An in vitro method was used to determine the availability of Zn from infant foods containing increasing amounts of phytate, and to quantify the effect of the phytate:Zn molar ratio on the availability. During the in vitro assay, digestive conditions of infants, younger and older than 4 months of age, were carefully simulated since the solubility of phytate -Zn complexes during digestion is pH dependent. Availability was measured with a continuous flow dialysis in vitro procedure with previous intralumen digestive stage. Zn concentrations were determined with flame atomic absorption spectrometry. Phytic acid content was measured with HPLC. Adding phytate to infant formula lowered Zn availability to 2 : 84 (SD 0 : 17) % when the phytate:Zn molar ratio increased to 2 : 2 ðP , 0 : 05Þ; as compared with cows' milk-based formula (6 : 65 (SD 0 : 55) %). Availability from vegetables (23 : 83 (SD 2 : 17) %) significantly decreased ðP , 0 : 05Þ at a ratio . 7 : 9 (15 : 12 (SD 1 : 63) %). Zn availability from soyabean-based formula (2 : 26 (SD 0 : 36) %) was lower ðP , 0 : 05Þ compared with cows' milk-based formula (6 : 65 (SD 0 : 55) %). Availability between soyabean-and cows' milk-based formula was similar ðP . 0 : 05Þ when a phytate:Zn ratio of 2 : 2 (2 : 84 (SD 0 : 17) %) was obtained in the cows' milk formula. The negative effect of phytic acid on Zn availability was dependent on the type of the food and the phytate content, and should be considered when using soyabean-based formulas during early infancy.
This study aimed to investigate the effect of limited hydrolysis on conformational and antioxidant properties of soy protein isolate-maltodextrin (SPI-Md) conjugates. Extrinsic fluorescence analysis showed unfolding of the protein molecule and exposure of hydrophobic groups in SPI-Md conjugate hydrolysates. Free amino acid analysis showed that, the contents of hydrophobic amino acids in SPI-Md conjugates increased after hydrolysis. The contents of leucine, isoleucine, phenylalanine increased from 0.32, 0.30 and 0.54 to 1.36, 1.86 and 2.60, respectively, when the hydrolysis degree (DH) gradually increased from 0% to 5.7%. The FT-IR spectrum showed that C = O absorption of the amide group formed by glycosylation continued unabated after limited hydrolysis (DH 2.9%). The glycated SPI products showed good reducing power and superior resistance to lipid oxidation (34%, 12 mg mL −1), whereas the limit hydrolysates (DH 2.9%) of SPI-Md conjugates showed more efficient radical-scavenging capacity (89.5%, at 12 mg mL −1) and iron-chelation activity (91.3%, at 12 mg mL −1). Results of this study indicated that, slight enzymatic hydrolysis (DH 0-2.9%) could help partially unfolding the globular structure of SPI-Md conjugates without deteriorating amide bonds and had a positive effect on their antioxidant properties.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.