基于计算机视觉的鸡蛋新鲜度无损检测

对鸡蛋的新鲜度、贮藏期进行无损检测,在鸡蛋生产、流通、加工领域具有重要意义。该文进行了鸡蛋新鲜度（哈夫值）常规指标在一定温度条件下随贮藏时间变化的试验,采用高分辨率的工业化数字摄像头,以冷光源背向照明方式（照度为10 000 Lx）获取数字图像,并提取了鸡蛋的图像特征蛋黄指数和气室指数。建立了鸡蛋新鲜度与蛋黄指数、贮藏时间与鸡蛋新鲜度、贮藏时间与蛋黄指数和气室指数的关系模型。得知鸡蛋新鲜度与蛋黄指数呈线性相关性,经检验实测值与预测值平均相对误差为6%;贮藏时间与鸡蛋新鲜度以及贮藏时间与鸡蛋蛋黄指数、鸡蛋气室指数均具有二次函数关系,经检验实测值与预测值绝对误差不超过2 d。结果表明基于计算机视觉技术、采用背向照明方式采集的鸡蛋的透射图像得到鸡蛋的蛋黄和气室的图像信息,可以预测鸡蛋的新鲜度和贮藏期。     

贮藏环境对鸡蛋新鲜度的影响及鲜鸡蛋货架期预测模型构建研究

为了比较不同贮藏环境条件对鸡蛋新鲜度的影响,将鲜鸡蛋置于不同贮藏温度(5、10、20、30℃)和光照/避光环境条件下,测定鸡蛋质量、哈氏单位、气室、蛋黄系数、浓蛋白含量、蛋白pH值、蛋黄pH值、挥发性盐基氮含量等新鲜度品质指标,分析品质指标与贮藏环境之间的相关性规律,并构建与应用鸡蛋货架期预测模型。结果表明,随着贮藏时间延长,低温(5℃、10℃)贮藏的鲜鸡蛋和避光条件下贮藏的鲜鸡蛋品质优于高温(20℃、30℃)贮藏和光照环境条件下贮藏的鲜鸡蛋,且贮藏温度与鲜鸡蛋质量、哈氏单位、浓蛋白含量、挥发性盐基氮含量等呈显著负相关(P0.01),而与气室变化呈显著正相关(P0.01)。根据贮藏过程中品质变化规律构建的鸡蛋货架期预测模型,为今后鲜鸡蛋贮藏及运输过程中品质分级和下架提供理论依据。     

鸡蛋透射光图像形态特征与其新鲜度的相关关系

该文结合鸡蛋内容物自身结构特点,研究鸡蛋图像形态特征与新鲜度的相关关系,快速无损检测新鲜度.用机器视觉装置获取鸡蛋图像,通过实验检测对应鸡蛋新鲜度(哈夫单位).采取有效图像处理,使蛋黄和气室特征显现.选取蛋黄与整蛋面积比值、气室高度与整蛋长轴长度比值作为形态特征参数,建立两特征值与新鲜度的关系模型,经检验通过两特征模型判别鸡蛋新鲜度的正确率分别为91%、93%.研究结果表明,鸡蛋图像蛋黄面积比、气室高度比随着新鲜度的降低而逐渐增大.     

速冻莲藕片贮藏过程中品质变化动力学模型

为了探寻贮藏温度对速冻莲藕片品质的影响及预测其货架期,该文研究在贮藏温度?5、?15和?25℃条件下,速冻莲藕片维生素C、色泽和硬度随着贮藏时间的变化,建立了3个指标变化动力学模型。结果表明:随着贮藏温度的升高,速冻莲藕片维生素C、色泽和硬度的变化速率逐渐增加,?5℃条件下贮藏的速冻莲藕片品质快速下降,?15和?25℃条件下贮藏前期莲藕片品质下降不显著(P0.05),随着时间的延长,?25℃部分玻璃态贮藏的莲藕片品质最佳;不同贮藏温度下速冻莲藕片维生素C和硬度变化符合一级反应,总色差和亮度变化符合零级反应,速冻莲藕片维生素C、色泽和硬度反应速率常数符合Arrhenius方程,并建立莲藕片货架期动力学模型,通过对其验证发现模型拟合度良好(R20.9),能预测速冻莲藕片贮藏期各品质指标变化和不同温度下的货架期寿命。研究结果可为速冻莲藕片低温贮藏品质变化和货架寿命预测提供理论依据。     

