菠菜MAP保鲜及低温贮藏研究

研究了不同初始O2/CO2气体比例的MAP及贮藏温度对菠菜品质的影响.菠菜经充气包装在2℃贮藏17d后分别测定其感官和理化指标,然后将筛选出最优的一组MAP8(0210% C0210%)分别在12℃、5℃和2℃进行贮藏研究.结果表明,MAP菠菜在2℃贮藏17 d后,MAP8(O210% CO210%)和MAP7(O210% CO25%)的保鲜效果好;同时表明MAP8在5℃贮藏17 d后菠菜的叶绿素含量和感官分值较大,可见在这个气体条件下,菠菜的最佳贮藏温度为5℃.     

芦笋采后品质变化及贮藏保鲜现状

综合分析了呼吸作用、贮藏条件、包装方式等因素对芦笋贮藏期限的影响,综述了国内外芦笋贮藏保鲜通常所采用的冷藏、化学处理、气调贮藏等三类方法对芦笋采后形态、色泽、重量、营养价值、酶活性等方面的品质因素的影响,对进一步研究芦笋的保藏技术具有借鉴作用。     

副结核分枝杆菌MAP1068胞外蛋白酶的特性研究

为研究副结核分枝杆菌(MAP)1068蛋白的特性,本研究以MAP参考株K10基因组为模板,PCR扩增其map1068基因,构建p ET28a-map1068重组载体,将其转化BL21后诱导表达并纯化MAP1068蛋白。利用纯化的重组蛋白免疫(100μg/只/0.1 m L)小鼠制备多克隆抗体,应用该抗体对MAP1068蛋白进行亚细胞定位。以酪蛋白为底物测定MAP1068蛋白的酶活性。结果显示,MAP1068蛋白以包涵体形式表达;经变性、复性、亲和层析纯化后获得目的蛋白;将该蛋白免疫小鼠后其血清抗体效价可达1∶204 800;该蛋白主要定位于MAP细胞壁,可降解酪蛋白,为胞外蛋白酶。本实验为进一步研究MAP的致病机制奠定了基础。     

薄膜包装中果蔬呼吸强度的测定

对薄膜包装果蔬的呼吸强度提出了新的测定方法,并与传统的密闭测定法进行了比较。新的测定法将包装系统中果蔬的呼吸与薄膜的气体透过同时加以考虑,先假设一系列的呼吸强度,并逐一代入气体收支平衡式,用计算机计算气体分压,并将计算值与包装中气体分压实测值比较,用最小二乘法算出两者差的平方和最小时,所对应假设的呼吸强度为测算得值。结果表明,密闭法算得的结果低于新法测算的呼吸强度值。可以认为新方法能适用于包括非平衡状态的整个贮藏阶段,并能更客观地反映薄膜包装条件下果蔬的呼吸强度     

Association between cow reproduction and calf growth traits and ELISA scores for paratuberculosis in a multibreed herd of beef cattle

The objective of this research was to assess the association between 4 cow reproductive and weight traits, and 2 preweaning calf traits and ELISA scores for paratuberculosis (0 = negative, 1 = suspect, 2 = weak-positive, and 3 = positive) in a multibreed herd of cows ranging from 100% Angus (A) to 100% Brahman (B). Cow data were 624 gestation lengths (GL), 358 records of time open (TO), 605 calving intervals (CI), and 1240 weight changes from November to weaning in September (WC) from 502 purebred and crossbred cows. Calf data consisted of 956 birth weights (BWT), and 923 weaning weights adjusted to 205 d of age (WW205) from 956 purebred and crossbred calves. Traits were analyzed individually using multibreed mixed models that assumed homogeneity of variances across breed groups. Covariances among random effects were assumed to be zero. Fixed effects were year, age of cow, sex of calf, year × age of cow interaction (except WC), age of cow × sex of calf interaction (only for WC), and covariates for B fraction of sire and cow, heterosis of cow and calf, and ELISA score. Random effects were sire (except for TO and CI), dam, and residual. Regression estimates of cow and calf traits on ELISA scores indicated that lower cow fertility (longer TO), lower ability of cows to maintain weight (negative WC), lower calf BWT, and lower calf WW205 were associated with higher cow ELISA scores. Further research on the effects of subclinical paratuberculosis in beef cattle at regional and national levels seems advisable considering the large potential economic cost of this disease.     

