The effect of inhomogeneous quinine and hydrocolloid distributions on the bitterness of model gels

This study investigated the effect of inhomogeneous distributions of quinine on bitterness intensity of gelatine–agar composite gels. It also investigated the effect of inhomogeneous distributions of the gel’s hydrocolloid constituents (the gelatine and agar) on the bitterness intensity of the quinine. Fifty-two screened subjects participated in four paired comparison tests comparing inhomogeneous designs of quinine (with a homogeneous hydrocolloid distribution) and inhomogeneous designs of the hydrocolloids (with a homogeneous quinine distribution), against a homogeneous control of identical overall quinine and hydrocolloid composition. Using the same gel designs, a mastication trial was undertaken where ten subjects were asked to chew each gel system until the point of swallowing, and eleven subjects participated in a time-intensity trial where bitterness intensity was monitored during mastication and after expectoration. Paired comparison tests showed that the inhomogeneous distribution of quinine increased bitterness intensity, while inhomogeneous distributions of the hydrocolloids did not. Mastication was not influenced by changes in the distribution of quinine or the hydrocolloids. Time intensity curves showed the gels having an inhomogeneous distribution of quinine had greater bitterness intensity throughout mastication, however no differences in bitterness intensity were observed between any gel designs in the latter stages of aftertaste measurements. Time intensity curves also showed a slight delay in time to maximum bitterness intensity for the gels with inhomogeneous distributions of hydrocolloids. Results suggest a homogeneous distribution of bitter compounds is the most suitable structure for minimising bitterness perception.     

Tasting shapes and words

We report a series of quick and simple paper-and-pencil demonstrations illustrating the reliable crossmodal correspondences that people have between commercially-available food and drink items and both visually-presented shapes and nonsense words. The foodstuffs tested in this study included still and sparkling water, Brie cheese and cranberry juice, and two kinds of chocolate. Participants were given paper-based line scales, anchored at either end with a nonsense word or simple outline shape. They were instructed to taste the foodstuffs and to indicate whether their perception of the flavour matched more one or other of the items anchoring the scales, and then mark the appropriate point on the scale. The results highlight the fact that certain of these foodstuffs (sparkling water, cranberry juice, and Maltesers - chocolate-covered malt honeycomb) were better associated with angular shapes and high-pitched meaningless words, such as ‘kiki’ and ‘takete’, whose pronunciation requires sharp inflection of the mouth. By contrast, still water, Brie, and Caramel Nibbles (chocolate-covered caramel) were all more strongly associated with rounded shapes and softer sounding, lower-pitched pseudo-words, such as ‘bouba’ and ‘maluma’. These results, which build on the classic literature on ‘sound symbolism’, have both theoretical and applied implications: On the one hand, they demonstrate that the phenomenon of sound symbolism extends beyond the visual modality, by showing that speech sounds carry meaning in the domain of flavour, and in terms of the oral-somatosensory attributes of foodstuffs as well. As a consequence, these results may also be useful on an applied level in terms of helping companies to design novel brand names and graphics for the packaging of their food and drink items that best connote the likely attributes of the product within.     

The effect of modifying the distribution of sucralose and quinine on bitterness suppression in model gels

This study investigated the effect of simultaneously manipulating the spatial distribution of a sweet masking agent and bitter tastant within gelatine–agar gels on bitterness suppression, using sucralose and quinine. Sixty subjects participated in a series of paired comparison tests comparing different gel designs containing both sucralose and quinine, against a homogeneous control gel of identical overall sucralose (0.3 mM) and quinine content (0.3 mM). Twenty subjects also determined the bitterness reduction achieved in the homogeneous control gel by the addition of 0.3 mM sucralose to 0.3 mM quinine. Separating quinine and sucralose into different portions of the gel had no influence on bitterness suppression. Inhomogeneously distributing the quinine and sucralose into the same parts of the gel reduced the effectiveness of bitterness suppression. Inhomogeneously distributing the sucralose, while maintaining a homogeneous distribution of quinine, had no influence on bitterness suppression. Although an inhomogeneous distribution of sucralose increased sweetness perception and the addition of sucralose (0.3 mM) was found to substantially reduce bitterness in the homogeneous control, bitterness suppression was not enhanced when distributing the masking agent (sucralose) inhomogeneously.     

