基于电子舌与人工感官的茶叶滋味属性参考物呈味强度相关性分析

目的:探究电子舌和人工感官对茶叶滋味属性参考物呈味强度的相关性。方法:以奎宁、明矾、谷氨酸钠、蔗糖和柠檬酸依次为苦、涩、鲜、甜、酸滋味属性参考物,在觉察阈值基础上,分析各滋味属性参考物电子舌和人工感官的浓度—呈味强度关系及其相关性。结果:奎宁苦味觉察阈值为0.015 mg/mL、对应电子舌响应值为4.91;明矾涩味觉察阈值为0.01 mg/mL、对应电子舌响应值为3.32;谷氨酸钠鲜味觉察阈值为0.03 mg/mL、对应电子舌响应值为1.32;蔗糖甜味觉察阈值为0.4 mg/mL、对应电子舌响应值为18.07,柠檬酸酸味觉察阈值为0.04 mg/mL、对应电子舌响应值为6.18。各滋味属性参考物的人工感官和电子舌浓度—呈味强度均呈一定函数曲线关系,符合Weber-Fechne定律;在所选浓度范围内,柠檬酸(酸味)和蔗糖(甜味)电子舌呈味强度与人工感官强度呈正相关,奎宁(苦味)和明矾(涩味)电子舌呈味强度与人工感官强度呈负相关。结论:茶叶中5种滋味属性参考物电子舌检测与人工感官浓度—呈味强度具有一定相关性。     

水中SiO3^2-对红茶茶汤滋味品质的影响

通过分析SiO3^2-与主要味感物间的滋味互作效应,探究其影响茶汤滋味品质的内在机制。研究表明,随着SiO3^2-质量浓度的增加,茶汤甜味上升,鲜味、涩味、苦味及综合滋味品质下降;茶汤中儿茶素、茶多酚、氨基酸、表没食子儿茶素没食子酸酯(EGCG)含量和Ca^2+、K^+、Mg^2+等离子浸出量下降是SiO3^2-导致茶汤滋味品质下降的原因。进一步研究发现,SiO3^2-可有效增强谷氨酸钠溶液的鲜味和蔗糖溶液的甜味,显著减弱咖啡碱溶液的苦味和EGCG溶液的苦涩味,具有明显的滋味互作效应。建议日常冲泡红茶应选用含有适量SiO3^2-(<48 mg/L)的水。     

The Stereochemical Basis of Bitterness in Sugar Analogues

Bitterness of sugars and their derivatives appears to be the result of polar as well as hydrophobic molecular features. It is multifunctional and the ring oxygen atom, the anomeric oxygen atom and the C-2 hydroxyl group (and possibly the C-6 hydroxyl group), all of which constitute the most polar and highly reactive “end” of the sugar molecule, together interact to elicit bitterness. The configuration of the substituents on C-1 and possibly on C-2 is critical in determining bitterness in many sugars an indeed β-glycosides and β-linked disaccharides are more likely to be bitter than α-linked anomers. Unlike sweetness, no distinct interorbital distances can yet be established for bitterness. However, current hydrogen bond theories of sweetness seem suffice to explain bitterness in most types of sugar analogue. “Polarisation” of bitter/sweet molecules on taste receptors are also discussed and evidence obtained suggests that at least some of the sweet and bitter receptor sites might be extremely close to one another, and probably within 3–4 Å.     

The applications and future implications of bitterness reduction and inhibition in food products

Numerous food and beverage products, bulking agents, and pharmaceuticals have pleasant as well as unpleasant bitter-tasting components in their taste profile. In numerous cases, the bitter taste modality is an undesirable trait of the product. Bitter characteristics found in some food systems have been removed or diminished by various known processes, but no universally applicable bitter inhibitor has ever been recognized. Some indications point to a receptor-mediated phenomenon for sweetness and bitterness. Research on sweet compounds has led to knowledge of sweetness inhibitors and could ultimately lead to bitterness inhibitors. To facilitate efforts to rationally design a universal bitter inhibitor or cocktail of such, a review of the bitter taste phenomena and known methods of bitterness reduction and inhibition have been compiled.     

