逆χ^2分布下正态模型参数的后验分布及其抽样

当正态线性模型中的参数取逆χ^2先验分布时,得出了回归系数和误差方差的联合后验分布和边际后验分布,特别导出了回归系数二次型的分布。利用回归系数和误差方差联合后验分布的分解形式,给出了一种抽样方案。     

The Emulsifying Properties of Commercial Milk Protein Products in Simple Oil-in-Water Emulsions and in a Model Food System

ABSTRACT: The emulsifying properties of six commercial milk protein products were studied. The products were separated into one of two groups depending on whether they contained aggregated (micellar) casein or disordered protein (casein or whey protein). Disordered proteins had a greater emulsifying ability than aggregated proteins. Dispersion of aggregated protein in dissociating buffer improved the emulsifying ability. Comparison of emulsion properties in simple oil-in-water emulsions with those in a model coffee whitener formulation showed that the lower emulsifying ability of aggregated protein could be partially compensated by other ingredients.     

Multivariate Optimisation and Validation of a Method for the Separation of Five Artificial Sweeteners by UPLC-DAD in Nine Food Matrices

Food Analytical Methods - A new, fast and efficient method was developed for the separation and simultaneous quantification of acesulfame-K, aspartame, cyclamate, neotame and saccharin in food by...     

Near Infrared Transmission Spectra of Barley of Malting Grade Represent a Physical‐Chemical Fingerprint of the Sample That Is Able to Predict Germinative Vigour in a Multivariate Data Evaluation Model

The physiological and physical‐chemical basis of barley germination was studied. Vigour was defined as germination percentage after 24 h and viability as that of 72 h. The barley samples were analysed under germination capacity and energy conditions after harvest and after long time cold storage at 7°C three‐six years. These parameters were each correlated by Partial Least Squares Regression (PLSR) to two separate multivariate data sets: a set of ten physical‐chemical parameters and to Near Infrared Transmission (NIT) spectra (850–1050 nm). Surprisingly high correlation coefficients for each of these two data sets were obtained especially with vigour, extract (%) and β‐glucan in wort (mg/L) when outliers with viability below 92% were removed. Hard, slowly germinating seeds were more resistant to decay in vigour and viability storage than soft seeds. This change could be predicted by PLSR correlations to the two physical‐chemical multivariate methods. Vigour was a more sensitive indicator for the ability to store than viability. The steep criterion was also found to have a physical‐chemical basis. The results indicate that NIT calibrations can be used to predict vigour in malting grade barley.     

Multivariate Optimization for the Development of a Fast and Simple Ultrasound-Assisted Extraction Procedure for Multielemental Determination in Tea Leaves by Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES)

The current study describes a fast and efficient procedure of ultrasound-assisted extraction for determination of Ca, Mg, K, Na, Cu, Zn, Mn, and Al in tea leaves by inductively coupled plasma optical emission spectrometry (ICP OES). The variables of procedure were optimized using the Box–Behnken design and the conditions selected were nitric acid concentration (1.0 mol L^?1), sonication time (7 min), and sonication temperature (75 °C). The extraction efficiency was calculated using the analyte concentration obtained by a total digestion procedure as reference. Accuracy was confirmed by analysis of certified reference material of apple leaves (NIST 1515) and spinach leaves (NIST 1570a) using the procedure proposed. A statistical evaluation using Student’s t test showed that there is no significant difference between the value obtained with the proposed procedure and the certified value, at 95% confidence level. The proposed procedure was successfully applied and is a good alternative to conventional acid digestion procedure and can be applied to routine analysis for determination of Ca, Mg, K, Na, Zn, Mn, Cu, and Al in tea leaves used for the preparation of infusions.     

Simple and easy method to evaluate uptake potential of nanoparticles in mammalian cells using a flow cytometric light scatter analysis

Many classes of nanoparticles have been synthesized and widely applied, however, there is a serious lack of information concerning their effects on human health and the environment. Considering that their use will increase, accurate and cost-effective measurement techniques for characterizing "nanotoxicity" are required. One major toxicological concern is that nanoparticles are easily taken up in the human body. In this study, we developed a method of evaluating the uptake potential of nanosized particles using flow cytometric light scatter. Suspended titanium dioxide (TiO2) particles (5, 23, or 5000 nm) were added to Chinese hamster ovary cells. Observation by confocal laser scanning microscopy showed that the TiO2 particles easily moved to the cytoplasm of the cultured mammalian cells, not to the nucleus. The intensity of the side-scattered light revealed that the particles were taken up in the cells dose-, time-, and size-dependently. In addition, surface-coating of TiO2 particles changed the uptake into the cells, which was accurately reflected in the intensity of the side-scattered light. The uptake of other nanoparticles such as silver (Ag) and iron oxide (Fe3O4) also could be detected. This method could be used for the initial screening of the uptake potential of nanoparticles as an index of "nanotoxicity".     

