Millet bran globulin hydrolysate derived tetrapeptide-ferrous chelate: Preparation, structural characterization, security prediction in silico, and stability against different food processing conditions
Bufan Xu, Xian Wang, Yajun Zheng, Panqi Shi, Ying Zhang, Yuxi Liu, Nengliu Long
Abstract
Through Sephadex gel chromatography, reverse-phase-high-performance-liquid-chromatography and ultra-high performance-liquid-chromatography coupled with electrospray ionization mass spectrometry analysis, a novel tetrapeptide (Ser-Glu-Leu-Glu) of excellent ferrous-chelating capacity (41.24 μmol/g) was identified in millet bran globulin hydrolysate. Physicochemical properties and security of SELE were predicted in silico. The result showed that SELE was no toxic. Based on a model generated from response surface methodology, the optimum preparation conditions of SELE-ferrous chelate were obtained with the mass ratio of SELE to FeCl2·4H2O of 43.3: 1, at pH 6.7 and 28.7 °C for 28.8 min. The ferrous-chelating ratio of SELE was 97.06% under these conditions. Structure of SELE-ferrous chelate was characterized with ultraviolet spectroscopy, Fourier-infrared spectroscopy and scanning electron microscope. The results demonstrated that amino group and carboxyl group of SELE were the primary ferrous-chelating sites. Moreover, SELE-ferrous chelate showed higher iron-solubility than FeCl2 and ferrous lactate against different pasteurization conditions, heating at 100 °C for 30 min, and various pH values (P < 0.05). SELE-ferrous chelate also demonstrated higher iron-solubility than FeCl2 and ferrous lactate against simulated gastrointestinal digestion (P < 0.05). These results indicated that SELE could be used as ingredient of iron fortifications and had potential applications in the food industry.