A novel method for the microencapsulation of curcumin by high-pressure processing for enhancing the stability and preservation.

Curcumin is used for the development of new pharmaceutical and food products, but its application is generally hindered by the poor solubility of curcumin and thermal instability during storage and processing. In this study, the liposomes of curcumin (cur-liposomes) were prepared by a novel combination of ethanol injection and high-pressure processing (HPP) to enhance the stability and preservation of curcumin. The pasteurization, mean particle size, size distribution, and encapsulation efficiency of cur-liposomes and the kinetics of their thermal degradation were also investigated in this research. From the results, the kinetic rate constants of curcumin in samples of free curcumin and cur-liposome at 25 °C were found to be 1.6 × 10-3 and 0.8 × 10-3 min-1, respectively. The phospholipid bilayer structure could protect curcumin. The results propose that the HPP method for liposome preparation is superior to the probe-sonication method in terms of stability, encapsulation efficiency, and homogeneity. Furthermore, the preparation of cur-liposomes by HPP with a hydrostatic pressure of 200 MPa could maintain the optimal particle size (206.4 nm) and polydispersity index (0.19). Conclusively, the combination of ethanol injection and HPP can not only successfully inactivate the microorganisms during liposome preparation for microencapsulation of bioactive compounds but also effectively preventthe thermal degradation of heat-sensitive substances in non-thermal processing for practical applications.

[Mechanism of reduced insecticidal protein expression in Bt cotton under high temperature and drought based on proteomics.] / 基于蛋白质组学的高温干旱下Bt棉杀虫蛋白表达下降机制.

To provide theoretical basis for the safety of insecticidal efficiency in Bt cotton, the effects of high temperature and drought stress on insecticidal protein expression and protein diffe-rently expression profile was studied. In this study, the Bt cotton cultivar Sikang 3 was used as expe-rimental material, with two treatments (40% field capacity and 38 ℃, HD, and 60% field capacity and 32 ℃, CK). Differences in proteomics of Bt cotton between HD and CK were compared using label-free quantitative proteomics technology. The results showed that high temperature and drought caused a significant reduction of insecticidal protein content in bolls, with a decrease of 38.2 ng·g-1 FM. The analysis of differential protein expression by label-free quantitative proteomic approach showed that 83 proteins were significantly up-regulated, but 104 proteins were significantly down-regulated in HD stressed cotton plants compared with CK. 122 new proteins were detected and 167 proteins expression was not observed under stressed conditions. Results from the enrichment analysis of differently expressed protein between two treatments showed that 14 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways were affected under stress. Three KEGG pathways were related to the Bt protein synthesis and degradation: carbohydrate digestion and absorption pathway, protein export pathway, and protein processing in endoplasmic reticulum pathway. In the carbohydrate digestion and absorption pathway, the starch hydrolysis ability of HD treated cotton plants increased, while the ability to phosphorylate the hexoses, fructose and glucose decreased. In protein export pathway, the peptide synthesis in HD treatment was not significantly affected, while the process of transferring peptides into the endoplasmic reticulum was prohibited. In the protein processing in endoplasmic reticulum pathway, the ability of ubiquitin mediated proteolysis was increased in HD treatment.