Effects of different types of potato resistant starches on intestinal microbiota and short-chain fatty acids under in vitro fermentation

The prebiotic effects of potato resistant starches RS1, RS2, RS3a, RS3b and RS4 were studied using simulated gut fermentation in vitro. The intestinal microbial composition was significantly changed by resistant starch (RS) after 24-h fermentation. All RSs (P < 0.05) decreased the ratio of Firmicutes/Bacteroidetes (F/B), and RS2 exhibited the lowest value of 0.95 ± 0.07. The relative abundance of Bifidobacterium was significantly increased by RS4, whereas Megamonas and Prevotella were promoted by RS2. Further, RS4 produced the highest levels of acetate (138.34 µM), whereas RS2 produced the highest levels of propionate (41.45 µM) and butyrate (21.65 µM). However, Bifidobacterium did not promote the production of propionate or butyrate, even though it was proficient in fermenting RS. Megamonas and Prevotella were positively associated with the higher production of propionate and butyrate. Here, different RSs played key roles in promoting intestinal health, and RS2 especially showed more abundant probiotic functions.     

优质蛋白玉米在产蛋鸡日粮中的应用研究

将157日龄海兰褐商品代产蛋鸡528只,分为3个处理,每个处理4重复,每个重复44只鸡,研究优质蛋白玉米和普通玉米组成的日粮对产蛋鸡生产性能和蛋品质常规指标的影响.处理1饲喂普通玉米日粮（添加赖氨酸）,赖氨酸水为平0.71%;处理2饲喂优质蛋白玉米日粮（等量替换普通玉米）,赖氨酸水平为0.78%;处理3饲喂优质蛋白玉米日粮（等量替换普通米,不添加赖氨酸）,赖氨酸水平为0.69%.试验结果表明：优质蛋白玉米日粮组的日采食量显著高于普通玉米组（P＜0.05）,表明优质蛋白玉米具有较好的适口性;处理3的产蛋率显著高于处理1和处理2（P＜0.05）,处理1和处理2间差异不显著（P＞0.1）;任意两个处理间的平均蛋重、饲料转化率、软破蛋率接近（P＞0.1）.总的来讲,处理3的生产性能优于其它处理组,处理2的生产性能最低;与普通玉米相比,在日粮中使用优质蛋白玉米可提高鸡蛋的蛋黄颜色评分（P＜0.1）,不会降低鸡蛋的哈夫单位和蛋壳强度（P＞0.1）.用优质蛋白玉米等量替换普通玉米,并维持适宜的赖氨酸水平,可提高产蛋高峰鸡的生产性能.     

食品中硒元素形态分析的研究进展

硒是人体必需的微量元素,具有丰富的化学形态,分为无机硒和有机硒,不同硒形态对人体的生物活性不同。无机硒主要包括硒酸Se(Ⅵ)、亚硒酸Se(Ⅳ),有机硒主要包括硒蛋白、硒核酸和硒多糖等大分子硒,及硒代胱氨酸(selenocystine,SeCys2)、硒代蛋氨酸(selenomethinonine,SeMet)、甲基硒代半胱氨酸(methyl selenocysteine,MeSeCys)、硒代乙硫氨酸(selenoethionine,SeEt)等小分子硒化物。无机硒不易吸收,可能对人体造成危害,有机硒易吸收,适当摄取对人体有多方面益处。准确测定食品中不同硒形态及具体含量,对人体按需摄入硒元素具有重要指导意义。本文总结了近年来食品行业中硒形态检测研究涉及的领域,包括果蔬、水产、药食同源的中药、茶叶、谷物等方面的研究,常用的提取、分离、分析技术,重点介绍了高效液相色谱-电感耦合等离子体质谱联用技术和液相色谱-氢化物发生-原子荧光光谱联用技术在不同食品中检测硒形态的应用情况,并展望了未来硒形态分析的前景。