Relating consumer preferences to sensory attributes of instant coffee

The sensory profiles of 11 instant coffees including pure coffees (PC), coffee blends (CB) and a chicory instant drink (CID), commercially available in South Africa, were described and quantified. These were then related to consumer preferences (n=199) for the instant coffees using preference mapping. Based on consumer preferences, four consumer groups were identified, “pure coffee lovers” (23%), “coffee blend drinkers” (30%), “general coffee drinkers” (37%) and “not serious coffee drinkers” (10%). The “pure coffee lovers” prefer the more astringent, bitter, roasted, nutty and full-bodied flavour of the pure coffee samples. The less intense coffee flavour character, but higher sweetness and root flavour, typical of chicory blended instant coffee, were attributes that were preferred by the “coffee blend lovers”. The “general coffee drinkers” seem to consume coffee out of habit and are less concerned about the specific sensory properties of the coffee.     

Evaluation of sensory attributes of coffee brews from robusta coffee roasted under different conditions

Robusta coffee beans with a different initial moisture of 5, 7.5 and 10% were convectively roasted at 230 °C, microwaved at 700 W, and roasted by the coupled convective-microwave method. Sensory attributes of brews prepared from these coffee samples were evaluated. Final temperature of microwaved coffee beans was lower than that of the beans processed by the two other methods, which resulted in a higher content of volatile aroma compounds and a lesser degree of charring of their surface. Lower initial humidity of coffee beans shortened the time of roasting. However, the aroma developed upon roasting of the moistest beans was the most intense and pleasant. Modification of roasting conditions increased shifting of the overall acceptability of coffee infusions by 2 points in a 10-point hedonic scale, which implies that, if roasting conditions are adequate to the type of coffee, its sensory characteristics can be improved. Thus, optimization of roasting parameters can increase the share of robusta in well-accepted commercial coffee blends, a convenient fact because of the significant difference in price between the latter and arabica coffee.     

不同焙炒程度对罗布斯塔咖啡豆香气成分的影响

咖啡作为当今世界上最受欢迎的饮料之一,其气味香醇,口感浓郁,具有提神醒脑、抗氧化、抗癌等作用。由于不同人群对咖啡的需求有所不同,市场上咖啡饮料的品类也日渐繁多,目前市场上除了纯咖啡饮料以外,以咖啡为原料之一研制而成的复合饮料产品也在逐渐增多,常见与咖啡复合加工的食品类型有水果、谷物、乳类、菌类等。近年来,开始出现更多与药食同源类食品复合加工而成的饮料。咖啡类饮料的加工方式大多为喷雾干燥、冷冻干燥、混合制粒、冷萃浓缩等,几种方法各有利弊,研究人员也在根据市场需求积极研发更多咖啡类饮料产品。本文综述了咖啡的主要功能性成分、咖啡类饮料的常见种类、加工方式以及发展趋势,为以后进一步开发咖啡类饮料产品提供参考。     

绿咖啡豆中总绿原酸提取工艺优化

研究了绿咖啡豆中总绿原酸的提取工艺。以未烘焙的绿咖啡豆为实验材料,采用浸提的方法提取总绿原酸。在单因素实验基础上,选择溶剂体积分数、温度、p H、料液比等4个影响因素进行响应面设计。采用Box-Behnken中心组合实验设计和响应面分析法,建立以绿咖啡豆中总绿原酸提取得率为响应值的二次回归方程。结果表明溶剂体积分数、温度、p H、料液比对多酚提取率的影响显著,最佳提取条件为乙醇体积分数75%、温度45℃、p H3、料液比1∶6,在此条件下能得到最大提取率为90.88%。     

Microwave-assisted extraction of chlorogenic acids from green coffee beans

Microwave-assisted extraction (MAE) has been considered as a potential alternative to conventional solvent extraction for the isolation of phenolic compounds from plants. Aqueous and alcoholic extracts of green coffee bean obtained by MAE were quantitatively analysed for total yield of extracts, chlorogenic acids, caffeine and total polyphenol content. The extracts were also evaluated for radical-scavenging activity, using 1,1-diphenyl-β-picrylhydrazyl radical. Under optimum conditions of time (5 min), temperature (50 °C) and wattage (800 W), the maximum chlorogenic acids and caffeine could be extracted with water as solvent. The extracts contained chlorogenic acids and caffeine in the ranges of 31–62% and 22–40%, respectively. The yields of MAE under optimum conditions were higher than those from the conventional solvent extraction at 5 min and 50 °C and the extracts showed radical-scavenging activity of >75%, even at the concentration of 25 ppm. The MAE process can thus be predicted and controlled for industrial application.     

