瓠瓜薄层热风干燥动力学研究

为掌握瓠瓜薄层热风干燥特性,研究了一定条件下风温与风速对瓠瓜薄层热风干燥过程的影响,拟合了干燥曲线方程,计算了对流传热系数α与传质系数kH等动力学参数。结果表明：风温、风速均对干燥速度影响较大,以75℃、1.04 m/s为宜;干燥方程符合Page模型;随风速增大α与kH均增大,但风温对两者影响不大。结果可以为瓠瓜干制工业化生产和控制提供理论依据。     

热风微波耦合干燥胡萝卜片工艺

该文通过对胡萝卜片进行热风微波耦合干燥来研究热风微波耦合干燥工艺的可行性及优异性。采用自行设计的热风微波耦合干燥设备, 在不同的热风温度（50～80℃）、微波功率密度（4.5～1.5 W/g）条件下对胡萝卜片进行干燥,研究这2个因素对耦合干燥的影响。选取热风温度（50、60、70℃）、微波功率密度（3.5、2.5、1.5 W/g）、热风风速（0.5、1.0、1.5 m/s）进行正交试验,试验结果表明：耦合干燥各因素对干燥速率影响的主次关系为微波功率密度>热风温度>热风风速。同时将热风微波耦合干燥与热风干燥、微波干燥进行比较,得出热风微波耦合干燥是一种快速、高效和节能的干燥方式,在农产品和食品的干燥中具有广阔的应用前景。     

均匀设计法优化冬瓜膨化工艺

为对冬瓜脆条真空微波联合气流膨化工艺进行优化,采用均匀设计法,考察预干燥后含水率、微波功率和时间、膨化温度、抽空干燥温度和时间6因素5水平对膨化率、脆度、亮度L*和终含水率的影响,并通过逐步回归法对数据进行分析。结果表明,最佳膨化工艺参数组合为:预干燥后含水率47.4%,微波功率8.5W·g-1,微波加热时间为135s,膨化温度为106℃,抽空干燥温度为72℃,抽空干燥时间为85min。研究结果可为真空微波联合气流膨化冬瓜脆条的工业化生产提供参考。     

杏子的气体射流冲击干燥特性

为了提高杏子干制的品质、缩短干制时间，该文将气体射流冲击干燥技术应用于杏子干燥，研究了杏子在不同干燥温度（50、55、60和65℃）和风速（3、6、9和12 m/s）下的干燥曲线、水分有效扩散系数以及干燥活化能。试验结果表明：干燥温度和风速对杏子的干燥速率均有显著影响，但干燥温度对其的影响比风速更为突出；杏子的整个干燥过程属于降速干燥，通过费克第二定律求出了干燥过程中杏子的有效水分扩散系数，其值在8.346～13.846×10-10 m2/s的范围内随着干燥温度和风速的升高而增大；通过阿伦尼乌斯公式计算出了杏子干燥活化能为30.62 kJ/mol，表明利用气体射流冲击干燥技术从杏子中除去1 kg水需要消耗大约1 701 kJ的能量。该研究为气体射流冲击干燥技术应用于杏子的干燥提供了技术依据。     

天麻产后干燥风速温度条件的控制模型

本文介绍了天麻干燥过程中风速、温度对其干燥特性的影响,通过各种模拟实验建立了天麻干燥的数学模型。实验表明,在65℃、1m/s,75℃、0.6m/s和75℃、1m/s三种温度和风速组合条件下,干燥效率较高、能耗较小,成品质量较好。     

