共查询到19条相似文献，搜索用时 171 毫秒
1.
温度对茶发酵叶色泽及茶色素含量的影响 总被引：4，自引：3，他引：1
为探究温度对发酵外形、汤色指标和品质成分的影响,并获得快速判别发酵适度的指标,该文以福鼎大白茶品种鲜叶为原料,设置25、30、35、40℃等4个发酵温度,首次检测在制品外形L值(亮度)、a值(红度)、b值(黄度)和△E值(总色差),汤色LC值(总汤色值)、LL值(汤色透亮度)、La值(汤色红度)和Lb值(汤色黄度)等色泽属性,以及TFs(茶黄素)、TRs(茶红素)和TBs(茶褐素)等品质成分的动态变化,建立3类指标的相关性。结果表明,发酵的进行会导致外形色泽L值、b值的下降,a值的增加,汤色LC值、La值和Lb值的先升后降,LL值的下降,各色泽属性的剧变期均发生在前90 min;不同温度比较,低温(25或30℃)有利于外形亮度L值、外形黄度b值、总汤色LC值、汤色黄度Lb值和汤色红度La的值的稳定,高温(35℃)有利于外形红度a值和汤色透亮度LL值的增加。品质成分TFs和TRs均呈先增后降的趋势,然茶红素峰值点出现时间晚于茶黄素,整体上以25℃发酵有利于TFs的形成和累积,而30℃发酵有利于TRs累积。相关性分析表明,TFs和TRs均与TFRB(茶黄素和茶红素之和与茶褐素的比值)呈极显著正相关,TFRB值较TFR值(茶红素与茶黄素的比值)更可有效代表茶黄素和茶红素在叶内的贡献表征;外形色泽属性与汤色色泽属性间呈极显著相关性,TFs与L值、b值、Lb值呈极显著正相关,与LC值、La值呈显著正相关,TRs仅与a值和Lb值呈显著正相关。通过线性回归分析获得了以LL值、Lb值和b值为变量的茶黄素回归模型,R2达到0.804,结合回归模型和相关性结果可以看出外形黄度b值最为关键,可作为判断发酵适度和衡量茶黄素含量的关键指标。 相似文献
2.
《南方农业》2018,(34)
试验比较了不同干燥方式的沱茶原料茶在常温密封贮藏1年过程中的品质变化规律。结果表明:1)4号茶样亮度(L*值)、茶汤绿度(a*值)下降缓慢,黄度(b*值)升高较慢;2)4号茶样叶绿素含量变化平缓,茶多酚和咖啡碱减幅及氨基酸增幅虽不及5号茶样,但均显著超越其他茶样;3)1, 2, 6, 7号茶样感官品质显著降低,3, 4, 5号茶样感官品质较稳定,其中,4号茶样感官品质显著优于3, 5号茶样,日晒味显著减弱,并透有栗香,滋味更醇厚,叶底更明亮。4号茶样呈现较优的耐贮藏性能,此工艺既能提升感官品质、形成独特风味,又能替代传统沱茶原料茶加工工艺,从而提高工效和安全性能。 相似文献
3.
为研究清酒乳杆菌固态发酵鳓鱼过程中品质的变化,以促进传统发酵水产品标准化生产中品质控制水平的提高,本研究综合测定了鳓鱼发酵过程中的理化、色度和质构等常规指标,采用电子舌技术对滋味特性进行分析,对感官品质进行了人工评价,并对各指标之间的相关性进行了分析。结果表明,在鳓鱼发酵过程中,pH值先下降后上升,最小值为4.88,水分含量减少,总酸度先升高后下降,最大值为13.4 g·kg-1,氨基酸态氮(ANN)、挥发性盐基氮(TVB-N)含量增加;内聚性、硬度和咀嚼性均先上升后下降,第9天达到最大值,分别为0.6、437.4 g和217.8 g,弹性和回复性持续下降;鳓鱼色泽变化显著(P0.01),L*值先升高后下降,a*值先下降后上升,b*值持续上升,逐渐呈现黄亮的发酵色泽。基于电子舌技术的滋味特性分析表明,发酵过程中主要形成酸味、苦味、甜味和复合滋味等,而鲜味和咸味的成分较少,且构建的主成分分析模型可明显区分不同发酵时间的样本。对感官品质的人工综合评价在第9天达到最大值(72.8)。综上所述,清酒乳杆菌固态发酵过程中,发酵鳓鱼的理化、质构、色度和滋味品质存在一定关联性,各指标在发酵中期达到最佳,发酵周期以9 d为宜,这为发酵水产品加工提供了一定的理论依据。 相似文献
4.
