酸乳饮料稳定性预测模型的研究

以果胶为稳定剂的调配型酸乳饮料(AMD)分别贮藏于25℃、35℃、45℃、55℃的恒温箱中,贮藏期为6个月,定期检测其理化指标(离心沉淀率、粘度、pH值、粒径)和感官指标。结果表明酸乳饮料贮藏期离心沉淀率增加、粘度降低、粒径增加,贮藏温度越高,理化指标变化越快。酸乳饮料贮藏期pH值没有发生变化,其他理化指标如离心沉淀率、粘度、粒径和感官质量显著相关。通过动力学和热力学分析,建立了以果胶为稳定剂的酸乳饮料的动力学和热力学稳定性预测模型。     

枇杷叶植物饮料悬浮稳定性和口味的优化

引用流变学原理改善枇杷叶植物饮料悬浮稳定性,以正交试验方案优化了辅料配方,制成口味优良的饮料。结果表明：澄清的枇杷叶水提液是一个复杂的多分散相系统,所含粒子颗粒(固相)大小、分散相介质(液相)粘度以及固液两相间的密度差是影响悬浮稳定性的主要因素,依Stokes定律进行改良可有效提高稳定性。枇杷叶植物饮料的口味配方为澄清的枇杷叶水提液用量70%,蔗糖6%,蜂蜜2.4%,柠檬酸0.4%,复合稠化剂0.15%,产品中含黄酮类化合物0.858～0.987 mg/L,氨基酸108～115 mg/L,可溶性糖210～230 mg/L。     

花生蛋白粉溶液流变学特性及功能性的研究

用旋转粘度计对花生蛋白粉溶液的流变学特性进行了研究。探讨了不同花生蛋白浓度、ｐＨ、温度对其溶解性、粘度、起泡性、持水性的影响。实验结果表明,当ｐＨ在４．２～５．３范围内为其等电点,此时花生蛋白粉的溶解性、粘度、起泡性、持水性最低,在其两侧这些特性逐渐增强;随着温度升高花生蛋白粉的粘度、持水性下降,而起泡性增加;当温度超过７０℃时,为花生蛋白溶液大幅度变性的临界温度,其溶解度显著下降,３％花生蛋白粉溶液的起泡性最高。花生蛋白粉的粘度随浓度增大而增大,为非牛顿型流体,具有剪切稀化现象     

柱花草种子超干贮藏的效果及其遗传稳定性

柱花草是一类优良的热带豆科牧草,它主要以种子繁殖。超干贮藏是一项节能、简便、有效的种子贮藏技术。为了研究柱花草种子超干贮藏的效果及其对遗传的影响,该研究以贮藏10 a的热研5号柱花草种子为材料,对种子超干、?20℃和常温（25～35℃）贮藏的效果进行比较,研究超干长期贮藏对种子发芽率、生活力、植物物候期、形态特征、农艺性状及遗传稳定性的影响。含水率为3.17%的超干种子贮藏10 a、含水率为8.70%的种子分别在?20℃和常温（25～35℃）贮藏10 a后,其发芽势分别为77.9%、71.3%、18.5%,活力指数分别为60.10、50.79、4.98;超干处理与?20℃贮存10 a的处理发芽势和活力指数之间的差异显著（P<0.05）,与常温贮存10 a的处理之间的差异极显著（P<0.01）,结果表明柱花草种子超干长期贮藏效果好。通过植物形态特征观察和扩增片段长度多态性（amplified fragment length polymorphism,AFLP）分子技术检测分析,柱花草种子超干贮藏不会引起种苗在植物形态表型变化和AFLP分子水平上的遗传变异。研究结果将为柱花草种子超干贮藏提供数据参考。     

压缩过程影响草捆形态稳定性的流变学试验研究

草捆的形态稳定性是衡量其质量的主要指标之一。目前常用的方捆机所生产的产品在不同程度上仍存在着草捆形状和尺寸不规范、外型和尺寸不稳定以及散捆率较高等问题。草物料属于粘弹性物料,在外力作用下所产生的变形由永久性变形和可恢复变形组成,而可恢复变形所产生的变形恢复力与草捆的密度和应力松弛有关。当草捆的密度不均匀时将引起草捆的不同部位所产生的变形恢复力出现差异,这是引起草捆形态不稳定的根源。该文在实际压捆生产条件下对不同物料进行试验,应用流变学的理论,研究压缩过程中由于喂入不均匀引起的草片上、下截面变形恢复力的变化规律和差异,以及应力松弛对变形恢复应力的影响,建立相应的数学模型,并为压捆机的设计和实际生产提供依据。     

