牛初乳中免疫球蛋白的测定

以单向免疫扩散法测定了牛初乳中的IgG。结果表明,产犊后第1次挤乳,初乳gG平均为67.23mg/mL,之后随泌乳进行迅速下降,24h后降到小于5mg/mL,到第5天已降到常乳水平。     

Bioactive Compounds of Colostrum and Its Application

Colostrum is the initial milk secreted by bovine during parturition and the first few days after birth. Colostrum is a gift of nature used to protect the newborn's immune system and provides passive immunity against pathogens. The presence of bioactive components such as insulin-like growth factor I and II (IGF-I and IGF-II), lactoferrin, lysozyme, lactoperoxidase, and immunoglobulin make the colostrum active against pathogens such as Escherichia coli, Salmonella typhimurium, Shigella dysenteria, Listeria monocytogens, Streptococcus mutans, Bacillus stearothermophilus, and Bacillus subtilis. It is also active against Herpes simple virus type-I (HSV-I), Human Immuno-deficiency virus-I (HIV-I), and human cytomegalovirus. Lysozyme is an antibacterial and lytic enzyme; whereas lactoperoxidase is a major antibacterial found in colostrum; it is toxic to gram-positive and gram-negative bacteria. Lactoperoxidase inactivates the polio virus, vaccinia, and human immunodeficiency virus type-I in-vitro. Immunoglobulins are considered an important bioactive component in colostrum, and it contains high levels of immunoglobulin G (Ig G). Immunosupplementation with bovine milk antibodies has been shown to provide local protection to the gastrointestinal tract against disease. The restricted technical and hygienic problems, along with the unstable physio-chemical nature of colostrum, has resulted in minimal utilization of colostrum on Industrial scale.     

乳制品中牛IgG含量间接竞争性ELISA检测方法的研究

建立了牛初乳制品和添加了牛初乳成分的乳制品中牛IgG含量间接竞争性酶联免疫吸附测定方法,主要研究步骤包括:制备牛IgG保守区(Fc段),以Fc段为免疫原免疫Balb/C小鼠,取其脾细胞进行细胞融合,制备特异性单克隆抗体及合成适合实际测定用途的ELISA试剂盒。应用本研究建立的方法对标准品和实际样品进行牛IgG含量检测的结果表明,该方法回收率在78.9%～117.5%,批内变异系数小于10%,批间变异系数小于15%,检测结果稳定可靠,可满足目前国内牛初乳制品和添加了牛初乳成分的乳制品品质监控的需要。     

Response surface methodology applied to the analysis of rice bran oil extraction process with ethanol

Vegetable oils can be extracted using ethanol as solvent. The main goal of this work was to evaluate the ethanol performance on the extraction process of rice bran oil. The influence of process variables, solvent hydration and temperature was evaluated using the response surface methodology, aiming to maximise the soluble substances and γ‐oryzanol transfer and minimise the free fatty acids extraction and the liquid content in the underflow solid. It can be noted that oil solubility in ethanol was highly affected by the water content. The free fatty acids extraction is improved by increasing the moisture content in the solvent. Regarding the γ‐oryzanol, it can be observed that its extraction is affected by temperature when low level of water is added to ethanol. On the other hand, the influence of temperature is minimised with high levels of water in the ethanol.     

Acrylamide content in potato chips on the Italian market determined by liquid chromatography tandem mass spectrometry

An easy‐to‐use and simplified liquid chromatography‐tandem mass spectrometry (LC‐ESI (+)‐MS/MS) method was adopted to determine the amount of acrylamide in thirty‐two samples of potato chips purchased on the South Italian market in 2009. Extract produced from matrices was directly analysed without derivatisation, the use of isotopically labelled acrylamide or the use of clean up cartridges. Quality analytical data were reported. The limit of detection and limit of quantification were 6 μg kg^?1 and 18 μg kg^?1, respectively and recovery values ranged from 90.7–96.3%. The relative standard deviation (RSD) ranged between 2.1% and 5.8%. The values ranged between 27 and 1400 μg kg^?1 and the arithmetic mean acrylamide content resulted 363 μg kg^?1. According to Foot et al. [Food Additives and Contaminants, 24 (2007)(S1), 37] and considering 500 μg kg^?1 as the minimum level possible with the actual available mitigation tools, the number of samples showing an acrylamide level higher than 500 μg kg^?1 resulted to be 22%. This paper gives a contribution to data collection in response to the monitoring activity of EFSA and following the Commission Recommendation 2007/331/EC: really, the number of Italian samples of potato chips and potato products for which acrylamide values was reported in the ‘results on the monitoring of acrylamide’ of EFSA ( http://www.efsa.europa.eu/cs/BlobServer/Report/datex_report_acrylamide_en,0.pdf?ssbinary=true , 2009) issued on 30 April 2009 is very limited.     

