苦味机理及苦味物质的研究概况

苦味是一种分布广泛、阈值极低的味感,而消费者往往拒食苦味食物,但苦味物质在食品风味和生理调节方面具有重要作用。简要论述了苦味呈味机理、几种苦味物质的功能特性以及苦味抑制剂方面的研究进展。     

啤酒花苦味物质综述

啤酒花是啤酒酿造中的重要原料。啤酒的苦味主要来自于酒花中最重要的物质——苦味物质。 1苦味物质的分类 目前，我们主要是根据欧洲啤酒协会（EBC）分析委员会（即根据Woellmer）的分类方法对酒花的苦味物质进行分类。     

苦味食品概述

苦味是五种基本味感之一，是动物在长期进化过程中形成的一种自我保护机制。研究发现，苦味食品具有很高的营养价值和保健功能，因而苦味食品逐渐成为人们消费的新嗜好。但苦味食品开发中存在如何将口感和保健功能相结合，开发出大众普遍接受和喜爱的低苦味或无苦味食品。食品加工新技术和其他领域的发展将推动这一问题的解决。     

苦味传递机制与苦味肽研究进展

味觉是人类的重要生理功能之一。人类能够识别五种基本味:苦味、咸味、酸味、甜味和鲜味。由食物蛋白水解产生的苦味肽成为研究热点。本文主要从苦味的信号传递机制、苦味肽结构特点、苦味肽消除或降低的方法等三个主要方面综述了苦味肽的研究进展,以期为低苦味食品开发研究提供参考。     

浓香型白酒中的苦味

酒的苦味主要来自原辅料、工艺和勾调过程。浓香型酒中的苦味物质主要有单宁类、多肽、氨基酸、杂醇、醛类和无机盐。苦味物质表现出阈值较低、在低温下较敏感、可变性小、可使浓香型酒风味复杂、舌各部位对苦味的敏感程度差异较大等特征。可通过对原辅料和工艺的控制及采用勾调等方法降低浓香型酒的苦味。（孙悟）     

食品中苦味物质检测方法的研究进展

苦味物质的存在会对食品的味感造成较大影响,为提高产品感官品质,部分食品在加工过程中会进行苦味物质的检测和控制。目前,食品中苦味物质的检测主要集中于感官分析、生物评价、动物评价和仪器评价等方法。本文论述了食品加工过程中苦味物质的来源及国内外对于苦味检测方法的研究进展,以期对食品中苦味物质的检测提供参考。     

白酒异味--苦味

大多情况下,苦味对白酒来讲属异味,适量的苦味对白酒的口感却是有益的。苦味的特征是阈值低,可达7.0×10-7;可变性小,不易区分单种苦味物质;感官灵敏度舌尖与舌根相差60倍左右;不同温度下显示出不同强度。苦味酒可用作调味酒,以增加酒的口感。常见苦味物质有杂醇油、醛类、氨基酸及无机盐类。(晓)     

大曲酱香酒味觉体验中的苦味

标准大曲酱香酒中苦味体验是客观存在的。苦味的来源一方面是“曲大酒苦”，另一方面来源于原辅料、生产酿造、蒸馏、贮存过程之中。大曲酱香酒老酒、陈酒中更容易出现苦味。这样的酒作为调味酒可以提高酒体醇厚感和酒体丰富度、丰满度。中国白酒其它香型大部分排斥苦味，而大曲酱香酒中的苦味确是不可或缺的重要味觉体验。苦味存在的意义延展了人们的味域，拉长了感官风味中口味体验的长度，与其它呈香、呈味物质一起形成了独特的大曲酱香酒口味偏好性。属于中、重酒体的大曲酱香酒在十二大香型白酒中之所以属于终极版消费，苦味体验是构成因素之一。大曲酱香酒感官风味中苦味体验必须恰到好处“，含而不露”或微有苦味（苦味长度不超过6s）。苦味必须与其它呈香、呈味物质协调共生，“糊苦”、“焦苦”、“枯苦”不受欢迎，苦味轻柔被其它香味裹挟、包裹，起到了香味对比，形成了香味落差，才会受到欢迎。     

天然苦味抑制剂的研究与应用

苦味抑制荆是一类能降低或消除苦味物质苦味的化合物。目前已发现多种天然的苦味抑制剂，如苯乙烯酸衍生物、单磷酸腺苷、磷脂酸等。简要论述了天然苦味抑制荆的种类、效果及其应用。     

