The physical and structural properties of acid-Ca2+ induced casein-alginate/Ca2+ double network gels.

The design of protein or polysaccharide interpenetrating network gels according to their physicochemical properties is required to obtain the desired properties of hydrogels. In this study, a method was proposed to prepare casein-calcium alginate (CN-Alg/Ca2+) interpenetrating double-network gels by the release of calcium from a calcium retarder during acidification to form calcium-alginate (Alg/Ca2+) gel and casein (CN) acid gel. Compared with the casein-sodium alginate (CN-Alg) composite gel, the CN-Alg/Ca2+ dual gel network with an interpenetrating network gel structure has better water-holding capacity (WHC) and hardness. The rheology and microstructure results showed that the dual-network gels of CN and Alg/Ca2+ induced by gluconic acid-δ-sodium (GDL) and calcium ions were the network structure of the Alg/Ca2+ gel, which was the "first network", and the CN gel, which was the "second network". It was proven that the microstructure, texture characteristics, and WHC of the double-network gels could be regulated by changing the concentration of Alg in the double-network gels and that the 0.3 % CN-Alg/Ca2+ double gels showed the highest WHC and firmness values. The aim of this study was to provide useful information for the preparation of polysaccharide-protein mixed gels in the food industry or other fields.

Effect of salt penetration and water migration on cooked salted egg yolk gel during storage: Physicochemical properties, structural characteristics and flavor changes.

There is an urgent need to explore the salt penetration and water migration in the cooked salted egg yolk (CSEY) gel. The aim of this study was to investigate the effect of salt and water on the physicochemical, structural and flavor characteristics of CSEY gel stored at 25 °C. The hardness of the yolk increased significantly (608.0 g â†’ 2730.7 g) during storage. The results of LF-NMR showed that the free water content in the yolk gel was enhanced. The microstructure of CSEY could be observed by SEM, which showed that during storage, polyhedral particles were dispersed due to the heating process. In addition, ethyl acetate (71.9 %) was completely undetectable in the CSEY-21 d. In summary, the sample at and before 14 d of storage had good processing value. Therefore, this work would provide theoretical guidance for the low-sodium pickling of SEY (salted egg yolk) and its suitable storage methods.

Improvement of O/W emulsion performance by adjusting the interaction between gelatin and bacterial cellulose nanofibrils.

This study was designed to improve the stability of medium internal phase emulsion by adjusting the electrostatic interaction between gelatin (GLT) and TEMPO-oxidized bacterial cellulose nanofibrils (TOBC). The influences of polysaccharide-protein ratio (1:10, 1:5, and 1:2.5) and pH (3.0, 4.7, 7.0, and 11.0) on the emulsion properties were investigated. The droplet size of TOBC/GLT-stabilized emulsion was increased with the TOBC proportion increasing at pH 3.0-11.0. Additionally, emulsion had a larger droplet size at pH 4.7 (the electrical equivalence point pH of mixtures). However, the addition of TOBC significantly improved the emulsion stability. The emulsions prepared with TOBC/GLT mixtures (mixing ratio of 1:2.5) at pH 3.0-7.0 were stable without creaming during the storage. It was because the formation of nanofibrils network impeded the droplet mobility, and the emulsion viscosity and viscoelastic modulus were increased with the addition of TOBC. These findings were meaningful to modulate the physical properties of emulsions.

Preparation of magnetic molecularly imprinted polymers with double functional monomers for the extraction and detection of chloramphenicol in food.

In this study, an efficient, selective, and simple analytical method for the extraction of chloramphenicol (CAP) from food using magnetic molecularly imprinted polymers (MMIPs) as the solid-phase extraction (SPE) sorbent was successfully developed. MMIPs with varying ratios of methacrylic acid to acrylamide were prepared by suspension polymerization on the surface of double-bond-modified Fe3O4 magnetic nanoparticles. Further, these MMIPs were characterized by Fourier transform infrared spectroscopy and scanning electron microscopy, as well as using a vibrating sample magnetometer. Furthermore, the adsorption capacities of MMIPs and MNIPs were investigated by binding experiments. Methodology evaluation for the detection of CAP from food was carried out using MMIPs as the SPE sorbent. By using an external magnetic field, MMIPs were separated by a simple and rapid method. The diameter of the so-obtained MMIPs, exhibiting good monodispersity, was 400-700 nm. The MMIPs exhibited the maximum apparent adsorption capacity of up to 42.60 mg g-1 with good selectivity. For the detection of food samples, the linear response range was 0.02-10.00 mg L-1, with a detection limit of 10 µg L-1, and intra- and inter-day stabilities ranged from 1.34% to 1.89% and from 1.76% to 2.77%, respectively, with good recoveries (95.31%-106.89%) and satisfactory relative standard deviations (1.21%-2.60%).

Strong opto-electro-mechanical coupling in a silicon photonic crystal cavity.

We fabricate and characterize a microscale silicon opto-electromechanical system whose mechanical motion is coupled capacitively to an electrical circuit and optically via radiation pressure to a photonic crystal cavity. To achieve large electromechanical interaction strength, we implement an inverse shadow mask fabrication scheme which obtains capacitor gaps as small as 30 nm while maintaining a silicon surface quality necessary for minimizing optical loss. Using the sensitive optical read-out of the photonic crystal cavity, we characterize the linear and nonlinear capacitive coupling to the fundamental ω(m)/2π = 63 MHz in-plane flexural motion of the structure, showing that the large electromechanical coupling in such devices may be suitable for realizing efficient microwave-to-optical signal conversion.

Non-Markovian dynamics of a microcavity coupled to a waveguide in photonic crystals.

In this paper, the non-Markovian dynamics of a microcavity coupled to a waveguide in photonic crystals is studied based on a semi-finite tight binding model. Using the exact master equation, we solve analytically and numerically the general and exact solution of the non-Markovain dynamics for the cavity coupled to the waveguide in different coupling regime. A critical transition is revealed when the coupling increases between the cavity and the waveguide. In particular, the cavity field becomes dissipationless when the coupling strength goes beyond a critical value, as a manifestation of strong non-Markovian memory effect. The result also indicates that the cavity can maintain in a coherent state with arbitrary small number of photons when it strongly couples to the waveguide at very low temperature. These properties can be measured experimentally through the photon current flowing over the waveguide in photonic crystals.