Sensory quality of ethylene‐exposed carrots (Daucus carota L,cv ‘Yukon’) related to the contents of 6‐methoxymellein,terpenes and sugars

Carrots were analysed for taste and odour and for contents of terpenes, 6‐methoxymellein and sugars during 3 weeks storage at 15 °C in an atmosphere containing ethylene (1 µl l⁻¹). The ethylene treatment caused an increase in 6‐methoxymellein and the conversion of higher amounts of sucrose to fructose and glucose compared to control carrots stored in air. This corresponded to higher sensory scores for bitterness and terpene flavour and a lower score for sweetness, as measured by an expert taste panel. Principal component analysis showed a more expressed bitter taste, earthy flavour, green flavour, terpene flavour and aftertaste in the ethylene‐treated carrots. Correlations were found between sweet taste and the content of sucrose (r = 0.91, p < 0.005) and between the contents of various terpenes (particularly γ‐terpinene, limonene and caryophyllene) and terpene flavour, green flavour, aftertaste and bitter taste (r ≥ 0.72, p < 0.05). In the air‐stored carrots these off‐flavours seemed to be masked by a high sucrose content. © 2000 Society of Chemical Industry     

Sensory characteristics of human milk: Association between mothers' diet and milk for bitter taste

It is unknown how consumption of bitter foods and beverages in the maternal diet influences sensory properties of fresh human milk. The aims of this study were (1) to determine the sensory characteristics of fresh human fore and hind milk, (2) to establish relationships between sensory properties and composition of fresh human milk, and (3) to assess the relationship between bitterness of the maternal diet and human milk. Twenty-two lactating mothers generated sensory terms to describe perception of their milk and received training on sensory attribute intensity rating. Mothers kept a 24-h food diary followed by a sensory self-assessment of their fore and hind milks. The odor of human fresh milk was described as neutral, creamy, and sweet, taste as sweet and bitter, and mouthfeel as thin, watery, smooth, and fatty. Sweetness was equivalent to 1.53 g of sucrose/100 mL and was not significantly different between fore and hind milk. Fore milk was significantly less creamy, less fatty, thinner, more watery, and lower in vanilla flavor intensity than hind milk. Carbohydrate content of human milk was positively correlated with sweetness and glutamic acid content with umami. The bitterness of the diet consumed 24 h before lactation was moderately positively correlated with bitterness of fore milk, but not hind milk. We conclude that the consumption of bitter foods may influence the bitterness of human fore milk, which may be another way for?breastfed children to learn to accept bitter vegetables and, hence, develop healthier food preferences.     

Sensory characteristics and relative sweetness of tagatose and other sweeteners

The present study investigated the sensory characteristics and relative sweetness of tagatose, an emerging natural low-calorie sweetener with various functional properties, compared to other sweeteners (sucrose, sucralose, erythritol, rebaudioside A), over a wide range of sweetness commonly found in foods and beverages (3% to 20% sucrose [w/v]). A total of 34 subjects evaluated aqueous solutions of the 5 sweeteners for the perceived intensities of sweetness, bitterness, astringency, chemical-like sensations, and sweet aftertaste, using the general version of the Labeled Magnitude Scale. The relationship between the physical concentrations of the sweeteners and their perceived sweetness (that is, psychophysical functions) was derived to quantify the relative sweetness and potency of the sweeteners. The results suggest that tagatose elicits a sweet taste without undesirable qualities (bitterness, astringency, chemical-like sensations). Out of the 5 sweeteners tested, rebaudioside A was the only sweetener with notable bitterness and chemical-like sensations, which became progressively intense with increasing concentration (P < 0.001). In terms of perceived sweetness intensity, the bulk sweeteners (tagatose, erythritol, sucrose) had similar sweetness growth rates (slopes > 1), whereas the high-potency sweeteners (sucralose, rebaudioside A) yielded much flatter sweetness functions (slopes < 1). Because the sweetness of tagatose and sucrose grew at near-identical rates (slope = 1.41 and 1.40, respectively), tagatose produced about the same relative sweetness to sucrose across the concentrations tested. However, the relative sweetness of other sweeteners to sucrose was highly concentration dependent. Consequently, sweetness potencies of other sweeteners varied across the concentrations tested, ranging from 0.50 to 0.78 for erythritol, 220 to 1900 for sucralose, and 300 to 440 for rebaudioside A, while tagatose was estimated to be approximately 0.90 times as potent as sucrose irrespective of concentration. Practical Application: The present study investigated the sensory characteristics and relative sweetness of tagatose, an emerging natural low-calorie sweetener, compared to other sweeteners. Study results suggest that tagatose elicits a sweet taste without undesirable qualities over a wide range of concentrations. Tagatose produced about the same relative sweetness to sucrose across the concentrations tested, while the relative sweetness of other sweeteners was highly concentration dependent. The present data provide a general guideline when considering the use of tagatose and other sweeteners in foods and beverages.     