为获得绿豆凉粉最佳冷却条件和冷却速率，本试验通过控制冰箱和恒温恒湿箱的冷却温度[冰箱（4、-10、-18℃）静冷和恒温恒湿箱（25、15、4℃）风冷]，创造绿豆凉粉不同的冷却速率，解析冷冻速率对绿豆凉粉在贮藏过程中色泽、质构、晶体结构及老化特性的影响。结果表明，不同冷却方式和冷却温度下，凉粉的冷却速率有显著差异，恒温恒湿箱4℃风冷的冷却速率最大；不同冷却速率对绿豆凉粉的色泽、质构品质和老化特性有一定的影响，冷却速率越大，制备的绿豆凉粉在贮藏期间的亮度值（L*）、硬度及老化焓值越低。同时，不同冷却速率对凉粉老化过程中晶型结构无显著影响，但对结晶度有显著影响，冷却速率越高，淀粉结晶度越低。可见，冷却速率对绿豆凉粉及其贮藏品质具有一定的影响，冷却速率越大，新鲜凉粉及其贮藏期间的品质越好。本研究结果为绿豆凉粉冷却加工工艺的制定提供了依据。 相似文献
5.
《南方农业》2017,(19)
试验比较了3个碱洗浓度洗茶鲜叶后对茶叶内含成分及品质的影响。结果表明,随着碱洗浓度的增加,鲜叶中茶多酚、咖啡碱、可溶性糖均呈增加的趋势,氨基酸、水浸出物分别呈先降后增、先增后降的趋势;成茶中,氨基酸含量呈增加,咖啡碱、水浸出物含量呈减少,茶多酚、可溶性糖含量分别呈先增后降、先降后增的趋势。色泽上,碱洗处理对鲜叶叶绿素a、b含量有所影响,但对鲜叶总叶绿素含量影响不显著,对成茶中叶绿素a、叶绿素b、总叶绿素含量均有所影响。感官品质上,碱洗鲜叶后对各审评因子的影响有所趋势,其中,碱洗浓度变化对干茶色泽影响不大,对茶叶滋味中涩味有所减缓,但香气中栗香逐渐减弱,叶底逐渐由绿变黄,综合得分对照最高。 相似文献
6.
该文分别从流变、色差、风味及脂肪酸组成等方面展开试验,旨在研究热辅助超高压技术对甜面酱感官品质等品质特性的影响。结果表明,复合甜面酱经热辅助超高压处理后,黏度降低,并随着压力增加,黏度逐渐下降。经300 MPa和400 MPa处理后的样品的黏度变化小于500 MPa处理的样品。经过加压处理后,甜面酱的色差值(ΔE)发生显著变化,棕色指数(browning index,BI)下降,但亮度(L*)和红绿色度值(a*)无显著变化(P0.05)。复合甜面酱中的挥发性风味物质以醛类、酯类为主,酯类含量在高压处理后减少。此外,400 MPa的热辅助超高压处理并没有对脂肪酸的组成和含量造成较大的影响。由此得知,400 MPa、45℃、10 min的热辅助超高压处理可以较好地保护复合甜面酱质地、色泽、风味等方面的品质。为热辅助超高压技术对复合调味酱的进一步研究及工业化生产提供了理论依据。 相似文献
7.
为明确辐照对樱桃番茄杀菌效果及其品质特性的影响,以樱桃番茄为材料,分析了樱桃番茄中大肠杆菌、沙门氏菌和李斯特氏菌3种致病菌D_(10)值,并对辐照样品在室温下贮藏0、2、4、6、8、10 d后的色泽和可溶性固形物含量进行了分析。结果表明,樱桃番茄中接种的大肠杆菌、沙门氏菌和李斯特氏菌的D_(10)值分别为0.088、0.243和0.264 kGy;辐照剂量低于2.0 kGy时对樱桃番茄在室温条件下色泽L*值、a*值、b*值及可溶性固形物含量无显著影响(P0.05)。因此,2.0 kGy可以作为樱桃番茄辐照的适宜剂量。本研究结果为降低樱桃番茄的致病微生物含量及辐照技术在保障生鲜果蔬受致病菌污染的应用提供了一定的技术支持。 相似文献
8.
