苦味受体的生物学特征、信号转导机制及苦味剂和苦味抑制剂对苦味受体的影响

苦味受体(bitter taste receptors,TAS2Rs)是一种G-蛋白偶联受体(GPCR),由30个基因组成的基因家族编码。苦味可使动物远离有毒有害物质,当动物尝到苦味物质时,会刺激舌头的味蕾中味觉受体细胞表达TAS2Rs,进而引发下游一系列信号转导反应,最终通过鼓索神经和舌咽神经将信息整合传到大脑,使动物产生厌恶的感觉,从而选择拒绝摄入这些苦味物质。本文就TAS2Rs的生物学特征、信号转导机制及苦味剂和苦味抑制剂对苦味受体的影响进行简要综述。     

苦味西葫芦粗提物抗炎作用的实验研究

研究苦味西葫芦粗提物的抗炎作用。采用醋酸诱导小鼠腹腔毛细血管通透性增加、角叉菜胶诱导大鼠足跖肿胀及棉球诱导大鼠肉芽肿模型研究苦味西葫芦粗提物的抗炎作用。ip苦味西葫芦粗提物(小鼠4 g／kg,大鼠2.8 g／kg)可显著抑制小鼠腹腔毛细血管通透性增强及大鼠棉球肉芽肿(P<0.05)、ip苦味西葫芦粗提物(大鼠1.4 g／kg及2.8 g／kg)均能显著抑制角叉菜胶诱导大鼠足跖肿胀(P<0.05)。苦味西葫芦粗提物具有抗急、慢性炎症作用。     

苦味西葫芦的抗炎作用研究

将苦味西葫芦制成水提醇沉物 ,选择小白鼠为靶动物 ,考察了苦味西葫芦水提醇沉物的抗炎作用。实验结果表明 ,苦味西葫芦水提醇沉物能明显抑制蛋清、二甲苯和 Freund完全佐剂引起的炎性水肿     

苦味西葫芦抗炎作用机理的初步研究

以Wistar大鼠和昆明小白鼠为靶动物,观察了苦味西葫芦粗提物的抗炎效果和作用机理.实验结果表明,苦味西葫芦粗提物对大鼠足跖肿胀和棉球肉芽肿有抑制作用,抗炎作用可能与HPAA系统有一定关系.     

苦味西葫芦药理作用初步研究

本实验对苦味西葫芦提取物的镇痛、催眠、抗病毒、抗菌等作用进行了初步研究。结果表明苦味西萌芦提取物可提高离体十二指肠的收缩力，具有明显的镇痛作用，并可增强阈下剂量的戊巴比妥钠的作用，提示有催眠作用；抗病毒和抗菌实验结果表明，该提取物对NDV、CPV的50％（IC50）抑制浓度分别为1：520.6及1：450.5，提示有较强的抗病毒作用；对金黄色葡萄球菌及猪霍乱沙门氏菌MIC均为50mg/ml，对大肠杆菌作用不明显。     

牛奶干酪中风味化合物的来源及其缺陷初探

本文概述了牛奶干酪中风味化合物的种类及其形成机制。探讨了干酪中苦味的形成及其脱苦,以及乳酸钙和有毒胺的形成机制,并预测了干酪中风味化合物存在的问题和发展趋势。     

重庆市三峡库区柑橘渣的营养物质和苦味物质研究

本文对重庆市三峡库区柑橘渣的营养物质和苦味物质含量进行了系统检测。结果表明,重庆市三峡库区的柑橘渣无氮浸出物、消化能和钙含量较高,氨基酸组成全面,但粗蛋白质和总磷含量低,水分、粗纤维和苦味物质含量高,作为潜在的饲料资源,经过适当处理可以大量开发作畜禽饲料。     

10kV配网耐张绝缘子遮蔽罩设计

随着我国社会经济的不断进步以及城市化建设的不断发展,我国的电力事业也得到了更为广泛的关注。在带电作业中应用的较为广泛的就是耐张绝缘子遮蔽罩,其遮蔽性的好坏直接影响着工作人员的人身安全,因此,提高耐张绝缘子遮蔽罩的遮蔽性能对于配网工程而言具有十分重要的现实意义。本文主要通过对遮蔽罩所存在的问题进行简要的分析和研究,并提出了有效的改进措施,对原有的遮蔽罩进行了优化改进,使其满足隔离带电体的作用。     