Perceived Taste Intensity and Duration of Nutritive and Non-nutritive Sweeteners in Water using Time-intensity (T-I) Evaluations

This investigation compared the sweet and bitter taste characteristics of aspartame, acesulfame K, and alitame at equisweetness levels with 10% sucrose/water solutions at 22°C using the time-intensity (T-I) sensory technique. Alitame was comparable to sucrose in all taste characteristics. Aspartame had similar taste characteristics to sucrose with the exception of having greater sweet intensities with longer duration (P<0.001) following sample expectoration. Acesulfame K differed remarkably from sucrose. The sweet attribute of acesulfame K appeared quickly (P<0.05) before sample expectoration. This was followed by a moderately intense and lingering bitter character (P< 0.001) which reached maximum intensity after sample expectoration.     

Structural basis of and interaction between sweetness and bitterness in sugars

The relationships between concentration and subjective intensity of (a) sweetness and (b) bitterness have been separately determined and the effect of each on the subjective intensity of the other has been evaluated. The depression of sweetness by bitter additives, or bitterness by sweet additives obeys a simple mathematical relationship which may be used to calculate the “true” sweetness of a bittersweet sugar. This facilitates the structural explanation of sweetness in model sugars.     

糖醇类甜味剂的甜味与副味影响因素研究

糖醇因甜味纯正、热量低、安全健康等优势,成为理想的代糖甜味剂,具有广阔的应用前景。然而,对糖醇类甜味剂感官属性的影响因素研究较少。作者以赤藓糖醇、木糖醇、麦芽糖醇和山梨糖醇为研究对象,采用成对比较和排序法等感官分析方法,研究不同粒径、温度以及溶液质量浓度对糖醇类物质的甜味、清凉感、苦味和异味的影响差异。结果显示,在室温下,不同粒径糖醇晶体的清凉感均表现出显著差异（P<0.05）,麦芽糖醇和山梨糖醇的甜味也有显著性差异（P<0.01）,这两个属性基本都显示出粒径越大、强度越小的特点;升温后,不同颗粒间的异味和苦味差异更容易分辨,也会使清凉感的感知变弱;高质量浓度赤藓糖醇在热饮中表现出了比较显著的增甜效果;对于木糖醇、麦芽糖醇和山梨糖醇,在冷热条件下的甜味感知差异在不同质量浓度溶液下的表现相似。     

EVALUATION OF THE SEPARATE CONTRIBUTIONS OF VISCOSITY AND SWEETNESS OF SUCROSE TO PERCEIVED VISCOSITY,SWEETNESS AND BITTERNESS OF VERMOUTH3

The separate effects of sweetness and viscosity of sucrose on the sensory properties of vermouth were evaluated in systems: (1) varying in sucrose concentration and viscosity (2) with constant sucrose concentration but varying in viscosity, and (3) constant viscosity, but varying sucrose concentration. Twenty-one trained judges rated oral viscosity, sweetness and bitterness, while the physical viscosity of the Newtonian systems was measured by capillary viscometry. Both perceived sweetness and oral viscosity increased, while bitterness decreased as sucrose was increased, and as the physical viscosity of the vermouths increased. However, samples in which viscosity was increased by the nonsweet Polycose® were rated sweeter and less bitter than vermouth solutions of the same sucrose concentration, but lower physical viscosity. Similarly, when vermouths of identical viscosity were compared, the vermouths with higher sucrose concentration were judged to be more viscous. Viscosity alone contributed 20-30% of the perceived increase in sweetness due to sucrose addition. The effect of viscosity in reducing bitterness was of the same magnitude. The increase in perceived viscosity caused by addition of sucrose arose from approximately equal contributions of physical viscosity and sweetness of sucrose.     

