Effect of Pulsed Electric Fields on the Lipidomic Profile of Lipid Extracted from Hoki Fish Male Gonad

Abstract

Processing of hoki, a commercially important fish species, generates substantial quantities of co-products, including male gonad, which contains valuable lipids, such as phospholipids, that could be recovered and utilised. Hoki fish male gonads (HMG) were subjected to pulsed electric fields (PEF) treatment at varying field strengths (0.625, 1.25, and 1.875 kV/cm) and frequencies (25, 50, and 100 Hz), at a fixed pulse width of 20 μs. The total lipid was extracted using an ethanol-hexane-based (ETHEX) extraction method, and the phospholipid and fatty acid compositions were determined using 31P NMR and GC-FID, respectively. The total lipid yield was increased from 4.1% to 6.7% by a relatively mild PEF pre-treatment at a field strength of 1.25 kV/cm and frequency of 50 Hz. A higher amount of EPA (8.2%), DPA (2.7%), and DHA (35.7%) were obtained by that treatment, compared to both un-heated (EPA: 8%; DPA: 2.5%; DHA: 35.2%) and heat-treated controls (EPA: 7.9%; DPA: 2.5%; DHA: 34%). No significant changes to the content of the major phospholipids were observed. PEF pre-treatment under mild conditions has potential for improving the total lipid yield extracted from fish male gonad.

Comparative studies on the lipid profiles of female and male gonads of abalone (Haliotis discus hannai)

“…Similarly, many studies have also shown that PC and PE were the dominant kinds of PLs in the by‐products of marine animals, and their contents in female organisms were higher than those in male ones. [ 35–38 ]…”

“…As shown in Table 3, lipids extracted from abalone gonads were abundant in palmitic acid (C16:0), which was also the most common saturated FA found in tissues of most marine organisms. [ 37 ] According to Gabbott, [ 42 ] in addition to being the primary end product of the FA synthetase system in animal tissues, this FA is the precursor for the de novo synthesis of long‐chain FAs. Besides, the contents of PUFA were shown as follows: LFG, 14.42% ± 1.20% of total FAs; LMG, 18.27% ± 0.33% of total FAs.…”

“…Similarly, many studies have also shown that PC and PE were the dominant kinds of PLs in the by-products of marine animals, and their contents in female organisms were higher than those in male ones. [35][36][37][38] TA B L E 2 Phospholipid class compositions (mg g −1 ) of the lipids from gonads of the female and male abalones (Haliotis discus hannai). Note: Values are presented as mean ± standard error (n = 3).…”

“…As shown in Table 3, lipids extracted from abalone gonads were abundant in palmitic acid (C16:0), which was also the most common saturated FA found in tissues of most marine organisms. [37] According to…”

Valorisation of food processing wastes using PEF and its economic advances – recent update

“…Especially under optimum PEF treatment conditions, 53.3% of phospholipids were extracted from male fish gonads. The extracted compounds have the potential to treat chronic disorders such as neurodegenerative disorders, cardiovascular diseases, diabetes, and so it can be used in nutraceutical applications (Burnett et al, 2022) (Fig. 4).…”