Xiuting Hu

Hybrid liposomes composed of amphiphilic chitosan and phospholipid: Preparation, stability and bioavailability as a carrier for curcumin

Hybrid liposomes, composed of amphiphilic chitosan and phospholipid, were prepared and used to evaluate the effect of amphiphilic polymers on the properties of liposomes. Successful preparation of the hybrid liposomes was confirmed using physicochemical characteristics, including morphology, particle size and zeta potential. Physical stability studies (exposure to solutions of increasing ionic strength and heat treatment) indicated that the hybrid liposomes had better ionic stability than amphiphilic chitosan-based polymeric liposomes and higher thermal stability than traditional phospholipid liposomes. Curcumin was then encapsulated in the hybrid liposomes. Compared with phospholipid liposomes, the hybrid liposomes displayed better storage stability and more sustained curcumin release. Cellular uptake experiments showed that the hybrid liposomes significantly increased the bioavailability of curcumin. The study highlights the potential of well-designed stable hybrid liposomes that increase the stability and bioavailability of lipophilic bioactive, such as curcumin.

Freeze-thaw stability of rice starch modified by Improved Extrusion Cooking Technology

This study aimed to explore freeze-thaw (FT) stability of rice starch modified by Improved Extrusion Cooking Technology (IECT). FT stability of IECT-modified rice starch was investigated and compared with native one. Syneresis and SEM analysis showed that IECT-modified rice starch had better FT stability than native starch. Furthermore, IECT-modified rice starch had less significant changes in the rheological parameters during the FT cycles than the native starch. XRD and iodine binding analysis demonstrated that IECT treatment inhibited the association of rice starch, especially amylose retrogradation. Additionally, the peak at around 20° was detected in XRD patterns of IECT-modified rice starch, which confirmed the formation of amylose-lipid complex during the IECT treatment. These results suggested that the IECT treatment could improve FT stability of rice starch, which was ascribed to inhibition of starch retrogradation by IECT.

Effect of endogenous proteins and lipids on starch digestibility in rice flour

The composition and structure of the food matrix can have a major impact on the digestion. The aim of this work was to investigate the effects of endogenous proteins and lipids on starch digestibility in rice flour, with an emphasis on establishing the underlying physicochemical mechanisms involved. Native long-grain indica rice flour and rice flour with the lipids and/or proteins removed were subjected to a simulated digestion in vitro. A significant increase in starch digestibility was observed after removal of proteins, lipids, or both. The starch digestibility of the rice flour without lipids was slightly lower than that without proteins, even though the proteins content was about 10-fold higher than the lipids content. Microstructural analysis suggested that the proteins and lipids were normally attached to the surfaces of the starch granules in the native rice flour, thus inhibiting their contact with digestive enzymes. Moreover, the proteins and lipids restricted the swelling of the starch granules, which may have decreased their digestion by reducing their surface areas. In addition, amylose-lipid complex was detected in the rice flour, which is also known to slow down starch digestion. These results have important implications for the design of foods with improved nutritional profiles.

Modification of the digestibility of extruded rice starch by enzyme treatment (β-amylolysis): An in vitro study

The rate and extent of starch hydrolysis in the digestive tract impacts blood glucose levels, which may influence an individuals susceptibility to diabetes and obesity. Strategies for decreasing starch digestibility are therefore useful for developing healthier foods. β-amylase is an exo-hydrolase that specifically cleaves α-1,4 glycosidic linkages of gelatinized starches. In this study, starch granules were disrupted by extrusion under different feed moisture conditions, and then subjected to β-amylolysis. The degree of starch gelatinization increased with increasing feed moisture content during extrusion, leading to faster β-amylolysis. The hydrolysis of in vitro starch digestion study was reduced for extruded samples treated with β-amylase, which was attributed to an increase in resistant starch (RS) after β-amylase treatment. Indeed, X-ray diffraction (XRD) indicated that the crystalline structure in the extruded starch was either partially or fully lost after β-amylase treatment. Similarly, Fourier transform infrared (FTIR) analysis indicated there was a higher level of amorphous regions in the starch after β-amylase treatment. Overall, our results suggest that enzymatic treatment of extruded starch with β-amylolysis reduces the ratio of crystalline-to-amorphous regions, which increases the level of resistant starch, thereby slowing down digestion. These results have important implications for the development of healthier starch-based foods.

Improvement in freeze-thaw stability of rice starch gel by inulin and its mechanism

Three types of inulin with different degree of polymerization (average DPu202f<u202f10, DPu202f≥u202f10, and DPu202f>u202f23) were used to improve the freeze-thaw stability of rice starch gel. The gels with or without addition of inulin were subjected to seven freeze-thaw cycles (FTC). Inulin enhanced the water holding capacity and reduced the amount of freezable water of the gels, thereby decreasing the syneresis of the gels during seven FTC. In addition, the amylose and amylopectin retrogradation of the gels were retarded. By adding inulin, the microstructure of gel network was stabilized, and the deterioration in viscoelastic properties of the gels during seven FTC was reversed. Therefore, inulin was an effective additive for preserving the quality of freeze-thawed rice starch gels. Furthermore, low DP inulin had higher water holding capacity than high DP one, as a result the inulin with lower DP was more effective.

Modification of potato starch by using superheated steam

Conventional hydrothermal modification of starches is a time- and energy-consuming process. In this study, superheated steam (SS) at different temperatures (100-160u202f℃) was used to modify the structural and physicochemical properties of potato starch (PS). The long- and short-range molecular structures were disrupted without affecting the granular structure of PS and the degree of disruption could be regulated by simply changing the treatment temperature. The swelling power, solubility, transparency, peak viscosity and breakdown of PS were positively correlated with each other and were significantly decreased by SS treatment, while the pasting temperature, final viscosity and setback were significantly increased. Considerable amount (>9%) of slowly digestible starch was converted to resistant starch by SS treatment at 100 and 120u202f°C. Considering the high thermal efficiency of SS and the short treatment time (1u202fh) used in this study, SS treatment could be a superior alternative to conventional hydrothermal modification.