基于香气活性值及感官属性对金银花尾酒酿造风味食醋特征的分析

以金银花尾酒为主要原料,经醋酸发酵酿造特色金银花风味食醋。应用顶空固相微萃取结合气相色谱质谱联用,分析风味食醋中的挥发性风味物质,利用香气活性值探讨风味食醋的关键风味物质,通过化学检测结合感官定量,比较分析风味食醋与品牌醋的香气结构差异性。结果表明,从风味食醋中定性定量出主要挥发性风味物质62种,其中萜烯类物质是风味食醋中特有的一类物质;分析确定了风味食醋中关键风味化合物15种;与3种品牌醋相比,风味食醋中的特征风味物质有28种,含量较高的为芳樟醇、对乙基愈创木酚和α-松油醇,经感官分析发现,花香、青香和木香是风味食醋的主要特征香气。该研究为金银花尾酒资源化利用提供理论依据,同时为食醋风味研究提供技术支持。     

A comparative study of chemical attributes and levels of amines in defective green and roasted coffee beans

Differences in chemical attributes (proximate composition, water activity, sucrose, acidity and pH levels) and amine levels between defective and healthy coffee beans were studied. Before roasting, significant differences (p < 0.05) were observed for the ash contents of the coffee samples, with the highest values found for black beans. Moisture content was higher for non-defective beans in comparison to defective beans. Non-defective coffee beans had higher lipids contents than both sour and black beans. There were no significant differences (p > 0.05) for protein levels between defective and non-defective beans. After roasting, protein levels remained constant, there was a small decrease in ash contents and a slight increase in oil contents of black and sour beans. Both black and sour beans had higher acidity levels than immature and non-defective beans. Acidity levels decreased after roasting. Water activity levels also decreased with roasting, with slightly higher levels for defective beans in comparison to non-defective ones. Sucrose levels were much higher in non-defective beans, and the lowest values were in black beans, prior to roasting. After roasting, only traces of sucrose were found. Total amine levels were much lower for black beans, in comparison to the other coffee samples. Putrescine was the prevailing amine in all samples. Histamine was only detected in the defective coffee samples. Small amounts of serotonin, cadaverine and tryptamine were found in some of the samples. After roasting to a light degree, only traces of serotonin were detected and no amines were detected after roasting to medium and dark degrees.     

Correlations of ingredients with sensory attributes in green beans and peas under different storage conditions

The total ascorbic acid contents and the antioxidant capacity in green beans and in peas were measured during deep-frozen storage and compared to storage at 4 °C and 20 °C. In green beans only, the flavonols quercetin and kaempferol were measured. The results were correlated with sensory attributes which were evaluated at the same storage stages. The total ascorbic acid content is a good parameter for the storage time of both vegetables and showed, for peas, a positive correlation with the attribute “sweet taste” and a negative correlation with the attribute “musty” odour. The total ascorbic acid content of green beans was positively correlated with a “squeaky” texture and negatively with a “musty” taste. The flavonol content and the antioxidant capacity were more stable during the storage process and showed less correlation with sensory attributes.     