杏鲍菇渗透脱水联合隧道式微波干燥工艺优化

为优化杏鲍菇渗透脱水联合隧道式微波干燥工艺,采用三因素二次正交旋转组合设计,分析了浸渍时间、微波功率和传送速度对产品的复水率、亮度L*、多糖保持率和单位脱水能耗的影响。结果表明:浸渍时间、微波功率和传送速度对产品的复水率、亮度L*和多糖保持率均影响显著,但单位脱水能耗受浸渍时间影响显著,受微波功率和传送速度影响不显著。在此基础上,由试验数据推导二次回归模型并对变量进行响应面分析,得到优化的联合干燥工艺条件:浸渍时间128 min,微波功率7.2 W·g-1,传送速度480 r·min-1。研究结果为杏鲍菇渗透脱水联合隧道式微波干燥的工业化生产提供了理论依据。     

气体射流冲击干燥对脱盐海参理化特性和微观结构的影响

为改善脱盐海参干燥时间长、干制品品质差的问题，该研究将气体射流冲击干燥（air impingement drying, AID）技术应用于脱盐海参干燥，研究了干燥温度（50、60和70 ℃）和气流速度（4、6和8 m/s）对脱盐海参干燥速率及干制品水分分布及状态、微观结构、硬度和皂苷含量的影响，并与热风干燥（hot air drying, HAD）进行对比。结果表明，随着干燥温度的增加，脱盐海参的干燥速率增加。AID不同干燥温度下脱盐海参的干燥时间比HAD 60 ℃的海参干燥时间缩短了6.67%～33.33%。温度为60 ℃时，风速对脱盐海参的干燥时间影响不显著（P>0.05）。微观结构分析表明，温度升高有利于增加物料表面的多孔结构，相同条件下AID海参样品的表面比HAD海参具有更多更大的多孔结构，使得AID海参干燥速率快于HAD。但随着风速的增加，脱盐海参表面因发生结壳现象阻止了形变，使得干海参孔洞结构变小，干燥速率降低。与HAD相比，AID海参的不易流动水弛豫时间向短弛豫时间移动更快，且峰幅度显著降低；干燥相同时间时（6 h），AID海参的质子密度信号比HAD减少更多，表明AID海参的水分迁移速率快于HAD的海参。随着AID温度和风速的升高，干海参的硬度呈先增加后减小的趋势。AID海参皂苷含量随着温度的升高而升高。AID海参的多孔结构不仅加速了水分迁移，而且利于营养成分渗出，提高了营养成分含量，相同条件下，AID海参的皂苷含量比HAD的海参增加了50.00%。综合考虑干燥效率和品质，温度为70 ℃，风速为6 m/s为脱盐海参AID的较好条件。研究结果有助于阐明AID提高脱盐海参干燥速率和营养成分保留率的机理，为生产高品质干海参提供理论依据和技术参考。     

红枣片冷冻－红外分段组合干燥工艺优化

为开发一种提质增效的红枣片干燥工艺,比较了单一干燥（冷冻干燥、红外干燥、热风干燥和微波真空干燥）对红枣片干燥特性及品质的影响,选用冷冻与红外干燥分段组合的方法干制红枣片,以干燥时间和维生素C保留率为评价指标,采用三元二次通用旋转组合设计优化红枣片冷冻-红外组合干燥工艺参数,并与红外干燥（64℃,6.75 W/g）、冷冻干燥（-40℃,12 Pa,64℃）产品的干燥时间和品质进行对比分析。结果表明：1）冷冻与热风干燥的干燥时间最长,微波真空干燥最短,红外干燥次之;2）冷冻干燥产品品质较好,但酥脆性一般,红外干燥产品在色泽、质构（硬/脆度）、微观结构方面均好于热风和微波真空干燥产品,且酥脆性较好;3）转换含水率、红外温度和切片厚度对红枣片冷冻-红外组合干燥过程有显著影响（P<0.05）,对干燥时间影响主次顺序依次为转换含水率、红外温度、切片厚度,对维生素C保留率影响主次顺序依次为红外温度、转换含水率、切片厚度;4）采用响应曲面法优化与试验验证确定出较佳工艺参数为：转换含水率34 %、红外温度64℃、切片厚度5 mm,此时,干燥时间3.62 h,维生素C保留率68.92%;5）冷冻-红外组合干燥产品品质优于红外干燥,干燥时间比冷冻干燥缩短57.6%,维生素C保留率比红外干燥提高了34.6%。结果表明冷冻-红外组合干燥缩短了干燥时间同时保证了干燥品质,可为红枣片干制加工提供一种新的组合干燥技术和理论依据。     

