Impact of ultrafiltration and nanofiltration of an industrial fish protein hydrolysate on its bioactive properties.
BACKGROUND
Numerous studies have demonstrated that in vitro controlled enzymatic hydrolysis of fish and shellfish proteins leads to bioactive peptides. Ultrafiltration (UF) and/or nanofiltration (NF) can be used to refine hydrolysates and also to fractionate them in order to obtain a peptide population enriched in selected sizes. This study was designed to highlight the impact of controlled UF and NF on the stability of biological activities of an industrial fish protein hydrolysate (FPH) and to understand whether fractionation could improve its content in bioactive peptides.


RESULTS
The starting fish protein hydrolysate exhibited a balanced amino acid composition, a reproducible molecular weight (MW) profile, and a low sodium chloride content, allowing the study of its biological activity. Successive fractionation on UF and NF membranes allowed concentration of peptides of selected sizes, without, however, carrying out sharp separations, some MW classes being found in several fractions. Peptides containing Pro, Hyp, Asp and Glu were concentrated in the UF and NF retentates compared to the unfractionated hydrolysate and UF permeate, respectively. Gastrin/cholecystokinin-like peptides were present in the starting FPH, UF and NF fractions, but fractionation did not increase their concentration. In contrast, quantification of calcitonin gene-related peptide (CGRP)-like peptides demonstrated an increase in CGRP-like activities in the UF permeate, relative to the starting FPH. The starting hydrolysate also showed a potent antioxidant and radical scavenging activity, and a moderate angiotensin-converting enzyme (ACE)-1 inhibitory activity, which were not increased by UF and NF fractionation.


CONCLUSIONS
Fractionation of an FPH using membrane separation, with a molecular weight cut-off adapted to the peptide composition, may provide an effective means to concentrate CGRP-like peptides and peptides enriched in selected amino acids. The peptide size distribution observed after UF and NF fractionation demonstrates that it is misleading to characterize the fractions obtained by membrane filtration according to the MW cut-off of the membrane only, as is currently done in the literature.
Picot
Laurent
L
UMR CNRS 6250 LIENSs, Université de La Rochelle, La Rochelle, France. laurent.picot@univ-lr.fr
Ravallec
Rozenn
R
Fouchereau-Péron
Martine
M
Vandanjon
Laurent
L
Jaouen
Pascal
P
Chaplain-Derouiniot
Maryse
M
Guérard
Fabienne
F
Chabeaud
Aurélie
A
Legal
Yves
Y
Alvarez
Oscar Martinez
OM
Bergé
Jean-Pascal
JP
Piot
Jean-Marie
JM
Batista
Irineu
I
Pires
Carla
C
Thorkelsson
Gudjon
G
Delannoy
Charles
C
Jakobsen
Greta
G
Johansson
Inez
I
Bourseau
Patrick
P
D000596:Amino Acids / Q000302:isolation & purification; D000818:Animals; D000975:Antioxidants / Q000302:isolation & purification / Q000494:pharmacology; D015740:Calcitonin Gene-Related Peptide / Q000302:isolation & purification; D002766:Cholecystokinin / Q000302:isolation & purification; D005396:Fish Products; D029941:Fish Proteins / Q000737:chemistry*; D005399:Fishes; D005755:Gastrins / Q000302:isolation & purification*; D006868:Hydrolysis; D008970:Molecular Weight; D010455:Peptides / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology; D007703:Peptidyl-Dipeptidase A / Q000302:isolation & purification / Q000494:pharmacology; D014462:Ultrafiltration / Q000379:methods
D000596:Amino Acids; D000975:Antioxidants; D029941:Fish Proteins; D005755:Gastrins; D010455:Peptides; D002766:Cholecystokinin; D007703:Peptidyl-Dipeptidase A; D015740:Calcitonin Gene-Related Peptide