Assessment of antimicrobial activity of coffee brewed in three different ways from different origins

The antimicrobial effect against pathogens such as Staphylococcus aureus, Enterecoccus faecalis, Listeria monocytogenes, Pseudomonas aeruginosa, Escherichia coli and Salmonella choleraesius was determined in four types of coffee (Coffea arabica L. cv. Colombia, decaffeinated cv. Colombia, cv. Ethiopia and cv. Kenya). Coffee was seen to have significant activity against the growth of food spoilage bacteria. Among the Gram-positive bacteria, coffee was strongly active against S. aureus, moderately active against L. monocytogenes and had a slightly inhibitory effect against E. faecalis. However, coffee samples were found to be less active against Gram-negative bacteria. The results show that espresso Colombia coffee has better antimicrobial activity than filter and Italian coffee with significant differences (p?<?0.05). Taking into account the origin, there were significant differences (p?<?0.05) between Kenya and decaffeinated Colombia, on the one hand, and Ethiopia and Colombia coffee, on the other, the two last showing the highest antimicrobial activity. The antimicrobial activity of the coffee from different origins studied in this paper increased with concentration. Typical coffee compounds were also analysed, and only caffeic and chlorogenic acids showed any inhibitory effect against the growth of all the analysed bacteria. The antibacterial properties of coffee means that it has a promising potential as natural food ingredient to extend the shelf life of foods such as cake, cookies or biscuits, coffee flavoured with shakes, yoghurt.     

云烟净油有机膜分离成分中关键香气成分与感官属性的关联系分析

[目的]研究云烟净油成分与卷烟感官指标的关联性.[方法]采用GC-MS分析云烟净油有机膜分离组分中的香气成分组成,计算ROAV值确定关键香气成分,用偏最小二乘回归分析法(PLSR)建立云烟净油有机膜分离组分的关键香味成分与感官指标的PLS模型.[结果](1)在100 kDa有机膜截留液中,有25种不同的挥发性香味物质,...     

咖啡生豆多糖提取及抗氧化活性

目的:为咖啡中多糖成分的研究和天然活性多糖的开发提供基础数据。方法:研究了云南小粒咖啡生豆多糖(GBP)的水提工艺和抗氧化活性。应用响应面法对咖啡生豆多糖提取工艺进行优化;运用傅里叶变换红外光谱(FT-IR)和扫描电镜(SEM)共同鉴定和表征咖啡生豆多糖的结构特点。采用DPPH自由基、ABTS自由基清除试验和FRAP法评估咖啡生豆多糖体外抗氧化能力。结果:咖啡生豆多糖水提法的最佳工艺条件：提取温度59℃、提取时间45 min、液料比(V_水∶m_咖啡生豆)21∶1 (mL/g)、浓缩体积1/8及乙醇体积分数75%,该条件下咖啡生豆多糖得率达9.56%。多糖样品经红外光谱和电镜扫描显示咖啡生豆是表面呈不规则的孔状结构的多糖。咖啡生豆多糖对DPPH自由基、ABTS自由基清除能力分别为2.32 mg/mL(IC₅₀)、0.011 mmol Trolox/g GBP,铁还原能力为0.95 mmol Fe²⁺/g GBP。结论:咖啡生豆多糖是具有抗氧化活性的不规则孔状结构多糖,具有进一步研究和开发的价值。     

蔗汁、糖浆和废糖蜜酿制甘蔗酒的风味比较

为了了解蔗汁、糖浆和废糖蜜酿制的甘蔗蒸馏酒在风味上的区别,了解甘蔗蒸馏酒的主要风味特征,从甘蔗制糖厂采集蔗汁、糖浆和糖蜜,用粟酒裂殖酵母发酵,通过蒸馏、陈酿得到甘蔗酒,用二氯甲烷萃取法提取香味成分,用GC-MS进行分析。结果表明:10种香味成分为3种原料甘蔗蒸馏酒所共有,可能是构成甘蔗蒸馏酒特征风味的主体香味成分;糖蜜甘蔗酒（朗姆酒）含有多种美拉德反应产物表现出焦香风味的特征,而蔗汁甘蔗酒和糖浆甘蔗酒没有明显的美拉德反应产物,表现出清香的甘蔗酒的风味特征。本研究对于甘蔗酒开发时原料的选择具有指导意义,同时有利于加深对甘蔗蒸馏酒风味特征和香气成分的认识。      