双孢菇微波冷冻干燥特性及干燥品质

为获得干燥时间短、产品质量高的蘑菇制品,采用微波冷冻干燥技术对双孢菇进行干燥处理,研究其在不同微波比功率(0.25,0.5,0.75 W/g)和系统压强(50,100,150 Pa)下的干燥曲线、有效水分扩散系数、复水比、收缩率、白度、维生素C保存率、能耗及基于模糊数学推理法下感官评定的变化规律;通过非线性拟合建立了适用于双孢菇微波冷冻干燥的数学模型;基于干燥能耗、干燥时间及部分品质指标对不同条件下双孢菇微波冷冻干燥过程进行加权综合评价。结果表明:微波比功率对干燥速率及干制品物理品质指标影响比对其他指标的影响更显著(P0.05);系统压强对干制品营养含量指标、干燥能耗以及感官评定的影响比对干燥特性的影响显著(P0.05);采用Henderson and Pabis模型能够准确(R20.9)描述干燥过程中水分变化规律;双孢菇有效水分扩散系数在10-10 m2/s数量级且受微波比功率影响更明显(P0.05);微波比功率和系统压强过高会造成双孢菇干制产品不被消费者接受;当微波比功率和系统压强分别为0.25 W/g和100 Pa时双孢菇微波冷冻干燥的综合评分值最高为0.67847,该条件较适合应用于双孢菇微波冷冻干燥中。研究探索了不同微波冷冻干燥条件下双孢菇干燥及品质特性的变化规律,为双孢菇微波冷冻干燥较优工艺参数组合的选择提供了理论依据。     

干燥过程对紫花苜蓿粗蛋白含量影响规律的试验研究

该文用二次正交旋转组合设计试验方法，探讨干燥因素对紫花苜蓿干燥生产率及其品质的影响，研究干燥温度、表观风速、初始含水率和干燥时间对苜蓿粗蛋白含量的影响规律。利用单因素分析法分析各因素与试验指标的关系，确定各因素在二次非线性模型中的主次顺序。试验分析结果表明，初始含水率对苜蓿品质影响最大，干燥温度次之，干燥时间再次之，表观风速的影响最小。通过优化与试验验证，得出了在温度为176.5℃、表观风速为0.32 m/s、初始含水率为79%wb、干燥时间为3 min的条件下，干制苜蓿的粗蛋白含量高，色泽翠绿，气味芳香的结论。     

