A practical and fast isolation of 12 cyclolinopeptides (linusorbs) from flaxseed oil via preparative HPLC with phenyl-hexyl column.

Linusorbs, known as cyclolinopeptides, are a group of cyclic hydrophobic peptides derived from flaxseed oil with various health benefits. However, the current research efforts on both the biological activities and antioxidant capacities of linusorbs are limited because of existing issues with their purification and characterization. A practical method based on preparative HPLC for isolating 12 linusorbs simultaneously was developed and factors such as the solvent selection, gradient elution program, flow rate, loaded mass, and loading concentration, were optimized. The optimum conditions were an initial acetonitrile (ACN) to water ratio of 40%, final ACN ratio of 80%, eluting time of 21 min, a flow rate of 16 mL/min, sample load of 12.5 mg, and concentration of 80 mg/mL (in methanol). The 12 linusorbs obtained were verified using off-line MS/MS, recording purities of above 95.5%. The method could serve as a practical and fast isolation method enabling further investigation of minor linusorbs.

Fine structure, crystalline and physicochemical properties of waxy corn starch treated by ultrasound irradiation.

As a simple and effective physical method, ultrasound irradiation has been used to modify starch. Native waxy corn starch was treated by ultrasound irradiation at 100 and 400 W in this study. Compared with native waxy corn starch, lower proportion of B1, B2, and B3, higher proportion of A chain were observed in ultrasonicated waxy corn starch. 1H NMR combined with HPSEC-MALLS-RI data showed that lower degree of branching was observed in ultrasonicated waxy corn starch, and α-1,4 glycosidic linkages were more stable than α-1,6 glycosidic linkages in waxy corn starches. 13C NMR data indicated that the content of double helices was decreased, and single helix and amorphous components were increased after ultrasound irradiation. The A-type crystal structure was scarcely affected according to X-ray diffraction (XRD) analysis. The granule surface of ultrasonicated waxy corn starch became notch and rough fragment, and lower particle diameter was observed in ultrasonicated waxy corn starch. These results demonstrated that ultrasound irradiation affected chain length distribution, double helices, single helices and amorphous state, especially α-1,4 glycosidic linkages and α-1,6 glycosidic linkages, of waxy corn starch.

Fabrication and Characterization of Quinoa Protein Nanoparticle-Stabilized Food-Grade Pickering Emulsions with Ultrasound Treatment: Effect of Ionic Strength on the Freeze-Thaw Stability.

The development of multilayered interfacial engineering on the emulsion freeze-thaw properties has recently attracted widespread attention, because of the essential freeze-thaw storage process in some emulsion-matrix food products. In this research, we studied the role of salt concentration on the freeze-thaw properties of quinoa protein (QPI) nanoparticles-stabilized Pickering emulsions. The QPI nanoparticles (particle concentration c = 2%, w/v) with increasing particle size and surface hydrophobicity ( H0) were fabricated by ultrasound treatment at 100 W for 20 min, by varying the NaCl addition (salt concentrations, 0-500 mM). The sonicated QPI nanoparticles with increasing salt concentrations showed higher ß-sheet structure contents and stronger hydrophobic interactions, which were attributed to the decreasing charged groups and particle aggregation by electrostatic interactions. As compared to the sonicated QPI nanoparticles-stabilized Pickering emulsions ( c = 2%, oil fraction φ = 0.5) without salt accretion, the emulsions with salt accretion exhibited better freeze-thaw properties after three freeze-thaw circulations, which might be mainly caused by the generation of gel-like three-dimensional structure and multilayered network at the droplets' interface with smaller droplet sizes. Increasing the salt concentration progressively enhanced the freeze-thaw properties of sonicated QPI nanoparticles-stabilized Pickering emulsions probably due to the inhibit formation of ice crystal by the "salting-out" effects. The results of this study would provide great significance to investigate the role of salt concentration in the freeze-thaw properties of protein-stabilized Pickering emulsions.