BACKGROUND Protein can be used as an emulsifier to improve emulsion stability at the interface of water‐in‐oil emulsion. However, natural soybean protein isolate (SPI) does not meet the high demands as an emulsifier in the food industry. The effect of acylation modification by ethylenediaminetetraacetic dianhydride (EDTAD; 0–300 g kg−1) on the physicochemical properties of SPI was studied. RESULTS The results of the Fourier transform infrared spectra analyses showed that carboxyl groups were introduced into the SPI structure by the EDTAD treatment. The carboxyl concentration of SPI was increased by 30–74.07% with an increase in EDTAD addition from 50 to 300 g kg−1. When 150 g kg−1 EDTAD was added, the surface hydrophobicity, the emulsifying activity, and the absolute value of the zeta potential were increased by 213%, 120%, and 68% respectively, and the particle size decreased to 247 nm. The droplet size of emulsion decreased to 10 μm when pH was 6. At the same concentration of SPI and pH, the absolute value of zeta potential of the emulsion was biggest. A comparison of the emulsions during storage showed the improvement of emulsion stability was related to the increase in the zeta potential and the decrease in the average particle size. The experimental group showed no destabilization on day 21, and no obvious aggregation phenomenon was observed. CONCLUSION Acylation modification by EDTAD changed the emulsifying properties of SPI and enhanced the stability of the SPI emulsion. © 2021 Society of Chemical Industry

A novel three‐stage treatment process corresponding to three reactors (R1, R2 and R3) was developed for advanced defluoridation from industrial wastewater with fluoride concentration as high as 245 mg/L. In the first stage (R1), 90.6 ± 0.8% of fluoride was removed through CaF2 precipitation. Subsequently, the second stage (R2) was operated for advanced defluoridation through fluorapatite (FAP) precipitation. Importantly, the residual calcium in effluent of R1 participated in FAP precipitation in R2, reducing extra calcium dosage. In the third stage (R3), further defluoridation was observed in R3, and the final fluoride content in the effluent was as low as 0.15 mg/L in Phase 2. Advanced defluoridation from industrial wastewater with high‐concentration fluoride could be obtained through this process without coagulant addition to reduce sludge production and obtain relative pure chemical precipitates, and residual reagents could be utilized again in the next step during the process to decrease reagents dosage.

Due to people's pursuit of healthy and green life, soy protein isolate (SPI) is occupying a larger and larger market share. However, the low solubility of SPI affects its development in the field of food and medicine. This paper aimed to investigate the effects of sodium trimetaphosphate (STMP) on the functional properties and structures of phosphorylated SPI and its lutein-loaded emulsion. After modification by STMP, the phosphorus content of phosphorylated SPI reached 1.2-3.61 mg/g. Infrared spectrum and X-ray photoelectron spectrum analysis confirmed that PO 4 3− had phosphorylation with -OH in serine of SPI molecule. X-ray diffraction analysis showed that phosphorylation destroyed the crystal structure of protein molecules. Zeta potential value of phosphorylated SPI decreased significantly. When STMP addition was 100 g/kg, particle size of protein solution decreased to 203 nm, and solubility increased to 73.5%. Furthermore, emulsifying activity and emulsifying stability increased by 0.51 times and 8 times, respectively. At the same protein concentration (1%-3% [w/w]), lutein-loaded emulsion prepared by phosphorylated SPI had higher absolute potential and smaller particle size. The phosphorylated protein emulsion at 2% concentration had the best emulsion stability after storage for 17 days.