F值，C值，E值及热力杀菌的最佳条件

目前,由于我国生产水平还比较落后,罐头食 品工业中的热力杀 菌主要凭经验,主要指标是核心温度,这样难以自动化,劳动强度大,营养损失严重。而发达的国家,特别是德国在罐头食品工业的热力杀菌中引入了F值、E值和C值,通过微机程序化,大大降低了劳动强度,同时又能使罐头食品品质达到最佳状态。不久我国就加入关贸协定,为了迎接世界市场的挑战,很有必要研究和引入F值、、E值和C值,来促进我国罐头食品工业的发展,为我国食品进入世界市场提供可靠的依据和保证。 一、罐头食品的冷点 杀菌锅和罐头都有温度最难达到之点,此点就…     

稻曲病菌不同颜色厚垣孢子超微结构比较

 The surface and internal structure difference of yellow and black dormant chlamydospores of Ustilaginoidea virens on mid-and late-season rice were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). SEM revealed that the spherical yellow and black chlamydospores had prominent spines, with the diameters from 3 to 6 μm and 4 to 6 μm, respectively. The spines were 200-700 nm and 400-1 100 nm long in yellow and black chlamydospores, respectively. Variance analysis showed that there was no difference in diameter of the yellow chlamydospores but significant difference among the black ones collected from both rice cropping types. Similarly, there was no difference in length of the spines on the same color chlamydospores but extremely different between the yellow and black chlamydospores collected from the two cropping types. TEM revealed that the cell wall of both color chlamydospores were composed of two layers, the thick endosporium and thin exosporium, and the thickness of the former layer of the black chlamydospores was nearly two times as that of the yellow ones. The organelles in yellow chlamydospores such as the nucleus were obviously visible, but invisible in black ones. The cytoplasm of black chlamydospores was occupied by a big lipid globule. This study suggests that the formation of dormant chlamydospores of U. virens is related with the structural changes in the cell.     

稻曲病菌休眠与非休眠厚垣孢子胞壁多糖结构与组分

 为揭示稻曲病菌厚垣孢子壁与厚垣孢子内源性休眠的关系,以典型的休眠型(黑色)和非休眠型(黄色)稻曲病菌厚垣孢子为材料,用液氮研磨,超声破壁后,经复合酶 热水浸提 Sevag法提取胞壁多糖,采用紫外光谱、红外光谱、刚果红实验、气相色谱分析其多糖的结构和组分。结果表明,黑色、黄色厚垣孢子胞壁多糖均含β型吡喃糖苷键,具有三股螺旋构象,为主要由葡萄糖、半乳糖、甘露糖3种单糖组成的杂多糖,黄色厚垣孢子中含有少量的木糖;黑色厚垣孢子壁中葡萄糖、半乳糖和甘露糖的摩尔百分比为58.23∶25.32∶16.46,黄色厚垣孢子壁中葡萄糖、半乳糖、甘露糖和木糖的摩尔百分比为3548∶30.58∶24.46∶9.45。这两种厚垣孢子壁多糖的组成和比例有明显差异,可能与厚垣孢子休眠有关。