Microalgae cell membrane permeabilization has been studied, for Chlorella sp., in a continuous 6-L prototype for different field strengths in order to minimize the specific energy supplied and the treatment time. Regarding lower electrical field strength values, the optimal results were achieved at 10 kV/cm, 200 Hz, and 5-µs per pulse, corresponding to an energy delivered of 9 kJ/kg of culture, with 97% of cells affected after 300 ms of treatment time. Regarding energy delivered per kilogram of Biomass, the best result was 2.7 MJ/kg of biomass with 95% of cells affected after 300 ms of treatment time and was achieved at 15 kV/cm, 200 Hz, and 5-µs per pulse. Pulsed electric field effect was quantified by flow cytometry using propidium iodide as a viability stain. The influence of conductivity and cell concentration was also analyzed. The final goal was to evaluate the use of this technology in terms of increasing bioaccessibility of bioactive compounds present in microalgae for food and feed purposes. These results, obtained only for chlorophyll a and b, did not show any beneficial effect of this technology against nontreated biomass.Index Terms-Bioaccessibility, Chlorella, electroporation, microalgae, pulsed electric field (PEF).
The quality of virgin olive oil (VOO) is largely determined by the technology used in the industrial process of extracting the oil. Technological innovations within this field aim to strike a proper balance between oil yield and the optimal chemical composition of VOO. The application of pulsed electric fields (PEF) that cause the electroporation of the plant cell membranes favors a more efficient breakage of the olive fruit tissue, which in turn could facilitate the extraction of the oil and some of its key minor components. Pilot-scale and industrial extraction tests have been conducted to assess the effect of PEF technology on the oil extraction yield and on the organoleptic and functional quality of VOO. The best results were obtained by combining the PEF treatment (2 kV/cm) with short malaxation times and a low processing temperature. Under these conditions, PEF technology could decisively improve the oil yield by up to 25% under optimal conditions and enhance the incorporation of phenolic and volatile compounds into the oils. The PEF treatment neither affected the physicochemical parameters used to determine the commercial categories of olive oils, nor the tocopherol content. Similarly, the sensory evaluation of the PEF-extracted oils by means of a panel test did not detect the appearance of any defect or off-flavor. In addition, the intensity of positive attributes (fruity, bitter and pungent) was generally higher in PEF oils than in control oils.
Nowadays, the standard media used in clinical-scale mesenchymal stem cell (MSC) production to supply hundreds of clinical trials uses animal-derived components as supplements, which raises several health concerns. Consequently, the development of xeno-free media supplements has emerged. In the current study, the effect of pulse electric field (PEF) application to platelet concentrates (PC) with no therapeutic value for producing platelet releasates (PR) able to sustain the ability of bone marrow-MSCs (BM-MSCs) to self-renew and differentiate was tested. It was demonstrated that PEF application to PC induces platelet activation and growth factor (GF) release, namely PDGF, FGF, IGF, and TGF-β. The highest GF release was observed for TGF-β, achieving similar levels to those attained in platelet lysates (PL). BM-MSCs expanded in the presence of PR obtained by the application of PEF (7 pulses of 10 and 12.5 kV/cm) to PC (PR PEF) retained the characteristic MSC cell-surface markers, and the ability to proliferate and differentiate into osteogenic, adipogenic, and chondrogenic lineages. In this study, evidence is provided that PR PEF represents a suitable alternative to fetal bovine serum (FBS) for use in MSC production.
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