基于撞击声的开心果分拣模型研究

基于碰撞声的开心果分拣技术主要通过撞击迫使坚果壳体振动发声,再经分析处理获得开闭口对应的声信号特征,最后实现不同坚果类型的识别和分离。将开心果抽象成不同开口状态的嵌套小球模型,对开心果从落地瞬间到最后自由振动衰减的整个过程进行模型分析,根据开口程度的不同表现出不同振动特性的原因,合理解释开心果的时域频域特性。提出一种根据开心果时域信号的综合对数衰减率进行分拣的方法,分拣准确率100%。     

碰撞位姿对开心果碰撞声离散性的影响

为了研究碰撞位姿对开心果碰撞声离散性的影响,在除碰撞位姿不作控制、其余条件均相同的情况下,分别对单个开闭口开心果进行100次重复碰撞试验,对两组碰撞声信号的频谱离散性和统计参数的离散性进行分析研究。频谱的离散性以样本信号频谱向量与其平均向量间的夹角均值和夹角变异系数作为度量;统计参数的离散性采用信号的能量、熵、过零率等参量,以其变异系数作为度量。试验结果显示:1单颗开口开心果重复碰撞声信号的频谱向量与其平均向量间夹角均值为30.94°,夹角变异系数为16.56%;能量、熵、过零率参数的变异系数分别为38.33%,2.30%,20.00%,均值分别为11.20,4.39,63.43;2单颗闭口开心果重复碰撞声信号的频谱向量与其平均向量间夹角均值为20.52°,夹角变异系数为25.11%;能量、熵、过零率参数的变异系数分别为18.36%,2.27%,13.08%,均值分别为6.08,4.28,62.94。结果表明:1不作控制的碰撞位姿对单颗开闭口开心果重复碰撞产生的声信号均有影响,会发生离散;2在由碰撞位姿导致的碰撞声的离散程度上,开口离散程度比闭口的高;3除碰撞位姿不作控制、其余试验条件均相同的情况下,虽然单颗开闭口开心果碰撞声的频谱和统计参数都会发生离散,但各参数均在其均值附近有限的范围内变动,所以,通过提取均值差异大且变异系数小的特征参数可以实现开口果和闭口果的有效分类。     

基于滑槽试验的小麦粉静电积累特性研究

为研究小麦粉静电积累特性，利用法拉第筒搭建粉体滑槽静电试验平台，以小麦粉为试验材料，测试滑槽倾斜角度、滑槽材质、滑动长度和粉体含水量对粉体荷电影响。结果表明，在含水率为11.62%、滑度长度100 cm的条件下，小麦粉在倾斜角度为45°和60°的不锈钢滑槽滑行后，荷质比均值分别为9.09,14.34 nC/g；在含水率为11.62%、倾斜角度60°的条件下，小麦粉在不锈钢、铝合金、玻璃材质滑槽滑行70 cm后，荷质比均值分别为11.29,16.48,2.94 nC/g；小麦粉荷质比随着滑动长度增加而增加；含水率为11.62%和16.7%的小麦粉荷质比均值分别为13.88,8.41 n C/g。研究为食品粉体除静电技术提供理论基础。     

箱式格栅除铁器有限元分析及在奶粉生产中的应用

目的:将箱式格栅除铁器应用在奶粉生产中.方法:在完全模拟奶粉工厂真实生产条件下,基于有限元仿真分析,探究除铁器的有效工作原理,进而通过单因素试验及矩阵分析,探究物料的下落高度、金属异物种类、场强强度、磁棒净距对箱式格栅除铁器有效拦截率的影响及优选设计方案.结果:假设最低可接受标准为对铸铁、304不锈钢、316不锈钢有效拦截率≥80%,则临界设计条件为:(1)当磁棒强磁环场强为1.0T时,下落高度≤100mm,磁棒层数≥6层,净距25 mm.(2)当磁棒强磁环场强为1.4T时,如物料下落高度≤100mm,则磁棒层数≥4层,净距25mm;如100m<物料下落高度≤300mm,则磁棒层数≥6层,净距25mm.结论:该研究成果可应用于奶粉及其他粉末状食品物料,如蛋白类原料、粉末油脂、淀粉、食品添加剂等.     

