Since collagen has naturally evolved to be durable, producing collagen hydrolysate with low molecular weight (LMW) peptides which typically results in high bioactivity is a challenge. Here, the efficiency of ultrasound (US) and pulsed electric field (PEF) pretreatments in enhancing the enzymatic hydrolysis of starfish collagen biomass (SFCB) and the antioxidant capacity of the resulting hydrolysate were evaluated. Both pretreatments significantly improved the degree of hydrolysis (DH) and reduced the required hydrolysis time compared to the conventional methods. The DH of SFCB hydrolysate pretreated with US reached 20 % at 60 min while that of the PEF treatment reached 21 % at 120 min, matching the DH of the conventional hydrolysis at 240 min. US and PEF hereby increased the collagen hydrolysate recovery, particularly compensating for a low enzyme-to-substrate ratio (0.5 % v/w). The pretreatments resulted in collagen peptides with significantly higher antioxidant properties, as assessed by ABTS and DPPH assays. The IC50 values of ABTS radical inhibition were found to be 0.68, 0.43, and 0.84 mg/ml for the collagen peptides produced by the US, PEF pretreatments and conventional enzymatic hydrolysis, respectively. Applying PEF and US pretreatment at an enzyme concentration of 0.5 % v/w, increased the proportion of collagen hydrolysate with MW < 10 KDa to 64 % and 59 %, respectively, compared to the conventional method which yielded only 43 %. The enhancements in the antioxidant activities were linked to the increased proportion of LMW peptides (<10 kDa) and elevated relative levels of antioxidative amino acids e.g. glycine, proline, basic amino acids, and hydrophobic amino acids in the peptides produced using US and PEF pretreatment. Overall, US and PEF pretreatments effectively increased collagen susceptibility to enzymatic hydrolysis, improving efficiency and generating peptides with superior antioxidant properties.

The efficiency of radio frequency (RF) seed pretreatment to mitigate lipid oxidation-related beany volatile compounds during pea protein isolation via wet fractionation and its underlying mechanism were evaluated. RF treatments above 110 °C for >20 min fully inactivated lipoxygenase (LOX) but caused up to 50% loss in protein yield. By optimizing sample thickness, electrode distance, and heating duration, RF heating achieved >90% LOX inactivation below 100 °C while preserving protein yield, outperforming conventional heating. Moderate RF treatment (∼75 °C) reduced LOX activity by 80% while retaining intrinsic phenolic compounds, which stabilized EPR-detectable free radicals and promoted the accumulation of hydroxyoctadecadienoic acids (HODE-13) rather than volatile off-flavor compounds. In contrast, more intense RF treatments (∼85-95 °C) degraded intrinsic antioxidants and accelerated lipid breakdown to hydroperoxides and volatile off-flavor compounds. Overall, optimized RF pretreatment can effectively limit lipid oxidation and off-flavor formation during pea protein isolation by combining LOX inactivation with phenolic-mediated radical stabilization, without compromising protein yield.

Enzymatic hydrolysis is one of the effective methods used to obtain the bioactive peptides from marine resources. This study aimed to evaluate effect of the enzyme type (Food Pro PNL (FP), Corolase8000 (C8), and Corolase7089 (C7)) and biomass pretreatment level (whole starfish (SF), deproteinized (DPSF) as well as deproteinized and demineralized starfish (DPDMSF)) on the hydrolysate yield, degree of hydrolysis (DH), generated peptides’ molecular weight (MW), and in vitro radical scavenging and antiproliferative effects. Regardless of the enzyme used, deproteinization reduced the hydrolysate yield (<8% dw/ww) and DH (40%) to SF. However, the protein content of hydrolysates from DPSF and DPDMSF was higher than that prepared from SF. C8 was not effective in hydrolyzing SF but was the only effective enzyme in hydrolyzing DPDMSF. The peptides’ MW distribution strongly depended on the pretreatment and enzyme type, mostly ranging from 17 to 70 kDa. Glycine content was higher in hydrolysates from DPSF and DMDPSF, indicating their collagenous nature. Hydrolysates from DPSF, rich in collagenous peptides, showed medium MW but the highest radical scavenging activity. Only SF-FP hydrolysate, rich in non-collagenous peptides, showed antiproliferative activity against melanoma cancer cells. Overall, the findings demonstrate that upstream biomass pretreatment and enzyme selection directly govern the yield and bioactivity of starfish protein hydrolysates, providing a rational basis for designing starfish protein hydrolysates with targeted functional properties.