产脂肪酶乳酸菌对羊肉发酵香肠脂肪酸的影响

脂肪酶在肉制品加工中会影响风味物质的积累与产生,发酵肉制品生产中常通过添加产脂肪酶菌株来改善制品的风味。通过乳酸菌在代谢过程中分解三丁酸甘油酯产生透明圈的大小,判断菌株产脂肪酶的活力,同时结合脂肪酶基因Lip0069、Lip0893表达量的变化情况,筛选产脂肪酶能力较高的乳酸菌,研究该菌株对发酵香肠中脂肪酸的影响。结果表明,瑞士乳杆菌TR1-1-3代谢过程中产酶活力最强,编码脂肪酶的基因Lip0069、Lip0893表达量最高。发酵香肠试验组共检测到34种脂肪酸,其中饱和脂肪酸(Saturated Fatty Acids, SFA)16种、单不饱和脂肪酸酸(Monounsaturated Fatty Acids, MUFA)9种和多不饱和脂肪酸(Polyunsaturated FattyAcids, PUFA)9种。含量较高的MUFA主要是油酸(C18:1C9)、棕榈油酸(C16:1)、十七碳烯酸(C17:1)、肉豆蔻烯酸(C14:1)。含量较高的PUFA主要是亚油酸(C18:2C9)、亚麻酸(C18:3N6、C18:3N3)、花生四烯酸(C20:4)、二十二碳六烯酸(C22:6,Docosahexaenoic Acid,DHA)。TR1-1-3和ZF22组发酵2 d后,MUFA的含量明显上升(P0.05)。12 d时5个试验组MUFA的含量均达到最高,其中TR1-1-3增长比例最高,且与ZR、M组差异显著(P0.05)。TR1-1-3组发酵2 d后PUFA的含量发生了明显的变化(P0.05),12 d时TR1-1-3组PUFA的含量增长了54.17%,且与其他试验组相比差异显著(P0.05)。乳酸菌TR1-1-3可降低产品中SFA在脂肪酸中所占比例,明显加快MUFA、PUFA的增加速度及其含量,可为研究改善香肠脂肪特性提供良好的前景。     

农用无过载离心泵水力性能与内部流动计算

试验研究证明水力效率偏低(比普通泵约低2％～8％)是无过载离心泵效率较低的主要原因。为了提高水力性能,对无过载离心叶轮内部流动进行了数值模拟。采用IKhalil等人的计算方法,在子午面上用势流计算确定流面位置,回转面的计算则采用了完全粘性的湍流场计算方法。结果表明,无过载离心叶轮内部流动既没有出现分离,也没有明显的尾迹区存在。因此,水力效率偏低系由叶片包角过大、流道狭长、沿程水力摩擦损失过大所致。     

动定刀同轴水稻秸秆切碎还田装置结构设计与试验

针对中国南方稻田留茬高、土壤黏重,油菜栽种复式作业机耕整地作业部件易缠草、壅泥,影响作业质量和油菜出苗的难题,提出了将田间稻秸秆收集切碎并绕过耕作部件后均匀覆盖于播种行行间的种植方法,研发了多功能油菜覆草直播播种机,围绕该机器设计了一种动刀与定刀及风送叶片同轴安装的稻秸秆切碎装置,并分别对稻秸秆的"站秆"和"残茬"进行切碎台架试验。结果表明:喂入压辊转速、动刀转轴转速、动定刀间隙3个影响因素对切碎长度合格率、功耗影响显著;对"站秆"和"残茬"切碎的各因素取值为:喂入压辊转速399.2、401.64 r/min,动刀转轴转速968.12、977.23 r/min,动定刀间隙0.52、0.49 mm时,稻秸秆切碎合格长度率为95.78%、96.98%,功率损耗为3.09、2.68 k W。经整机田间试验,该装置的秸秆田间覆盖效果达到油菜种植农艺要求。该研究为多功能油菜覆草直播播种机产业化提供了技术参考。     

苗盘钵苗自动识别及控制装置的设计与试验

针对全自动移栽机在田间作业中,因苗盘的钵苗格缺苗而导致的漏栽问题,研制了一种苗盘钵苗自动识别及控制试验装置。该试验装置采用单苗爪取苗,步进电机驱动钵苗盘纵向和横向移动,光电传感器作为钵苗识别装置,由可编程逻辑控制器(programmable logic controller,PLC)为控制核心,触摸屏作为人机界面,可适应不同规格的苗盘参数,可选择对该装置进行手动或自动控制。试验结果表明,该装置可有效地对钵苗格是否缺苗进行自动识别,并控制苗盘输送装置,使缺苗的钵苗格快速跳过取苗爪,提高取苗爪的抓取效率,以降低漏栽率;相对于没有采用钵苗自动识别的移栽模式,该系统漏栽率整体降低了约12%。该研究可为全自动移栽机的进一步自动化智能化设计提供参考。     