柚子苦味物质及其分析检测方法的概述

文章综合介绍了柚子中所含有的主要苦味物质的种类及分析检测方法的研究进展。简述了柚子中所含有的柚皮苷、橙皮苷及新橙皮苷等类黄酮化合物和柠檬苦素类似物的功能、性状、应用等,柚皮苷、橙皮苷及新橙皮苷等类黄酮化合物和柠檬苦素类似物在柚子不同部位和果汁中的含量。介绍了类黄酮化合物和柠檬苦素类似物的主要分析检测方法,介绍了液相色谱、气相色谱、质谱、核磁共振等色谱法在类黄酮化合物和柠檬苦素类似物的分析检测中的应用     

动物常用健胃药的种类及使用方法

1苦味健胃药 苦味健胃药特点是具有强烈的苦味，口服可刺激舌部味觉感受器，反射性地兴奋食物中枢，加强唾液和胃液分泌，提高食欲，促进消化机能。     

The first report of urine overmarking of pro-oestrus female dung by a male white rhino

Although observed in other Perrisodactyla, urine overmarking in white rhinos has not been described. Using a single opportunistic sighting, we were able to collect two dung samples from one oestrous female white rhino; one unmarked and one overmarked with male urine. Because of the behaviour of both the male and the female, we suggest that the female was in pro-oestrus. We hypothesised that the function of overmarking by the male was for oestrus concealment (i.e. odour masking), as observed in horses. Because dung from oestrous female white rhinos emits a higher proportion of alkanes than non-oestrous dung, we expected the proportion of alkanes emitted from oestrous dung to decrease after overmarking. In contrast, we found that after overmarking the proportion of alkanes emitted increased. We suggest that the function of urine overmarking in white rhinos could be to conceal all signals of reproductive condition, so that neither oestrous nor non-oestrous signals are recognisable, or that a signal is added to indicate that the female has been mated.     

Brain stem auditory potentials evoked by clicks in the presence of high-pass filtered noise in dogs

This study evaluates the effects of a high-frequency hearing loss simulated by the high-pass-noise masking method, on the click-evoked brain stem-evoked potentials (BAEP) characteristics in dogs. BAEP were obtained in response to rarefaction and condensation click stimuli from 60 dB normal hearing level (NHL, corresponding to 89 dB sound pressure level) to wave V threshold, using steps of 5 dB in eleven 58 to 80-day-old Beagle puppies. Responses were added, providing an equivalent to alternate polarity clicks, and subtracted, providing the rarefaction-condensation potential (RCDP). The procedure was repeated while constant level, high-pass filtered (HPF) noise was superposed to the click. Cut-off frequencies of the successively used filters were 8, 4, 2 and 1 kHz. For each condition, wave V and RCDP thresholds, and slope of the wave V latency-intensity curve (LIC) were collected. The intensity range at which RCDP could not be recorded (pre-RCDP range) was calculated. Compared with the no noise condition, the pre-RCDP range significantly diminished and the wave V threshold significantly increased when the superposed HPF noise reached the 4 kHz area. Wave V LIC slope became significantly steeper with the 2 kHz HPF noise. In this non-invasive model of high-frequency hearing loss, impaired hearing of frequencies from 8 kHz and above escaped detection through click BAEP study in dogs. Frequencies above 13 kHz were however not specifically addressed in this study.     