不同品种绿豆的品质及饮料加工特性研究

为研究绿豆品种品质差异并从中筛选适宜饮料加工的优良品种,本研究选取16个国内主栽绿豆品种,研究了品种的营养组成及制成饮料的营养、感官、稳定性等指标,并对原料与产品指标间的关系进行了相关性分析。结果表明,国产绿豆品种间的营养与加工品质特性存在不同程度的差异,绿豆原料组成中粗脂肪含量虽然较低,平均仅为1.33%,但变异系数较大,CV达到38.31%;淀粉、蛋白质平均含量分别达50.23%和27.08%,但品种间差异较小,CV仅4.53%和6.86%。不同绿豆品种所制备的饮料中,感官评分最高的为中绿1号(92分)。相关性分析结果显示,饮料中蛋白含量由原料中粗蛋白含量决定,两者呈极显著正相关(r=0.937**)。根据营养成分、稳定性和感官评价等指标,筛选出适合制作饮料的绿豆品种有:中绿1号、冀绿7号和白绿8号。     

蓝莓饮料花青素稳定性研究

以蓝莓饮料中花青素的稳定性为指标,研究不同杀菌方式和包装的透光程度对蓝莓饮料中花青素稳定性的影响。结果表明,蓝莓原汁添加量200g·L~(-1),蔗糖添加量70g·L~(-1),柠檬酸添加量1.1g·L~(-1),柠檬酸钠添加量0.3g·L~(-1)时,蓝莓饮料的p H较稳定,适口性较好。采用高温瞬时杀菌(121℃,10s)、常压下100℃杀菌12min后灌装和灌装后100℃杀菌14min的杀菌方式,花青素保留率分别为83.20%、78.21%、80.83%。在全标(瓶体遮盖率96%)、半标(瓶体遮盖率60%)和裸标(瓶体遮盖率0)3种包装方式下,花青素保留率分别为91.58%、89.15%、86.16%。因此,在高温瞬时杀菌(121℃,10s)和全标包装条件下贮存,有利于维持花青素的稳定性。本研究为蓝莓饮料的生产及贮存提供了参考。     

燕麦β-葡聚糖的流变学特性研究

该文主要探讨了燕麦β-葡聚糖溶液的流体流变学性能和黏弹性能及其相关影响因素,为燕麦β-葡聚糖在食品增稠和食品凝胶领域的应用提供理论依据。以中国山西产燕麦为原料提取制备燕麦β-葡聚糖产品,采用动态流变仪测定动态黏度和黏弹性能指标,利用计算机拟合牛顿幂律方程和Maxwell方程,系统考察了β-葡聚糖浓度、分子量、温度等因素对燕麦β-葡聚糖流体流变性能和黏弹性能的影响。结果表明,燕麦β-葡聚糖溶液黏度随剪切速率的增高而逐渐降低,表现为典型的剪切稀化型非牛顿流体;当溶液浓度从0.1%增加到1%时,其对应牛顿幂律方程的流动指数n从0.998降低至0.842,流体的剪切稀化行为增强;燕麦β-葡聚糖溶液黏度与其分子量成正比,与溶液温度成反比;在相同浓度下,燕麦β-葡聚糖分子量越大则其流体牛顿幂律方程的流动指数n越小;与中性溶液相比,弱酸性或弱碱性环境均可导致β-葡聚糖溶液黏度的下降;燕麦β-葡聚糖的黏弹性能受β-葡聚糖浓度、分子量和体系温度的影响。随着燕麦β-葡聚糖浓度的增加和分子量的增大,其流体的黏性行为特征减少而弹性行为特征增强;随着流体温度升高,燕麦β-葡聚糖流体的黏性和弹性行为均逐渐减弱。     