桃果实冲击损伤规律的研究

利用自制的冲击试验台,对桃果实由碰撞引起的机械损伤和耐贮特性的变化规律进行较系统的研究。通过多因素组合试验,摸清了下落高度、冲击表面、成熟度、果实大小对果实损伤的影响规律;找到了不同果实的耐冲击高度;通过回归分析,建立了果实冲击损伤的数学预测模型,其理论值与实测值具有很好的一致性。最后分析了桃果实在耐冲击高度范围内下落时碰撞对果实耐贮性的影响。     

经直溜槽与螺旋溜槽装入筒仓的玉米减损效果的实验研究

让不同含水率(11.64、13.54、15.43、16.43 %w.b.)的玉米从粮仓仓顶出发,经直溜槽与螺旋溜槽流入筒仓,下落与仓底碰撞;又让其从粮仓仓顶自由下落,与仓底碰撞。测定两种方式下落碰撞的玉米籽粒破碎率,使用质构仪对两种碰撞后的玉米籽粒及未碰撞的玉米籽粒进行静态压缩试验,测定它们的破坏力(抵抗破坏的力)、破坏能(抵抗破坏的能)。实验结果表明：玉米的含水率越大,经过碰撞后破碎率越小;不同含水率的玉米,经过溜槽下落碰撞的平均破碎率是3.84%, 自然下落碰撞的平均破碎率是7.65%, 经过溜槽下落后碰撞的玉米籽粒破碎率明显小于自由下落碰撞的玉米籽粒破碎率;经过溜槽下落碰撞的玉米籽粒的破坏力和破坏能比自由下落碰撞的玉米籽粒的破坏力和破坏能大;实验结果表明溜槽起到了缓冲碰撞的作用,减损效果明显。     

经溜槽装入筒仓的玉米减损效果试验

不同含水率(11.64%、13.54%、15.43%、16.43%w.b.)的玉米从仓顶入仓,一种工况是玉米经直溜槽与螺旋溜槽流入筒仓与仓底碰撞;另一种工况是玉米从仓顶自由下落与仓底碰撞。测定2种工况下落碰撞的玉米籽粒破碎率,并使用质构仪测定2种碰撞后的玉米籽粒及未碰撞的玉米籽粒的破坏力和破坏能。结果表明:玉米的含水率越大,经过碰撞后破碎率越小;不同含水率的玉米,经过溜槽下落碰撞的平均破碎率是3.84%,自然下落碰撞的平均破碎率是7.65%;不同含水率的玉米,经过溜槽下落碰撞的玉米籽粒的破坏力平均值是234.96 N,破坏能平均值是49.71 m J,自由下落碰撞的玉米籽粒的破坏力平均值是219.09 N,破坏能平均值是42.43 m J;说明溜槽起到了缓冲碰撞的作用。     

飞行条件下飞机表面声载荷测试方法研究

文章对飞行条件下飞机表面声载荷测试方法进行了研究。为了降低表面传声器安装产生的额外气动噪声,给出了采用过渡圆盘安装表面传声器的方法,并对飞行过程中其他测试设备的安装及固定方法进行了介绍。另外还对测试步骤以及数据处理方法进行了研究。最后,对飞行过程中表面传声器安装和环境变化对测试结果产生的影响的修正方法进行了研究,以最大的程度还原机体表面的真实声载荷。     

