Jianwei Mao

Stability and encapsulation efficiency of sulforaphane microencapsulated by spray drying.

Sulforaphane (SF) has received much attention because of its anticarcinogenic, antioxidant and anti-inflammatory properties, but it is quite unstable. Microencapsulation is one way to improve its stability. The aim of this work was to produce microcapsules containing sulforaphane using a spray drying technique. The effects of different wall materials, inlet air temperature and core to wall ratio on the SF stability, encapsulation efficiency, encapsulation yield, moisture content and SF content were determined. The results indicated that optimal encapsulation conditions for SF were: maltodextrin for the wall material, 170 °C for the inlet air temperature and 1:20 for the core/wall ratio. Characterization study showed that the microcapsules had a regular spherical shape. The stability of SF in spray dried microcapsules was greatly enhanced compared with that of free SF.

Effect of quaternization degree on physiochemical and biological activities of chitosan from squid pens.

Chitosan was prepared by alkaline N-deacetylation of β-chitin from squid pens, and N-(2-hydroxy) propyl-3-trimethyl ammonium chitosan chloride (HTCC) derivatives, with different degrees of quaternization (DQ) ranging from 0.77 to 1.06, were synthesized. It was identified by FT-IR, 1H NMR and XRD analysis. All of the HTCC showed good water solubility in a wide pH range. The moisture absorption and retention abilities of all the HTCC were much better than that of the chitosan. The moisture absorption and retention values of all the HTCC at 43% RH for 24 h were above 49% and 92%, respectively. The scavenging ability of HTCC against hydroxyl and ABTS radicals improved with increasing concentration. The effectiveness of HTCC against hydroxyl radicals was lower than that of chitosan. These results indicated that HTCC, which has a much better moisture absorption and retention capacity, may act as a potential moisturizer in vitro.

Biochemical activities of 6-carboxy β-chitin derived from squid pens

TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical)-mediated 6-carboxy β-chitin derivatives (T-chitin) with different carboxylate content were successfully synthesized by controlling the addition level of NaClO as the primary oxidant. The structural and biochemical properties of the derivatives were investigated. The carboxylate contents of the derivatives calculated by electrical conductivity titration were 1.33, 1.68, 1.80, and 2.08 mmol/g, respectively. The yield of T-chitin with carboxylate content of 2.08 mmol/g reached 74.55%. T-chitin exhibited stronger bile acid binding capacities than that of β-chitin. The scavenging ability of T-chitin against hydroxyl radicals improved with increasing concentration, and EC(50) values were below 1.2 mg/mL. All T-chitin exhibited a strong ferrous ion chelating effect. At 8 mg/mL, the chelating effects of T-chitin with carboxylate content of 0.81 mmol/g reached 80.15%. These results showed that T-chitin had good bile acid binding capacity and antioxidant activities and it may be a potential antioxidant in vitro.

Optimization of total polysaccharide extraction from Herba Lophatheri using RSM and antioxidant activities

Effects of extraction temperature, extraction time and ratio of water to material as well as their interactions on the yield of total polysaccharide from Herba lophatheri were studied by response surface methodology (RSM). The optimal conditions for the extraction of polysaccharides were determined to be the ratio of liquid to solid of 39.01, extraction time of 2.11h and extraction temperature of 97.09°C. Under these optimal conditions, the yield of polysaccharides obtained was 5.73±0.10%, which was well matched with the value predicted by the model. In vitro antioxidant assays showed that the polysaccharides HLP possessed significant inhibitory effects on superoxide radical. It also exhibited strong 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities, hydroxyl radical scavenging activities and its reducing power, ferrous ions chelating effect was also strong. These results suggested that H. lophatheri polysaccharides could be a suitable natural antioxidant and may be the functional foods for humans.

Preparation, Characterization, and Biochemical Activities of N-(2-Carboxyethyl)chitosan from Squid Pens

Chitosan was prepared by alkaline N-deacetylation of β-chitin from squid pens, and N-carboxyethylated derivatives (N-CECS) with different degrees of substitution (DS) were synthesized. The carboxyethylation of the polysaccharide was identified by Fourier transform infrared, (1)H and (13)C nuclear magnetic resonance (NMR), and X-ray diffraction analyses. The DS of the derivatives was calculated by (1)H NMR and elemental analysis. All three N-CECS samples showed good water solubility at pH > 6.5. The antioxidant properties and bile acid binding capacity of the derivatives were studied in vitro. The highest bile acid binding capacity of all N-CECS reached 36.9 mg/g, which was 2.6-fold higher than that of chitosan. N-CECS showed a stronger scavenging effect on 2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) radical ability, and EC50 values were below 2 mg/mL. The scavenging ability of N-CECS against superoxide radicals correlated well with the DS and concentration of N-CECS. These results indicated that N-carboxyethylation is a possible approach to prepare chitosan derivatives with desirable in vitro biochemical properties.

Study on degradation kinetics of sulforaphane in broccoli extract.

