Optimization of ultrasound assisted extraction of abalone viscera protein and its effect on the iron-chelating activity

This study aims to investigate effects of ultrasound assisted extraction on the abalone viscera protein extraction rate and iron-chelating activity of peptides. The optimal conditions for ultrasound assisted extraction by response surface methodology was at sodium hydroxide concentration 14 g/kg, ultrasonic power 428 W and extraction time 52 min. Under the optimal conditions, protein extraction rate was 64.89%, compared with alkaline extraction of 55.67%. The iron-chelating activity of peptides affected by ultrasound technology was further evaluated by iron-chelating rate, FTIR spectroscopy and LC-HRMS/MS. Alcalase was the suitable enzyme for the preparation of iron-chelating peptides from two abalone viscera proteins, showing no significant difference between their iron-chelating rate of 16.24% (ultrasound assisted extraction) and 16.60% (alkaline extraction). Iron binding sites from the two hydrolysates include amino and carboxylate terminal groups and peptide bond of the peptide backbone as well as amino, imine and carboxylate from side chain groups. Moreover, 24 iron-chelating peptides were identified from hydrolysate (alcalase, ultrasound assisted extraction), which were different from the 27 iron-chelating peptides from hydrolysate (alcalase, alkaline extraction). This study suggests the application of ultrasound technology in the generation of abalone viscera-derived iron-chelating peptides which have the ability to combat iron deficiency.

Preparation and characterization of iron-chelating peptides from whey protein: An alternative approach for chemical iron fortification

Iron fortification of staple food is a strategy utilized worldwide to address the concern of dietary iron deficiency. However, traditional salt-based fortification methods have limitations with gastrointestinal stability and bioavailability. Iron chelating peptides from easily available and scalable proteins such as whey protein have been proposed as promising candidates to circumvent the above mentioned limitations by enhancing iron absorption and bioavailability. In this study, we report methods to produce whey protein derived iron-chelating peptides and describe their physicochemical characteristics. Peptides derived from whey proteins prepared by ultrafiltration of whey followed by hydrolysation were iron chelated to produce peptide-iron complexes. These complexes had a size of 422.9 ± 3.41 nm, chelated iron content of 36.42 µg/ mg protein, and a low zeta potential (-10.80 mV) compared to whey peptides. Spectra analysis using ultraviolet-visible absorption and Fourier transform infrared spectroscopy showed structural transformation indicating iron chelation. Mass spectrometric analysis using LC-MS/MS confirmed the presence of both hydrophilic and hydrophobic peptides in the complexes with sizes ranging from 275 Da to 1916 Da. Furthermore, reduction in the antioxidant property of peptides following iron complexing indicates iron chelation. Our results suggest that whey protein derived peptide-iron complexes can be used as a potential alternative for chemical iron fortificants for food products and also as iron supplements.