Analysis of tea catechins in vegetable oils by high‐performance liquid chromatography combined with liquid–liquid extraction

In this study, a method was developed for the determination of various tea catechins in vegetable oils. Firstly, vegetable oils including tea seed oil, sunflower seed oil and soya bean oil were extracted by methanol/water (40:60, v/v), and then, a high‐performance liquid chromatography (HPLC) method was developed for the simultaneous determination of GA, caffeine, EGC, EGCG, EC, ECG, GC, GCG, C and CG. For the compounds detected in tested vegetable oils, LODs were in the range of 0.05–1.65 ng, both intraday and interday relative standard deviations (RSDs) were <5.0%, and the recovery rates were in the range of 96.2–100.5% with RSD <3.7%. The results showed in vegetable oils which declared to had added tea catechins in, the concentrations of tea catechins were less than that showed in package label, and the content of EGCG was the highest in all samples. Therefore, the advancement made in our study will facilitate studies of tea catechins in oil industry.     

Simulation of heat transfer for solid–liquid food mixtures in cans and model validation under pasteurization conditions

During processing of canned mixtures of solid–liquid foods, conduction and convection occur simultaneously. The literature lacks in a complete simulation study where a large number of solids are dispersed in the liquid phase, e.g. canned peas. Therefore, the objectives of this study were to determine temperature changes inside a can containing solid–liquid food mixtures. For this purpose, dispersed stationary solids (canned peas in water) in a 2D (axi-symmetrical) configuration were applied. Ansys V11 (Ansys Inc., Canonsburg, PA) was used to solve continuity, energy and momentum equations. For experiments, canned pea samples were prepared in 500 g cans, and heating process was conducted in a retort under pasteurization conditions at ≈98 °C. Temperature changes were measured using needle type thermocouples, and simulation results were validated against experimental data. This study is expected to be a significant contribution to the literature for further optimization studies and to form basis of an industrial project to improve canning process of solid–liquid mixtures.     

Zein nanoparticles produced by liquid–liquid dispersion

Variables during production of zein nanoparticles using a liquid–liquid dispersion process were researched in this work for the potential development of food-grade nanoscalar delivery systems. The process was based on dissolving zein in 55–90% aqueous ethanol, followed by shearing the stock solutions into deionized water. The size of zein nanoparticles was typically 100–200 nm, and smaller particles were formed at a higher shear rate, and a higher ethanol concentration or a lower zein concentration in stock solutions. The addition of 1% zein nanoparticles into 0.5% carboxymethylcellulose solutions (adjusted to pH 3–9) increased the viscosities of the polymer solutions, and the increase was found to be larger at higher pH. The results showed that liquid–liquid dispersion is a simple and scalable process to manufacture nanoscalar delivery systems of many bioactive compounds. However, physical properties of eventual food products are to be examined for the potential influence of the added delivery systems.     

直接酶联免疫吸附法检测猪血清IgG的影响因素

直接酶联免疫吸附法检测猪血清中G型免疫球蛋白（IgG）,最小检测量为10ng,最适检测范围纯IgG为10～60ng,猪血清IgG为10～40ng。酶标抗体最适稀释度为1／3500。酶标板内与酶标板间平行测定变异系数均小于5％。     

Liquid–liquid equilibria for systems composed of rice bran oil and alcohol-rich solvents: Application to extraction and deacidification of oil

The liquid–liquid equilibria of systems composed of rice bran oil, free fatty acids, ethanol and water were investigated at temperatures ranging from 10 to 60 °C. The results of the present study indicated that the mutual solubility of the compounds decreased with an increase in the water content of the solvent and a decrease in the temperature of the solution. The experimental data set was correlated by applying the UNIQUAC model. The average variance between the experimental and calculated compositions was 0.35%, indicating that the model can accurately predict behavior of the compounds at different temperatures and degrees of hydration. The adjustment of interaction parameters enables both the simulation of liquid–liquid extractors for deacidification of vegetable oil and the prediction of phase compositions for the oil and alcohol-rich phases that are generated during cooling of the stream exiting the extractor (when using ethanol as the solvent).     

Modeling of ohmic heating patterns of multiphase food products using computational fluid dynamics codes

Modeling of the thermal behavior of multiphase food products with various electrical conductivities under ohmic heating has been a challenge. Distortion of electric field due to heterogeneous food properties and electrical conductivity distribution should be taken into consideration for accurate prediction of the thermal performance of ohmic heaters. The objective of this study was to model ohmic heating pattern of solid–liquid food complex that contain three different solid particles with substantially different electrical conductivities and 3% NaCl solution. The solid food samples used in this experiment were potato, meat, and carrot, which are less conductive than carrier medium. The transient heating patterns of each solid food and carrier medium were simulated using computational fluid dynamics (CFD) codes with user defined functions (UDFs) for electric field equations. The predicted temperature values were in good agreement with the experimental data with the maximum prediction error of 6 °C. Hot spots existed on the continuous phase in zones perpendicular to the solid cubes and cold spots were in between the particles where the current density lacks. CFD model prediction of detailed thermal profiles of multiphase food mixtures under the static ohmic heating will assist in designing of a continuous flow ohmic heater with pursuit of heating uniformity, furthermore, ensuring food safety and quality.