Yibin Zhou

Characterization, antioxidant activity and immunomodulatory activity of polysaccharides from the swollen culms of Zizania latifolia.

The swollen culms of Zizania latifolia have been used as a vegetable and traditional herbal medicine in China, Japan, Korea and Southeast Asia countries. Up to date, there is little information about the polysaccharides from the swollen culms of Zizania latifolia and their potential bioactivities. In the present study, water extractable polysaccharide (ZLPs-W) and alkali extractable polysaccharide (ZLPs-A) was sequentially prepared from the swollen culms of Zizania latifolia. Both of ZLPs-W and ZLPs-A was found to be non-starch polydisperse heterpolysaccharide with β-type glycosidic linkage. ZLPs-W with triple helix conformation mainly composed of GalA, Glc and Gal. ZLPs-A without triple helix conformation mainly composed of Glc, Gal, Xyl and Ara. In in vitro antioxidant assay, ZLPs-W and ZLPs-A exhibited good scavenging activities. The EC50 of DPPH radical, superoxide radical and hydroxy radical scavenging activities for ZLPs-A is 1.87, 1.13 and 0.38mg/mL compared with that for ZLPs-W is 2.95, 3.99 and 0.5mg/mL, respectively. Moreover, in vitro cell assay revealed that ZLPs-W without cytotoxicity has higher immunomodulatory activity than ZLPs-A in terms of stimulation of phagocytic ability and NO production in murine macrophage RAW 264.7. At the treated concentration of 400μg/mL and 100μg/mL, ZLPs-W induced a highest phagocytosis index (1.76) and NO product (29.12μmol/L), respectively. The results suggest that polysaccharide from the swollen culms of Zizania latifolia could be explored as potential natural antioxidant and immunomodulatory agents in medicine or functional food fields.

Encapsulation of epigallocatechin gallate in zein/chitosan nanoparticles for controlled applications in food systems

The objective of this study was to prepare chitosan nanoparticles (CS NPs) coated with zein as a promising encapsulation and delivery system for epigallocatechin gallate (EGCG). The factors influencing the nanoparticle fabrication, including zein concentration, zein/chitosan weight ratio and EGCG encapsulation percentage, were systematically investigated. The physicochemical and structural analysis showed that the electrostatic interactions and hydrogen bonds were the major forces responsible for nanoparticles formation. The transmission electron microscopy study revealed the spherical nature with smooth surface of obtained nanoparticles. The release profile of EGCG showed a burst effect, followed by slow release. EGCG release was relatively higher from zein/chitosan nanoparticles (zein/CS NPs) with higher DPPH scavenging activity, than that of NPs without zein coating in 95% ethanol fatty simulant. These results indicated that controlled-release of EGCG from zein/CS NPs and its corresponding antioxidant activities in 95% ethanol fatty simulant may provide long-term protection against oxidation for fatty foods.

Physicochemical, mechanical and thermal properties of chitosan films with and without sorbitol.

The effect of sorbitol on the physicochemical, mechanical and thermal properties of chitosan films with different degrees of deacetylation (DD; i.e., DD85% and DD95%) was investigated. The thickness, moisture content (MC), water solubility (WS) and water-vapor permeability (WVP) of the films were evaluated. Sorbitol addition reduced MC, increased WS and significantly (p<0.01) reduced WVP of both film types. DD95% films had lower MC and WVP, and higher WS than DD85% films. Static (thermomechanical analysis) and dynamic (dynamic mechanical analysis) tests indicated that sorbitol increased the strain and decreased stress for both DD films, but DD95% could sustain higher strain and DD85% could sustain higher stress. Thermogravimetrics analysis and differential scanning calorimetry showed that sorbitol elicited a lower degradation temperature for both films, and that DD95% films exhibited higher thermal stability than DD85% films.

