Bitterness and astringency of flavan‐3‐ol monomers,dimers and trimers

Intensity of astringency and bitterness of seven flavonoid compounds was evaluated by a time‐intensity (TI) procedure. Eighteen trained judges rated intensity continuously from ingestion, through expectoration at 10 s until extinction of the sensation. The seven stimuli included two flavan‐3‐ol monomers, (+)‐catechin and (−)‐epicatechin, three dimers and two trimers synthesised from catechin or epicatechin by condensation with (+)‐dihydroquercitin. As the degree of polymerisation increased, maximum bitterness intensity (I_max) and total duration (T_tot) decreased whereas astringency I_max increased. The monomers were significantly higher in bitterness at I_max than the dimers, which were significantly higher than the trimers. Astringency I_max of the monomers was lower than the dimers or trimers, although no significant difference was found in T_tot among the polymer classes. The bond linking the monomeric units had an influence on both sensory properties. The catechin‐catechin dimer linked by a 4→6 bond was more bitter than both catechin‐(4→8)‐catechin and catechin‐(4→8)‐epicatechin. Astringency was affected by both the specific linkage and the identity of the monomeric units with the dimer, catechin‐(4→8)‐catechin, being lower in astringency than either catechin‐(4→6)‐catechin or catechin‐(4→8)‐epicatechin. © 1999 Society of Chemical Industry     

Perception and acceptance of selected high-intensity sweeteners and blends in model soft drinks by propylthiouracil (PROP) non-tasters and super-tasters

Individual variation in the perception of saccharin has been related to genetic sensitivity to the bitterness of 6-n-propylthiouracil (PROP). But, data on other intense sweeteners are sparse, particularly when tasted in real foods. The objectives of this study were (1) to identify the sensory attributes of intense sweeteners that influenced perception and acceptability of citrus-flavored model soft drinks and (2) to investigate the influence of PROP taster status on these responses. The sweeteners were: 10% and 8% high-fructose corn syrup (HFCS) (controls), sucralose (SUC), aspartame (ASP), acesulfame-K (ACE), ASP/ACE and SUC/ACE. Twenty-nine PROP non-tasters (NT) and 30 PROP super-tasters (ST) rated nine attributes for intensity and liking. Data were analyzed using principal component analysis (PCA). The sweeteners were described in three dimensions. Factor 1 was a bitter-citrus contrast for which overall liking was associated with higher citrus impact and lower bitterness. Factors 2 and 3 were related to overall flavor and carbonation, respectively. The sensory profiles of ASP, ASP/ACE and SUC were most similar to 10% HFCS. SUC/ACE was more bitter and less acceptable than 10% HFCS; ACE was the most bitter and was liked the least. PCA also revealed that NT placed more emphasis on the perception of sweetness and citrus flavor (Factor 1; 37% variance), whereas ST tasters placed more emphasis on bitterness (Factor 1; 43% variance). Liking was uniquely related to lower bitterness for NT. For ST, liking was negatively related to bitterness and weakly positively related to persistence of sweetness. These data suggest that ST experience intense sweeteners differently than NT but these differences play a minor role in soft drink acceptance.     

The efficacy of bitter blockers on health-relevant bitterants

Current strategies for decreasing the bitterness of conventional foods often involve the addition of sucrose and sodium chloride. However this has limited application with functional foods, as they are health promoting, and other approaches are required. This study assesses the efficacy of high and low concentrations of five bitter inhibiting compounds [β-cyclodextrin (β-CYCLO), homoeriodictyol sodium salt (HED), zinc sulphate monohydrate (ZnSO₄), magnesium sulphate (MgSO₄), carboxymethylcellulose sodium salt (CMC)] on the perceived bitterness of high and low concentrations of (+)-catechin and caffeine – two ingredients used in functional food formulations. Intensity ratings (bitterness, sourness, saltiness, sweetness, savoriness, astringency, ‘other’) of bitterant-bitter blocker binary solutions were collected from a panel of twelve, in duplicate, using a 15 cm line scale. Overall, β-CYCLO and HED were the most effective blockers at decreasing the bitterness of (+)-catechin, while the bitterness of caffeine was reduced most effectively by HED. Results also demonstrate that the bitter reducing capacity of these blockers is bitterant dependent. In general, these bitter blockers elicit minimum side tastes and sensations, although astringency and viscosity intensities are increased under some conditions. We conclude that some bitter blockers show considerable potential for decreasing the bitterness of phenols and caffeine in functional food formulations.     