The objective of this study was to investigate the thermal degradation kinetics of sulforaphane (SF) in broccoli extract at selected temperatures (60, 75, 82 and 100°C) and pH values (2.2, 3.0, 4.0, 5.0 and 6.0). The results indicated that SF is unstable at high temperatures, but is more heat-stable when present in acidic food products. The degradation rate constants of SF in broccoli extract were lower than those obtained in purified SF. The thermal degradation of SF followed first-order reaction kinetics, and the rate constant increased with increase of temperature and pH values. The rate constant vs temperature relationships, which yield linear Arrhenius plots, were described by a simpler exponential equation, and a mathematical model was developed, using the steady-state kinetic parameters obtained to predict the retentions of SF at various pH values, heating times and temperatures.

Effect of carboxyethylation degree on the adsorption capacity of Cu(II) by N-(2-carboxyethyl)chitosan from squid pens

Chitosan was prepared by N-deacetylation of squid pens β-chitin, and N-carboxyethylated chitosan (N-CECS) with different degrees of substitution (DS) were synthesized. DS values of N-CECS derivatives calculated by (1)H nuclear magnetic resonance (NMR) spectroscopy were 0.60, 1.02 and 1.46, respectively. The adsorption capacity of Cu(II) by N-CECS correlated well with the DS and pH ranging from 3.2 to 5.8. The maximum Cu(II) adsorption capacity (qm) of all three N-CECS at pH 5.4 was 207.5mg g(-1), which was 1.4-fold higher than that of chitosan. The adsorption equilibrium process was better described by the Langmuir than Freundlich isotherm model. Adsorption of Cu(II) ion onto N-CECS followed a pseudo-second order mechanism with chemisorption as the rate-limiting step. In a ternary adsorption system, the adsorption capacity of Cu(II) by N-CECS also presented high values, and qm for Cu(II), Cd(II), and Pb(II) were 150.2, 28.8, and 187.9mg g(-1), respectively.

Effects of hydroxypropyl degree on physiochemical activities of chitosan from squid pens.

Chitosan was prepared by alkaline N-deacetylation of β-chitin and hydroxypropyl derivatives with different degrees of substitution (DS) were synthesized. It was characterized by Fourier transform infrared (FT-IR) and elemental analysis. The DS of hydroxypropyl chitosan (HPCS) calculated by an element analyzer were 0.42, 0.75, 1.20, 1.82 and 2.25. HPCS showed better foam capacity and stability than that of chitosan, and the effectiveness correlated well with the DS of HPCS. The highest bile acid-binding capacity of all five HPCS reached 56.02 mg/g, which was 4.0-fold higher than that of chitosan. The scavenging ability of HPCS against hydroxyl and ABTS radicals improved with increasing concentration. The correlation between the hydroxypropyl content (DS) of HPCS and scavenging ABTS radical ability was positive. The hydroxyl radicals scavenging activity of HPCS correlated well with its increasing concentration, and EC50 values were below 12.5 mg/mL. These results indicated that hydroxypropylation is a possible approach to obtain chitosan derivatives with desirable physiochemical properties.

Hydrolysis before Stir-Frying Increases the Isothiocyanate Content of Broccoli

Broccoli is found to be a good source of glucosinolates, which can be hydrolyzed by endogenous myrosinase to obtain chemopreventive isothiocyanates (ITCs); among them, sulforaphane (SF) is the most important agent. Studies have shown that cooking greatly affects the levels of SF and total ITCs in broccoli. However, the stability of these compounds during cooking has been infrequently examined. In this study, we proved that the half-lives of SF and total ITCs during stir-frying were 7.7 and 5.9 min, respectively, while the myrosinase activity decreased by 80% after stir-frying for 3 min; SF and total ITCs were more stable than myrosinase. Thus, the contents of SF and total ITCs decreased during stir-frying largely because myrosinase was destroyed. Subsequently, it was confirmed that compared to direct stir-frying, hydrolysis of glucosinolates in broccoli for 90 min followed by stir-frying increased the SF and total ITC concentration by 2.8 and 2.6 times, respectively. This method provides large quantities of beneficial ITCs even after cooking.

A sequential separation of linderane and norisoboldine using supercritical fluid and ionic liquid-based ultrasonic-assisted extraction from Lindera aggregate

ABSTRACT Linderane (LDR) and norisoboldine (NOR) are two typical active compounds in Lindera aggregate (Sims.) Kosterm. In this study, a new method of sequential extraction of LDR and NOR from L. aggregate was developed by supercritical fluid extraction (SFE) and ionic liquid-based ultrasonic-assisted extraction (IL-UAE) for the first time. The suitable SFE with CO2 conditions for LDR were 60 min dynamic extraction time, 40°C temperature and 30 MPa pressure. And the optimal IL-UAE factors for NOR were 2.06 mol/L 1-butyl-3-methylimidazolium bromide ([Bmim] Br) aqueous solution, 44 mL/g liquid–solid ratio, and 67 min ultrasonic time. Compared with the traditional extraction process, the sequential methods not only can obtain higher extraction efficiency, but also can realize the selective extraction for two different kinds of constituents with less consumption of traditional organic solvent. In addition, this environmentally friendly method could be used in a large-scale industry.