鲜带鱼不同贮藏温度的货架期预测模型（简报）

为了研究鲜带鱼在冷链流通中的品质变化与货架期,通过不同温度下的贮藏试验研究了鲜带鱼的货架期预测模型。将鲜带鱼贮藏在268、273、278、283和293 K条件下,测定了鲜带鱼的总菌落数、总挥发性盐基氮（T-VBN）、鲜度指标（K值）与感官品质指标的变化。在Arrhenius动力学方程基础之上,建立了菌落总数、总挥发性盐基氮和鲜度指标（K值）与贮藏时间及贮藏温度之间的动力学模型。试验表明一级化学反应动力学模型和Arrhenius方程对总菌落数、总挥发性盐基氮（T-VBN）及鲜度指标（K值）的变化具有较高的拟合精度。菌落总数变化预测模型中的活化能（EA）及速率常数（k0）分别为：71.26 kJ/mol和3.987×1013,挥发性盐基氮变化的活化能（EA）及速率常数（k0）分别为：68.86 kJ/mol和2.159×1012,鲜度指标（K值）变化的活化能（EA）及速率常数（k0）分别为：41.26 kJ/mol和2.539×107。结果表明,鲜带鱼的总菌落数、总挥发性盐基氮（T-VBN）、鲜度指标（K值）随着贮藏时间的延长而增加,且随着贮藏温度的升高而增加迅速,其感官品质指标随着贮藏时间的延长而下降,且随着贮藏温度的升高而下降迅速。该试验建立的带鱼货架期预测模型所获得货架期预测值准确率达到±10%以内,可根据菌落总数、T-VBN值及K值在268～293 K范围内,对带鱼的剩余货架期进行预测。     

基于乙醇质量分数的草莓果实腐烂指数预测模型

为应用电子鼻快速检测草莓物流过程中果实腐烂状况,建立了一种基于乙醇质量分数的果实腐烂指数预测模型。将草莓果实贮藏于不同温度（273、278、283、288、293和298 K）下,测定其腐烂指数和乙醇质量分数的变化。首先,基于Arrhenius动力学方程建立了草莓果实乙醇质量分数与贮藏时间和温度之间的动力学预测模型;其次,基于零级反应方程式建立了腐烂指数与贮藏时间和温度之间的动力学预测模型;最后,根据果实腐烂指数和乙醇质量分数变化的线性关系,进一步建立了基于乙醇质量分数的果实腐烂指数预测模型。在275、280、285、290、295和300 K贮藏温度下对上述3个预测模型进行验证,预测的相对误差（RE）分别为0.76%、5.89% 和7.08%,预测精度较高。将基于果实乙醇质量分数的腐烂指数预测模型与传统的腐烂指数动力学预测模型进行比较,发现二者的预测精度无显著差异。因此,基于乙醇质量分数的腐烂指数预测模型可以较好地预测在273～300 K贮藏温度下草莓果实的腐烂状况,从而为应用电子鼻无损检测果实品质提供理论依据。     

植物精油抗菌乳状液涂膜对鸡蛋的保鲜效果

为了延长鸡蛋的保藏期,采用牛至、大蒜、生姜、丁香提取油分别复配成抗菌乳状液对鸡蛋进行涂膜保鲜试验,在5周的贮藏期间,通过对鸡蛋各项感官指标和内部品质指标变化的分析发现,上述植物精油乳状液保鲜剂保鲜效果均优于对照组,尤其以牛至精油乳状液与丁香精油乳状液保鲜效果最好。经牛至精油乳状液和丁香精油乳状液涂膜保鲜过的鸡蛋,在30℃,80%～90%相对湿度情况下,好蛋率为100%,失重率分别为2.824%和2.656%,蛋黄系数为0.1965和0.2129,哈夫单位为40.311和41.312。     