Effect of background noise on food perception

We investigated the effects of auditory background noise on the perception of gustatory food properties (sugar level, salt level), food crunchiness and food liking. Participants blindly consumed different foods whilst passively listening to either no sound, or quiet or loud background white noise. The foods were then rated in terms of sweetness, saltiness and liking (Experiment 1) or in terms of overall flavour, crunchiness and liking (Experiment 2). Reported sweetness and saltiness was significantly lower in the loud compared to the quiet sound conditions (Experiment 1), but crunchiness was reported to be more intense (Experiment 2). This suggests that food properties unrelated to sound (sweetness, saltiness) and those conveyed via auditory channels (crunchiness) are differentially affected by background noise. A relationship between ratings of the liking of background noise and ratings of the liking of the food was also found (Experiment 2). We conclude that background sound unrelated to food diminishes gustatory food properties (saltiness, sweetness) which is suggestive of a cross-modal contrasting or attentional effect, whilst enhancing food crunchiness.     

Effects of noise and distraction on alcohol perception

Recent research demonstrated that noise unconnected to the target stimulus can alter taste perception of food, but it is not clear whether similar effects might be seen with respect to alcohol. This is particularly important, as it might help explain previous reports of higher/faster alcohol consumption in loud music environments. In the between subjects experiment here, participants (n = 80) completed standardised taste and olfactory tests, followed by a taste test of alcoholic beverages varying in strength (0, 1.9, 3.9, 5.6, and 7.5 pct abv) in a randomly allocated distractive or control condition. Distractive conditions were either music, shadow (listening and repeating a news story) or shadow and music (S-Music). We found that exposure to music led to higher sweetness ratings compared to all remaining groups. Interestingly, discrimination of alcohol strength was impaired for individuals in the S-Music compared to remaining groups which was accompanied by increased negative mood. This is the first experimental work to demonstrate how music and other forms of distraction alter taste perception of alcohol and suggest a mechanism by which distraction leads to increases in alcohol consumption.     

Bioresponse-guided decomposition of roast coffee beverage and identification of key bitter taste compounds

Sensory-guided fractionation of a roasted coffee brew by means of sequential solvent extraction, ultrafiltration, and RP-HPLC demonstrated a group of ethyl acetate soluble compounds formed from O-hydroxycinnamoyl quinic acid derivatives upon coffee roasting as the key compounds contributing to the bitter taste of roasted coffee beverages. LC-MS/MS studies, 1D- and 2D-NMR spectroscopy, syntheses, and model roast experiments with 5-O-caffeoyl- and 5-O-feruloylquinic acid led to the unequivocal identification of 3-O-caffeoyl-γ-quinide (2a), 4-O-caffeoyl-γ-quinide (3a), 5-O-caffeoyl-epi-δ-quinide (4a), 4-O-caffeoyl-muco-γ-quinide (5a), 5-O-caffeoyl-muco-γ-quinide (6a), 3-O-feruloyl-γ-quinide (2b), and 4-O-feruloyl-γ-quinide (3b) as intense coffee bitter tastants. Besides these individual bitter compounds, a highly complex and intensely bitter HPLC fraction was isolated from the ethyl acetate extractables of coffee brew. Application of COSY spectroscopy and alkaline hydrolytic degradation gave strong evidence that the bitter taste of that fraction is due to a multiplicity of rather complex quinic acid lactone isomers multiply esterified with p-coumaric acid, caffeic acid, ferulic acid, 3,4-dimethoxycinnamic acid, and quinic acid, respectively. As representatives of this fraction, 3,4-O-dicaffeoyl-γ-quinide (10), 3,5-O-dicaffeoyl-epi-δ-quinide (11), and 4,5-O-dicaffeoyl-muco-γ-quinide (12) have been isolated, purified, and identified as strongly bitter-tasting compounds in roasted coffee. For the first time, bitter taste recognition thresholds were determined for the individual compounds showing that, strongly depending on their chemical structure, the bitter threshold levels ranged between 9.8 and 180 μmol/l (water).     

