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pH-driven method is an effective strategy to prepare complex protein. This study provides guidance on how to select acidifiers and alkalizers from view of Hofmeister ion effects. Cations and anions regulated the molecular structure (particle size, surface charge, protein folding/unfolding, structural orderliness) of complex rapeseed proteins (CRPs) mainly via electrostatic and hydrogen bond. No evident changes were found in the molecular weight distribution, but their distribution on oil/air-water interface varied greatly. Various techno-functional properties of CRPs were synergistically improved: Citrate 3- and Na + increased the emulsifying activity index of CRPs from 80 to 102.21 m 2 /g; Citrate 3- , K + and Na + made the foaming stability of CRPs close to 80 % after 60 min of storage. Moreover, the oil/water-holding and gel properties of CRPs were regulated effectively. These findings demonstrate the key role of Hofmeister ion effects in improving CRPs properties, contributing to develop, select, and apply novel acidifiers and alkalizers during pH-driven treatment., Competing Interests: Declaration of competing interest The authors declare that there are no conflicts of interest., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The aim of this study was to purify and identify antioxidant peptides from watermelon seed protein hydrolysates (WSPHs-I: Mw < 1 kDa) and further evaluate their cytoprotective effects against H 2 O 2 -induced oxidative stress in HepG2 cells. After purification by Sephadex G-15 and semi-preparative reversed-phase high performance liquid chromatography (RP-HPLC), five peptides, RDPEER (P1), KELEEK (P2), DAAGRLQE (P3), LDDDGRL (P4), and GFAGDDAPRA (P5) were sequenced by LC-MS/MS and synthesized with solid-phase synthesis method. These peptides showed desirable 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging capacity (IC 50 : 0.216 ± 0.01-0.435 ± 0.03), 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical scavenging capacity (IC 50 : 0.54 ± 0.02-1.23 ± 0.03), and oxygen radical absorbance capacity (ORAC) (82.36 ± 1.2-130.67 ± 2.2 μM TE/mg). Among them, peptide P1 exhibited the strongest antioxidant capacity. Moreover, the results suggested that peptide P1 may protect HepG2 cells from H 2 O 2 -induced oxidative damage by significantly inhibiting reactive oxygen species (ROS), [Ca 2+ ]i, malondialdehyde (MDA) levels and increasing antioxidative enzyme activities., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier Ltd. All rights reserved.)