The mycobiota of coffee beans and its influence on the coffee beverage

The quality of coffee beverage is influenced by several factors, including the species or botanical variety of the beans, agricultural practices, harvesting, drying and storage techniques and also the preparation of the beverage. Apart from these, there is the input of microbial contamination during the processing of the beans. Numerous studies have demonstrated that fungi are important contaminants of coffee beans, especially just after harvesting and drying. However, the relationship between fungal contamination and the sensorial characteristics of the beverage has yet to be described. The aim of this research was to analyze the mycobiota of coffee beans collected from different stages of the coffee production chain and to correlate these data with the sensorial characteristics of the final beverage. Fungal infection of 22 coffee bean samples from the southwest of São Paulo state was analyzed. Samples were collected from the tree (mature cherries), from the ground, from the patio (mature, immature and dried floaters or overripe cherries from the tree) and from storage facilities. In general, coffee samples from this region showed high fungal infection and contamination was higher than 70% in about 45% of the samples. A high diversity of fungi was isolated from all the coffee samples analyzed and the most common were Penicillium brevicompactum, Aspergillus section Nigri, Penicillium sp. nov. (closely related to Penicillium crustosum) and Fusarium sp. Both P. brevicompactum and Penicillium sp. nov. were found at all processing stages, including in the cherries, showing that these fungi are naturally found in the coffee beans from this region. Floater coffee and coffee from the ground showed negative sensorial evaluation with attributes such as moldy, dirty and fermented and presented a high contamination by Aspergillus section Nigri and Aspergillus westerdijikiae.     

Profiles of volatile compounds and sensory characteristics of Robusta coffee beans roasted by hot air and superheated steam

Although superheated steam (SHS) roasting has proved to be capable of improving selected quality of roasted Robusta coffee beans, impact of SHS roasting on aroma characteristics of the beans is not well understood. This study therefore aimed to investigate the effect of SHS roasting on aroma profiles and sensory characteristics of Robusta beans undergone SHS roasting at 190–250 °C; results were compared with those of beans roasted by hot air (HA). Sensory characteristics of selected samples were also compared with HA-roasted Arabica beans. Forty five aroma compounds were identified; most were fully developed in beans roasted at 230 °C and tended to degrade in beans roasted at 250 °C. SHS roasting led to more extensive formation of aroma compounds contributing to caramel note, while helped reduce formation of major contributors to spicy, roasty and burnt notes. SHS-roasted Robusta beans exhibited more resemblance to Arabica beans than their HA-roasted counterpart.     

Strontium and oxygen isotope fingerprinting of green coffee beans and its potential to proof authenticity of coffee

Multicollector inductively coupled plasma mass spectrometry (MC-ICP-MS) and Isotope Ratio Mass Spectrometry (IRMS) were applied to combine strontium and oxygen isotope abundance ratios of green coffees from 20 geographical origins in order to evaluate the suitability of these parameters as indicators of geographical origin, which is an important parameter of coffee quality. Results show that both isotopic systems of green coffee beans show a relation to environmental factors that influence processes occurring during the growth of the coffee bean. The final results allowed discrimination of local provenances investigated in this study by principal component analysis (PCA) and exhibit the potential to proof authenticity of world coffees. A good discrimination was obtained especially for coffee of South America region and coffees originating from islands.     

绿咖啡豆中绿原酸的分离纯化

对未烘焙绿咖啡豆中绿原酸的分离纯化进行深入研究.采用热水重复分批浸提法,在单因素实验基础上,采用Box-Behnken中心组合实验设计响应面分析法,获得了绿咖啡豆中绿原酸的最佳提取条件:温度79.8℃,溶剂pH值2.8,料液比1∶6,提取时间3.0 h,绿原酸的最大提取得率为92.0％.比较了多种不同规格的树脂对绿原酸的分离纯化效果,最终选用XDA-8大孔树脂,在优化后的最适工艺条件下,绿原酸含量可达70.9％,回收率达85.4％.进一步采用高效液相制备色谱获得了高纯度(95.2％)的绿原酸.所建立的绿原酸制备工艺操作简便、高效环保,产品功效明确,具有良好的市场应用前景.