Soybean preference for Bradyrhizobium japonicum for nodulation

For examining the probability of increase in the occupation ratio of inoculated rhizobium in nodules, various Rj-soybean cultivars including the Rj ₂ Rj ₃ Rj ₄-lines of soybean were grown in a field of the Kyushu University Farm. Bradyrhizobium japonicum USDA110 that carries uptake hydrogenase (Hup⁺) was used as an inoculum. The relative efficiency of nitrogen fixation generally increased by the inoculation. However, there were no significant differences in the effects among the genotypes of the host plants. The occupation ratio of serogroup USDA110 in the nodules on the taproot of the inoculated plants was in the range of 77–100%, suggesting that the B. japonicum strain USDA110 infected taproots immediately after inoculation. The occupation ratios in the nodules on the lateral roots were 53–67, 40–86, 63–83, and 62–77% in inoculated plants of the non-Rj-, Rj ₂ Rj ₃-, Rj ₄-, and Rj ₂ Rj ₃ Rj ₄-genotypes, respectively, and they decreased in all the genotypes with the progression of growth. At the time of the first sampling, the occupation ratios on the lateral roots of these Rj ₂ Rj ₃ Rj ₄-genotypes showed values intermediate between those of IAC-2 (Rj ₂ Rj ₃) and Hill (Rj ₄) , which were the parent cultivars of the Rj ₂ Rj ₃ Rj ₄-lines, B340, B349, and C242. The reduction in the occupation ratio of the serogroup USDA110 for about 1 month after the first sampling was the lowest (0.13–0.16) in the Rj ₂ Rj ₃ Rj ₄-genotypes, excluding B349, followed by the non-Rj- and Rj ₂ Rj ₃-genotypes and highest (0.52–0.69) in the Rj ₄-genotypes, excluding Hill. Therefore, it was considered that the population of compatible rhizobia with host soybean plants increased in the rhizosphere with the progression of the development and growth. The results showed that with the expansion of the root area of host plants, the occupation ratio of type A rhizobia including the serogroup USDA110 was high. Therefore, the Rj ₂ Rj ₃ Rj ₄-genotypes were superior to other Rj-genotypes in terms of the inoculation effects of nodulation type A rhizobium, B. japonicum USDA110. However, the preference of the Rj ₂ Rj ₃ Rj ₄-genotype for serogroup USDA110 is not sufficient to rule out the competition with the other serogroups in this study. Therefore, the study should be centered on the isolation of more efficient (Hup⁺) and highly compatible rhizobial strains with the Rj ₂ Rj ₃ Rj ₄- genotypes.     

Soybean preference for Bradyrhizobium japonicum for nodulation

For the increase of the occupation ratio of inoculum strain in the competition with indigenous rhizobia, the relationship between Rj-genotypes of soybean and the preference of Rj-cultivars for various types of rhizobia for nodulation was investigated by using the Rj ₂ Rj ₄-genotype of soybean isolated from the cross between the Rj ₂ Rj ₃-cultivar IAC-2 and Rj ₄-one Hill (Ishizuka et al. 1993: Soil Sci. Plant Nutr., 39, 79-86). Firstly, these Rj ₂ Rj ₄-genotypes were found to harbor the Rj ₃-gene. The Rj ₂Rj₃Rj₄-genotypes of soybean were considered to exhibit a more narrow microsymbiont range for nodulation than the Rj ₂ Rj ₃-and Rj₄-cultivars. Therefore, rhizobia were isolated from the nodules of various Rj-genotypes of soybeans grown in soils, and the preference of the Rj ₂ Rj ₃ Rj ₄-genotype for indigenous rhizobia was examined. The nodule occupancy of serotype 110 was significantly higher in the bacteroids of the nodules from the Rj ₂ Rj ₃ Rj ₄-rgenotypes than in those from the other genotypes, non Rj-, Rj ₂ Rj _3-, and Rj ₄-cultivars. These results demonstrated that the Rj ₂ Rj ³ Rj ⁴-genotype prefers more actively serogroup USDA110 to the others of rhizobia. Thus, Rj ₂ Rj ₃ Rj ₄-genotype is superior to non- Rj-, Rj ₂ Rj ₃-, and Rj ₄-genotypes for the formation of efficient nodules for nitrogen fixation.     

Soybean preference for Bradyrhizobium japonicum for modulation

Abstract

Caldwell and Vest (1968) planted soybeans (Glycine max L. Merr.) with various genotypes at Beltsville, USA, without inoculating them with Bradyrhizobium japonicum, and showed that soybeans preferred certain serotypes of rhizobial strains for nodulation. Recently, the authors have reported that soybeans carrying nodulation-conditioning genes preferred appropriate strains showing specific behavior for nodulation (Ishizuka et al. 1991). For instance, nodulation of soybean cv. Hardee which carries the nodulation-conditioning genes, Rj ₂ and Rj ₃, does not occur with B. japonicum USDA122, USDA33, Is-1, etc. Nodulation of cv. Hill which carries the Rj ₄ gene, does not occur with B. japonicum USDA61, Is-21, etc. while A62-2 which carries a recessive gene rj ₁, does not nodulate with almost any of the strains of B. japonicum. Therefore, the B. japonicum strains can be classified into three nodulation types based on the compatibility with these Rj-cultivars, that is, type A strains which effectively nodulated both Rj ₂ Rj ₃-cultivars and Rj ₄-ones, type B strains which did not nodulate the Rj ₂ Rj ₃-cultivars and type C strains which did not nodulate the Rj ₄-cultivars. When the nodulation types of the isolates from nodules of field-grown soybeans were examined, it was suggested that the Rj ₂ Rj ₃-cultivars and Rj ₄-cultivars preferred the type C and type B strains, respectively (Ishizuka et al. 1991).     