9.
针对中国油梨市场油梨进口储运过程中储藏时间和品质变化难以把控及油梨损坏严重等问题,对常温常湿((25±1)℃、75%相对湿度)条件下果皮色泽、果肉硬度及感官品质指标进行测定,监测其在常温后熟过程中的内在变化规律,对色差、硬度、呼吸速率、质量损失率与果肉受喜爱程度进行皮尔逊相关性分析,利用无损检测指标色差a*值与储藏时间之间logistic方程,建立油梨后熟时间预测模型。结果表明:油梨平均单果质量随储藏时间的延长而减少,每日质量损失率和呼吸速率均呈现先增加后减少的趋势,果皮色泽在储藏时间小于3d时显著增加,其后趋于平衡,而果肉硬度表现相反的趋势,干基质量损失率、色泽(L*,a*和b*值)和硬度均与感官喜爱度呈显著相关性(P0.01)。基于色差测定的无损、快速、便捷,选取色差a*值进行预测模型的建立,色差a*值的logistic方程拟合效果较好,R2为0.993。模型的检验发现,在色差a*值4时,模型预测值与实测值有很好的线性相关性,决定系数为0.996,说明该模型在果皮色差a*值4时可以用于油梨常温后熟期的预测,研究结果可为油梨品质控制提供指导和依据。 相似文献
10.
为深入了解不同干燥方法对即食扇贝柱干燥后品质的影响,以海湾扇贝柱为原料,研究了微波干燥、真空冷冻干燥、自然干燥和烘箱干燥四种方法对即食扇贝柱理化特性和感官品质的影响。结果表明：不同干燥方法所得产品在水分活度、pH值、硬度、咀嚼性和粘聚性方面存在着显著性差异,不同干燥方法对产品的色泽（L*,a*,b*）和弹性影响均不显著;烘箱干燥产品感官品评得分8.82分,其氨基酸总量最高,微波干燥氨基酸总量最低;真空冷冻干燥后产品中必需氨基酸和呈味氨基酸含量最高,自然干燥最低。综合考虑,烘箱干燥是即食扇贝柱最适宜的干燥方法,产品感官品质较高。 相似文献
11.
Effect of microbial fermentation on content of statin, GABA, and polyphenols in Pu-Erh tea 总被引：3，自引：0，他引：3
Jeng KC Chen CS Fang YP Hou RC Chen YS 《Journal of agricultural and food chemistry》2007,55(21):8787-8792
Besides cancer prevention, the hypolipidemic effects of tea have been well studied in animals and humans. Recently, statin has been identified in Pu-erh tea extract. Clinical trials have confirmed that statin decreases the incidence of major coronary and cerebrovascular events and this may be due to its hypolipidemic and antiinflammatory effects. Since a good Pu-erh tea needs longer storage (10 years or more) of fermentation to enhance the flavor and fragrance, we screened microorganisms from two Pu-erh teas, 20 and 25 years old. Species of fungi and bacteria strains that contributed to a good taste of Pu-erh tea were isolated. The effect of fermentation was investigated by inoculating fresh tea leaves with individual strains of isolated microorganisms. Results showed that statin, total polyphenol content, and the scavenging activities of alpha,alpha-diphenyl-beta-picrylhydrazyl (DPPH) radicals increased during fermentation. Tea leaves inoculated with Streptomyces bacillaris strain R9 had the highest polyphenol content (3.3 mg/100 g) and scavenging ability to DPPH radicals (92%). Streptomyces cinereus strain Y11 was equally good for polyphenol content but yielded the highest amount of statin (1012 ng/g) after 42 days of fermentation. Interestingly, the statin content of fresh tea leaves fermented with strain R9 or Y11 after 180 days was much higher (4- and 8-fold, respectively) than that of the 25-year-old Pu-erh tea (513 ng/g) as measured by the HPLC method. Similarly, these two strains also increased the content of gamma-aminobutyric acid (GABA) 5.7- and 4.7-fold in tea fermented for 180 days as compared with the fresh leaves (1270 microg/g) and that were higher than that of the Pu-erh tea (4900 microg/g). Taken together, the present results indicate that tea short-term fermented with S. bacillaris or S. cinereus enhances the color and content of statin, GABA, and polyphenols. 相似文献
12.
