中国奶粉进口贸易发展的新态势、问题与建议

2001—2020年中国奶粉进口贸易发展呈现规模持续增扩与地位提升,产品结构趋于优化,进口来源有效拓展,进口均价持续攀升等特征。但也存在着进口增势迅猛,冲击国内产业;来源市场集中,均价不断高涨;假洋奶粉泛滥,扰乱市场秩序;走私花样繁多,海关监管困难等问题。提出新时期应积极扶持国产奶粉生产企业转型升级,提升核心竞争力;拓展来源渠道,分散风险集聚;整顿行业乱象,规范市场秩序;从严海关监管,打击非法走私,实现国内奶粉行业可持续健康发展。     

西番莲粉喷雾干燥工艺研究

采用酶解西番莲汁为原料,以麦芽糊精为助干剂,通过喷雾干燥法制备了西番莲粉,研究麦芽糊精添加量、进风温度、进料流量和进料浓度对西番莲粉产率、VC含量和含水率的影响。在单因素试验的基础上,采用正交试验优化了西番莲粉喷雾干燥工艺参数。结果表明,西番莲粉喷雾干燥的最佳工艺参数为:麦芽糊精添加量60%(按照喷雾干燥前料液总固形物含量计算),进风温度170℃,进料流量9 mL/min,进料浓度30%,此条件下西番莲粉的产率50.47%,VC含量58.88 mg/100 g,含水率4.8%。制得的产品具有西番莲特有的果香,研究为西番莲的产品多样化提供新的方法和思路。     

Combined mutations in five wheat STARCH BRANCHING ENZYME II genes improve resistant starch but affect grain yield and bread-making quality

Increases in the proportion of amylose in the starch of wheat grains result in higher levels of resistant starch, a fermentable dietary fiber associated with human health benefits. The objective of this study was to assess the effect of combined mutations in five STARCH BRANCHING ENZYME II (SBEII) genes on starch composition, grain yield and bread-making quality in two hexaploid wheat varieties. Significantly higher amylose (∼60%) and resistant starch content (10-fold) was detected in the SBEII mutants than in the wild-type controls. Mutant lines showed a significant decrease in total starch (6%), kernel weight (3%) and total grain yield (6%). Effects of the mutations in bread-making quality included increases in grain hardness, starch damage, water absorption and flour protein content; and reductions in flour extraction, farinograph development and stability times, starch viscosity, and loaf volume. Several traits showed significant interactions between genotypes, varieties, and environments, suggesting that some of the negative impacts of the combined SBEII mutations can be ameliorated by adequate selection of genetic background and growing location. The deployment of wheat varieties with increased resistant starch will likely require economic incentives to compensate growers and millers for the significant reductions detected in grain and flour yields.     

安徽省猪伪狂犬病毒的分离鉴定及其主要毒力基因分子特征

猪伪狂犬病是由猪伪狂犬病毒(porcine pseudorabies virus,PRV)引起的一种急性、热性传染病。自2011年底以来,PRV发生了变异,传统的PRV弱毒疫苗已不能对PRV变异株提供完全保护,这给我国PR防控带来了巨大挑战。为了解安徽省PRV流行特征及其主要毒力基因遗传变异情况。利用PCR技术、细胞接种试验、电子显微镜观察、间接免疫荧光试验及兔体接种试验等方法,对安徽省临诊病例中疑似PRV感染的病猪进行病原检测及PRV分离鉴定,并通过设计6对特异性引物对PRV分离株主要毒力基因(gE、gI、TK、gB、gC、gD)进行克隆及测序分析。2016—2018年安徽省临诊病例中共分离鉴定15株PRV;PRV分离株主要毒力基因序列均与2011年后国内PRV变异株同源性较高;与2011年前国内PRV经典株序列比对,PRV分离株gE、gB、gC及gD基因存在多个位点的一致性替换、插入或缺失,且gE、gC基因多位点突变位于其重要的抗原表位区。本研究分离的15株PRV均为变异株,变异株已成为安徽省主要的流行毒株。15株PRV分离株的gI、TK基因序列较为保守,而gE、gC蛋白抗原表位区域氨基酸的突变可能导致其毒力及抗原性发生改变。部分PRV分离株与邻近地区PRV序列同源性均为100%,可能与频繁跨省调运生猪、跨区引种等原因有关。     

白花蛇舌草超微粉对小鼠免疫功能的影响

The assay was aimed to study the effect of Hedyotis diffusa Willd superfines powder on immune function. Three groups of mice were gavaged with the drugs at doses of 1.75,1.25 and 0.75 g/kg once a day for 7 consecutive days, repectively. The mice of control group were administered with the same volume of saline.At the last time, mice were injected into the muscle with Newcastle disease vaccine,and get peripheral blood on days 7, 14 and 21 after the medicine administration. The enhancement of innate immune responses were evaluated by using CCK-8 method, hemagglutination inhibition test, macrophage phagocytic function test and organ coefficient method. The levels of lymphocytes proliferative capacity, serum antibody, peritoneal macrophage phagocytosis and the indexes of immune organs in mice were extremely significantly enhanced (P＜0.01). Hedyotis diffusa dWilld superfines powder could extremely significantly regulate the immunity function of mice (P＜0.01).     