Purification, characterization and immunomodulatory activity of water extractable polysaccharides from the swollen culms of Zizania latifolia

The swollen culms of Zizania latifolia is a popular vegetable and traditional herbal medicine mainly consumed in some Asian countries. In our previous study, water extractable polysaccharide (ZLPs-W) and alkali extractable polysaccharide (ZLPs-A) was sequentially prepared from the swollen culms of Zizania latifolia. In vitro cell assay revealed that ZLPs-W without cytotoxicity had higher immunomodulatory activity than ZLPs-A. Therefore, in this study, ZLPs-W was further separated to three purified polysaccharides of ZLPs-W1, ZLPs-W2, and ZLPs-W3 by anion exchange chromatography and size exclusive chromatography in sequence. They were found to be homogeneous polysaccharides in β-type glycosidic linkage. ZLPs-W1 and ZLPs-W2 without triple helix conformation mainly contained Glc in molar percentage of 96.47% and 85.1%, respectively. ZLPs-W3 with triple helix conformation mainly consisted of Man, Rha, GalA, Glc, Gal and Ara in the molar ratio of 10.23:14.14:37.44:17.14:16.54:4.51. In addition, all the three purified polysaccharides could effectively enhanced the proliferation, phagocytosis, and nitric oxide production of murine macrophage RAW 264.7, suggesting that they possessed a potent immunostimulatory activity and could be developed as immunomodulator in medicine or functional food areas.

Preparation and structural characterization of corn starch–aroma compound inclusion complexes

BACKGROUND Six corn starch inclusion complexes were synthesized using small nonpolar or weak polar aroma compounds (heptanolide, carvone and menthone) and small polar aroma compounds (linalool, heptanol and menthol). The objectives of this study were to (a) investigate the ability of corn starch to form inclusion complexes with these aroma compounds and (b) characterize the structure of the corn starch inclusion complexes. RESULTS The resulting inclusion ratios were 75.6, 36.9, 43.8, 91.9, 67.2 and 54.7% for heptanolide, carvone, menthone, linalool, heptanol and menthol respectively. The inclusion complexes had laminated structures with a certain amount of holes or blocky constructions. Compared with gelatinized corn starch, the transition temperatures, peak temperatures and enthalpies of the inclusion complexes were significantly different. The major peak of CO at 1771 cm-1 and significant peak shifts revealed the formation of inclusion complexes. X-ray diffractometry (XRD) analyses revealed that the crystallinity of corn starch-polar aroma compound inclusion complexes increased. Based on cross-polarization magic angle spinning 13 C nuclear magnetic resonance (CP-MAS 13 C NMR) results, novel peaks and chemical shifts were attributed to the presence of small aroma compounds, thereby confirming the formation of corn starch inclusion complexes. CONCLUSION Small nonpolar and polar aroma compounds can be complexed to corn starch.

Preparation, release and physicochemical characterisation of ethyl butyrate and hexanal inclusion complexes with β- and γ-cyclodextrin

Abstract Complexes of ethyl butyrate and hexanal encapsulated by β-cyclodextrin (β-CD) and γ-cyclodextrin (γ-CD) were prepared by coprecipitation, and gas chromatography was used to quantity the flavour compounds in the complexes. The ethyl butyrate–γ-CD complex had the highest inclusion ratio (12.20%) followed by the ethyl butyrate-β-CD, hexanal-β-CD and hexanal-γ-CD complexes (11.29, 4.41 and 3.33%, respectively). Release experiments were performed under different relative humidities (RH 93, 75 and 52%) and temperatures (4 and 25 °C). The flavour release behaviours of the complexes were described by the Avrami equation. The rate of flavour release was enhanced with both increasing temperature and RH, although the effect of RH was stronger. Physicochemical characterisation using FT-IR, XRD, DSC and SEM analyses demonstrated that crystalline complexes were formed. Both β-CD and γ-CD were able to encapsulate ethyl butyrate and hexanal, and lower RH and temperature were more suitable for the storage of these complexes.