Soil protection for a sustainable future: options for a soil monitoring network for Ireland

The increased recognition of the importance of soil is reflected in the UN Post‐2015 Development Agenda with sustainable development goals that directly and indirectly relate to soil quality and protection. Despite a lack of legally binding legislation for soil protection, the European Commission remains committed to the objective of soil protection. However, the achievement of a legally binding framework for soil protection relies on the implementation of a soil monitoring network (SMN) that can detect changes to soil quality over time. As beneficiaries do not pay for the provision of soil information, the options for soil monitoring are limited. The use of existing data sets should be considered first. Using Ireland as an example, this research explored the opportunities for a SMN for Ireland considering three existing national data sets. The options for a SMN are considered in terms of their spatial and stratified distribution, the parameters to be measured and an economic analysis of the options proposed. This research finds that for Ireland, either a 10 or a 16 km² grid interval stratified by land use and drainage class offers the best potential in relation to the spatial distribution of existing data sets to reflect local data at a national level. With existing data, the stratified SIS data using the 16 km² grid offers the best value for money, with baseline costs for analysis, excluding field costs, of between €706 481 and €2.8 million. Acknowledging the impossibility of measuring all parameters with ideal frequency, this study proposes a two‐tier system for optimized monitoring frequency. Parameters must anticipate future policy requirements. Finally, the implementation of a SMN must be accompanied by standardized methods, defined thresholds and action mandates to maintain soil quality within allowable limits.     

Recommendations for preparing test samples for AOAC collaborative studies of microbiological procedures for foods

Preparation of test samples for microbial collaborative studies poses problems not encountered in studies on chemical analytes. For Associate Referees who are considering a collaborative study of a microbiological procedure for food analysis, these problems have not been adequately addressed. Types of contamination (natural or artificial), number of test samples required, analyte selection, proper controls, and container selection are addressed herein. The discussion is a supplement to the guidelines contained in the Handbook for AOAC Members.     

Evaluation of soil extractants for silicon availability for sugarcane

Adequate evaluation and interpretation of silicon (Si) phytoavailability in soil is a key to fertilizer recommendation. This study was conducted to determine the effect of soil texture on the choice of Si extractant, and provide baseline data on the relationship between extractable Si and sugarcane Si accumulation. The effects of soil texture and extractant solutions of Si were investigated on soil of nine areas of sugarcane cultivation. Si contents in clayey soils were higher than in sandy soils only in the extraction with standard calcium chloride, acetic acid, potassium chloride (KCl), and sodium acetate buffer. Other extractants failed to reveal differences in the Si availability among the three soil textures. The choice of the extractant should consider soil texture for the determination of adequate Si contents in soils planted with sugarcane, and the extractants that proved to be more efficient in the three soil textures was acetic acid and KCl.     