冰温贮藏对梭子蟹品质影响及其货架期模型的建立

为延长梭子蟹的保存期,以即死三疣梭子蟹为研究对象,以冷藏及冰藏为对照,研究冰温(272K)贮藏对梭子蟹品质的影响,并结合梭子蟹的理化指标变化和零级化学动力学模型与Arrhenius方程,建立梭子蟹货架期预测模型,对其剩余货架期进行预测。结果表明,冰温保鲜可有效缓解梭子蟹品质劣变,在贮藏过程中,总挥发性盐基氮(TVB-N)、菌落总数(TVC)及K值的变化速率均较冷藏、冰藏缓慢,货架期延长了1~2 d;建立的梭子蟹货架期预测模型具有较高的拟合精度,预测值和实测值之间的相对误差小于10%,表明该模型能够准确地预测梭子蟹在特定条件下的剩余货架期。本研究结果为冰温技术在梭子蟹保鲜中的应用及梭子蟹剩余货架期的预测提供了理论依据。     

基于介电特性与蛋黄指数回归模型的鸡蛋新鲜度无损检测

为了更准确、快速的实现鸡蛋新鲜度品质指标蛋黄指数的无损检测,基于介电特性建立了鸡蛋新鲜度无损检测模型,获取鸡蛋的蛋黄指数信息。试验以不同新鲜度鸡蛋为研究对象,采用平行极板法测量不同新鲜度鸡蛋在温度为20℃,相对湿度为72%~89%,频率为1~200 k Hz下的介电特性参数,分析鸡蛋介电特性的变化规律,并建立鸡蛋介电特性与蛋黄指数之间的数学模型。分析了鸡蛋介电特性随测量信号频率及新鲜度指标蛋黄指数的变化曲线,发现其介电参数随频率及蛋黄指数的增大而减小。构建了蛋黄指数与相对介电常数的拟合方程,鸡蛋样品的实际蛋黄指数与模型预测的蛋黄指数间的决定系数R2为0.9115,蛋黄指数的误差为±4.2%,试验结果表明:利用拟合方程预测检验鸡蛋蛋黄指数取得了较好的预测效果,为无损检测鸡蛋新鲜度提供了一种新的可行方法。     

基于电子鼻的带鱼货架期预测模型

为探索通过气味分析判断海产品贮藏品质的方法,利用电子鼻对带鱼在不同贮藏温度与贮藏时间下的挥发性气味变化进行了分析,对所获数据进行了主成分分析与货架期分析,并与理化品质指标值挥发性盐基氮（total volatile basic nitrogen,TVBN）相联系,建立了带鱼在273～283 K下的货架期预测模型。结果表明：电子鼻18个金属传感器能很好地将贮藏于273与283 K下的带鱼随着贮藏时间变化的气味进行区分。贮藏于不同温度条件下的带鱼的TVBN值与菌落总数值均随着贮藏时间的增加而增长,且均符合一级化学动力学模型（R2＞0.9）。基于电子鼻货架期分析获得的273～283 K下的气味变化结果与该温度下理化品质指标变化具有较好的对应关系,采用Arrhenius动力学模型推导公式求得带鱼在（273～283 K）温度段内TVBN的Q10（温差为10 K的货架寿命之比）值,对照该温度段下电子鼻货架期分析获得的气味变化货架期分析值,得到带鱼在该温度段内的Q10货架期预测模型,经验证,其预测误差小于20%。可根据获得的货架期预测模型对带鱼在273～283 K条件下的货架期进行预测。     