Nutrient composition and starch characteristics of Quercus glandulifera Bl. seeds from China

The chemical composition and starch characteristics of acorn (Quercus glandulifera Bl.) were studied. The moisture content of acorn seeds was 7.55%. The crude fat, crude protein, dietary fiber, total ash, and nitrogen-free extract contents of acorn seed were 4.20%, 10.16%, 2.95%, 0.03%, and 82.66%, respectively, on a dry weight basis. Linoleic, oleic, and palmitic were the most predominant fatty acids. UFA:SFA and SFA:MUFA:PUFA ratios were 2.6:1 and 1.25:1.34:1, respectively. The essential amino acid content from acorn seeds was low based on FAO reference values. Acorn seeds were a good source of Fe, Zn, and Mn. The contents of vitamins A and E were 1.40 mg RE/100g and 10.78 mg/100 g, respectively. Starch extracted from acorn seeds had round, triangle, and elliptical morphology with granule size of 3.3-126.2 μm. The ratio between amylose and amylopectin contents was 25.39:72.94. Acorn starch had a typical A-type crystal pattern with 23.53% relative crystallinity. The gelatinization temperature was 66.53 °C and the transition enthalpy was 4.33 J/g.

Anti-hyperlipidaemic and hepatoprotective properties of wheat bran of different particle size: Anti-hyperlipidaemic and hepatoprotective properties of wheat bran of different particle size

BACKGROUND Wheat bran has been shown to have health-promoting benefits in relation to diabetes, colorectal cancer, cardiovascular disease, constipation, irritable bowel syndrome, diverticulitis, and gastrointestinal disease. However, its effects on obesity, hyperglycemia, hepatotoxicity, and hyperlipidemia are not yet clear. The effects of the consumption of wheat bran of different particle sizes (coarse, 427.55 µm versus ultra-fine, 11.63 µm) on body weight, serum glucose, liver, and blood lipid metabolism levels in high-fat-diet induced rats fed for 5 weeks were investigated. RESULTS The high-fat diet significantly increased body weight, serum glucose, serum and liver lipids, and malondialdehyde levels. However, addition of coarse and ultra-fine wheat bran to a high-fat diet decreased weight gain, reduced the levels of serum and liver total cholesterol, triglycerides, malondialdehyde, serum low-density lipoprotein, and serum glucose, and improved serum high-density lipoprotein. Moreover, when two particle sizes were compared, the highest impact was exhibited by the wheat bran containing the larger particle size. CONCLUSIONS The results suggest that micronized wheat bran significantly improves anti-hyperlipidemic and hepatoprotective properties that might provide a safeguard to protect humans against metabolic syndrome abnormalities and other acute, recurrent, or chronic diseases.

Effects of particle size on physiochemical and in vitro digestion properties of durum wheat bran

In order to promote the potential health benefits of high fibre products, wheat bran is the main focus of the food industry. The physiochemical and in vitro digestion properties of wheat bran containing different particle size were investigated and compared against raw bran samples. Firstly, the bran sample containing superfine particles (11.63 lm) was hydrolyzed by the a-amylase, pepsin, and pancreatin enzymes separately using a single factor and orthogonal test. Secondly, optimized hydrolysis parameters of superfine particles were employed to measure in vitro digestibility of macronutrients in raw, coarse, medium, and superfine bran particles. The maximum degree of hydrolysis obtained via a-Amylase (concentration 10 mg mL , pH 6.6, and time 12.5 min) was 55.71%; pepsin (concentration 50 mg mL , pH 1.2, and time 9 h) was 82.10%; and pancreatin (concentration 100 mg mL , pH 7.0 and time 12 h) was 84.71%, respectively. The highest in vitro digestibility rate of reducing sugar, protein, fat, and soluble fibre content was observed in superfine bran samples to 33.4%, 82.55%, 91.53%, and 21.66%, respectively.

Composition, structure and physicochemical properties of three coloured potato starches

Composition, structure and physicochemical properties of starch from redand purple-fleshed potatoes were investigated and compared to those of typical yellow-fleshed potatoes. The starch from yellow has highest amylose (25.23%) content, following by purple (23.30%) and red (20.26%). The growth ring of the three starches differed, but granule morphology was largely similar. Each potato starch exhibited B-type crystalline patterns, with crystallinity ranging from 20.33% to 22.25%. The molecular weights and z-average radius of gyration exhibited significant difference among the three starch samples. The branch chain length distribution showed that purple potato starch had highest population of A chains and lowest population of B1 chains. Moreover, the pasting properties of the three samples differed remarkably. The purple (90.92%) and red (86.41%) potato starches presented extremely good light transmittance compared with the yellow potato starch (34.03%). Dynamic rheological analysis showed that all samples possessed a weak elastic gel-like structure.