Improving the Extraction of Juice and Anthocyanin Compounds from Blueberry Fruits and Their by-Products by Pulsed Electric Fields

Pulsed electric fields (PEF) have been reported to increase the total oil extraction yield (OEYTOTAL) of fresh pecan nuts maintaining oil characteristics and increasing phenolic compounds in the remaining by-product. However, there is no information regarding the PEF effect on dry pecan nuts. Dry kernels were pretreated at three specific energy inputs (0.8, 7.8 and 15.0 kJ/kg) and compared against untreated kernels and kernels soaked at 3, 20 and 35 min. OEYTOTAL, kernels microstructure, oil stability (acidity, antioxidant capacity (AC), oil stability index, phytosterols and lipoxygenase activity), along with by-products phenolic compounds (total phenolics (TP), condensed tannins (CT)) and AC were evaluated. Untreated kernels yielded 88.7 ± 3.0%, whereas OEYTOTAL of soaked and PEF-treated kernels were 76.5–83.0 and 79.8–85.0%, respectively. Kernels microstructural analysis evidenced that the 0.8 kJ/kg pretreatment induced oleosomes fusion, while no differences were observed in the stability of extracted oils. PEF applied at 0.8 kJ/kg also increased by-products CT by 27.0–43.5% and AC by 21.8–24.3% compared to soaked and untreated kernels. These results showed that PEF does not improve OEYTOTAL when it is applied to dry pecan nuts, demonstrating that kernelsʹ moisture, oil content and microstructure play an important role in the effectiveness of PEF.

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Accelerated Solvent Extraction and Pulsed Electric Fields for Valorization of Rainbow Trout (Oncorhynchus mykiss) and Sole (Dover sole) By-Products: Protein Content, Molecular Weight Distribution and Antioxidant Potential of the Extracts

Marine Drugs ◽

10.3390/md19040207 ◽

2021 ◽

Vol 19 (4) ◽

pp. 207

Author(s):

Min Wang ◽

Jianjun Zhou ◽

Maria Carmen Collado ◽

Francisco J. Barba

Keyword(s):

Rainbow Trout ◽

Solvent Extraction ◽

Antioxidant Capacity ◽

Electric Fields ◽

New Technologies ◽

Pulsed Electric Fields ◽

Accelerated Solvent Extraction ◽

Biologically Active ◽

Added Value ◽

By Products

Fishery by-products are rich in biologically active substances and the use of green and efficient extraction methods to recover these high-added-value compounds is of particular importance. In this study, head, skin and viscera of rainbow trout and sole were used as the target matrices and accelerated solvent extraction (ASE) (45–55 °C, 15 min, pH 5.2–6.8, 103.4 bars) and pulsed electric fields (PEF) (1–3 kV/cm, 123–300 kJ/kg, 15–24 h) were applied as extraction technologies. The results showed that ASE and PEF significantly increased the protein extract efficiency of the fish by-products (p < 0.05) by up to 80%. SDS-PAGE results showed that ASE and PEF treatments changed the molecular size distribution of the protein in the extracts, which was specifically expressed as the change in the area or number of bands between 5 and 250 kDa. The antioxidant capacity of the extracts was evaluated by oxygen radical absorbance capacity (ORAC) and total antioxidant capacity (ABTS) assays. The results showed that both ASE and PEF treatments significantly increased the antioxidant capacity of rainbow trout and sole skin and head extracts (p < 0.05). ASE and PEF extraction processes can be used as new technologies to extract high-added-value compounds from fish by-products.

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