不同抗生素检测方法检测乳清粉样品结果差异性分析

乳清粉是婴幼儿配方乳粉行业的主要原料之一,对其进行抗生素检测是原料验收的重要参考指标。本研究针对8个批次乳清粉原料,采用4种不同的抗生素检测方法进行了抗生素检测,包括国标法1、国标法2、利普斯50抗生素检测试剂盒法、Charm MRL酶联免疫试剂盒法。不同方法的检测结果存在很大差异,其中国标法1和酶联免疫试剂盒法获得了相同的结果,8个样品均为抗生素阴性。而国标法2及依据此法开发的快速检测试剂盒利普斯50检测则分别显示全阳性和部分阳性的矛盾结果。从上述结果可见,依据国标法2通过嗜热芽孢杆菌检测乳清粉产品抗生素,其结果稳定性欠佳,影响其检测结果可靠性的因素还有待进一步研究。     

高效液相色谱法测定婴儿配方奶粉中乳铁蛋白含量.

本研究建立了一种用高效液相色谱测定婴儿配方奶粉中乳铁蛋白的方法。色谱条件:色谱柱为Hi Trap Heparin肝素琼脂糖亲和柱(0.7×2.5cm,1m L),流动相A为50mmol/L的Na2HPO4溶液(p H7.00),流动相B为50mmol/L的Na2HPO4+1.0mol/L的Na Cl溶液(p H7.00),检测波长为230nm。结果表明:乳铁蛋白的检出限为3.0mg/100g,回收率在86%~99%之间,相对标准偏差(RSD)为3.4%。用此方法检测婴儿配方奶粉中乳铁蛋白,操作简单,结果准确可靠,精密度高,重现性好。     

Ligand-binding characteristics of feline insulin-binding immunoglobulin G

Polyclonal immunoglobulin (Ig) G autoantibodies against insulin have been identified in sera of healthy cats. We purified and fractionated insulin-binding IgGs from cat sera by affinity chromatography and analyzed affinity of insulin-binding IgGs for insulin and their epitopes. Following the passing of fraction A, which did not bind to insulin, insulin-binding IgGs were eluted into two fractions, B and C, by affinity chromatography using a column fixed with bovine insulin. Dissociation constant (KD) values between insulin-binding IgGs and insulin, determined by surface plasmon resonance analysis (Biacore™system), were 1.64e⁻⁴ M for fraction B (low affinity IgGs) and 2e⁻⁵ M for fraction C (high affinity IgGs). Epitope analysis was conducted using 16 peptide fragments synthesized in concord with the amino acid sequence of feline insulin by an enzyme-linked immunosorbent assay. Fractions B and C showed higher absorbance (affinity) of the peptide fragment of 10 amino acid residues at the carboxyl-terminal of the B chain (peptide No. 19), followed by peptide fragments of 6 to 15 amino acid residues of the B chain (peptide No. 8). Fraction C showed a higher absorbance to 7 to 16 amino acid residues of the B chain (peptide No. 5) compared with the absorbance of fraction B. Polyclonal insulin-binding IgGs may form a macromolecule complex with insulin through the multiple affinity sites of IgG molecules. Feline insulin-binding IgGs are multifocal and may be composed of multiple IgG components and insulin.     

氟喹诺酮类药物粉剂中非法添加四种喹噁啉类药物的UPLC检测方法研究

建立了超高效液相色谱法测定氟喹诺酮类药物粉剂中非法添加喹乙醇、乙酰甲喹、卡巴氧及喹烯酮的方法。采用purospher RP-18色谱柱(2.1 mm×100 mm,粒径2.0μm)分离四种喹噁啉类药物,以磷酸溶液和甲醇-乙腈(7.5∶7.0)为流动相进行梯度洗脱,流速0.3 m L/min,二极管阵列检测器检测,采集波长范围为200~400 nm,分辨率为1.2 nm,记录光谱图和365 nm波长处的色谱图。结果显示,四种喹噁啉类药物的浓度在0.2~100μg/m L范围内的线性良好,相关系数r均为0.9999,回收率在98.0%~100.2%范围内,RSD在0.27%~0.89%之间,检测限200 mg/kg。本方法快速、准确,可用于氟喹诺酮类粉剂中非法添加喹噁啉类药物的定性和定量检测。