低氮和干旱胁迫对富士和秦冠生长及氮素利用的影响

【目的】以富士（Fuji）、 秦冠（Qinguan）嫁接在平邑甜茶（Malus hupehensis Rehd.）上的当年生盆栽苗为试验材料,采用砂培方法,研究了缺氮胁迫和干旱对富士和秦冠生长情况、 光合参数、 植株各部位氮磷钾含量及氮素利用效率的影响,分析比较了低氮干旱条件下富士和秦冠生长及氮素利用的差异,以期为果树生产高效肥水利用提供理论指导。【方法】试验共设四个处理: 正常氮正常水（ZZ）、 低氮正常水（DZ）、 正常氮干旱（ZG）、 低氮干旱（DG）。氮素和水分均设置两个水平,分别为正常氮（6 mmol/L NO-3-N）、 低氮（0.3 mmol/LNO-3-N）、 正常供水（保持盆中砂子相对含水量为饱和含水量的80%~85%）、 干旱处理（保持盆中砂子相对含水量为饱和含水量的60%~65%）。【结果】富士和秦冠的生物量（茎和叶）、 株高茎粗等生长指标以及光合速率、 气孔导度、 蒸腾速率均为正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）,并且相对应处理下秦冠的以上指标均高于富士;正常供水下,缺氮处理使富士、 秦冠的根冠比比正常氮处理均有所增加,富士提高了2.05%,秦冠提高了22.40%。富士和秦冠的氮、 磷、 钾含量均表现出正常氮正常水（ZZ）＞低氮正常水（DZ）＞正常氮干旱（ZG）＞低氮干旱（DG）; 氮、 钾元素含量在植株各部位的分布顺序依次是叶＞根＞茎,磷元素则是根＞叶＞茎;光合氮素利用效率（PNUE）和氮素利用效率表现为秦冠处理之间差异极显著,富士处理之间差异不显著;秦冠的PNUE和NUE明显高于富士,在低氮正常水（DZ）处理下,秦冠氮肥利用率比富士高42.07%,在低氮干旱（DG）处理下高64.14%;低氮胁迫下富士和秦冠的NUE显著提高,并且秦冠提高的幅度高于富士。【结论】施用氮肥能够显著提高富士与秦冠的干物质量,同等水肥条件下,秦冠生长优于富士;水分亏缺会减少叶片对氮的吸收,干旱条件下适度增施氮肥,可提高果树的抗旱能力;低氮干旱胁迫下秦冠的生长指标、 光合指标及氮素利用效率指标均优于富士,表现出较强的抗低氮干旱胁迫的能力。     

Biodiversity and ecogeography of wild Lactuca spp. in some European countries

Staff members of the Department of Botany of Palacký University in Olomouc and Gene Bank Department – Workplace Olomouc, Research Institute of Crop Production in Prague, Czech Republic, conducted an expedition in seven European countries (Austria, Czech Republic, France, Germany, Italy, the Netherlands, Switzerland) in August/September 1999 to collect wild Lactuca spp. germplasm and study its geographic distribution, ecology and biodiversity. During the mission, more than 600 locations were visited resulting in the collection of 602 seed samples (accessions) of wild Lactuca species and 13 seed samples of related genera (Chondrilla and Mycelis). Lactuca serriola f. serriola, L. serriola f. integrifolia, L. saligna and L. viminea subsp. chondrilliflora were prevalent in southern Europe (Italy, France), however, only L. serriola was common in central and western Europe (Austria, Czech Republic, Germany, Netherlands, Switzerland). The greatest diversity of Lactuca species was found in France, where also the most seed samples (165) were collected. The most characteristic habitats with a high density of Lactuca spp. populations were observed along roads and highways, grassy ditches, ruderal communities, and dust-heaps. Natural infections by powdery mildew (Erysiphe cichoracearum) and downy mildew (Bremia lactucae) on some wild Lactuca spp. were observed. Recent observations concerning the geographic distribution, population structure, habitats, and natural occurrence of diseases of Lactuca spp. are discussed. This assemblage of genetic resources of Lactuca spp. can serve as the basis of future studies of species diversification, spatial population structure, plant microevolution, domestication processes, and genetic variability of host-parasite interactions.     