基于水温对肉牛生长性能影响的冬季恒温饮水系统优选

为缓解西北地区拴系肉牛在冬季产生的冷应激,提高肉牛生长性能,研究根据连通器原理设计恒温饮水系统,为牛只提供温水。试验选取西门塔尔牛作为试验牛,对饮水器内水温、肉牛的饮水行为、生理以及日增质量进行测定。试验结果表明:恒温饮水系统能为处理组牛只提供17.69℃的温水,处理组牛的日增质量为1.53 kg/(d·头),较对照组提高0.36 kg/(d·头),差异极显著(P0.01)。在处理组中,牛只饮用16~18℃的温水表现出更多的饮水次数和更好的增重效果(日增质量达到(1.69±0.44)kg/(d·头))。饮水后牛只瘤胃处体表温度处理组比对照组高3.29℃,差异极显著(P0.01)。结果表明,在拴系肉牛舍中采用这种恒温饮水系统能够有效改善肉牛因冬季饮用冷水造成的冷应激,并能显著提高肉牛生长性能,具有技术和经济可行性。     

不同耕作方式对小麦旗叶光合特性和水分利用效率的影响

在豫西丘陵旱作条件下，对少耕、免耕覆盖、深松覆盖、一年两熟和传统耕作5种耕作处理的冬小麦旗叶光合、荧光特性和产量、水分利用效率进行了研究，结果表明：免耕覆盖和深松覆盖灌浆中后期小麦旗叶叶绿素和类胡萝卜素含量明显高于传统耕作，且有较高的叶绿素a和叶绿素b的比值和叶绿素和类胡萝卜素的比值；开花期免耕覆盖和深松覆盖光化学猝灭系数、非光化学猝灭系数和光化学效率值较传统耕作高，光抑制程度较传统耕作小；灌浆中期免耕覆盖和深松覆盖净光合速率略低于传统耕作，分别为传统耕作的96.4%和99.7%，但差异不显著。免耕覆盖和深松覆盖小麦生育期间耗水量较高，产量和水分利用效率显著提高，与传统耕作相比，产量增加19.3%和9.4%，水分利用效率提高17.5%和8.5%。     

Sweet and sour cherry phenolics and their protective effects on neuronal cells

The identification of phenolics from various cultivars of fresh sweet and sour cherries and their protective effects on neuronal cells were comparatively evaluated in this study. Phenolics in cherries of four sweet and four sour cultivars were extracted and analyzed for total phenolics, total anthocyanins, and their antineurodegenerative activities. Total phenolics in sweet and sour cherries per 100 g ranged from 92.1 to 146.8 and from 146.1 to 312.4 mg gallic acid equivalents, respectively. Total anthocyanins of sweet and sour cherries ranged from 30.2 to 76.6 and from 49.1 to 109.2 mg cyanidin 3-glucoside equivalents, respectively. High-performance liquid chromatography (HPLC) analysis revealed that anthocyanins such as cyanidin and peonidin derivatives were prevalent phenolics. Hydroxycinnamic acids consisted of neochlorogenic acid, chlorogenic acid, and p-coumaric acid derivatives. Glycosides of quercetin, kaempferol, and isorhamnetin were also found. Generally, sour cherries had higher concentrations of total phenolics than sweet cherries, due to a higher concentration of anthocyanins and hydroxycinnamic acids. A positive linear correlation (r2 = 0.985) was revealed between the total anthocyanins measured by summation of individual peaks from HPLC analysis and the total anthocyanins measured by the pH differential method, indicating that there was in a close agreement with two quantifying methods for measuring anthocyanin contents. Cherry phenolics protected neuronal cells (PC 12) from cell-damaging oxidative stress in a dose-dependent manner mainly due to anthocyanins. Overall results showed that cherries are rich in phenolics, especially in anthocyanins, with a strong antineurodegenerative activity and that they can serve as a good source of biofunctional phytochemicals in our diet.     

