Authenticity green coffee bean species and geographical origin using near-infrared spectroscopy combined with chemometrics

To prevent the adulteration of agricultural resources and provide a solution to enhance the green coffee bean supply chain, authentication using the near-infrared spectroscopy (NIRS) technique was investigated. Partial least square with discrimination analysis (PLS-DA) models combined with various preprocessing methods were built from NIR spectra of 153 Vietnamese green coffee samples. The model combined with the standard normal variate and the first order of derivative yielded excellent performance in predicting coffee species with the error cross-validation of 0.0261. PLS-DA model of mean centre and first-order derivative spectra also yielded good performance in verifying geographical indication of green coffee with the error of 0.0656. By contrast, the predicting abilities of post-harvest methods were poor. The overall results showed a high potential of the NIRS in online authentication practices.     

High‐intensity sweeteners in espresso coffee: ideal and equivalent sweetness and time–intensity analysis

The efficient substitution of sucrose by a sweetener in beverages requires the application of some sensory techniques. First, one must determine the concentrations of the sweeteners under study, equivalent in sweetness to the ideal sucrose concentration. In addition, it is fundamental to determine which is most similar to sucrose. The objectives of this study were to determine the ideal sweetness for espresso coffee and the equivalent concentrations in sweetness of different sweeteners, as well as characterise the time–intensity profile of each sweetener in relation to sweetness. The sweeteners evaluated were sucralose, aspartame, neotame, a cyclamate/saccharin mixture (2:1) and stevia. The sucrose concentration considered ideal by consumers was 12.5% (w/v), and the equivalent concentrations of the sweeteners were 0.0159% for sucralose, 0.0549% for aspartame, 0.0016% for neotame, 0.0359% for the cyclamate/saccharin mixture and 0.0998% for stevia. The time–intensity analysis indicated that possibly the sweeteners neotame, aspartame and sucralose would be the best substitutes for sucrose.     

Simultaneous determination of mycotoxin in commercial coffee

Mycotoxins are secondary metabolites produced by filamentous fungi that usually contaminate food products. Coffee is a natural product susceptible to mycotoxin contamination. The present study evaluates the presence of nivalenol, deoxynivalenol, T-2 and HT-2 Toxin, diacetoxyscirpenol, aflatoxin B₁, aflatoxin B₂, aflatoxin G₁, aflatoxin G₂, fumonisin B₁, fumonisin B₂, ochratoxin A, zearalenone, enniatin A, enniatin A₁, enniatin B, enniatin B₁, and beauvericin in coffee samples, using liquid chromatography tandem mass spectrometry (LC-MS/MS). The results show that zearalenone was not present in any sample. In the positive samples the contents of fumonisins ranged from 58.62 to 537.45 μg/kg, emerging mycotoxins ranged from 0.10 to 3569.92 μg/kg, aflatoxins ranged from 0.25 to 13.12 μg/kg, and trichothecenes, excepting nivalenol, ranged from 5.70 to 325.68 μg/kg. Nivalenol presented the highest concentrations, from 0.40 to 25.86 mg/kg. Ochratoxin A ranged from 1.56 to 32.40 μg/kg, and five samples exceeded the maximum limit established by the European Commission.     

The impact of roasting on the ochratoxin A content of coffee

Roasting coffee led to a drop in the ochratoxin A (OTA) concentration, as measured by the reference method, especially for dark type roasts. The way the beverage was prepared also affected the OTA content, which could paradoxically be higher than that of the initial roasted coffee. Assays on the thermal stability of pure OTA showed that it ought to be found in larger quantities in roasted coffee. This suggested that OTA was masked by reactions with the substrate during roasting. The absence of OTA in green coffee is therefore the best guarantee of safety.     

Improvement of Coffee Aroma by Removal of Pungent Volatiles Using A-Type Zeolite

Experimental studies were conducted using molecular sieve zeolites to remove pungent smell components from a coffee aroma-containing gas evolved from roasted and ground coffee packed in a percolation vessel. The components such as methyl mercaptan or acetaldehyde were selectively adsorbed from coffee volatiles, and a decrease of pungent odor was recognized on sensory evaluation. The adsorption selectivity was based on pore sizes of adsorbents and molecular sizes of adsorbates. Zeolite 5Å was preferable to 4Å for separation efficiency of methyl mercaptan and recovery yield of residual volatile compounds.     

基于无线传感器网络的小粒种咖啡园滴灌自动控制系统

为实现小粒种咖啡种植园的精量灌溉,达到节水增收的目的,基于无线传感器网络（WSNs）设计了一种滴灌自动控制系统,主要由传感器节点、簇头、控制节点和汇聚节点组成.测试了节点间的有效通信距离为50m,并在此基础上,采用静态簇和节点定位布置的方法进行了灌区划分和节点部署,每个灌区为边长50m的正方形,内设1个簇头、1个控制节点和4个传感器节点.采用定时通信与时间同步技术、休眠技术相结合的方法实现节点数据的无线传输,融合土壤含水率、光强和空气温湿度等信息,采用分区轮灌策略实现滴灌的自动控制.实验结果表明：系统实现了预期设计目标,能应用于小粒咖啡园的精量灌溉管理.     

咖啡纤维结构与性能研究

介绍了咖啡纤维的生产过程和物理性能,通过红外光谱仪、X射线粉末衍射仪和扫描电子显微镜研究了咖啡纤维的亲水基团、吸湿性、结晶度和形态结构等,并与棉纤维和麻纤维进行了对比,证明了咖啡纤维的可纺性,有利于咖啡纤维的进一步开发和利用.     

咖啡壶的失效评估

本文对某型咖啡壶样品进行了分解和剖析,对各元、器件的特性、工作原理与过程进行了研究.通过工作试验、模拟试验,对整个系统的工作流程进行了实测;在预制失效的情况下,对系统的应激反应进行了监测;根据元件的材料、结构特点和使用环境等因素对其失效模式进行了分析.在以上工作的基础上,采用预先危险分析、失效模式与效果分析和故障树分析等可靠性分析手段,对咖啡壶系统进行了失效评估.评估结果表明,咖啡壶在结构、系统、安全防护设计等方面较为合理,咖啡壶在意外发生时安全保护系统较为完善,符合安全设计准则;咖啡壶金属制弹簧类元件普遍存在抗腐蚀性能差的问题,电阻保持架的加工质量存在问题.     

惩戒解雇事由研究

《劳动合同法》第39条对惩戒解雇的规定在实际应用中出较多问题.理论上,如何合理界定归于雇员的原因,使用人单位的自由用工权与劳动者的劳动权达到平衡,是惩戒解雇事由需要重点解决的问题.我国应从劳动法的视角建构起用人单位惩戒解雇的法律规则,并完善相关的权利救济制度,使用人单位的自由用工权与劳动者的劳动权达到平衡.     

基于PIC16F877A的咖啡机智能温控系统

分析了传统滴漏式咖啡机存在的问题,提出了一种基于Microchip公司8位单片机PIC16F877A的智能咖啡机温控系统方案.应用该方案的智能咖啡机可根据咖啡量的不同而进行自调节式控温,具有较高的恒温精度.