甜高粱茎秆汁液成分分析及浓缩贮藏的试验研究

为提高甜高粱茎秆汁液制取燃料乙醇的原料利用率,延长甜高粱茎秆及其汁液贮藏期限,测定了辽甜1号、早熟1号、醇甜2号三个甜高粱品种茎秆及其汁液的营养成分,采用浓缩法对甜高粱茎秆汁进行了贮藏试验.结果表明,三个品种都含有丰富的糖分,可以为酵母菌发酵制取酒精提供良好的碳源,但总氮和某些矿物质元素(如:Fe3 )不能满足酒精酵母的营养需要;甜高粱茎秆汁浓缩至4～5倍时,可以抑制汁液中大多数微生物的活动,使其中糖分不受损失;在试验设定的真空浓缩工艺条件下(55～60℃,0.15 Mpa)甜高粱茎秆汁中产酸微生物或水解酶类仍保持活性,使得还原糖占总糖的比率随贮藏时间延长而升高,这有利于酒精发酵.     

黄土高原雨养区坡面土壤蓄水量时间稳定性

分析区域土壤蓄水量（SWS）时间稳定性为准确预测土壤墒情提供了理论保障,同时为植被恢复和重建工作提供帮助。利用中子仪获得黄土高原雨养区六道沟流域坡面2005年10月至2006年9月间剖面SWS,通过时间稳定性分析,研究该区域SWS的时间稳定性特征。结果表明：不同月份SWS均表现为中等变异,干旱条件下的变异系数比湿润条件下小。0～4 m的SWS累积概率比其他土层的变化小,平均相对偏差的变化范围（-39%～53%）及标准差（5.6%）较小,spearman秩相关系数均达到0.8以上且呈现出极显著相关,通过时间稳定性分析可以初步确定研究区平均SWS的代表性测点。SWS变化较大时,spearman秩相关系数较小,而SWS变化较小时,spearman秩相关系数较大。spearman秩相关系数为分析该区域SWS的时间稳定性提供了便捷途径。     

基于流变学法研究容重和含水率对土壤结构力学稳定性的影响

土壤结构力学稳定性不仅与土壤质量和肥力密切相关,而且还与农业器具设计和农业水土工程建设紧密联系。该研究以黄土高原广泛分布的塿土和黄绵土为研究对象,采用振幅扫描试验模拟振荡荷载过程,研究土壤容重和含水率对土壤结构力学稳定性的影响。结果表明：1）随土壤容重的增加,土粒间接触点增多,使得剪切强度参数：线性黏弹区的剪切应力和储能模量均增加,土壤结构强度增强;黄绵土屈服点的剪切应变和塿土的积分z随容重增加先增大后降低,表明土壤颗粒存在一个最稳定的排列组合方式。同时,剪切强度参数对土壤容重的响应更为敏感。2）随含水率的增加,土壤颗粒间黏聚力和摩擦力降低,剪切强度参数：线性黏弹区的剪切应力、屈服点的剪切应力、最大剪切应力均降低,土壤结构强度降低;当剪切应变在线性黏弹区时,塿土的弹性随含水率的增加而增加,而较大的剪切应变下的塿土的弹性和黄绵土总的弹性随含水率增加均降低。3）对比2种土壤,因塿土的黏粒、有机质、阳离子交换量、比表面积等较高,增加了土粒间的胶结强度,使得塿土的弹性和剪切强度较高,而黄绵土结构更具脆性。该研究结果表明基于流变仪中的振幅扫描测试所获取的流变学参数能够定量表征土壤细观结构力学稳定性,为进一步深入认识土壤微观力学特性提供了丰富的评价参数。     

Time stability of soil water storage measured by neutron probe and the effects of calibration procedures in a small watershed

