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. 2021 Oct 25;10(11):2565.
doi: 10.3390/foods10112565.

Elucidating the Calcium-Binding Site, Absorption Activities, and Thermal Stability of Egg White Peptide-Calcium Chelate

Zhijie Bao  1 , Penglin Zhang  1 , Na Sun  1 , Songyi Lin  1
Affiliations

Elucidating the Calcium-Binding Site, Absorption Activities, and Thermal Stability of Egg White Peptide-Calcium Chelate

Zhijie Bao et al. Foods. .

Abstract

With the current study, we aimed to determine the characteristics and calcium absorption capacity of egg white peptide-calcium complex (EWP-Ca) and determine the effect of sterilization on EWP-Ca to study the possibility of EWP-Ca as a new potential calcium supplement. The results of SEM and EDS showed a high calcium chelating ability between EWP and calcium, and the structure of EWP-Ca was clustered spherical particles due its combination with calcium. The FTIR and Raman spectrum results showed that EWP could chelate with calcium by carboxyl, phosphate, and amino groups, and peptide bonds may also participate in peptide-calcium binding. Moreover, the calcium absorption of EWP-Ca measured by the intestinal everted sac model in rats was 32.38 ± 6.83 μg/mL, significantly higher than the sample with CaCl2, and the mixture of EWP and Ca (p < 0.05) revealed appropriate calcium absorption capacity. The fluorescence spectra and CD spectra showed that sterilization caused a decrease in the content of α-helix and β-sheet and a significant increase in β-turn (p < 0.05). Sterilization changed the EWP-Ca structure and decreased its stability; the calcium-binding capacity of EWP-Ca after sterilization was decreased to 41.19% (p < 0.05). Overall, these findings showed that EWP could bind with calcium, form a peptide-calcium chelate, and serve as novel carriers for calcium supplements.

Keywords: calcium supplement; characterization; egg white; peptide–calcium chelate; thermal stability.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
SEM images of EWP and EWP-Ca. (A) SEM image of EWP at a magnification factor of 1000×; (B) SEM images of EWP-Ca at a magnification factor of 1000×; (C) SEM images of EWP at a magnification factor of 10,000×; (D) SEM images of EWP-Ca at a magnification factor of 10,000×.
Figure 2
Figure 2
The EDS pattern and percentage of EWP (A) and EWP-Ca (B) elements.
Figure 3
Figure 3
FTIR spectra of EWP and EWP-Ca from 4000 to 450 cm−1.
Figure 4
Figure 4
Raman spectra of EWP and EWP-Ca from 600 to 2200 cm−1.
Figure 5
Figure 5
The calcium absorption of CaCl2, EWP-Ca, CPP-Ca, and EWP + Ca. The different letters indicate a significant difference (p < 0.05).
Figure 6
Figure 6
Fluorescence spectra (A) and circular dichroism spectra (B) of EWP-Ca and sterilization treatment EWP-Ca. * indicates significant differences (p < 0.05).
See this image and copyright information in PMC

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