Joint effects of enzymatic and high-intensity ultrasonic on the emulsifying propertiesof egg yolk.

This study investigated the joint effect of the enzymatic and high-intensity ultrasonic (HIU) treatments on the emulsifying and structural properties of egg yolk (EY). The evaluation was performed under different HIU powers (i.e., 0, 240, and 480 W) and for different durations (10, 20, and 30 min). Results reveal that the emulsification activity and emulsification capacity at 240 W for 10 min significantly increase than that of the samples without HIU treatment (P < 0.05). The thermal stability reached a maximum of 90.33% in 480 W + 30 min. The HIU treatment under low power and for a short time (240 W + 10 min) reduced the average particle size of the EY to 224.77 nm. The combined treatment produced high zeta potential and total sulfhydryl contents. The highest hydrophobicity was 111.49 µg at 240 W for 20 min. The joint treatment enhanced the hardness and cohesiveness of the EY. Moreover, the α-helix content significantly decreased from 37.13% to 25.02% after the enzymatic treatment, while the ß-sheet content increased with time in the 240 W treatment. The G' and G″ curves show an increasing tendency, and the highest G' and G″ were obtained in the 240 W + 30 min group, which is consistent with the dense microstructure. These results reveal that the combined treatment can improve the emulsifying characteristics, which could influence the structural properties of EY, expanding its application in the food industry.

Exogenous glycine inhibits root elongation and reduces nitrate-N uptake in pak choi (Brassica campestris ssp. Chinensis L.).

Nitrogen (N) supply, including NO3--N and organic N in the form of amino acids can influence the morphological attributes of plants. For example, amino acids contribute to plant nutrition; however, the effects of exogenous amino acids on NO3--N uptake and root morphology have received little attention. In this study, we evaluated the effects of exogenous glycine (Gly) on root growth and NO3--N uptake in pak choi (Brassica campestris ssp. Chinensis L.). Addition of Gly to NO3--N agar medium or hydroponic solution significantly decreased pak choi seedling root length; these effects of Gly on root morphology were not attributed to the proportion of N supply derived from Gly. When pak choi seedlings were exposed to mixtures of Gly and NO3--N in hydroponic culture, Gly significantly reduced 15NO3--N uptake but significantly increased the number of root tips per unit root length, root activity and 15NO3--N uptake rate per unit root length. In addition, 15N-Gly was taken up into the plants. In contrast to absorbed NO3--N, which was mostly transported to the shoots, a larger proportion of absorbed Gly was retained in the roots. Exogenous Gly enhanced root 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and oxidase (ACO) activities and ethylene production. The ethylene antagonists aminoethoxyvinylglycine (0.5 µM AVG) and silver nitrate (10 µM AgNO3) partly reversed Gly-induced inhibition of primary root elongation on agar plates and increased the NO3--N uptake rate under hydroponic conditions, indicating exogenous Gly exerts these effects at least partly by enhancing ethylene production in roots. These findings suggest Gly substantially affects root morphology and N uptake and provide new information on the specific responses elicited by organic N sources.