Subcritical water extraction (SWE) of phenolics was investigated from marigold (Tagetes erecta L.) flower residues. The total phenolics content (TPC), total flavonoids content (TFC) and antioxidant capacities of extracts were determined, furthermore, antioxidant activities of individual compounds were evaluated with on-line HPLC–ABTS•+ system. The optimum SWE time was 45 min, solid-to-liquid ratio was 1:50, and the highest TPC and TFC were obtained at 220 °C respectively. The effect of SWE temperature on TPC and TFC was significant (p < 0.05), and TPC was ranged from 28.42 ± 0.94 to 124.27 ± 1.94 (mg GAE/g), and TFC ranged from 34.21 ± 0.36 to 133.22 ± 1.57 (mg GAE/g) between 80 and 220 °C. On-line HPLC–ABTS•+ profiles revealed that quercetagetin from SWE at 200 °C had nearly twofold radical scavenging activities than that by leaching extraction.

The aim of the present study was to examine the factors (pH, iron chelators, free radical scavengers) influencing the chemical stability of WPI-stabilized β-carotene emulsions and investigate the correlations between WPI oxidation and β-carotene degradation during the storage of emulsions. The pH of the emulsion had a significant influence on the stability of β-carotene, with rapid degradation in emulsions at low pH (3.0, 4.0) and relatively higher stability at high pH (6.0, 7.0). Addition of EDTA or α-tocopherol significantly increased the stability of β-carotene, exhibited a greater improvement at pH 7.0 compared to pH 4.0 and α-tocopherol was much more effective than EDTA. It revealed that both transition metals and free radicals induced β-carotene degradation, nevertheless free radicals were found to be the predominant mechanism of β-carotene degradation. WPI oxidation was measured by the loss of tryptophan fluorescence and increase in fluorescent protein oxidation products using fluorescence spectroscopy. The tryptophan fluorescence decreased in all samples during the storage and emulsions with more protein oxidation products exhibited greater β-carotene degradation rate, which confirmed that there existed a good correlation between the protein oxidation and β-carotene loss.

The aim of the present study was to investigate the impact of whey protein isolate (WPI)-beet pectin conjugation on the physical and chemical properties of oil-in-water emulsions incorporating beta-carotene within the oil droplets. Covalent coupling of WPI to beet pectin was achieved by dry heating of WPI-beet pectin mixtures of different weight ratios at 80, 90, 100 degrees C and 79% relative humidity for incubation times ranging from 1 to 9 h. It was confirmed by SDS-polyacrylamide gel electrophoresis that WPI covalently linked to beet pectin. The physical and chemical stability of beta-carotene emulsions was characterized by droplet size and distribution, transmission profiles using novel centrifugal sedimentation technique, microstructure and beta-carotene degradation during the storage. Compared with those stabilized by WPI alone and unheated WPI-beet pectin mixtures, beta-carotene emulsions stabilized by WPI-beet pectin conjugates had much smaller droplet sizes, more homogenous droplet size distribution, less change in centrifugal transmission profiles and obviously improved freeze-thaw stability, indicating a very substantial improvement in the physical stability. Rheological analysis exhibited that emulsions stabilized by WPI-beet pectin conjugates changed from a shear thinning to more like Newtonian liquid compared those with WPI alone and unheated WPI-beet pectin mixtures. Degradation of beta-carotene in emulsion during storage was more obviously retarded by WPI-beet pectin conjugate than WPI and unheated WPI-beet pectin mixture, probably due to a thicker and denser interfacial layer in emulsion droplets. These results implied that protein-polysaccharide conjugates were able to improve the physical stability of beta-carotene emulsion and inhibit the deterioration of beta-carotene in oil-in-water emulsions. (C) 2012 Elsevier Ltd. All rights reserved.

The stability of the β-carotene emulsions coated with WPI-beet pectin conjugates prepared by dryheating for different reaction times were studied.Results showed that β-carotene emulsion stabilized with conjugate prepared at 80 ℃ for 5 h had small particle size and good stability.The stability of the conjugate coated β-carotene emulsion was not affected by heating,freeze-thawing,low pH and high salt concentration.

Previous works showed that the limonoids had many kinds of biological functions,such as anticancer,anti-inflammatory,antioxidant,insect resistance and regulation of blood sugar level.Therefore,more and more attention paid to their investigation.This paper summarized the extraction,purification,analysis and bioactivity of the limonoids.

In this paper, the effect of supercritical carbon dioxide (SC-CO2) treatment on the structure and conformation of whey protein isolate (WPI) were investigated. The WPI solution treated with SC-CO2 at 20 MPa and 3060 C for 1 h showed that its turbidity and particle size were increased. The effect of SC-CO2 treatment at 60 degrees C on the fluorescence intensity of WPI was elevated indicating partial denaturation of its fractions and exposure of more hydrophobic regions. The secondary structure change of SC-CO2 treated WPI revealed a decrease in the a-helix content, hydrogen bonds and an increase in the amount of beta-sheet. A high shift of endothermic peak after SC-CO2 treatment was observed by the thermal analysis of WPI. These results confirmed that the structure and conformation of protein were modified with SC-CO2 treatment.Industrial relevance: There is a strong interest in the food industry in studying the modifying protein functionality to produce higher quality products. Supercritical carbon dioxide (SC-CO2) treatment described as green method has raised interests in its application for polymer modification. SC-CO2 is a unique processing method offering many advantages over conventional thermal processing methods, including the ability to retain the quality of food, which may be lost during conventional thermal processing. This work explores the SC-CO2 effect on the structural and conformational modification of protein which would be extremely helpful in understanding the improving of the protein functionalities such as, emulsifying and rheological properties in order to produce higher quality food products. (C) 2010 Elsevier Ltd. All rights reserved.

In order to elucidate the micro-configuration and mechanism of anticancer activity of Fe(II)-PYM complex in solution, the coordination of high spin paramagnetic ferrous ion, Fe(II), and Pingyangmycin, (PYM) was studied in D2O solution by using the paramagnetic ion probe principle and PMR technique and compared with the inactive complexes, e.g., Cu(II)-PYM and Fe(III)-PYM. The basic configuration parameter of the complexes were determined. When the pyrimidine methyl proton was close to the central ion, 6.5 x 10(-10) m was taken as standard, the absolute distance between the central ion and other protons or ligand could be calculated. Results showed that, in Fe(III) solution, the proton of pyrimidine methyl and the terminal acyl group of the sugar moiety were closer to the central ion, but other protons were relaxed and the distance was between 7.0 x 10(-10) m and 15 x 10(-10) m. In the case of Fe(II) complex, the distance of the central ion and the ligand group was between 4.91 x 10(-10) m and 8.85 x 10(-10) m. The distinctive structure diversity with those of inactive complexes was observed and the relationship of the activity mechanism was postulated.