Effect of compaction,delayed sealing and aerobic exposure on forage choice and short‐term intake of maize silage by goats

Forage choice and intake by ruminants depend on various factors. This study aimed to determine the effects of compaction, delayed sealing and aerobic exposure on forage choice and short‐term dry‐matter intake (DMI) of maize silage by goats. Whole‐crop maize (277 g/kg dry matter [DM]) in 120‐L silos was compacted at either low (194 kg DM/m³) or high (234 kg DM/m³) density, and sealed immediately at day 0 or with a delay at day 2 or day 4 post‐filling, making a total of six treatments. After ensiling for at least 175 days, silages were exposed to air for 6 days. In 2‐day intervals, silages were sampled for chemical analyses and were vacuum‐stored for use in preference trials. During the experimental phase, each possible two‐way combination of the aerobically exposed silages (days 0, 2, 4 and 6 post‐opening) of the treatments and lucerne hay was offered as free choice to goats (n = 5) for 3 hr. Exposing silages to air for >4 days post‐opening caused strong avoidance and lowest intakes. Under the conditions of the study, aerobic exposure after ensiling had a more pronounced effect on silage preference and short‐time DMI than compaction and delayed sealing. Increasing fibre fractions, a deteriorating microbial status and poor silage sensory properties, probably caused by a combination of different fermentation products, can be considered for decrease in preference.     

库尔勒香梨采后果实褐变与多酚氧化酶、酚类物质及细胞膜结构的关系

库尔勒香梨果实褐变是贮藏中经常发生的一种生理病害,与酚类底物和多酚氧化酶（PPO）含量、分布有关,还与细胞膜结构变化密切相关。对库尔勒香梨果实褐变机理及防止措施进行了较深的研究,结果表明：在气调贮藏中,库尔勒香梨果实褐变指数与多酚氧化酶（PPO）含量成正相关,与酚类底物含量成负相关,与细胞膜相对电导率成正相关。     

Exploring the Potential of Icelandic Seaweeds Extracts Produced by Aqueous Pulsed Electric Fields-Assisted Extraction for Cosmetic Applications

A growing concern for overall health is driving a global market of natural ingredients not only in the food industry but also in the cosmetic field. In this study, a screening on potential cosmetic applications of aqueous extracts from three Icelandic seaweeds produced by pulsed electric fields (PEF) was performed. Produced extracts by PEF from Ulva lactuca, Alaria esculenta and Palmaria palmata were compared with the traditional hot water extraction in terms of polyphenol, flavonoid and carbohydrate content. Moreover, antioxidant properties and enzymatic inhibitory activities were evaluated by using in vitro assays. PEF exhibited similar results to the traditional method, showing several advantages such as its non-thermal nature and shorter extraction time. Amongst the three Icelandic species, Alaria esculenta showed the highest content of phenolic (mean value 8869.7 µg GAE/g dw) and flavonoid (mean value 12,098.7 µg QE/g dw) compounds, also exhibiting the highest antioxidant capacities. Moreover, Alaria esculenta extracts exhibited excellent anti-enzymatic activities (76.9, 72.8, 93.0 and 100% for collagenase, elastase, tyrosinase and hyaluronidase, respectively) for their use in skin whitening and anti-aging products. Thus, our preliminary study suggests that Icelandic Alaria esculenta-based extracts produced by PEF could be used as potential ingredients for natural cosmetic and cosmeceutical formulations.     

名优炒青绿茶挥发性成分研究进展

香气是评价茶叶品质的关键指标之一,众多香气化合物通过复杂的相互作用决定了茶叶的香气品质.名优炒青绿茶一般具有滋味好、香气高的特点,是我国优质绿茶的典型代表.近年来,关于名优炒青绿茶香气成分的研究逐渐增多,但针对不同名优炒青绿茶挥发性成分的组成特点等尚缺乏系统阐述.综述了近二十年来名优炒青绿茶挥发性成分的研究进展,汇总已...     

