title: A simple and convenient method for the preparation of antioxidant peptides from walnut (Juglans regia L.) protein hydrolysates.
abstract: BACKGROUND
  Walnut (Juglans regia L.), that belongs to the Juglandaceae family, is one of the nuts commonly found in Chinese diets. Researchers had obtained peptides from walnut protein hydrolysates, and these peptides exhibited the high antioxidant activities. The objective of this study was to develop a simple and convenient method for a facile and reproducible preparation of antioxidant peptides from walnut protein hydrolysates.
  
  
  RESULTS
  Walnut proteins were extracted from walnut kernels using continuous countercurrent extraction process, and were separately hydrolyzed with six types of proteases (neutrase, papain, bromelain, alcalase, pepsin, and pancreatin). Then, hydrolysates were purified by ultrafiltration. The yields and purity of the peptides prepared using neutrase and papain were 16 and 81 % at least, respectively, higher than others, and had low molecular weight, 99 % of which were less than 1500 Da. Furthermore, the bioassay indicated that the two peptides exhibited the high antioxidant activities in the DPPH (IC50 values: 59.40 and 31.02 µg/mL, respectively), ABTS (IC50 values: 80.36 and 62.22 µg/mL, respectively), and superoxide radical scavenging assay (IC50 values: 107.47 and 80.00 µg/mL, respectively).
  
  
  CONCLUSIONS
  The method combines the advantages of generality, rapidity, simplicity, and is useful for the mass production of walnut peptides.Graphical AbstractPreparation of antioxidant peptides from walnut (Juglans regia L.) protein hydrolysates.
authors.affiliation: R&D Center, Sinphar Tian-Li Pharmaceutical Co., Ltd., Hangzhou, 311100 China.
authors.forename: Ming-Chuan
authors.initials: MC
authors.lastname: Liu
authors.affiliation: R&D Center, Sinphar Tian-Li Pharmaceutical Co., Ltd., Hangzhou, 311100 China.
authors.forename: Sheng-Jie
authors.initials: SJ
authors.lastname: Yang
authors.affiliation: R&D Center, Sinphar Tian-Li Pharmaceutical Co., Ltd., Hangzhou, 311100 China.
authors.forename: Da
authors.initials: D
authors.lastname: Hong
authors.affiliation: R&D Center, Sinphar Tian-Li Pharmaceutical Co., Ltd., Hangzhou, 311100 China.
authors.forename: Jin-Ping
authors.initials: JP
authors.lastname: Yang
authors.affiliation: R&D Center, Sinphar Tian-Li Pharmaceutical Co., Ltd., Hangzhou, 311100 China.
authors.forename: Min
authors.initials: M
authors.lastname: Liu
authors.affiliation: R&D Center, Sinphar Tian-Li Pharmaceutical Co., Ltd., Hangzhou, 311100 China.
authors.forename: Yun
authors.initials: Y
authors.lastname: Lin
authors.affiliation: R&D Center, Sinphar Tian-Li Pharmaceutical Co., Ltd., Hangzhou, 311100 China.
authors.forename: Chia-Hui
authors.initials: CH
authors.lastname: Huang
authors.affiliation: R&D Center, Sinphar Tian-Li Pharmaceutical Co., Ltd., Hangzhou, 311100 China ; School of Life Science and Biopharmaceutics, Shenyang Pharmaceutical Univerisity, Shenyang, 110016 China ; R&D Center, Sinphar Pharmaceutical Co., Ltd., Ilan (Taiwan), 269 China.
authors.forename: Chao-Jih
authors.initials: CJ
authors.lastname: Wang
keywords: Antioxidant; Large scale preparation; Peptide; Proteases; Protein; Walnut