Effects of cobalt-60 γ-ray irradiation on fresh-keeping and storage of kiwifruits

The boxes contained kiwifruits were irradiated with cobalt-60 γ-rays at different dosages (0.6 , 1.8 and 3.6 KGy) and stored in a room ventilated at night, the natural ambient air being used as cool source.The results showed that the treatment which fruits irradiated with 0.6 KGy was the best after 85 days. It gave the normal-fruit rate of 95.10%, fruit flesh hardness of 4.10 Kg · cm^-2, fresh and plump fruits, good quality and less Vc loss.     

Preparation and evaluation of a novel molecularly imprinted SPE monolithic capillary column for the determination of auramine O in shrimp

A novel method combining molecular imprinting and SPE was developed in a capillary column for the determination of auramine O in shrimp. The capillary monolithic column was prepared by UV‐initiated in situ polymerization, using auramine O as template and methacrylic acid and ethylene dimethacrylate as functional monomer and cross‐linker, respectively. The properties of the prepared capillary monolithic column were investigated under the optimized conditions coupled with HPLC, and then the morphologies of the inner polymers were characterized by SEM. The calibration curve was expressed as A = 103C + 19.8 (r = 0.9992) with a linear range of 0.25–25.0 μg/mL, and the recoveries of auramine O at different concentrations in shrimp ranged from 90.5 to 92.4% with RSDs ranging from 2.1 to 4.4%. The capacities of the molecularly imprinted polymer and nonimprinted polymer columns were 0.722 and 0.147 μg/mg, respectively, and the LOD (S/N = 3) of auramine O in shrimp was 17.85 μg/kg. Under the selected conditions, the enrichment factors obtained were higher than 70‐fold. The results indicate that the prepared molecularly imprinted capillary monolithic column was reliable and applicable to the analysis of auramine O in shrimp.     

反相高效液相色谱法测定对虾组织中噁喹酸残留

建立了测定对虾血淋巴、肌肉和肝胰腺等组织中噁喹酸含量的反相高效液相色谱法。采用乙腈提取对虾血淋巴、肌肉、肝胰腺和鳃组织中噁喹酸,色谱柱为Aglient Zorbax SB-C18柱(150×4.6mm,5μm),以乙腈-0.01mol·L-1四丁基溴化铵(磷酸调节pH为2.75)为流动相,流速1.0mL·min-1,荧光检测器检测。噁喹酸在0.002~10μg·mL-1范围内线性关系良好,相关系数R2=0.9996~0.9999。加标回收率为84.70%~90.60%,日内、日间精密度(RSD)分别为1.60%~4.02%、2.91%~4.73%,定量限分别为0.02μg·mL-1、0.01μg·g-1、0.02μg·g-1和0.02μg·g-1。该方法操作简单,重现性好,适用于对虾样品中噁喹酸含量的分析。     

A monoclonal antibody-based time-resolved fluoroimmunoassay for chloramphenicol in shrimp and chicken muscle

A time-resolved fluoroimmunoassay (TR-FIA) for determination of chloramphenicol (CAP) in shrimp and chicken muscle was developed. The method was based on a direct competitive immunoassay using europium-labeled anti-CAP monoclonal antibody (MAb) and CAP-ovalbumin as coated antigen. The limit of detection was 0.05 ng g⁻¹ and limit of quantification was 0.1 ng g⁻¹. Recoveries ranged from 101.2 to 112.5% for shrimp and 104.9 to 115.3% for chicken muscle at spiked levels of 0.1-5 ng g⁻¹, with intra-assay and inter-assay variations 8.7-14.6 and 9.6-17.8%, respectively. The results obtained by the TR-FIA and ELISA correlated well. The established TR-FIA was validated for the determination of incurred shrimp samples and confirmed by gas chromatography with microcell electron capture detector (GC-μECD).     

High-intensity ultrasound improved the physicochemical and gelling properties of Litopenaeus vannamei myofibrillar protein

The effects of high-intensity ultrasound on the physicochemical and gelling properties of Litopenaeus vannamei (L. vannamei) myofibrillar protein (MP) were investigated. MP solutions were subjected to ultrasound treatment (power 100 W, 300 W, and 500 W). It was found that the carbonyl and free amino contents of MP increased significantly with increasing ultrasound power, accompanied by enhanced emulsification properties. The increase of free radical and carbonyl content indicated that ultrasound induced the oxidation of MP. With the increase of ultrasound power, it was found that the total sulfhydryl content of the shrimp MP decreased, but the surface hydrophobicity increased significantly, which might be closely related to the conformational changes of MP. Meanwhile, a significant increase of β-sheet but a decrease of α-helix in the secondary structure of MP was observed with increasing ultrasound power, indicating that ultrasound treatment induced the stretching and flexibility of MP molecules. SDS-PAGE showed that L. vannamei MP consisted of myosin heavy chain, actin, myosin light chain, paramyosin and tropomyosin. Ultrasound treatment could lead to some degree of oxidative aggregation of MP. The results of rheological properties indicated that ultrasound treatment enhanced the viscoelasticity of MP and further improved the gel strength of MP gel. This study can provide a theoretical basis for the functional modification of shrimp MP and the processing of its surimi products.     

