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.     

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.     

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.     

HPLC法测定焙烤咖啡中咖啡因的含量

建立高效液相色谱法简便准确测定焙烤咖啡中咖啡因的含量.采用色谱分析柱(UltimateTM XB-C18,5μm,4.6×150 mm),流动相:甲醇-水(含2 mL/L乙酸),梯度洗脱,柱温30℃;流速1.0 mL/min;检测波长286 nm;咖啡因质量浓度在5～200 μg/L范围内与色谱峰面积呈良好线形关系(R2=0.9997),平均回收率有97.93%,精密度测试结果的RSD为0.14%.该方法操作简单、结果准确、重复性好.     

喷墨打印墨滴成形机理及其在含能领域应用进展

喷墨打印技术是以墨滴为基础,集喷射工艺、离散堆积数控制造及计算机辅助设计于一体的先进精细微加工制造技术,是微机电系统（MEMS）火工品等微结构含能器件的重要装药途径之一。在喷墨打印过程中,如何实现墨滴的精确控制是提高材料可打印性和打印精度的关键。本文在系统调研喷墨打印成型机理研究的基础上,探讨了墨水的物理特性、打印工艺参数对墨滴形成方面的影响规律,梳理了“咖啡环”效应出现的原因及控制方法,归纳了喷墨打印过程中墨滴成形和沉积的控制策略,与此同时,综述了喷墨打印技术在传爆药、纳米铝热剂等方面的应用情况,展望了喷墨打印技术下一步在含能领域应用的发展方向。喷墨打印技术的按需滴加、皮升级沉积为微纳米结构含能药剂的精确装药提供了前提,在MEMS火工品、异形含能器件方面具有较好的应用前景。     

咖啡连锁事业营销策略研究——以星巴克与85度C为例

本研究的目的系针对国内两大咖啡连锁业者——星巴克及85度C,借由问卷调查方式,以了解不同咖啡连锁体系服务质量差异。透过随机抽样方式,共搜集157份有效调查问卷,经由分析探讨消费者对于此两家连锁咖啡店的服务质量认知。研究结果发现,星巴克及85度C在五大质量板块(有形性、可靠性、反应性、保证性、关怀性)的19个服务品质问项中,有15个问项皆具有显著差异(p<0.05),其中14个问项为星巴克优于85度C。但值得注意的是,虽然问项"对店家的整体满意程度"为星巴克优于85度C(4.81:4.39,p<0.01),但在"整体服务所对应的价格"问项中,85度C则显著优于星巴克(4.18:3.69,p<0.05),显示两者在市场的定位中具有差异化。本研究建议,两家业者除持续提高服务质量外,85度C可突显或拉大其在价格上的优势,以强化其差异化策略,并弥补整体服务质量分数低于竞争对手的劣势。