Analyses of free amino acid and taste sensor traits in egg albumen and yolk revealed potential of value-added eggs in chickens

To create high-quality eggs by using different breed and feed materials, we investigated free amino acid contents and taste sensor traits using two chicken breeds (Rhode Island Red; RIR and Australorp; AUS) fed two feeds (mixed and fermented feeds). Two-way ANOVA revealed significant breed and feed main and interaction effects on albumen bitterness and a significant interaction effect on yolk bitterness. Albumen from RIR fed mixed feed and AUS fed fermented feed was higher bitterness, whereas yolk from those groups was lower bitterness. Significant breed effects were detected in four albumen amino acid traits (His, Met, Ile, and Lys) and a yolk His, whereas significant feed effects were found in 15 albumen amino acid traits (Asp, Glu, Ser, His, Gly, Thr, Ala, Tyr, Val, Met, Trp, Ile, Leu, Lys, and Pro) and a yolk cystine trait. Compared to albumen amino acids, yolk amino acids had limited effects by breed and feed. The present results suggest that genetic and nutritional factors can alter not only amino acid contents but also sensor values of bitterness, indicating that selecting the combination of breed and feed enable us to make amino acids enriched and taste added designer eggs in future.     

饲用甜味剂的作用及使用中的注意事项

甜味剂是诱食剂之一,它在动物生产中的主要作用是增强饲料的甜味,掩盖饲料中的不良味道,提高动物的采食量。此文主要综述了饲用甜味剂的作用及使用中的注意事项。     

The use of contralateral masking noise in the detection of unilateral deafness in Dalmatian puppies

BACKGROUND: The brainstem auditory-evoked response (BAER) is currently the standard evaluation method of hearing in dogs. In asymmetrical hearing loss in human patients, simultaneous presentation of masking noise to the nontest ear is routinely performed during BAER to eliminate the crossover effect. HYPOTHESIS: The crossover effect occurs during canine BAER, and masking noise of 20 decibels (dB) below click stimulus intensity is sufficient to abolish this effect. ANIMALS: Fifty-six Dalmatian puppies with confirmed unilateral deafness. METHODS: The BAER was elicited with 80 and 100 dB normalized hearing level (dBnHL) stimulus intensity in the deaf ear. The 100 dBnHL stimulus was repeated while simultaneously applying 80 dBnHL white masking noise to the nontest ear. RESULTS: Ten dogs were excluded because of BAER trace baseline fluctuation. In the remaining 46 dogs, 8 dogs had no waveforms, but 38 dogs had an identifiable wave-V in the deaf ear BAER at 80 dBnHL intensity stimulus. At 100 dBnHL intensity stimulus, all but 1 dog had a discernible wave-V in the deaf ear BAER. The deaf ear BAER waveforms were abolished by white masking noise at 80 dBnHL in the nontest ear in all dogs. CONCLUSIONS AND CLINICAL IMPORTANCE: Abolition of BAER wave-V in the deaf ear by white masking noise in the nontest ear suggests that this wave is caused by the crossover effect. beta distribution indicates 95% confidence that white masking noise, at 20 dB below click stimulus intensity, would abolish this crossover effect in over 90% of the dogs. This supports using masking noise in the nontest ear during canine BAER.     

Evaluation of changes in the taste of cooked meat products during curing using an artificial taste sensor

The purpose of this study was to assess an evaluation method using an artificial taste sensor, in comparison with chemical analysis and sensory evaluation of the taste of meat during curing. Samples of Canadian pork were treated with salt, nitrite and phosphate. Curing time ranged from 0 to 168 h. In the sensory evaluation, there were no significant differences in the all characteristic items at 72‐h cured sample compared to the 0‐h sample. Some of the characteristic items for the 168‐h sample (umami, overall taste, richness and overall palatability) showed significant difference (P < 0.05) compared to the 0‐h sample. Taste sensor analysis indicated that the sensor outputs of bitterness and saltiness were significantly correlated with curing time (R = 0.98 and 0.97, respectively), and total free amino acids (R = 0.91 and 0.96, respectively). The sensor output of bitterness was significantly correlated (R = 0.96) with the sum of amino acids corresponding to bitter taste. The increase in the chemical components contributing to bitterness and/or saltiness was indicated as the cause of the characteristic taste. Taste sensor analysis may be applicable as a qualitative method for evaluating taste characteristics generated during the curing of manufactured cooked meat products.     