Pasture Vegetation Elemental Analysis by Laser-Induced Breakdown Spectroscopy

Laser-induced breakdown spectroscopy (LIBS) is a new technique for the analysis of plant material. This study investigates the application of LIBS to pasture-based plant samples. The LIBS measurements were obtained from pelletized pasture samples (100 samples) that had been also analyzed by inductively coupled plasma–optical emission spectroscopy (ICP-OES) following microwave digestion for calibration and comparison purposes. Comparisons for elements sodium (Na), potassium (K), magnesium (Mg), calcium (Ca), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), boron (B), phosphorus (P), and sulfur (S) showed that LIBS could be used for almost all the standard profile total elements with concentrations down to low mg/kg levels (observed error of Na: 0.024 percent, K: 0.18 percent, Mg: 0.016 percent, Ca: 0.073 percent, P: 0.017 percent, Mn: 31 mg/kg, Fe: 150 mg/kg, Zn: 6.6 mg/kg, and B: 1.1 mg/kg). Elemental analysis at less than mg/kg levels was not possible using LIBS. The elements S and Cu were particularly difficult to analyze with reliability using LIBS at the concentration levels found in the plant samples. Replacing microwave digestion and subsequent ICP analysis with a direct analysis of dried plant samples using LIBS has the potential to improve the productivity and reduce the cost of testing.     

Properties of anaerobically digested and composted municipal solid waste assessed by linking soil mesofauna dynamics and nitrogen modelling

We have studied the effect of anaerobically digested (ADMSW) and composted municipal solid waste (CMSW) on mineralization and foodweb dynamics to verify the hypothesis that ADMSW would immobilize N right after addition to soil in contrast to addition with CMSW. Another hypothesis was that the mesofauna (enchytraeids and microarthropods) would stimulate N release from the decomposer community. We measured excretion of -N and urea-N from the mesofauna and hypothesized that enchytraeids would release urea. ADMSW and CMSW were amended to pots with sandy loam and barley. The pots were divided into treatments with or without mesofauna. Mesofauna, plant N and biomass, soil N and ergosterol (fungal biomass) were measured over a 113-day period of four equidistant samplings. Soil respiration, N mineralization and N release by the mesofauna were modelled from concurrent studies. ADMSW- and CMSW-treated soils initially (<20 days) immobilized N. The amendments did not increase plant growth substantially, and this was probably due to N-limitation in the early stages of plant growth. Enchytraeid abundance was about three times higher in ADMSW- than CMSW-treated soils, indicating that ADMSW contained more labile compounds, bacteria, and microfauna. The mesofauna did not affect N-content, but the cumulated -N excreted by the mesofauna was estimated to be substantial and about one-fifth of total plant N in ADMSW. An explanation for this discrepancy might be that in the absence of the mesofauna, other members of the detrivore and microbivore community performed the mesofauna’s function. Neither enchytraeids nor microarthropods excreted urea.     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions: Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Faculty positions:Center for Agricultural Resources Research,Chinese Academy of Sciences

正The Center for Agricultural Resources Research(CARR),the Institute of Genetics and Developmental Biology(IGDB),Chinese Academy of Sciences,invites applicants for several research group leader positions.CARR is one of the research organizations in Chinese Academy of Sciences(CAS).We seek nominations and applications from individuals who have expertise and a record of accomplishment in research areas related to ecology,agro-hydrology,     

Macroinvertebrates in North American tallgrass prairie soils: effects of fire, mowing, and fertilization on density and biomass