Pu-erh tea, a well-known traditional beverage in China, has attracted more attention because of its beneficial health effects and special flavor and taste. Generally, it is believed that Pu-erh tea with a longer preservation period has better quality and taste. Antioxidant activity is one of the major beneficial activities of tea. In this study, a HPLC-DAD-MS coupled with 2,2'-azinobis (3-ethylbenzthiazolinesulfonic acid) diammonium salt (ABTS) assay was employed for identification and quantification of free radical scavengers in different samples of Pu-erh tea. Among 12 main peaks detected in Pu-erh raw tea, 11 compounds were identified as gallic acid, (-)-gallocatechin, (-)-epigallocatechin, (+)-catechin, caffeine, (-)-epicatechin, (-)-epigallocatechingallate, rutin, (-)-epicatechingallate, quercetin-3-glucoside, and kaempferol-3-glucoside by comparison of their UV and MS data with standard compounds or literature data, respectively. The contents of 12 investigated compounds were also determined or estimated using caffeine, (-)-epicatechin, or rutin as standard. ABTS assay showed that 10 out of 12 compounds were free radical scavengers. Their total amount was used as the marker for evaluation of free radical scavenging activities of different Pu-erh teas, which indicated that the activity of different Pu-erh teas varied; Pu-erh raw tea was stronger than the ripe one, and the activity decreased with the increase of preservation period. 相似文献
13.
为了揭示茶叶籽贮藏时间对发酵法茶叶籽毛油产率与质量的影响,每2周从贮藏的茶叶籽中取样,利用茶叶籽油发酵法生产工艺进行茶叶籽毛油生产,并对工艺中各项剩余物的含油量及毛油的重要质量指标进行了测定,结果如下。室温条件下,茶叶籽贮藏47周后,毛油产率下降了23.5%、酸值及过氧化值分别升高了44.88%及69.4%,毛油色泽基本没有变化。滤渣、发酵沉淀的质量分别升高了20.27%及23.35%;淀粉、油渣质量分别降低了6.13%及3.64%。滤渣、发酵沉淀、淀粉及油渣含油率分别升高了15.63%、22.77%、206%及12.88%。发酵沉淀质量对毛油产率的影响是正向的,淀粉、油渣及滤渣质量对毛油产率的影响是负向的;发酵沉淀及滤渣含油率对毛油产率的影响是正向的,淀粉及油渣含油量对毛油产率的影响是负向的,影响大小的排序为:油渣淀粉滤渣发酵沉淀。综合分析表明,滤渣是通过滤渣质量的增加导致毛油产率随贮藏时间下降的,其下降作用的贡献占全部下降因素的79.28%。贮藏47周后的茶叶籽仁,利用发酵法生产工艺仍然具有毛油生产价值。该研究可为茶叶籽油合理生产提供理论支撑。 相似文献
14.
Sun B Neves AC Fernandes TA Fernandes AL Mateus N De Freitas V Leandro C Spranger MI 《Journal of agricultural and food chemistry》2011,59(12):6550-6557
The objective of this work was to study the evolution of the phenolic composition of red wine during vinification and storage and its relationship with some sensory properties (astringency and bitterness) and antioxidant activities. Thus, red wine was made by a classic vinification method with Castela?o and Tinta Miu?da grapes (Vitis vinifera L.) harvested at maturity (3:2; w/w). Samples were taken at 2 and 7 days of maceration, at second racking, at the time of bottling and at 6 and 14 months after bottling. The total polyphenols extract (TPx) in each sample was isolated by column chromatography. The phenolic composition (anthocyanins and proanthocyanidins), in vitro antioxidant activity, and sensory property (astringency, bitterness) of the isolated TPx from different winemaking stages were evaluated through high-performance liquid chromatography-diode array detection, 1,1-diphenyl-2-picrylhidrazyl radical test, ferric reducing antioxidant power assay, total phenolic index, MWI (polyphenol molecular weight index), TSA (tannin specific activity), and sensory panel tasting. The results showed that the phenolic composition of red wine varied significantly during winemaking. The intensity of astringency (IA) and the intensity bitterness (IB) of the isolated TPx from different winemaking stages increased from 2 days of maceration until second racking and then decreased. Furthermore, MWI and TSA are positively correlated with IA and IB. The in vitro antioxidant activity of the isolated TPx from different winemaking stages maintained unchanged after alcoholic fermentation, which was independent of the variation of phenolic composition and sensory properties. 相似文献
15.