啤酒生产过程中苦味物质的控制

优质啤酒应具有细腻、爽口、令人愉快的苦味。本文分析了啤酒中苦味物质的来源及影响酒花中苦味物质的主要因素,介绍了酒花中α－酸、β－酸及成品啤酒中苦味值的测定方法,分析了导致啤酒不正常苦味的原因,并提出了控制啤酒中苦味物质的具体措施。     

基于GC/HPLC检测和苦味评定解析黄酒苦味

为分析黄酒苦味与其成分的关系,使用气相色谱（GC）和高效液相色谱仪（HPLC）测定16种半干型黄酒样品中的挥发性成分、氨基酸及理化指标,采用Pearson相关性分析计算各成分与苦味值的相关系数,并以测定成分为X变量、以苦味值为Y变量,建立偏最小二乘法回归（PLSR）分析模型,验证苦味相关成分和模型预测的准确性。结果表明,黄酒中的苦味物质以挥发性成分为主,集中在异戊醇（R=0.808）、异丁醇（R=0.642）、正丙醇（R=0.623）和乳酸乙酯（R=0.771）,氨基酸与苦味相关性不高（R=-0.536～0.464）,酒精与苦味相关性最高（R=0.850）,总酸对苦味有促进作用（R=0.649）,总糖对苦味有明显抑制作用（R=-0.735）。PLSR分析模型证实了Pearson相关性分析的可靠性,且能很好的预测黄酒苦味值,预测准确性达到90%,这为确定黄酒苦味提供了科学分析的客观方法。     

Evaluation of bitterness in Ragusano cheese

The appearance of undesirable bitter taste in Ragusano cheese was investigated by comparing the composition of 9 bitter cheeses with that of 9 reference cheeses of good quality by means of chemical, electrophoretic, and chromatographic analyses. Rates of proteolysis were significantly affected in cheeses of different quality. Primary proteolysis, as measured by pH 4.6-soluble N, was significantly greater in bitter cheeses compared with reference samples. Urea-PAGE profiles showed an almost complete breakdown of caseins in bitter cheeses and the further degradation of primary peptides into smaller compounds not detectable by this technique. Cheeses with defects had significantly lower levels of secondary proteolysis as reflected by the percentage of pH 4.6-soluble N soluble in 12% trichloroacetic acid and the amounts of total free amino acids. Peptides separated by reversed phase-HPLC revealed that the large and significant differences in peptide profiles of the soluble fractions between bitter and reference cheeses were mainly due to a much higher proportion of hydrophobic peptides in the former. The occurrence of bitterness in Ragusano cheese was therefore attributable to unbalanced levels of proteolysis and peptidolysis. Extensive degradation of caseins and primary peptides by activities of proteases produced large amounts of small- and medium-sized hydrophobic peptides that were not adequately removed by peptidases of microflora and therefore accumulated in cheese potentially contributing to its bitter taste. The presence of these compounds in bitter cheeses was related to high salt-in-moisture and low moisture contents that limited the enzymatic activities of microflora important in secondary proteolysis. Combining salt-in-moisture and the ratio of hydrophobic-to-hydrophilic soluble peptides resulted in the best logistic partial least squares regression model predicting cheese quality. Although bitterness is known to be rarely encountered in cheese at salt-in-moisture levels >5.0, all of the bitter cheeses analyzed in this study had salt-in-moisture levels much greater than this value. According to the logistic model, a risk of bitterness development may exist for cheeses with a midrange (5 to 10%) salt-in-moisture content but with an inadequate level of secondary proteolysis.     

酒用活性炭对荔枝烈酒苦味物质影响的研究

采用气质联用对荔枝烈酒的苦味成分进行分析,并探索酒用活性炭对荔枝烈酒苦味的影响。结果表明:所研究的荔枝烈酒的香气成分中,高级醇与醛类苦味强度较高,是主要的致苦物质。采用酒用活性炭吸附处理后,糠醛去除率51.73%,杂醇油去除率30.66%,对荔枝烈酒苦味的去除有一定的效果,改善了酒体的风味。     

Explaining tolerance for bitterness in chocolate ice cream using solid chocolate preferences