弧形辊改造原理及其应用

介绍了佳纸集团^#3纸机弧形辊的改造与设计情况。实践证明，改造后的弧形辊完全满足^#3纸机的使用要求，并且便于维修，为企业节约资金30余万元。     

Aroma–taste interactions between a model cheese aroma and five basic tastes in solution

The flavour perception of cheese results from complex sensory interactions between tastes and aromas. Using a model cheese solution, this study investigated perceived interactions between each of five basic tastes and a cheese aroma mixture containing ten volatile compounds commonly found in cheese. The five tastes – sucrose (sweetness), sodium chloride (NaCl) (saltiness), monosodium glutamate (MSG) (umami), lactic acid (sourness), and caffeine (bitterness) – were individually mixed with cheese aroma in water using a 5 taste level (0.2 log series) by 3 aroma level (0.5 log series) design. Aroma controls with no added taste were also included. This resulted in 18 samples for each single taste–aroma combination. An additional 18 samples were produced using a mixture of all 5 tastes with the 3 aroma levels. A panel of trained assessors (n = 10) evaluated cheese flavour intensity and taste intensity using 100 point line scales. Evaluation was carried out in duplicate, with samples grouped by taste type; 1 evaluation session per taste per replicate. Within type, order of presentation was balanced, and taste type order was randomised between replicates. Cheese flavour intensity was enhanced by sucrose and NaCl, while being suppressed by lactic acid. NaCl enhanced cheese flavour intensity the most at high aroma level, while lactic acid suppressed the most at low aroma level. When MSG level was increased, cheese flavour intensity was enhanced at both low and medium aroma levels, but was suppressed at the high aroma level. The greatest enhancement of cheese flavour intensity was found with the mixture of 5 tastes. Aroma significantly enhanced umami and bitterness, but did not enhance sweetness, saltiness, or sourness. This study showed that the perceived interaction between taste and cheese aroma depended on taste type and on the concentration levels of both taste type and aroma. The mixture of tastes was more effective at enhancing cheese flavour intensity than single tastes. This study provides knowledge that will underpin further study of taste–aroma interactions in a model cheese that aims to optimise cheese flavour intensity and character.     

磷脂的化学改性方法

本文主要介绍了磷脂的化学改性方法，例如：羟基化、氢化、酶水解、酰化等。     

淀粉物理改性技术研究进展

淀粉是一种非常重要的植物多糖,同时也是重要的工业原料。由于天然淀粉耐热、耐剪切、耐酸能力差,且易回生,因此需要对淀粉进行物理改性、化学改性和酶改性。在淀粉改性尤其是化学改性中,化学试剂易残留于改性淀粉中,所以快速、安全的物理改性越来越受到大家关注。主要概述了六种近些年常用的物理改性技术对淀粉结构及性能的影响,并从样品处理时间、损害程度和成本高低等五个方面进行比较,有助于大家选择合适的技术进行淀粉改性。     

食品蛋白质改性研究

该文综述酰化作用、磷酸化作用、脱酰胺作用、糖基化作用、共价交联作用、蛋白水解作用、物理改性及基因工程改性等8种蛋白质改性技术及最新进展。     

钠基膨润土的有机改性

采用十六烷基三甲基溴化铵（CTMAB）对钠基膨润土进行了有机纳米改性。对制得的插层土进行了扫描电镜、热重分析、X-射线衍射实验分析,结果表明插层剂已进入了膨润土片层间,减量率可达23％,且片层间距由原来的1．272nm增大到2．628nm。     

牦牛毛改性技术研究进展

叙述了牦牛毛纤维的性状以及目前牦牛毛纤维改性技术的研究进展.介绍了近几年来高新技术在牦牛毛纤维改性技术上的应用,重点分析了纤维拉伸细化技术对牦牛毛纤维的结构和性能的影响.提及了牦牛毛纤维拉伸细化在假发生产上的应用.     

Contribution of staling compounds to the aged flavour of lager beer by studying their flavour thresholds

The effect of 26 staling compounds on the aged flavour of a Belgian lager beer was studied. Strikingly, thresholds were regularly found to be substantially lower than those previously reported, and it appeared important to consider threshold values as indicative rather than absolute because of very large variations in sensitivity of individuals. In addition, a masking effect of isoamyl acetate and various interactions were observed between flavour compounds, which can considerably influence their flavour activity, even at sub-threshold concentrations. Cardboard flavour was essentially caused by (E)-2-nonenal. Additionally, methional, 3-methylbutanal, 2-furfuryl ethyl ether, β-damascenone and acetaldehyde were confirmed as key contributors to the aged flavour and to a lesser extent, (E,E)-2,4-decadienal, phenylacetaldehyde, 2-methylpropanal, diacetyl and 5-hydroxymethyfurfural. Finally, the addition of a selection of compounds could fairly well reproduce the flavour of aged lager beer, indicating that these compounds account for the major part of this flavour.     

大豆磷脂改性及其改性技术分析

该文介绍几种重要大豆磷脂改性技术并对其技术途径进行简要分析。