Selection of Dominant NSLAB from a Mature Traditional Cheese According to their Technological Properties and in vitro Intestinal Challenges

Abstract: Isolates (47) of lactobacilli from 5 different productions of Melichloro cheese were examined for potential use as adjunct cultures. The sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) of whole‐cell proteins classified 29 isolates as L. paraplantarum and 18 as L. paracasei subsp. paracasei. Randomly amplified polymorphic DNA‐polymerase chain reaction (RAPD‐PCR) analysis differentiated the L. paraplantarum and L. paracasei subsp. paracasei isolates at strain level and both, RAPD analysis and whole‐cell protein profiling provided useful information about the diversity of nonstarter lactic acid bacteria (NSLAB) in the different cheese productions. The isolates were slow acidifiers and about 70% of them degraded, preferentially α_s‐casein. The amounts of amino acids accumulated in the milk increased with the incubation time. A similar enzyme profile was exhibited by strains of both species, except for α‐mannosidase and α‐fucosidase, which were not detected in the L. paracasei subsp. paracasei strains. All strains grew in the presence of bile at 0.3% and the majority was able to withstand pH 2.5 and pancreatin at 0.1%. Moreover, all strains reduced cholesterol in vitro, with higher removal ability recorded for strains of L. paraplantarum. A narrow spectrum of antibacterial activity was recorded for 88% of the strains. Selected isolates with appropriate technological and interesting in vitro intestinal challenges could be used as adjuncts and deserve further studies. Practical Application: Strains selected by this study could be used as adjuncts to make the Melichloro cheese. Their contribution to cheese flavor is then going to be studied to select the most appropriate. Of course these strains have to be also studied for their probiotic potential, to say that we have a probiotic food.     

Development and Validation of a Matrix Solid-Phase Dispersion Method to Determine Acrylamide in Coffee and Coffee Substitutes

ABSTRACT: The present study describes the development and validation of a new method based on a matrix solid-phase dispersion (MSPD) sample preparation procedure followed by GC-MS for determination of acrylamide levels in coffee (ground coffee and brewed coffee) and coffee substitute samples. Samples were dispersed in C₁₈ sorbent and the mixture was further packed into a preconditioned custom-made ISOLUTE bilayered SPE column (C₁₈/Multimode; 1 g + 1 g). Acrylamide was subsequently eluted with water, and then derivatized with bromine and quantified by GC-MS in SIM mode. The MSPD/GC-MS method presented a LOD of 5 μg/kg and a LOQ of 10 μg/kg. Intra and interday precisions ranged from 2% to 4% and 4% to 10%, respectively. To evaluate the performance of the method, 11 samples of ground and brewed coffee and coffee substitutes were simultaneously analyzed by the developed method and also by a previously validated method based in a liquid-extraction (LE) procedure, and the results were compared showing a high correlation between them.     

高分辨率反式脂肪酸测定方法的建立及市售食用油反式脂肪酸的测定

本文建立了高分辨率的反式脂肪酸测定方法,并考察了市售食用油的反式脂肪酸含量及其种类的情况。结果表明:采用高极性的色谱柱HP-88在优化后色谱条件下,可以实现4种亚油酸异构体、8种亚麻酸异构体、37种常见脂肪酸良好的色谱分离,而且反式脂肪酸与常见的顺式脂肪酸在同时检测条件下出峰时间不重叠,可以进行高分辨率的脂肪酸包括反式脂肪酸组成分析;市售主要品种的食用油都存在一定量的反式脂肪酸,其中调和油、花生油、大豆油含有2~3%的反式脂肪酸(反式亚麻酸含量在1.5~2%之间);玉米油和葵花籽油中反式亚油酸的含量在0.7~2%之间;稻米油的反式脂肪酸的含量最高,接近4%;橄榄油和山茶油的反式脂肪酸含量一般在0.5%以下;各油样的反式脂肪酸异构体的种类也存在区别。     

Studies on resistance to insecticides in Tribolium castaneum (Herbst)—III. Selection of a strain resistant to lindane and its biological characteristics

A strain of Tribolium castaneum (Herbst) resistant to lindane was selected from a heterogeneous parent stock by continuous breeding in wheat flour treated with lindane. Starting with 20 ppm in the first, the concentration of lindane in each subsequent generation was increased till a concentration of 600 ppm was reached in the ninth generation. A tenth generation was reared in 600 ppm lindane and the adults which emerged were used for further investigations.

The resistance was estimated by three testing methods, namely, treatment of the rearing medium, film exposure, and direct spray. The level of resistance was assessed in comparison with (i) the parental strain, and (ii) the susceptible strain developed when the parental stock was reared for ten generations without any insecticidal treatment. The lindane-resistant strain when tested by rearing medium, film exposure and direct spray methods was found to be 54·8, >87, and 13·05 times as resistant as the parental, and 90·2, >86, and 12·48 times as resistant as the susceptible strain respectively.

The resistant strain had a lower fecundity than the susceptible strain, but did not show any change in the duration of the preimaginal stages when reared in untreated medium. However, there was a prolongation of the larval period in the rearing medium treated with lindane.     

Validation of a High-performance Liquid Chromatography-Ultraviolet Method to Quantify Soy Sapogenols A and B in Soy Germs from Different Cultivars and in Soy Isoflavone-Enriched Supplements

An increasing number of studies investigating the health effects of soy phytochemicals has led to the commercialization of many soy‐based products. Due to its particularly high concentration in many secondary metabolites, the use of soy germ as raw material is emerging for the processing of soy dietary supplements. However, the soybean seeds and germs do not exhibit the same major phytochemical profiles. This is particularly the case for soy saponins. Due to their structural diversity, the analysis of each individual soy saponin remains difficult. In this study, the total amount of these health‐protective phytochemicals was determined through the quantification of their aglucon precursors, soy sapogenols A and B. A simple and rapid analytical method was developed using high‐performance liquid chromatography coupled with an ultraviolet detection. The within‐day and between‐day variabilities of total soy sapogenol concentration were 7.3% and 10.9% in the whole seed and 3.3% and 4.7% in the germ, respectively. The total soy sapogenol contents investigated among the germs from 43 cultivars ranged from 32.8 μmol/g to 63.1 μmol/g. High amounts of soy saponins were also observed in several soy‐based dietary supplements, from 5.5 μmol/g to 107.8 μmol/g, with an A/B ratio varying from 0.3 to 8.6, showing large differences between the raw materials and concentration process used. These results indicate that these compounds have to be clearly determined when discussing the biological activity of dietary supplements issued from soy.