基于机器视觉的残缺饼干分拣系统开发

为降低机器人拾取强度,提高分拣效率,该研究提出了识别分拣残缺饼干的方法。基于机器视觉技术,采用三次拍照对比识别残缺饼干算法,解决了在拍照区域边缘位置因饼干只有部分被拍到会被识别为残缺品和部分饼干粘连导致误识别的问题;通过识别算法获取行进中的输送带上的饼干中心坐标位置,通过对比t时间间隔饼干中心坐标的差值是否等于输送带t时间运行的距离,以确认三次拍照获取的饼干图像哪些是同一饼干,并获取此饼干的图像特征数据;当获取的饼干图像特征数据与标准饼干的视觉特征参数不同时,识别为残缺品,输出该饼干中心坐标给并联机器人进行拾取。本文对程序的有效性进行了实验验证,并对影响识别率的因素进行了实验讨论。通过实验验证,程序运行可靠,对残缺饼干识别准确率保持在100%。另外镜头高度对识别准确率影响较小,但对可识别半径影响较大,呈线性关系;输送带运行速度增加至19 mm/s后,识别准确率直线下降;光照强度达到400 Lux后,识别准确率可保持100%。该研究建立的方法能够很好的对残缺饼干进行识别,为今后饼干在线检测分拣提供了技术支持。     

复合诱变皮状丝孢酵母选育高产油脂菌株

采用紫外线与硫酸二乙酯对皮状丝孢酵母进行复合诱变。研究结果表明:用15 W紫外灯在照射距离30 cm条件下照射60 s,可以筛选到油脂含量30.4%,生物量1.135 4 g/100 mL的突变菌株皮-60;利用硫酸二乙酯诱变皮-60,在硫酸二乙酯质量分数1.0%,处理时间为70 min条件下,可以筛选到油脂含量35.7%,生物量1.257 3 g/100 mL的突变菌株皮-60-70,较出发菌株,油脂含量提高了33.7%。     

Effect of different ozone treatments on aflatoxin degradation and physicochemical properties of pistachios

This study evaluated the efficiency of ozone for the degradation of aflatoxins in pistachio kernels and ground pistachios. Pistachios were contaminated with known concentrations of aflatoxin (AF) B₁, B₂, G₁ and G₂. Pistachio samples were exposed to gaseous ozone in a chamber at 5.0, 7.0 and 9.0 mg L^?1 ozone concentrations for 140 and 420 min at 20 °C and 70% RH. Aflatoxin degradation was determined by high performance liquid chromatography (HPLC). The efficiency of ozone for aflatoxin degradation in pistachios increased with increasing exposure time and ozone concentration. The results indicated that AFB₁ and total aflatoxins could be reduced by 23 and 24%, respectively, when pistachio kernels were ozonated at 9.0 mg L^?1 ozone concentration for 420 min. Only a 5% reduction in AFB₁ and total aflatoxin levels could be achieved for ground pistachios under the same conditions. No significant changes occurred in pH, color, moisture content and free fatty acid values of pistachio kernels and ground pistachios. Fatty acid compositions of pistachios did not change significantly after the ozonation treatments. No significant changes were found between sweetness, rancidity, flavor, appearance and overall palatability of ozonated and non‐ozonated pistachio kernels. Significant changes were observed in the organoleptic properties of ground pistachios, except rancidity, after 5.0 mg L^?1 ozone treatment for 140 min. Ozonation was found to be more effective for degrading aflatoxins in pistachio kernels than ground pistachios. Copyright © 2006 Society of Chemical Industry     

开心果过敏原的分离纯化及紫外光谱分析

目的 对开心果中的过敏蛋白进行分离纯化, 了解开心果过敏蛋白的初级结构和致敏性。方法 将不同加工处理的开心果用二氯甲烷、TBS缓冲液进行过敏蛋白的提取分离, 采用硫酸铵分级沉淀来初步提纯过敏蛋白, 再通过透析、离子交换柱层析手段对开心果的致敏蛋白进一步纯化, 最后通过考马斯亮蓝测蛋白含量, 用紫外分光光度计波峰表征, 确定开心果致敏蛋白质种类, 通过SDS-PAGE电泳分析和WB免疫印迹实验验证开心果分离蛋白的致敏性。结果 不同比例的有机溶剂提取开心果蛋白的分离效果不同, 原味开心果1:3的得率最高达到49.49%; 不同饱和度的硫酸铵沉淀蛋白质不同, 浓度越小, 析出蛋白质种类越多; 经离子交换层析柱分离纯化之后, 蛋白质的种类组分稳定, 结合之外扫描图谱分析所测物质的结构中含有双键或三键, 属于复合蛋白质的结构。结论 开心果过敏原属于蛋白复合结构, 主要以双键和三键的形式存在, 热处理和盐焗加工会降低开心果过敏原的致敏性。     