Critical loads for nitrogen deposition for Great Britain

There is currently much interest in mapping critical loads for nitrogen deposition as part of a strategy for controlling nitrogen emissions. While nitrogen deposition may cause acidification and excess nutrient effects, the former were considered previously in studies of sulphur deposition. In the UK, work on developing nutrient nitrogen critical loads maps has used several methods and databases. Two approaches are described here, one a steady state calculation using a nitrogen saturation limit for soil systems, the other an empirical estimate of critical loads set to prevent changes to vegetation communities. The empirical method uses national species records and land cover data derived from satellite imagery. Maps drawn from the available data are dependent upon a number of factors which reflect the approach used. To apply the nutrient critical loads to a strategy for future abatement measures, the nutrient nitrogen values for soils have been incorporated within a “critical loads function” which takes into account both acidity and nutrient effects as related to deposition loads for sulphur and nitrogen. This function may be used with deposition data to identify the need for sulphur and nitrogen emission reductions.     

Strategy for Innovation in Soil Tests Illustrated for P Tests

Soil phosphorus (P) tests are used for P fertilization recommendations, environmental evaluations, and occasionally for legislation purposes. The basis of fertilization recommendation as function of soil P status was established in the 1950s–1960s. Since then the agroeconomic environment has altered: Environmental protection became increasingly important and P rock resources for fertilizers appeared exhaustible. Also, new insights in soil testing and fertilization recommendations reflecting more efficient use of P became available. However, these new insights seem hard to implement into agricultural practice, to a large extent because replacing existing soil tests and recommendations would imply a very significant effort with respect to introducing new tests and recommendations by fertilization trials in practice. The same would apply for environmental evaluations. Here, a novel, three-step schedule for introducing new soil tests is proposed: (1) establishing new promising soil tests, (2) creating regression models between the old and new soil tests, and (3) implementing the new soil test stepwise by fertilization trials. In this way, the knowledge based on the old soil tests can be used until the new soil tests and their subsequent crop responses are validated sufficiently. As a novel P test we considered combining soil P intensity [as reflected by P–calcium chloride (CaCl₂)] with P capacity [as reflected by P-ammonium lactate (Al)] and P-buffering capacity (as reflected by P-Al/P-CaCl₂ ratio) characteristics. Researchers tested whether this novel soil test can predict P water (Pw), P–calcium lactate?/?acetate (CAL), and P-Olsen values. To test the hypothesis, four datasets were used (two with Pw, one with P-CAL, and one with P-Olsen). In all datasets additional soil characteristics were available including soil type. Regression models with R_adj ² from 0.80 to 0.93 were obtained by using P-Al, P-CaCl₂, and soil type. It can be concluded that these regressions can be used as a helpful intermediate instrument when introducing fertilization recommendations based on new soil tests. Predicting one soil P test out of other soil characteristics, analogous to the predicted Pw, P-CAL, and P-Olsen, could also be helpful in comparing P statuses of agricultural land in different nations.     

Methodology for Creating an Information Tool for Animal Food Facilities

The U.S. Food Safety Modernization Act, administered by the Food and Drug Administration (FDA), requires animal feed and pet food facilities to conduct a hazard analysis by identifying and evaluating potential hazards in animal food. This paper describes the creation of an information tool designed to help animal food facilities comply with this requirement. A thorough search of the scientific literature and FDA recall data identified the occurrence of hazards in animal food, assessed the severity of the hazards, and provided a scoring system useful for the identification and prioritization of specific animal food-hazard-species combinations.     

温室透光覆盖材料流滴性测试方法

作为温室透光覆盖材料的塑料薄膜的流滴性日益受到关注，为此，已开发出各种无滴膜、无滴板，以改善温室透光覆盖材料的流滴性。但国内外对材料流滴性的监测与判断规则却很不统一，给温室用户带来了困难。该文分析了目前几种常用的流滴性检测方法的原理及其适用性，在此基础上，结合温室生产的实际条件，提出在15°～30°倾斜面上形成露滴后，材料表面凝结水滴面积占整个测试面积比例的检测方法——倾斜面上滞留水滴面积比法，并通过对塑料薄膜和聚碳酸酯板的分析测试，提出了将材料表面上计算水滴滞留面积小于10%作为透光覆盖材料流滴性的判别标准，为标准化检测覆盖材料的流滴性提供了依据。