Sensory evaluation of bitterness and astringency of 3R(−)-epicatechin and 3S(+)-catechin

Bitterness and astringency of the monomeric flavan-3-o!s ( + )-catechin and (?)-epicatechin were rated using time-intensity (T-I) methodology. Three concentration levels (0.5. 0.9 and 1.2 g liter^?1) oi each compound were assessed, and the parameters time to maximum intensity (TMAX), intensity at the maximum (IMAX) and total duration (TTOT) were extracted from the T-I curves. No differences in TMAX for either bitterness or astringency were found between these chiral isomers or as a function of concentration within a compound. Epicatechin had a significantly higher bitter IMAX than catechin at all three concentration levels, and had a significantly longer TTOT at the two higher concentrations. Epicatechin was more astringent than catechin. but this was only significant at one concentration. Astringency TTOT was longer for epicatechin, although this was nonsignificant at the lowest concentration. The three concentrations of catechin were significantly different for both bitterness and astringency IMAX and TTOT. Epicatechin showed evidence for the astringency response plateauing above the 0.9 g litre^?1 level. n-Propylthiouracil status had no effect on perception of either bitterness or astringency.     

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。     

不同脱苦涩处理刺梨果汁风味品质分析

以刺梨果汁为原料,采用感官评定方法结合电子舌技术,探讨不同苦涩味的脱除方法对刺梨果汁风味品质的影响,并确定最佳脱除条件。结果表明：刺梨汁整体味感以酸味、涩味和苦味为主。添加剂组合方法脱除刺梨汁苦涩味效果明显优于单一方法,其最佳脱苦涩味的方法为添加质量分数0.12%单宁酶和质量分数0.015%三氯蔗糖,该方法处理的刺梨汁感官评定分值最高、结果最佳、口感适宜、苦涩味最轻,经电子舌检测在苦味和涩味2 个传感器上的响应值最小。在食品风味评价中,应将电子舌技术结合传统感官评定方法进行分析,利于获得更准确、可靠的结论。     

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.     

Juice blends--a way of utilization of under-utilized fruits, vegetables, and spices: a review

The post-harvest shelf life of maximum of fruits and vegetables is very limited due to their perishable nature. In India more then 20-25 percent of fruits and vegetables are spoiled before utilization. Despite being the world's second largest producer of fruits and vegetables, in India only 1.5 percent of the total fruits and vegetables produced are processed. Maximum amounts of fruit and vegetable juices turn bitter after extraction due to conversion of chemical compounds. In spite of being under utilized, the utilization of highly nutritive fruits and vegetables is very limited due to high acidity, astringency, bitterness, and some other factors. While improving flavor, palatability, and nutritive and medicinal value of various fruit juices such as aonla, mango, papaya, pineapple, citrus, ber, pear, apple, watermelon, and vegetables including bottle gourd, carrot, beet root, bitter gourd, medicinal plants like aloe vera and spices can also be used for juice blending. All these natural products are valued very highly for their refreshing juice, nutritional value, pleasant flavor, and medicinal properties. Fruits and vegetables are also a rich source of sugars, vitamins, and minerals. However, some fruits and vegetables have an off flavor and bitterness although they are an excellent source of vitamins, enzymes, and minerals. Therefore, blending of two or more fruit and vegetable juices with spices extract for the preparation of nutritive ready-to-serve (RTS), beverages is thought to be a convenient and economic alternative for utilization of these fruits and vegetables. Moreover, one could think of a new product development through blending in the form of a natural health drink, which may also serve as an appetizer. The present review focuses on the blending of fruits, under-utilized fruits, vegetables, medicinal plants, and spices in appropriate proportions for the preparation of natural fruit and vegetable based nutritive beverages.     