Chocolate ice cream is commonly formulated with higher sugar levels than nonchocolate flavors to compensate for the inherent bitterness of cocoa. Bitterness, however, is an integral part of the complex flavor of chocolate. In light of the global obesity epidemic, many consumers and health professionals are concerned about the levels of added sugars in foods. Once a strategy for balancing undesirable bitterness and health concerns regarding added sugars has been developed, the task becomes determining whether that product will be acceptable to the consumer. Thus, the purpose of this research was to manipulate the bitterness of chocolate ice cream to examine how this influences consumer preferences. The main goal of this study was to estimate group rejection thresholds for bitterness in chocolate ice cream, and to see if solid chocolate preferences (dark vs. milk) generalized to ice cream. A food-safe bitter ingredient, sucrose octaacetate, was added to chocolate ice cream to alter bitterness without disturbing other the sensory qualities of the ice cream samples, including texture. Untrained chocolate ice cream consumers participated in a large-scale sensory test by indicating their preferences for blinded pairs of unspiked and spiked samples, where the spiked sample had increasing levels of the added bitterant. As anticipated, the group containing individuals who prefer milk chocolate had a much lower tolerance for bitterness in their chocolate ice cream compared with the group of individuals who prefer dark chocolate; indeed, the dark chocolate group tolerated almost twice as much added bitterant in the ice cream before indicating a significant preference for the unspiked (control) ice cream. This work demonstrates the successful application of the rejection threshold method to a complex dairy food. Estimating rejection thresholds could prove to be an effective tool for determining acceptable formulations or quality limits when considering attributes that become objectionable at high intensities.     

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.     

Ultrafiltered milk reduces bitterness in reduced-fat Cheddar cheese made with an exopolysaccharide-producing culture

The objectives were to reduce bitterness in reduced-fat Cheddar cheese made with an exopolysaccharide (EPS)-producing culture and study relationships among ultra-filtration (UF), residual chymosin activity (RCA), and cheese bitterness. In previous studies, EPS-producing cultures improved the textural, melting, and viscoelastic properties of reduced-fat Cheddar cheese. However, the EPS-positive cheese developed bitterness after 2 to 3 mo of ripening due to increased RCA. We hypothesized that the reduced amount of chymosin needed to coagulate UF milk might result in reduced RCA and bitterness in cheese. Reduced-fat Cheddar cheeses were manufactured with EPS-producing and nonproducing cultures using skim milk or UF milk (1.2×) adjusted to a casein:fat ratio of 1.35. The EPS-producing culture increased moisture and RCA in reduced-fat Cheddar cheese. Lower RCA was found in cheese made from UF milk compared with that in cheese made from control milk. Ultrafiltration at a low concentration rate (1.2×) produced EPS-positive, reduced-fat cheese with similar RCA to that in the EPS-negative cheese. Slower proteolysis was observed in UF cheeses compared with non-UF cheeses. Panelists reported that UF EPS-positive cheese was less bitter than EPS-positive cheese made from control milk. This study showed that UF at a low concentration factor (1.2×) could successfully reduce bitterness in cheese containing a high moisture level. Because this technology reduced the RCA level (per g of protein) to a level similar to that in the control cheeses, the contribution of chymosin to cheese proteolysis would be similar in both cheeses.     

Quinoa bitterness: causes and solutions for improving product acceptability

Awareness of the several agronomic, environmental, and health benefits of quinoa has led to a constant increase in its production and consumption not only in South America, where it is a native crop, but also in Europe and the USA. However, producing wheat or gluten‐free based products enriched with quinoa alters some quality characteristics, including sensory acceptance. Several anti‐nutritional factors such as saponins are concentrated in the grain pericarp. These bitter and astringent substances may interfere with the digestion and absorption of various nutrients. Developing processes to decrease or modify the bitterness of quinoa can enhance palatability, and thus consumption, of quinoa. In addition to the production of sweet varieties of quinoa, other processes have been proposed. Some of them (i.e. washing, pearling and the combination of the two) have a direct effect on saponins, either by solubilization and/or the mechanical removal of seed layers. Others, such as fermentation or germination, are able to mask the bitterness with aroma compounds and/or sugar formation. This review presents the major sources of the undesirable sensory attributes of quinoa, including bitterness, and various ways of counteracting the negative characteristics of quinoa. © 2018 Society of Chemical Industry     

A study of beer bitterness loss during the various stages of the Romanian beer production process

Beer is one of the oldest known alcoholic beverages produced by a yeast fermentation of a cereal extract that was germinated in water beforehand. The bitter taste of beer comes from the group of substances introduced during wort boiling, which are the extracted components of hops. The aim of this study was to determine some characteristics of beer (original extract, alcohol content, colour, pH, total acidity, carbon dioxide and bitterness values) during the three stages of the beer production process in a typical Romanian brewery. Measurements were carried out on 60 samples of beers, 10 measurements for each step of the process examining wort, unfiltered fermented beer and bottled beer (final product) from two different types of beer (light and dark). Statistical process control of the beer was performed. Losses in the bitterness units during the production process were between 24.7 and 41.54%, reported in terms of final product. Copyright © 2013 The Institute of Brewing & Distilling