MAP沉淀法回收垃圾渗滤液中高浓度氨氮试验研究

以实际垃圾渗滤液为对象,采用MgSO4.7H2O和Na2HPO4.12H2O使NH3-N生成MgNH4PO4.6H2O结晶沉淀的MAP(硫酸铵镁)法去除回收垃圾渗滤液中高浓度氨氮的效能,研究了pH、反应时间、药剂配比对NH3-N去除率的影响。结果表明:MAP法回收垃圾渗滤液中NH3-N的适宜pH为8.5~9.5;过高的pH会破坏硫酸铵镁晶体结构,导致固定氨从结晶中游离,不利于氨氮的去除;在pH为8.5、反应时间为20 min、n(Mg2+)∶n(NH4+)∶n(PO43-)=1.4∶1.0∶1.4的最佳条件下,渗滤液中NH3-N的质量浓度由初始的1 671 mg/L降至30 mg/L,去除率达98.2%;同时回收的MAP可作缓释肥。     

青花菜采后保鲜技术研究

青花菜采后衰老中呼吸强度呈现跃变型,呼吸高峰出现在采后第2天内,随后黄化率急剧上升;蛋白质含量和Vc含量则随贮期延长而下降。0℃低温与调节气体包装均可抑制青花菜的采后衰老,0℃低温辅以0.04mm厚的聚乙烯袋包装贮藏41天后,青花菜的黄化率为0.0%,失重率低于4.0%,花球青绿无异味,切口鲜度正常。     

不同保鲜膜包装对低温储藏铁皮石斛的保鲜效果影响

将刚采收的铁皮石斛放置在0℃下进行储藏,研究不同保鲜膜包装对铁皮石斛保鲜效果的影响。采用薄膜自发气调包装保鲜技术（MAP）,分别使用PVC保鲜膜、PE保鲜膜及微孔膜对鲜石斛进行包装,以散装石斛作为对照,通过对石斛失重率、膜透性、丙二醛、可溶性固形物进行测定,探讨不同保鲜膜对石斛保鲜效果的影响。结果表明,PVC保鲜膜包装的石斛保鲜效果最好,有效地保持了石斛在低温储藏期间的品质,可以延长其货架期,为果蔬的贮藏保鲜提供技术参数。     

Chemical composition and microstructure of uroliths associated with the feeding of high-level cottonseed meal diet to sheep

The chemical composition and microstructure of five urolith samples (4 bladder stones and one kidney stone) associated with the feeding of high level of cottonseed meal (CSM) diet to Chinese merino fine wool sheep (Junken breed, Xinjiang) were examined by optical microscope, X-ray diffraction, X-ray energy dispersive spectrometry (EDS), scanning electron microscopy (SEM), and infrared spectroscopy analysis. The bladder stone samples appeared yellow or white, small powder and loose mass, and as finely granular under the optical microscope. However, the kidney stone samples from a experimental sheep were found as small brown mass, higher hardness, and as a cracklike structure. Oxygen, phosphorus, potassium and magnesium were found as four major elements in these uroliths by X-ray energy dispersive spectrometry (EDS). Potassium magnesium phosphate (MgKPO₄) and potassium magnesium phosphate hexahydrate (MgKPO₄·6H₂O) were major components in the bladder stones, while less magnesium ammonium phosphate hexahydrate (MgNH₄PO₄·6H₂O) examined by X-ray diffraction and infrared spectroscopy analysis. However, the newly found prismatic crystals, which were rich in magnesium and pyrophosphate, were identified as magnesium pyrophosphate (Mg₂P₂O₇) in the kidney stone. The bladder stone samples appeared irregular mass and balls, cracked under SEM with low magnification, while appeared cracked, irregular layer-like, honeycomb-like or tiny balls under high magnification. The kidney stone samples were observed as cone, irregular block or layered crystal structures.