Abstract:

The present study investigated the effect of different degraded products of konjac glucomannan (KGM) on the
structure of myofibrillar protein from glass carp meat during frozen storage by ultraviolet spectroscopy, infrared spectroscopy
(IR) and scanning electronic microscope (SEM), in order to elucidate the cryoprotective mechanism of degraded products
of konjac glucomannan on myofibrillar protein. The results showed that α-helix and β-sheet were the major secondary
structures of myofibrillar protein from grass carp meat. The content of α-helix structure increased with prolonged frozen
storage, while the content of β-sheet structure decreased. And there were little changes in the contents of β-turn structure and
random coil. The degraded KGM by irradiation or β-glucanase could protect α-helix and β-sheet of myofibrillar protein from
grass carp meat and stabilize the proportions of the two secondary structures. Sucrose-sorbitol mixture could promote the
formation of α-helix structure but hinder the formation of β-turn. The microstructure of myofibrillar protein exhibited that
the degraded products of KGM from both treatments could retard the aggregation of myofibirillar protein, while the addition
of sucrose and sorbitol could result in formation of lamellar structure.

Key words: myofibrillar protein, frozen storage, secondary structure, microstructure