橡胶籽冲击特性研究

用碰撞的原理破碎橡胶籽是一种重要的方式,为了研究橡胶籽在碰撞过程中的破碎力学规律,采用RFP数据采集系统对橡胶籽所受的瞬时碰撞力进行动态测量试验,分析高度、角度、初速度对橡胶籽所受碰撞力的影响。试验结果表明:高度从0.5m提高到2.0m,碰撞力从1.712N增加到3.461N;角度从30~°增加到90~°,碰撞力从0.831 N增加到2.401N;初速度从0.5m/s增加到5.0m/s,碰撞力从1.781N增加到3.311N;通过SPSS软件进行单因素曲线估计,并拟合出各因素与碰撞力的最优曲线关系图,经分析得出高度、角度和初速度均与碰撞力呈较强正线性相关关系,在此基础上进行多因素线性回归分析,根据试验数据推出具有显著性的公式,并用插入法验证了公式的准确性;研究结果可结合不同情况下的橡胶籽破碎力,设计合理的破壳机结构,使得橡胶籽进入破壳机后能够更有效地完成脱壳工作。     

Effect of pistachio on brachial artery diameter and flow-mediated dilatation: A systematic review and meta-analysis of randomized,controlled-feeding clinical studies

Background: Results of previous clinical trials evaluating the effect of pistachio supplementation on endothelial reactivity (ER) are controversial. Aims: We aimed to assess the impact of pistachio on ER through systematic review of literature and meta-analysis of available randomized, controlled-feeding clinical studies (RCTs). Methods: The literature search included SCOPUS, PubMed-Medline, ISI Web of Science and Google Scholar databases up to 1st August 2017 to identify RCTs investigating the impact of pistachio on ER. Two independent reviewers extracted data on study characteristics, methods and outcomes. Overall, the impact of pistachio on ER was reported in 4 trials. Results: The meta-analysis did not suggest a significant change in brachial artery flow-mediated dilatation (FMD) (WMD: +0.28%; 95%CI: ?0.58, 1.13; p = 0.525) while brachial artery diameter (BAD) improved (WMD: +0.04%; 95%CI: 0.03, 0.06; p<0.001) following pistachios consumption. Conclusion: The present meta-analysis suggests a significant effect of pistachios on ER, affecting BAD but not FMD.     

Effect of roasting on colour and volatile composition of pistachios (Pistacia vera L.)

Pistachios have been roasted following the Iranian traditional method (soaking in salty water, drying and roasting at 135 °C). Three Iranian pistachio cultivars (Ahmad Aghaei, Akbari and Kaleghouchi) were compared for their volatile compositions, colour and odour intensity. Lightness decreased in the course of roasting, which resulted from Maillard reaction. Raw pistachios had lower concentrations of most volatiles than roasted. A total of twenty‐six compounds were detected in roasted pistachios; these included aldehydes, terpenes, alcohols and only two pyrazines and one furan. These mixtures of volatiles implied that the Iranian roasting system is very soft, and samples retained most of the vegetable notes from fresh pistachios and some roasted notes were generated as well (from 2‐ethyl‐5‐methylpyrazine and 2,6‐dimethyl‐3‐ethylpyrazine). Sample from cultivar Akbari presented higher odour intensity than those by the other two cultivars, due mainly to higher concentrations of pyrazines developed during the roasting step.     