The knowledge of soil water storage (SWS) of soil profiles is crucial for the adoption of vegetation restoration practices. With the aim of identifying representative sites to obtain the mean SWS of a watershed, a time stability analysis of neutron probe evaluations of SWS was performed by the means of relative differences and Spearman rank correlation coefficients. At the same time, the effects of different neutron probe calibration procedures were explored on time stability analysis, mean SWS estimation, and preservation of the spatial variability of SWS. The selected watershed, with deep gullies and undulating slopes which cover an area of 20 ha, is characterized by an Ust-Sandiic Entisol and an Aeolian sandy soil. The dominant vegetation species are bunge needlegrass (Stipa bungeana Trin.) and korshinsk peashrub (Caragana Korshinskii kom.). From June 11, 2007 to July 23, 2008, SWS of the top1 m soil layer was evaluated for 20 dates, based on neutron probe data of 12 sampling sites. Three calibration procedures were employed: type I, most complete, with each site having its own linear calibration equation (TrE); type II, with TrE equations extended over the whole field; and type III, with one single linear calibration curve for the whole field (UnE) and also correcting its intercept based on site specific relative difference analysis (RdE) and on linear fitting of data (RcE), both maintaining the same slope. A strong time stability of SWS estimated by TrE equations was identified. Soil particle size and soil organic matter content were recognized as the influencing factors for spatial variability of SWS. Land use influenced neither the spatial variability nor the time stability of SWS. Time stability analysis identified one site to represent the mean SWS of the whole watershed with mean absolute percentage errors of less than 10%, therefore, this site can be used as a predictor for the mean SWS of the watershed. Some equations of type II were found to be unsatisfactory to yield reliable mean SWS values or in preserving the associated soil spatial variability. Hence, it is recommended to be cautious in extending calibration equations to other sites since they might not consider the field variability. For the equations with corrected intercept (type III) , which consider the spatial variability of calibration in a different way in relation to TrE, it was found that they can yield satisfactory means and standard deviation of SWS, except for the RdE equations, which largely leveled off the SWS values in the watershed. Correlation analysis showed that the neutron probe calibration was linked to soil bulk density and to organic matter content. Therefore, spatial variability of soil properties should be taken into account during the process of neutron probe calibration. This study provides useful information on the mean SWS observation with a time stable site and on distinct neutron probe calibration procedures, and it should be extended to soil water management studies with neutron probes, e.g., the process of vegetation restoration in wider area and soil types of the Loess Plateau in China.     

Effects of tillage on soil microrelief, surface depression storage and soil water storage

Conservation of soil water is an important management objective for crop production in the semi-arid tropics where droughts are persistent. Identification of the best tillage methods to achieve this objective is thus imperative. The integrated effects of conservation tillage on soil micro topography and soil moisture on a sandy loam soil were evaluated. The field experiment consisted of five tillage treatments, namely tied ridging (TR), no till (NT), disc plough (DP), strip catchment tillage (SCT) and hand hoe (HH). Data measured in the field included soil moisture content, surface roughness, infiltration and sorghum grain yield. A depth storage model was used to estimate depression storage TR treatment and the higher the surface roughness, the greater the depression storage volume. Regression analysis showed that random roughness decreased exponentially with increase in cumulative rainfall. Higher moisture contents were associated with treatments having higher depressional storage. Infiltration rate was significantly higher in the tilled soils than the untilled soils. The DP treatment had the highest cumulative infiltration while NT had the lowest. The Infiltration model which was fitted to the infiltration data gave good fit. Grain yield was highest in TR and least in NT, whereas DP and HH had similar yields.     

蚯蚓粪与椰糠配施对盐渍土的改良效应

选用蚯蚓粪和椰糠为改良剂,不同浓度人工海水淹泡的土壤为改良对象,通过盆栽试验种植空心菜研究未施肥、单施蚯蚓粪、单施椰糠、蚯蚓粪+椰糠不同比例组合配施对盐渍土的改良效应.结果表明:(1)对于20％、60％和100％人工海水淹泡的盐渍土,蚯蚓粪与椰糠分别按1:2.5、3:2.5和3:3.5配施种植空心菜效果最好,空心菜平均...     