The responses of tallgrass prairie plant communities and ecosystem processes to fire and grazing are well characterized. However, responses of invertebrate consumer groups, and particularly soil-dwelling organisms, to these disturbances are not well known. At Konza Prairie Biological Station, we sampled soil macroinvertebrates in 1994 and 1999 as part of a long-term experiment designed to examine the effects and interactions of annual fire, mowing, and fertilization (N and P) on prairie soil communities and processes. For nearly all taxa, in both years, responses were characterized by significant treatment interactions, but some general patterns were evident. Introduced European earthworms (Aporrectodea spp. and Octolasion spp.) were most abundant in plots where fire was excluded, and the proportion of the total earthworm community consisting of introduced earthworms was greater in unburned, unmowed, and fertilized plots. Nymphs of two Cicada genera were collected (Cicadetta spp. and Tibicen spp.). Cicadetta nymphs were more abundant in burned plots, but mowing reduced their abundance. Tibicen nymphs were collected almost exclusively from unburned plots. Treatment effects on herbivorous beetle larvae (Scarabaeidae, Elateridae, and Curculionidae) were variable, but nutrient additions (N or P) usually resulted in greater densities, whereas mowing usually resulted in lower densities. Our results suggest that departures from historical disturbance regimes (i.e. frequent fire and grazing) may render soils more susceptible to increased numbers of European earthworms, and that interactions between fire, aboveground biomass removal, and vegetation responses affect the structure and composition of invertebrate communities in tallgrass prairie soils.     

Assessing the effectiveness of conservation measures: Resolving the “wicked” problem of the Steller sea lion

“Wicked” problems are those that are complex and that change when solutions are applied. Many conflicts in conservation fall into this category. The study approached the problem of how to constrain the apparent wickedness of a problem in the conservation management of a species by using simple empirical indicators to carry out iterative assessment of the risk to a population and to document how this risk evolves in relation to the addition of new data and the implementation of management actions. Effects of high levels of uncertainty within data and also concerning population structure were examined through stochastic simulation and by exploration of scenarios. Historical trends in the example used, the Steller sea lion, showed rapid declines in abundance in some regions during the 1980s. The current total population is 130,000-150,000 Steller sea lions through Alaska and British Columbia and this number has been stable since about 1990 in spite of regional differences in population dynamics. Regional differences in the sequence of changes in the number of pups and non-pups, suggested that an internal re-distribution of juveniles could have happened between 1980 and 1990. Current productivity also appears close to the long-term mean. Stochastic population projection using various scenarios showed that, based upon this history, the risk of extinction for the population has declined and is below reasonable thresholds for considering the population to be endangered. The trends in risk suggest that management actions taken since 1990 have probably been effective. Consequently, the conservation management objectives for the Steller sea lion are probably being met. The approach provides a mechanism, based upon experience and scenario analysis, for exploring future policy options and may help to constrain the debate amongst stakeholders about the cost-benefit trade-offs associated with different options.     

Soil-profile distribution of primary and secondary plant-available nutrients under conventional and no tillage

Nutrient distributions under no tillage (NT) compared with conventional disk-and-bed tillage (CT) management in the warm, humid region of the southeastern USA need to be assessed so that future placement, quantity, and type of fertilizers can be altered, if necessary, to efficiently match crop demands. We determined soil-profile distributions of pH, N, P, S, K, Ca, Mg, Na, Zn, Fe, Mn, and Cu to a depth of 0.9 m at the end of 8.5 years of continuous CT and NT management on a Weswood silty clay loam (fine, mixed, thermic Fluventic Ustochrept) in southcentral Texas. Most dramatic changes occurred within the 0–0.05 m depth, where soil under NT had lower pH, Fe, and Cu than under CT, but greater P, K, Zn, and Mn. Greater P and K under NT than under CT also occurred below the till-zone (0.15–0.3 m). At a depth of 0–0.3 m, soil under NT contained greater amounts of extractable P, K, Zn, Fe, Mn, and Cu than under CT. Nitrogen fertilization had little effect on nutrient distributions, except resulting in greater extractable K at 0–0.05 m and greater nitrate at 0–0.15 m. Few changes in soil-profile distributions were observed for extractable S, Ca, Mg, and Na. Long-term continuous use of NT on this fine-textured, high-fertility (except for N) soil had no apparent adverse effects on nutrient distributions relative to CT, but enhanced conservation and availability of P, K, Zn, Fe, Mn, and Cu near the soil surface where crop roots proliferate.