Storage stability of pistachios as influenced by radio frequency treatments for postharvest disinfestations

There has been an increased interest in developing alternative physical methods for disinfesting postharvest nuts under growing international pressures to replace chemical fumigation due to its adverse effects on human health and environment. The present research explored the possibility of using radio frequency (RF) heating as a non-chemical treatment for disinfestations of pistachios. A pilot-scale, 27 MHz, 6 kW RF unit was used to study RF heating uniformity, develop a treatment protocol, and evaluate quality attributes and storage stability in treated samples. Only 5.6 and 5.5 min were needed to raise the centre temperature of 1.8 kg in-shell and 2.0 kg shelled pistachios to reach 55 °C using RF energy, respectively, compared to about 82 and 117 min when using hot air heating at 55 °C. RF heating uniformity in both types of pistachios was improved by adding forced hot air, sample movements on the conveyor and a single mixing in the middle of the treatment time. The final average temperatures on the surface and in the interior of both types of pistachio kernels exceeded 52 °C, following a holding step at 55 °C for 2 min using hot air. This provided a conservative and 100% mortality of fifth-instar Indianmeal moth (Plodia interpunctella [Hübner]). RF treated samples were not significantly different from control samples in weight loss, peroxide values, fatty acid values, fatty acid composition and kernel colour. RF treatments can, therefore, potentially provide an effective and rapid protocol against stored product pests in pistachios as an alternative to chemical fumigation.Industrial relevanceA pilot-scale 6 kW RF system with conveyor belt was used to determine the heating uniformity and quality changes of pistachios. For a combination with hot air surface heating and mixing, an effective and continuous RF disinfestation method could be developed for pistachios. The RF heating technology has been successfully demonstrated for disinfesting walnuts in California, USA. We tried to expand the industrial applications of RF heating for disinfesting pistachios, to replace the chemical fumigation. This research may provide potential industrial applications of RF treatments for disinfestations based on fast and uniform heating.     

Several physical properties of aflatoxin-contaminated pistachio nuts: Application of BGY fluorescence for separation of aflatoxin-contaminated nuts

The primary objective was to evaluate and find a proper method for visual identification of aflatoxin-contaminated pistachio nuts. The feasibility of using bright greenish yellow fluorescence (BGYF) in pistachio nut as a discriminating factor for identification of Aspergillus flavus-infested nuts, at harvest and in post-harvest, is investigated. Results show a strong relationship between BGYF and aflatoxin content at harvest. The factors affecting the application of this method in post-harvest stages are also discussed. The relationship between inside-brown kernels and aflatoxin presence is confirmed. At harvest, the brown kernels are a subdivision of fluorescent fraction. The share of different pistachios based on hull types (with sound hull, growth split and early-split) in contamination is studied. The early-split nuts are the most contaminated nuts, growth split nuts are less contaminated, and pistachios with sound hulls are almost clean. The effect of inappropriate handling on the percentage of fluorescent nuts is studied. The percentage of visible mould in samples is observed which shows a good relationship with the presence of BGY fluorescence.     

Identification of hidden allergens: Detection of pistachio traces in mortadella

An analytical method based on the detection of specific DNA was developed and applied to mortadella samples with and without pistachio (Pistacia vera). The method is proposed for the detection of traces of pistachio deriving from previous processes or from accidental contamination, since in predisposed individuals pistachios can cause allergic reactions leading to anaphylactic shock. Three pairs of primers were identified and tested by polymerase chain reaction (PCR) on mortadella samples prepared with pistachio. Accidental contamination was also simulated. The optimized PCR was able to detect the presence of pistachio, even at low concentrations. The primers pair PSTC 1-2 is suggested for unambiguous identification of pistachio in mortadella. The limit of detection for this primers pair was 100 mg kg^-1. No interference was observed from other spices or ingredients utilized in the formulation of the mortadella. The method enabled the identification of possible traces of pistachio remaining in the production plant after less than thorough washing.     

Cover Caption

July Online Cover : Clustered fresh pistachios, ready for packaging; uninfected samples of fresh pistachios in multilayer films containing both gas compounds at the end of storage time; respiration rate in different packaging; and contamination of control samples in PE and multilayer films at the end of storage time, from “The effect of packaging and storage time on quality of clustered fresh pistachio”, by Behjat Tajeddin and Ahmad Shakerardekani. p. 2943–2952.