Identification and characterization of cryoprotective peptides extracted from silver carp (Hypophthalmichthys molitrix) hydrolysates

Qingjing Liu,Yongle Liu,Jian Yu,Faxiang Wang,Xianghong Li

doi:10.1080/10942912.2019.1622563

Qingjing Liu, Yongle Liu + Show 3 more

Open Access

https://doi.org/10.1080/10942912.2019.1622563

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Abstract

ABSTRACT The cryoprotective effects on surimi matrix of hydrolysates with different hydrolyzing times prepared from silver carp using Protamex were compared with commercial sorbitol-sucrose cryoprotectants. Cryoprotective assays showed that FPH-30 (hydrolysate with 30 min hydrolyzing) was a more effective cryoprotectant than other hydrolysates, because the FPH-30 group displayed lower salt-soluble protein extractability loss (29.90 ± 0.84%), less actomyosin Ca2+-ATPase activity decrease (48.85 ± 2.56%) and unfrozen water content decrease (10.39 ± 0.63%) after six freeze-thaw cycles. To exploit industrial utilizations, FPH-30 was further purified with ultrafiltration membranes. The cryoprotective activity of the fraction (<3 kDa) was superior to the others by reducing the salt-soluble protein extractability loss (27.21 ± 0.98%) and impeding the actomyosin Ca2+-ATPase activity decrease (30.54 ± 1.21%). Mass spectrometry analysis showed that the fraction (<3 kDa) was mainly composed of three peptides of the sequences GVDNPGHPFIM(T) and IITNWDDMEK. The results clearly support that silver carp could be a potential source of cryoprotectant peptides for industrial applications.

Highlights

Approximately 4.9 million metric tons of silver carp (Hypophthalmichthys molitrix) are produced globally.[1]
Our studies reveal that controlled enzymatic hydrolysis produces protein hydrolysates with different structures and functional properties from silver carp surimi by-products, which are low-cost materials.[14]
There were no significant differences in protein, ash or moisture content of the hydrolysates produced with different hydrolyzing times (P > .05)

Summary

Introduction

Approximately 4.9 million metric tons of silver carp (Hypophthalmichthys molitrix) are produced globally.[1]. Cryoprotectants are often used to avoid deterioration of surimi quality induced by freezing and/or fluctuating temperatures. Some protein hydrolysates and peptides are effective cryoprotectants for frozen fish surimi that experiences repeated freeze-thaw treatments. The cryopreservation effects are equal or superior to that of commercial SuSo.[2,4,5,6,7,8,9,10,11] the use of protein hydrolysates as cryoprotectants in surimi would be preferable. Protein hydrolysates are composed of a wide variety of peptides with different molecular weights and free amino acids.[12] This makes it difficult to define the cryoprotective mechanism of hydrolysates in surimi quality preservation and how hydrolysate properties and cryoprotectant efficiency are related. Considering other cryoprotective applications of hydrolysates, such as being cryoprotective agents for uses in cells[10]

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