Sulčių spaudimas iš sušaldytų/atšildytų mėlynių taikant impulsinio elektrinio lauko metodą

Abstract

Pulsed electric field is an efficient method for cell membrane permeabilization of food tissues with most research being done on fresh plant cells. Freeze/thawing is also known to be capable of cell membrane permeabilization. In this work, frozen/thawed European blueberry (Vaccinium myrtillus L.) fruits were treated with pulsed electric field in order to further enhance the cell membrane permeabilization and, hence, the quality of blueberry juice during the subsequent pressing process. Blueberries tissues were exposed to 20 µs monopolar square wave pulses of different electric field strength (E = 1-3-5 kV cm -1 ) and total specific energy input (W T = 1-5-10 kJ kg -1 ), with their permeabilization being characterized by electrical impedance measurements and cell disintegration index (Z p ). The juice, obtained after pressing (1.32 bar), was characterized for total polyphenols, anthocyanins content and antioxidant activity. The cell disintegration index (Z p ) significantly (p < 0.05) increased from 0.2 up to 0.6 with increasing pulsed electric field treatment intensity (E and W T ). As a results, in comparison with control, pulsed electric field treatment induced a slightly higher release of polyphenols (up to +8.0%) and anthocyanins (up to +8.3%), thus improving the antioxidant activity of the juice (up to +16.7%). In conclusion, frozen/thawed blueberries could be pulsed electric field treated in order to further increase juice quality.

Pulsed electric fields as an alternative to thermal processing for preservation of nutritive and physicochemical properties of beverages: A review

“…This was also observed in other juices, such as grape (Puértolas, Saldaña, Condón, Álvarez, & Raso, ), vegetable, and tomato juice (Vallverdú‐Queralt et al, ) where authors noticed higher contents of hydroxycinnamic acids and flavanones, while flavonols, coumaric, and ferulic acid remained unaffected by processing. When blueberries were exposed to PEF (1–5 kV/cm, 20 µs monopolar) prior pressing to juice ( p = 1.32), that increased polyphenolic and anthocyanins contents for 8.0% and 8.3%, respectively and enhanced antioxidant activity by 16.7% (Lamanauskas et al, ). Similarly, it was reported that after PEF (2 kV/cm, 1 µs), blueberries had 10% more anthocyanins and 25% polyphenolic compounds (Yu et al, ).…”

Effective valorization of food wastes and by‐products through pulsed electric field: A systematic review

“…PEF pre‐treatment (3 kV/cm, 1.25 ms) was used to recover phenolics from apple pomace, sorghum flour, frozen European blueberries (1 kV/cm, 10 kJ/kg) (Lamanauskas et al, 2015). Red apples, mango, and papaya peels were examined to extract the polyphenols after PEF pre‐treatment.…”

Antioxidant and Anticancer Activity of Pulsed Electric Field Treated Grape Extract

“…Results showed that there was an insignificant difference between the control groups and the PEF treated apple juice [16]. Lamanauskas et al [17] reported that the application of PEF treatment (5 kV/cm) to blueberries resulted in enhanced antioxidant activity (up to +16.7%). More recently, Rodriguez-Roque et al [18] also observed an improved antioxidant capacity (up to +12.9%) of PEF treated (35 kV/cm, 1800 μs) fruit juice-based beverages compared to thermal processing (90°C, 60 s).…”