Show me the color in your mind: A study of color-flavor associations in virtual reality

We conducted a virtual reality (VR) study to examine the color that first came to a person’s mind when he or she was drinking tea. The participants were asked to drink Chinese green or red tea without any visual cues, and then to show the first color in their mind on a circle or a cup of tea in VR. The results revealed that they were able to detect the difference in the bitterness and astringency of the two types of tea. Despite variations in the specific colors chosen by different individuals, their color responses for Chinese green tea were more greenish than those for Chinese red tea, thus indicative of some associations between the green–red component of color and the bitterness and astringency. Moreover, the results also revealed that the color responses made on the virtual tea were more similar to the actual color of tea beverages than those made on the virtual circle, suggesting that the participants may rely on a concrete object to exemplify a given flavor they experienced without visual cues. These results provide novel findings about color-flavor associations for complicated and subtle flavors, and shed some light on how to modulate the participants’ color-flavor associations via modifying the food or drink that they bring up to their mind to exemplify a certain flavor.     

POTATO FLAVOR AS RELATED TO CHEMICAL COMPOSITION

SUMMARY— A study was made on the relationship of flavor of potatoes to their phenolic and ascorbic acid content. Material for the study was from two main sources: (1) clones that are hybrids between varieties of Solanum tuberosum subsp. tuberosum grown in New York and varieties of Solanum tuberosum subsp. andigenum grown in Peru; (2) established commercial American varieties such as Ontario, Pontiac, and Katahdin. Bitterness and astringency were selected as the character notes most related to phenolic content. A significant correlation was found between phenolic content and bitterness and a highly significant correlation between phenolic content and astringency. No significant correlation was found between ascorbic acid content and flavor.     

Application of the dual attribute time‐intensity (DATI) sensory method to the temporal measurement of bitterness and astringency in sorghum

Bitterness and astringency are attributes generally cited as the cause of tannin sorghums being unpalatable. The objective here was to determine the effect of sorghums with varying tannin content on bitterness and astringency simultaneously using dual attribute time‐intensity (DATI). A trained panel assessed bitterness and astringency of bran infusions of tannin and tannin‐free sorghums. In both sorghum types, bitterness developed and reached maximum intensity faster (T_max 22.5 s; P < 0.001) than astringency (27.9 s). The duration of the astringent sensation (D_tot 69.9 s) lasted longer than bitterness (66.3 s). Overall, the temporal parameters for bitterness distinguished infusions from tannin and tannin‐free sorghums slightly more clearly than those for astringency. The research established that, for sorghum, bitterness and astringency are related. The DATI method also revealed that panellists’ perceptions of the time course of bitterness and astringency differ.     

酚类物质与果蔬品质研究进展

酚类物质是植物体内重要的次生代谢物质,与果蔬品质密切相关。文章综述了果蔬中酚类物质的来源和种类;酚类物质对果蔬色泽、风味(涩、苦、香、甜)的影响及其与果蔬保健功效和酶促性褐变的关系,并从提高果蔬品质的角度,指出了果蔬中酚类物质调控的几个方面。     

Effects of phenolics in sorghum grain on its bitterness,astringency and other sensory properties

Despite the fact that condensed tannins are potentially important antioxidants, there is a general belief that tannins in sorghum confer objectionable sensory attributes. The objective of this study was to determine differences in the sensory attributes of sorghums containing different levels of total phenolic compounds. A trained sensory panel described and quantified the sensory attributes of different sorghums (condensed‐tannin containing and tannin‐free). All the sorghum cultivars were perceived as bitter and astringent. Bran infusions of tannin sorghums were perceived as darker, clearer, more bitter and more astringent than those of the tannin‐free sorghums, while those of tannin‐free sorghums were perceived as sweeter and cloudy. Sorghum whole‐grain rice from the tannin sorghums which had relatively soft endosperm texture (PAN 3860 and Ex Nola 97 GH) was perceived as dark, hard, chewy, bitter and astringent, while that from tannin‐free sorghums having relatively hard endosperm texture (Segaolane and Phofu) was perceived as soft, sweet and had a maize‐flavour. Surprisingly, the bitterness and astringency, as well as other sensory attributes of NS 5511 (tannin sorghum), were perceived as similar to PAN 8564 (tannin‐free sorghum) even though NS 5511 had more than twice the total phenol content of PAN 8564. This suggests not all condensed‐tannin containing sorghums have objectionable sensory attributes. Copyright © 2007 Society of Chemical Industry     