Dietary habits and the perception and liking of sweetness among Australian and Malaysian students: A cross-cultural study

This study examined whether the perception of, and preference for, varying levels of sucrose in water, orange juice, custard and biscuit were related to dietary intakes of sugar and sweet foods in 69 Caucasian Australian and 63 Malaysian university students living in Australia. The two ethnic groups were equally able to discriminate the relative differences in sucrose concentration among the test samples, and a similar percentage of each group were sweetness likers or dislikers. Some significant differences between the ethnic groups' sweetness intensity and preference ratings were observed, but the differences were food-specific and were not always apparent for the same sucrose level in the different test foods. Within each ethnic group, more subjects had greater difficulty discriminating different sucrose levels in a solid, high fat biscuit. The Australian group had higher mean liking ratings than the Malaysian group for the orange juice and biscuit samples. However, both groups preferred similar levels of sucrose in the juice, custard and biscuit, which were similar to the amounts of sucrose present in current commercial products. The hedonic response pattern to the sucrose solution was not a good predictor of the hedonic responses to the other test stimuli, which indicates that preferred levels of sweetness are food-specific. Sweetness intensity ratings were not significantly associated with any of the dietary intake variables or bitterness ratings to 6-n-propylthiouracil. However, subjects who preferred higher levels of sucrose in the test stimuli tended to have higher dietary intakes of sugar and sweet foods.     

Taste interaction of ethyl alcohol with sweet, salty, sour and bitter compounds

The influence of ethyl alcohol in concentrations ranging from 4 to 24%, on the perceived taste intensities of sucrose, citric acid, quinine, and sodium chloride was determined by 24 subjects. A paired comparison method was used in which subjects selected the sample with the greater taste intensity (sweetness, sourness, bitterness or saltiness) as well as rating the intensity on a 13-point scale. The alcohol generally enhanced the sweetness of sucrose, with results varying slightly according to the subjects' task. The sourness of citric acid, and the saltiness of sodium chloride at all but the lowest concentration, were depressed by increasing additions of alcohol. Alcohol significantly enhanced the bitterness of quinine at all four concentrations. Although these results disagree with previously reported electrophysiological measurements on alcohol-quinine mixtures, they were internally consistent, and meaningful in terms of alcoholic beverage consumption behaviour.     

Sweet–bitter interactions and the solution properties of chlorinated sugars

Among chlorinated sugars, some are intensely sweet, some are bitter and others are tasteless. Although chlorination of sugars provokes an increase in lipophilicity, a certain hydrophilic/lipophilic balance is needed for sweeteners to be perceived. Two chlorinated sugars, sucralose (trichlorogalactosucrose) and methyldichlorogalactoside, respectively known for their enhanced sweetness (650×) and inhibitory effect on the sweetness of sucrose, are studied. Their sapid properties are interpreted on the basis of their physicochemical properties (intrinsic viscosity, apparent specific volume, surface tension, contact angle and vibrational spectra). It is particularly shown that the perturbation of the structure of water by these molecules, compared with that by simple sugars, helps in understanding their taste mechanism.     

不同抑制剂对苦瓜粉味觉的修饰效果

以苦瓜粉浸泡液为对象,分别添加乳酸锌、新甲基橙皮苷二氢查尔酮、γ-氨基丁酸、酪朊酸钠、全脂乳粉、阿魏酸、聚葡萄糖、三氯蔗糖、新地奥明、单磷酸腺苷,采用感官评定结合标签量值评估（general labeled magnitude scale,gLMS）法评价不同抑制剂对苦瓜粉浸泡液苦味、后苦味、甜味、后甜味、涩味以及特征风味的影响;通过模糊评判筛选抑制效果最佳的3?种抑制剂进行正交试验,评价复合抑制剂对苦瓜粉浸泡液苦味及后苦味的影响。结果表明,10?种抑制剂对苦瓜粉浸泡液的苦味、后苦味、涩味均有显著抑制作用。其中新甲基橙皮苷二氢查尔酮对苦味、后苦味抑制作用最强;乳酸锌对后苦味、γ-氨基丁酸对苦味也有较好的抑制作用;酪朊酸钠对涩味的抑制作用最为明显;三氯蔗糖、聚葡萄糖、酪朊酸钠、全脂乳粉会增加整个体系的甜味及后甜味。以乳酸锌、新甲基橙皮苷二氢查耳酮、γ-氨基丁酸3?种抑制剂进行正交试验,结果表明1?g苦瓜粉添加0.60?mg新甲基橙皮苷二氢查耳酮、3.98?mg?γ-氨基丁酸、4.46?mg乳酸锌时,苦瓜粉浸泡液苦味和后苦味可以从明显降低到基本察觉不到,且苦瓜特征风味保留较好,无其他异味存在。