraction maintains the EVOO quality and improves the oil yield. The equivalent biological effects in atherosclerosis and fatty liver disease of PEF-obtained EVOO further support its safe use as a food.