Effects of ultrasonic–microwave combination treatment on the physicochemical,structure and gel properties of myofibrillar protein in Penaeus vannamei (Litopenaeus vannamei) surimi

The objective of this study was to evaluate the effects of single ultrasound (360 W, 20 min), single microwave (10 W/g, 120 s) and ultrasonic–microwave combination treatment on shrimp surimi gel properties. The structure and physicochemical properties of myofibrillar protein (MP) were also determined. Low-field nuclear magnetic resonance showed that the fluidity of water molecules and the moisture content decreased, the stability and water holding capacity (WHC) increased after single ultrasound, single microwave and ultrasonic–microwave combination treatment. Compared with the traditional water bath treatment, ultrasound and microwave treatment reduced the total sulfhydryl content and promoted the formation of intermolecular disulfide bonds and hydrophobic interactions, which improved the compactness of the network structure of shrimp surimi gel. Moreover, Fourier transform infrared spectroscopy and sodium dodecyl sulfate–polyacrylamide gel electrophoresis analysis revealed that these treatments not only inhibited the degradation of MP, but also decreased the α-helix content and increased the β-sheet content. The three treatments also significantly reduced the particle size and decreased the solubility of MP. Overall, the effect of ultrasonic–microwave combination treatment was superior to that of either single treatment.     

The incarnate rhythm of geometrical knowing

Rhythm is a fundamental dimension of human nature at both biological and social levels. However, existing research literature has not sufficiently investigated its role in mathematical cognition and behavior. The purpose of this article is to bring the concept of “incarnate rhythm” into current discourses in the field of mathematical learning and knowing. Our study is part of a 2-year longitudinal project focused on theorizing the role of the body in elementary students’ mathematics. Drawing on an exemplary episode in which a group of third-graders were asked to classify three-dimensional objects, we illustrate how rhythmical patterns can emerge in dimensions such as beat gestures, body position, and object orientation. Based on a detailed microanalysis of the episode, which was selected among other structurally similar examples, we conclude that incarnate rhythm is an irreducible feature in the emergence of mathematical sense and the production of mathematical communication.     

Shellfish waste-derived mesoporous chitosan for impressive removal of arsenic(V) from aqueous solutions: A combined experimental and computational approach

Novel shellfish waste-derived chitosan (CS) has been developed to adsorb As(V) from simulated wastewater under evaluating adsorption process parameters. The coexistence of some competing ions, like SiO₃^2-, Cl^-, NO₃^– and PO₄^3- as well as the regeneration capacity of the spent adsorbent, was explored. The experimental data were modeled using several kinetics and isotherm models to understand the mechanism related to the uptake process. As(V) uptake was relatively rapid and highly dependent on pH. The Avrami-fractional-order expression supported data best, while the Liu equation described well isotherm data at pH 5.0. The maximum uptake capability (Liu) was 12.32 mg/g, and the highest removal performance (99 %) was obtained at optimum pH 5.0. Molecular dynamics simulations were performed to more clearly illuminate the atomic-level interactions between arsenic species and CS surface in both acidic and basic mediums. After four adsorption–desorption cycles, CS exhibited more than 90 % As(V) removal efficiency. The results of this study indicates that low cost shellfish derived chitosan is promising for efficient removal of As(V) from water body and can be used to remove other pollutants from watewater.     

Preparation of a novel biodegradable film by co-fermentation of straw and shrimp shell with Aureobasidium pullulans and Photobacterium sp. LYM-1

The green and high-value recycling of shrimp shell and straw remains a worldwide problem. This study aimed to investigate the potential utilization of a fermentation broth (FB) which contains shrimp shell and straw as a new source for preparation of biodegradable films. Aureobasidium pullulans and Photobacterium sp. LYM-1 were used in the fermentation. The cellulase activity was 115.92 U/mL and chitinase activity was 17.89 U/mL in FB. The polysaccharides concentration in FB was 1.05 mg/mL after 7 days of fermentation. An eco-friendly PVA-reinforced FB biodegradable film (FBBF) was successfully prepared and the effect of different plasticizers and surfactants on the mechanical, structural, and impermeability properties of the film was determined. The formation of new bonds between PVA and FB was proved by FTIR spectroscopy. The FBBF containing 0.25 % (w/v) glycerol and 0.01 % (v/v) tween-20 showed better strength properties. Elongation and water-swelling properties were highly improved by adding 0.2 % (m/v) citric acid. According to FE-SEM images, the smooth and tight surface of citric acid added FBBF was observed. Interestingly, the FBBF film showed good heat/moisture capacity, antifungal, and degradation properties. This report reveals a new green, and high-value recycling of straw and shrimp shell by the co-fermentation with A. pullulans and Photobacterium sp. LYM-1. It is also a novel way for the preparation of biodegradable film.     

高效液相色谱-荧光法测定对虾组织中红霉素的残留量

建立了高效液相色谱-荧光法测定对虾组织中红霉素残留量的检测方法。主要研究了样品前处理方法。提出了以乙腈为提取剂,正己烷去脂、二氯甲烷反萃的新的样品处理方式。该方法简单,灵敏度高,方法检出限为150μg／kg,回收率≥75％。