Improvement of the emulsifying properties of Zanthoxylum seed protein by ultrasonic modification

Characteristics of Quinoa Protein Isolate Treated by Pulsed Electric Field

“…The display of images of PEF-QPI treated with approximately 30 and 50 pulses is less porous but fluffy and rough. The 7.5 kV/cm 30-pulse treatment had a positive effect on the compactness and uniformity of the QPI’s structure, leading to an ordered matrix with a smaller void, conducive to the formation of a stable interfacial layer at the gas–liquid interface and the adsorption capacity of proteins at the oil–water interface [ 28 ]. However, excessive processing (7.5 kV/cm 50 pulses) will destroy this stable structure and reduce the protein’s foaming and emulsifying properties [ 24 ].…”

“…The UV and intrinsic fluorescence spectra represented the tertiary structures of N-QPI and PEF-QPIs. The maximum absorption peaks of the UV spectra of tryptophan and tyrosine are usually at approximately 270 nm [ 28 ]. Figure 5 A shows that N-QPI had an absorption peak at 257 nm, while PEF-QPIs had no significant redshift or blueshift, but had different UV spectral absorption intensities.…”

“…The intrinsic fluorescence spectrum is one of the main features of the microenvironment information of fluorescent chromogenic groups in protein molecules (tyrosine and tryptophan). A wavelength of 290 nm was chosen as the excitation wavelength to determine the effect of PEF treatment on the tertiary structure of quinoa proteins [ 28 ]. Figure 5 C shows that the maximum emission wavelength (λ max ) of N-QPI was 340 nm, while the maximum emission wavelength of PEF-QPIs was slightly blueshifted at 340 nm, indicating that PEF treatment changed the tertiary structure of quinoa protein, and the tryptophan residues transferred to the hydrophobic region increased the average hydrophobicity of quinoa protein [ 27 ].…”

“…The UV spectrum measurement was based on the method described by Liu et al [ 28 ]. The N-QPI and PEF-QPIs (7.5 kV/cm 10, 30, 50 pulses) obtained in Section 2.2 and Section 2.3 were separately dissolved in deionized water (1 mg/mL) and stirred at 25 °C for 2 h, and the UV spectrum of 200–400 nm was measured by a UV–visible spectrophotometer (Agilent Technologies Co., Ltd., Shanghai, China).…”

“…The intrinsic fluorescence spectrum measurement was based on the method described by Liu et al [ 28 ]. The N-QPI and PEF-QPIs (7.5 kV/cm 10, 30, 50 pulses) obtained in Section 2.2 and Section 2.3 were separately dissolved in deionized water (1 mg/mL) and stirred at 25 °C for 2 h. The emission wavelength was in the range of 300–400 nm, and the excitation wavelength was 290 nm, as measured by a Fluorospectro Spectrometer (RF-5301 Shimadzu International Trading Co., Ltd., Shanghai, China).…”