Augmenting soil water storage using uncharred switchgrass and pyrolyzed biochars

Biochar is an amendment that can augment soil water storage; however, its projected cost per ton could be financially limiting at field application scales. It may be more monetarily convenient if an alternate amendment was available that could deliver similar soil enhancements. We compared two switchgrass biochars pyrolyzed at 250 and 500 °C with raw switchgrass (uncharred) on moisture storage and bulk density changes in a Norfolk loamy sand (fine‐loamy, kaolinitic, thermic Typic Kandiudult). Amendments were mixed into triplicate pots at 20 g/kg along with untreated controls. Soils were laboratory incubated at 10% moisture content (w/w) for 118 days, and the pots were irrigated three times with 1.3 pore volumes of deionized water every 30 days. Soil bulk densities were recorded before each irrigation event. Assessment of alterations in soil water storage was examined through cumulative water evaporative losses from incubation day 0 to day 33 and by monitoring soil water contents for 13 consecutive days past each irrigation event. Rankings of soil water evaporative losses were as follows: uncharred switchgrass ≤ switchgrass (500 °C) ≤ switchgrass (250 °C) < control. After the first irrigation event, uncharred switchgrass amendment significantly increased moisture storage compared with soil treated with biochar and the control. While all amendments increased water storage relative to the control, uncharred switchgrass delivered equivalent, if not slightly better, moisture storage improvements compared with the two switchgrass biochars. Uncharred switchgrass would likely not be as effective over the long term (years to decades) as pyrolyzed biochars, due to greater degradation of uncharred material.     

Rewetting of milled peat: laboratory investigation of water movement and storage

Abstract. Air- dried milled peat (0.45 g g^-1 wet weight basis) is used as an electricity generating fuel in Ireland. It is stored on peat bogs in triangular section stockpiles. These stockpiles comprise of milled peat of varying types, classified by poured density, and are subject to rewetting during storage which incurs an economic penalty. A water applicator was constructed to study the nature of rewetting mechanisms in laboratory-scale milled peat stockpiles, and to assess some potential protection strategies. Results indicated that there were few consistent short-term mechanisms linked to milled peat type. Over a longer period, low density milled peat stored most water, high density milled peat generated most runoff from the stockpile surface, and under certain conditions, throughflow was very important in all milled peat types. The industrial implications of the findings conclude that protection strategies should focus on lower density stockpiles.     

基于LF-NMR研究包装方式和温度对鲶鱼片保水性的影响

为了考察贮藏过程中包装方式和温度对鲶鱼片保水性的影响,该试验将新鲜鲶鱼片分别经空气包装(air-package,AP)、真空包装(vacuum package,VP)和气调包装(modified atmosphere package,MAP,60%CO_2+40%N_2)后贮藏于4℃和-0.7℃的冷库中,于贮藏第0、1、4、7、10、15、20、30天测定鲶鱼片的pH值、蒸煮损失率、离心失水率等指标变化,利用低场核磁共振(low-field nuclear magnetic resonance,LF-NMR)技术测定鲶鱼片的水分弛豫时间(T22)、弛豫面积(P22)和质子密度成像(magnetic resonance imaging,MRI),并利用扫描电镜(scanning electron microscopy,SEM)观察鲶鱼片肌纤维结构的变化,对鲶鱼片贮藏过程中保水性变化及原因进行综合判断。结果显示,随着贮藏时间的延长,各组鲶鱼片保水性均呈下降趋势,表现为蒸煮损失率和离心失水率比新鲜鲶鱼片增加,弛豫时间T22和弛豫面积P22降低。相比较而言,冰温气调(-0.7°C-MAP)样品的保水性下降最为缓慢,是鲶鱼片品质保持的较佳贮藏方法。皮尔逊相关系数分析表明弛豫面积P22与贮藏时间、蒸煮损失率及离心失水率显著相关(P0.05);MRI结果显示,鲶鱼片的水分在贮藏过程中逐渐从肌纤维内部渗出,集聚在肌束膜上;SEM表明肌纤维细胞结构发生改变,这可能是引起保水性下降的根本原因。综上所述,该研究证明利用LF-NMR技术可快速表征鲶鱼肉保水性的变化,研究结果为选择鲶鱼片的较佳贮藏条件提供了理论依据。     

蓄水坑灌单坑土壤水分运动有限元模拟

为了合理设计干旱地区果树蓄水坑灌,该文根据土壤水动力学原理和单坑入渗土壤水分运动特点,建立了单坑二维土壤水分运动数学模型,采用有限单元法求解,并根据质量守恒原理建立了确定坑内水位变化过程的数学模型。室内单坑入渗土壤水分运动验证试验结果表明坑内水位变化过程、土壤含水率、湿润锋的实测值与模型计算值吻合较好,说明所建立的单坑二维土壤水分运动数学模型和坑内水位变化过程数学模型是正确的,采用有限元法对其求解是可行的,该模型可用于模拟单坑土壤水分分布规律。