混合菌种固态发酵法发酵豆粕生产大豆肽的研究

大豆肽是由大豆蛋白经水解所得到的由5～6个氮基酸残基组成的低分子肽混合物，分子量以低于1000Da的为主。以豆粕为原料，采用黑曲霉、米曲霉混合菌种固态发酵法生产大豆肤，制得的大豆肽具有较好的理化特性和生理活性，克服了酶解法产品苦味大和口感差等缺点，在很多领域得到了广泛应用。     

酶解对脱脂牛乳蛋白抗原性及感官特性的影响

以脱脂牛乳为原料,采用间接竞争酶联免疫吸附测定法和三(羟甲基)甲基-甘氨酸-聚丙烯酰胺凝胶电泳等方法研究碱性蛋白酶（Alcalase,AT）、复合蛋白酶（Protamex,PT）和风味蛋白酶（Flavorzyme,FT）处理对脱脂牛乳的抗原性、分子质量分布、滋味和色泽的影响。结果表明：AT对主要致敏乳蛋白的脱敏效果显著优于PT和FT(P<0.05),当酶底比为500 U/g、酶解时间为20 min时,其对α-乳白蛋白、β-乳球蛋白和酪蛋白的抗原抑制率分别达到64.01%、76.00%和69.10%;AT、PT和FT处理后脱脂牛乳中低分子质量肽段明显增加,且苦味、涩味、苦后味、涩后味随酶解时间延长、酶底比的增加而升高,FT处理脱脂牛乳的滋味优于AT和PT;酶解脱脂牛乳的亮度值显著降低,红度值显著升高（P<0.05）,透光性增加,AT处理脱脂牛乳的色泽更接近于牛乳。     

红糖酸乳的加工工艺优化

将阿斯巴甜、三氯蔗糖分别和安赛蜜进行复配,确定较优配比,制作红糖酸乳.以红糖添加量、甜味剂复配组合以及淀粉添加量为因素进行均匀试验,以感官评定和黏度为指标进行最优组合优化.结果表明:当用红糖全部替代白砂糖时,酸乳微苦,用甜味剂部分代红糖可以改善风味.最优组合为红糖质量分数4％,淀粉质量分数6％,甜味剂组合Ⅱ即为三氯蔗糖和安赛蜜质量分数分别为0.003 5％和0.007 0％.在此工艺条件下制备的红糖酸乳甜度适中,组织状态均匀细腻,口感清爽.     

迪庆藏猪与野藏杂交猪肌肉全谱游离氨基酸味道强度值比较

本研究旨在探明迪庆藏猪与野猪×迪庆藏猪（野藏杂交猪）肌肉全谱游离氨基酸（FAA）味道强度值（TAV）的差异。选择胎次相同、出生日期相近、体重20 kg左右的迪庆藏猪和野藏杂交猪各12头（公、母各半）,以迪庆藏猪为对照,采用相同饲粮在相同饲养条件下直线育肥,100 kg左右屠宰,采集背最长肌,沸水蒸30 min后,用高效液相色谱-四级杆离子阱串联质谱仪检测其全谱游离氨基酸,计算呈味氨基酸TAV并比较其差异。结果显示,与迪庆藏猪相比,野藏杂交猪肌肉游离氨基酸总鲜味TAV降低16.27%（P<0.05）,总甜味、酸味和苦味TAV分别降低3.50%、11.68%和1.50%,但差异均不显著（P>0.05）;野藏杂交猪肌肉谷氨酰胺（Gln）鲜味TAV、甜味TAV均降低22.89%（P<0.05）,缬氨酸（Val）甜味、苦味TAV均增加36.32%（P<0.05）;天冬氨酸（Asp）、甘氨酸（Gly）、谷氨酸（Glu）与组氨酸（His）等其他游离氨基酸的鲜味、甜味、酸味和苦味TAV与迪庆藏猪间均差异不显著（P>0.05）。以上结果表明,与野猪杂交会降低迪庆藏猪肌肉鲜味TAV,降低Gln的鲜味、甜味TAV,提高Val甜味、苦味TAV,该结果可为迪庆藏猪的开发利用提供依据。