感官评定方法确定麻竹笋苦涩味物质成分及与口感的关系

通过分析测定麻竹笋苦涩味物质含量与感官评定方法确定竹笋苦涩味物质成分及与口感的关系。麻竹鲜笋在100℃纯净水中分别进行0、30、90、150 s和420 s 5个时间梯度水煮处理,并测定煮后笋汤、笋渣的可溶性单宁、草酸和游离苦味氨基酸(Phe、Val、Arg、Met和Leu)含量,感官评定小组对其涩味、苦味强度评定,并通过对食品级草酸、单宁标准样品配制的不同质量浓度溶液进行苦涩味感官评定,建立单宁、草酸、单宁和草酸混合液的质量浓度与滋味强度的特征曲线函数。结果表明,影响麻竹笋苦涩味的主要物质是可溶性单宁,竹笋苦味和涩味均与单宁含量呈极显著关系,相关系数分别达0.896和0.867;竹笋涩味与草酸含量呈显著关系,相关系数为0.448,而竹笋苦味与草酸含量无显著关系;竹笋苦涩味与游离苦味氨基酸含量均无显著关系。利用单宁特征曲线函数对竹笋苦涩味偏重的成因进行了分析,对9个笋渣、笋汤的分析结果表明,单宁特征曲线函数对竹笋涩味的解释程度达60.6%~136.4%,对竹笋苦味的解释程度达63.4%~132.0%,较高的可溶性单宁含量是引起麻竹笋苦涩味偏重的主要原因。     

Changes in phenolic compounds and Rancimat stability of olive oils from varieties of olives at different stages of ripeness

BACKGROUND: Recently, diets rich in natural foods and food‐derived components, such as phenolic compounds, have received a great deal of attention because they are perceived as ‘safe’ and ‘non‐medicinal’. In fact, some are known to function as chemopreventive agents against oxidative damage, cerebrovascular disease, and aging. RESULTS: Phenolic compounds, natural antioxidants present in virgin olive oil, play an important role in oil quality by contributing significantly to protecting oil stability against oxidation. In addition, polyphenols are the main contributors to olive oil bitterness, astringency and pungency. The data were fit by linear regression, giving Rancimat stability (h) = 0.18× Total polyphenols (mg L^?1) in the virgin olive oil. CONCLUSIONS: The practice of harvesting ripe olives as soon as possible to produce oils of high phenolic contents and thus high oxidative stability implies bitter and piquant oils, this being admissible for oils of some varieties but detrimental to others appreciated in the market for being more fruity and sweeter. Copyright © 2010 Society of Chemical Industry     

分步酶解小麦面筋蛋白制备低苦味肽粉的研究

目的 研究分步酶解小麦面筋蛋白(wheat gluten, WG)制备低苦味肽粉的工艺。方法 选用中性蛋白酶、木瓜蛋白酶、胃蛋白酶水解WG至8%水解度,接着用风味蛋白酶对水解产物进行脱苦处理,对不同酶解产物中苦味肽的特性进行系统研究,探究苦味肽含量、氨基酸组成、分子量分布、表面疏水性等指标变化对WG酶解物苦味值的影响,对比风味蛋白酶对不同单酶酶解物的脱苦效果差异,分析风味蛋白酶对WG酶解物脱苦的内在机理,进而确定制备低苦味小麦蛋白肽粉的最佳酶解工艺。结果 中性蛋白酶的酶解产物经风味蛋白酶作用后,脱苦效果最显著,苦味肽苦味值从4.08降至2.25,酶解产物的苦味值可下降56.42%。木瓜蛋白酶的酶解产物经风味蛋白酶作用4 h后,酶解产物的苦味值最低,制备出苦味值为1.28的WG低苦味肽粉。结论 经分步酶解作用后,酶解产物中苦味肽的含量下降;疏水性氨基酸比例的下降和游离氨基酸含量的升高引起苦味肽苦味阈值的增大,共同导致酶解产物苦味值显著降低,该研究为酶解脱苦技术的快速发展和WG活性肽工业化生产提供新的参考。