在啤酒酿造工艺的煮沸和主发酵阶段分别添加乌龙茶,探讨茶叶不同添加方式对啤酒理化特性、抗氧化能力、啤酒贮存稳定性以及感官特性的影响。结果显示,与未添加茶叶的啤酒产品(对照组CG)相比,在煮沸阶段(煮沸添加组BG)和主发酵阶段(主发酵添加组MG)分别添加0.3g/L的茶叶均提高了酵母发酵速率;添加茶叶的两个茶啤酒产品(煮沸添加组和主发酵添加组)的DPPH自由基清除能力分别提升至82.74%和89.21%、ABTS+自由基清除能力分别提升至41.53%和51.49%、铁离子还原能力分别提升至36.49和43.83 mg/L,且成品茶啤酒贮藏期间的抗老化能力提高;茶啤酒中总酚以及儿茶素(EGC、C、EGCG、EC、GCG、ECG)和咖啡碱(CAF)含量升高,其中,主发酵添加组茶啤酒样品总酚和EGCG含量显著高于对照组和煮沸添加组啤酒(P0.05),分别达到734.40和8.43 mg/L。进一步的感官品评结果显示添加茶叶提高了啤酒产品的茶香气和茶滋味,其中主发酵添加组啤酒的茶香气、茶滋味及酒体协调性最好。由此可知,在啤酒酿造工艺中添加茶叶提高了酵母发酵速率,增强了啤酒中酚类物质含量及其抗氧化和抗老化性能,同时也为啤酒增添了新的茶风味产品。 相似文献
16.
17.
发酵是红茶加工过程中关键的一道工序,对红茶的品质形成有着重要影响。该研究以大叶种英德红茶中的英红九号为研究对象,试验收集了204份不同发酵时间的红茶样品并使用便携式近红外光谱仪和工业相机获取红茶发酵中的信息,基于近红外光谱数据、图像数据和数据融合策略分别建立了红茶发酵程度判别模型。通过分析茶多酚和儿茶素类含量的变化,将红茶的发酵划分为3个阶段,即发酵不足、发酵适度和发酵过度。采用Savitzky-Golay光滑对原始光谱进行预处理,利用竞争自适应重加权采样（Competitive Adaptive Reweighted Sampling, CARS）、连续投影算法（Successive Projections Algorithm, SPA）和主成分分析（Principal Components Analysis, PCA）对近红外光谱变量进行降维处理;相应地,图像进行去阴影后提取了9个颜色特征变量,采用皮尔森（Pearson）相关分析和主成分分析进行特征变量提取。最后采用线性判别分析（Linear Discriminant Analysis, LDA）和支持向量机（Support Ve... 相似文献
18.
为了有效开发利用枸杞子资源,进一步提高枸杞子附加值,该文以新鲜枸杞子为原料,在传统干制工艺的基础上,基于美拉德反应原理,开发熟化枸杞子新产品,并对其活性进行检测。研究结果表明,熟化枸杞子三段式干制工艺为:干制预处理阶段温度为60℃,时间为12 h;熟化阶段温度为80℃,时间为24 h,相对湿度65%;定型阶段温度45℃,干制6 h即可。制备的熟化枸杞子为黑褐色、酸甜适口、抗氧化活性显著高于(P0.05)普通干制枸杞子,其总还原能力、羟自由基清除能力、DPPH自由基清除能力分别是普通干制枸杞子的1.87倍、1.45倍和2.21倍,是一种较好的抗氧化食品,枸杞子的附加值得到了有效提高,并且该熟化枸杞子的制备工艺简单、成果易转化,具有很好的应用前景。 相似文献
19.
Pu-erh tea is a popular beverage in southwestern China and South Asian countries. To explain the differences of aged pu-erh tea and ripened pu-erh tea, the chemical constituents of these teas were identified by HPLC-DAD-ESI-MS(n). In addition, HPLC was used to determine the contents of the major polyphenols, gallic acid, caffeine, and theobromine, in various types of teas. These results showed that the majority of chemical constituents in ripened pu-erh tea and aged pu-erh tea were similar, but the contents of catechins and gallic acid presented significant differences between these two teas. After fermentation by microorganism, the levels of catechins in ripened pu-erh tea were decreased, but the contents of gallic acid and caffeine were conversely elevated compared with aged pu-erh tea. 相似文献