氮、硫供应对章丘大葱生长和含硫有机物含量的影响

以章丘大葱为材料,并以珍珠岩为栽培基质,采用盆栽试验研究了不同氮、硫供应水平对大葱生长前期的干物质累积及含硫有机物含量的影响。结果表明,氮、硫供应及其交互作用显著影响大葱生长和含硫有机物含量。在硫不足（SO42- 0.01 mmol/L）和硫充足（SO42- 4.00 mmol/L）供应条件下,随氮供应水平提高,大葱植株干物重明显增加,当供氮水平为N 6.0 mmol/L时,植株干物重及氮素吸收数量达到最大;增加硫素供应可显著提高植株的硫含量和总硫量。然而,硫供应不足时,随着供氮水平提高,植株含硫有机物含量逐渐下降;反之,充足供硫条件下,随着氮供应水平的提高,大葱含硫有机物含量出现先增加后降低。当供氮水平为N 12.0 mmol/L时,含硫有机物含量最高,达到7.23 μmol/g,FW。过量氮供应（N 24.0 mmol/L）则抑制植株生长,降低含硫有机物含量。因此,充足供硫条件下,氮素调控水平对保证大葱高产和高含硫有机物含量至关重要。     

一种光合细菌复合制剂对草鱼的生长及非特异性免疫功能的影响

在基础饲料中添加一种光合细菌复合制剂持续饲喂草鱼30 d和60 d,探讨草鱼的生长及非特异性免疫指标的变化。结果表明,饲喂30 d时,添加光合细菌复合制剂的处理组草鱼白细胞吞噬百分比、血清总超氧化物歧化酶(SOD)活力、血清和肝脏谷胱甘肽过氧化物酶(GSH-Px)活力极显著高于饲喂基础饲料的对照组草鱼(P<0.01);饲喂60 d时,处理组草鱼血清抗菌活力、血清和肝脏总SOD活力较对照组极显著升高(P<0.01),血清丙二醛(MDA)含量显著升高(P<0.05)。结论为所选光合细菌复合制剂持续饲喂草鱼30 d或60 d,对草鱼生长量有促进作用,能提高草鱼的非特异性免疫功能。     

鱼类蛋白质酶水解研究进展

对鱼类蛋白质酶水解的各种方法与原理、水解产物苦味形成机理及其强度的影响因素、脱除苦味的方法与机理以及水解产物中活性与功能物质的分离、提取方法等方面的研究进展进行了综述,并对存在的问题与今后的研究方向进行了讨论与展望.     

两种人工合成生物无机化合物对水稻幼苗抗寒性的影响

在水稻幼苗一叶一心期用质量浓度分别为６ｍｇ．Ｌ＾－１的ＳＯＤ（超氧化物歧化酶）模型化合物（ｓｕｐｅｒｏｘｉｄｅ ｄｉｓｍｕｔａｓｅ ｍｏｄｅｌ ｃｏｍｐｏｕｎｄ：ＳＯＤＭＣ）和１０ｍｇ．Ｌ＾－１的含锌复合物进行叶面喷施,结果表明：两种化合物均能相应提高低温胁迫后稻苗的ＰＯＤ和ＣＡＴ活性,增加叶绿素,可溶性糖和可溶性蛋白质的含量,对冷害后幼轩     

响应面法优化高抗氧化麦芽糊精糖基化乳清浓缩蛋白的制备

为改善乳清浓缩蛋白的抗氧化活性,运用超声波辅助水浴湿热法制备麦芽糊精糖基化乳清浓缩蛋白,以褐变程度、中间产物生成量、反应后pH、铁离子还原力、DPPH自由基清除力为测试指标,通过单因素法和响应面法优化改性工艺。结果显示,在乳清浓缩蛋白浓度为30 mg·mL^-1,乳清浓缩蛋白:麦芽糊精质量比为1:5 mg·mg^-1,初始pH 11,水浴时间为7 h,水浴温度为100 ℃,超声时间为40 min,超声温度为60 ℃,超声次数为2次时最佳,测得终产物褐变0.603,中间产物0.497,反应后pH 6.51,铁离子还原力1.196,DPPH自由基清除率60.07%。乳清浓缩蛋白经麦芽糊精糖基化修饰后与未修饰的蛋白相比铁离子还原力增大2.45倍,DPPH自由基清除能力增大4.33倍。通过糖基化反应使麦芽糊精对乳清浓缩蛋白进行改性,改善了乳清浓缩蛋白的抗氧化能力。