The adoption of annual subsoiling as conservation tillage in dryland maize and wheat cultivation in northern China

Soil compaction caused by random traffic or repetitive tillage has been shown to reduce water use efficiency, and thus crop yield due to reduced porosity, decreased water infiltration and availability of nutrients. Conservation tillage coupled with subsoiling in northern China is widely believed to reduce soil compaction, which was created after many years of no-till. However, limited research has been conducted on the most effective time interval for subsoiling, under conservation tillage. Data from conservation tillage demonstration sites operating for 10 years in northern China were used to conduct a comparative study of subsoiling interval under conservation tillage. Three modes of traditional tillage, subsoiling with soil cover and no-till with soil cover were compared using 10 years of soil bulk density, water content, yield and water use efficiency data. Cost benefit analysis was conducted on subsoiling time interval under conservation tillage. Yield and power consumption were assessed by based on the use of a single pass combine subsoiler and planter. Annual subsoiling was effective in reducing bulk density by only 4.9% compared with no-till treatments on the silty loam soils of the Loess plateau, but provided no extra benefit in terms of soil water loss, yield increase or water utilization. With the exception of bulk density, no-till and subsoiling with cover were vastly superior in increasing water use (+10.5%) efficiency and yield (+12.9%) compared to traditional tillage methods. Four years of no-till followed by one subsoiling reduced mechanical inputs by 62%, providing an economic benefit of 49% for maize and 209% for wheat production compared to traditional tillage. Annual subsoiling reduced inputs by 25% with an increased economic benefit of 23% for maize and 135% for wheat production. Yield and power consumption was improved by 5% and 20%, respectively, by combining subsoiling with the planting operation in one pass compared with multipass operations of subsoiling and planting. A key conclusion from this is that annual subsoiling in dryland areas of northern China is uneconomical and unwarranted. Four years of no-till operations followed by 1 year subsoiling provided some relief from accumulated soil compaction. However, minimum soil disturbance and maximum soil cover are key elements of no-till for saving water and improving yields. Improved yields and reduced farm power consumption could provide a significant base on which to promote combined planter and subsoiling operations throughout northern China. Further research is required to develop a better understanding of the linkages between conservation tillage, soil quality and yield, aimed at designing most appropriate conservation tillage schemes.     

Effects of rake angle of chisel plough on soil cutting factors and power requirements: A computer simulation

A computer simulation was conducted to predict the effects of rake angle of a chisel plough and soil bulk density on angle of soil failure plane, rupture distance, width of side crescent, frictional, overburden, cohesion and adhesion soil cutting factors, draft forces and drawbar power requirements. The experimental work was carried out in two locations. Soil of the first location was sandy clay with the soil bulk densities of 1.75 and 1.70 g/cm³ for firm and loose soil conditions, respectively, with an angle of internal friction of 30° and a surface friction angle of 20°, cohesion of 2.5 kN/m² and adhesion of 1.2 kN/m². Soil of the second location was clay loam with the soil bulk densities of 1.65 and 1.50 g/cm³ for firm and loose soil conditions, respectively, with an angle of internal friction of 34° and a surface friction angle of 23°, cohesion of 2.4 kN/m² and adhesion of 1.14 kN/m². The prediction showed that the angle of failure plane found to decrease with the rake angle. The rupture distance decreased with the rake angle from 15° to 55° and then increased as the rake angle increased over 55°. The width of the side crescent increased as the rake angle increased and the maximum value and the minimum value were recorded at 75° and at 15°. Values of frictional and overburden factors decreased as rake angle increased. The maximum and minimum values were recorded at 15° and 75°, respectively. The values of cohesion factor increased as rake angle increased. The maximum value was recorded at rake angle of 75° and the minimum value was recorded at rake angle of 15°. Adhesion factor was found to change inversely with the rake angle from 15° to 55° and then to change directly with the rake angle over 55°. The draft force decreased with the rake angle and reached its minimum value at 45° rake angle. Over 45°, the draft force increased and reached its maximum value at 75° rake angle. The draft increased with soil bulk density. The power required for moving the plough recorded the maximum value at rake angle of 15°, while the minimum value was recorded at 55° rake angle. The values of power increased with decrease of soil bulk density. The predicted values demonstrated some deviations from the experimental values of the draft force and the drawbar power.     

典型黑土pH值变化对微量元素有效态含量的影响研究

采用室内培养实验的方法 ,控制典型黑土样品的酸碱度值 ,探讨典型黑土中 Cu、Zn和 Mn等微量元素有效态含量与 p H值的关系。结果表明 :p H值变化 0 .5个单位左右 ,有效态铜含量变化约 0 .5～ 1倍 ;有效态锰含量变化约 3～ 5倍 ;有效态锌含量变化 9～ 1 5倍之多。说明精确掌握土壤的酸碱度值对于土壤诊断、微肥的合理施用、提高作物产量和实现土地的可持续利用都具有重要的理论与实践意义