Application of pulsed electric field in the production of juice and extraction of bioactive compounds from blueberry fruits and their by-products.
The influence of Pulsed Electric Field (PEF) pre-treatment of blueberry fruits (Vaccinium myrtillus L.), both on the extraction yield and antioxidant properties of juice obtained by pressing and on the on the recovery of bioactive compounds from berry by-products (press cake) by extraction with solvent, was investigated. PEF treatments carried out at field strengths of 1, 3, and 5 kV/cm and an energy input of 10 kJ/kg achieved a cell disintegration index (Z p ) of 0.70, 0.80, and 0.87, respectively. Mechanical pressing (1.32 bar for 8 min) of PEF-treated berries (1, 3, and 5 kV/cm at 10 kJ/kg) significantly increased the juice yield (+28 %) compared with the untreated sample. The juice obtained from PEF pre-treated berries also had a significantly higher total phenolic content (+43 %), total anthocyanin content (+60 %) and antioxidant activity (+31 %). However, PEF treatment intensity higher than 1 kV/cm did not significantly improve the quantitative or qualitative characteristics of the juice. Compared to the untreated sample, higher amounts of total phenolics (+63 %), total athocyanins (+78 %) and antioxidant activity (+65 %) were detected in the press cake extracts. PEF treatment of higher intensity resulted in better extractability of bioactive compounds from blueberry press cake. The results obtained from this study demonstrate the potential of PEF as a mild pre-treatment method to improve the efficiency of the industrial processing of berry fruits.
Department of Biology, Vytautas Magnus University, K. Donelaičio st. 58, 44248 Kaunas, Lithuania.
Ramunė
R
Bobinaitė
Department of Industrial Engineering, University of Salerno, via Giovanni Paolo II 132, 84084 Fisciano, SA Italy.
Gianpiero
G
Pataro
Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, Kaunas st. 30, 54333 Babtai, Kaunas distr. Lithuania.
Nerijus
N
Lamanauskas
Department of Biology, Vytautas Magnus University, K. Donelaičio st. 58, 44248 Kaunas, Lithuania.
Saulius
S
Šatkauskas
Institute of Horticulture, Lithuanian Research Centre for Agriculture and Forestry, Kaunas st. 30, 54333 Babtai, Kaunas distr. Lithuania.
Pranas
P
Viškelis
Department of Industrial Engineering, University of Salerno, via Giovanni Paolo II 132, 84084 Fisciano, SA Italy ; ProdAl Scarl - University of Salerno, via Ponte don Melillo, 84084 Fisciano, SA Italy.
Giovanna
G
Ferrari
Bioactive compounds; Blueberry; By-products; Extraction; PEF; Pressing