不同提取方法黑米花青素的稳定性研究

比较以浸提、超声波及微波辅助的最佳提取工艺法提取出来的黑米花青素在7种不同因素影响下花青素的稳定性差异。测定不同温度、pH、光照强度、金属离子、氧化剂、还原剂及食品添加剂等因素对花青素稳定性的影响,观察黑米花青素溶液的颜色变化趋势,并测定其中花青素含量,以比较这3种提取方法对花青素的稳定性影响。结果表明,微波法提取的花青素稳定性最强,而超声波法提取花青素的效率最高,但稳定性最弱,浸提法提取的花青素稳定性介于二者之间,但提取率最低。     

环境因素和添加物对紫苏花青素稳定性的影响

采用酸化乙醇法提取紫苏花青素并测定多种环境因素和添加物对其稳定性的影响。结果表明,酸性(pH=3～4)、避光、低温条件有利于紫苏花青素溶液稳定保存。氧化剂(H2O2)对紫苏花青素稳定性的破坏作用随H2O2浓度升高而增加。还原剂VC、蔗糖和NaCl溶液浓度分别为3%,15%和7%时,对保持紫苏花青素溶液稳定性效果最好;Fe3+和Cu2+离子对紫苏花青素降解作用较大,而Al3+、Mg2+和Zn2+对紫苏花青素降解具有一定的保护作用。     

茄子皮红色素稳定性研究

以茄子皮为原料,采用微波辅助法提取红色素,研究了pH值、光照、加热条件以及食品添加剂对茄子皮红色素的稳定性的影响.实验结果表明茄子皮红色素水溶性好,在酸性溶液中稳定,对光有一定耐受性,但对热的稳定性较差.氧化剂、还原剂以及金属离子对茄子皮红色素稳定性均有不同的影响.     

紫薯花青素的提取及稳定性比较研究

采用有机溶剂浸提法、超声波辅助法和微波辅助法提取紫薯花青素,并对温度、酸碱度、氧化剂、还原剂、金属离子、光照强度、食品添加剂等7种不同因素对所提取的紫薯花青素进行稳定性综合评价。结果表明,超声波法提取紫薯花青素含量最高,微波法居中,浸提法最低;从稳定性来看,微波法提取的紫薯花青素热稳定性效果最佳,超声波法提取的紫薯花青素对其他干扰因素稳定性最佳。     

金属离子对紫甘蓝花青素颜色稳定性的影响

以紫甘蓝花青素水提液为研究对象,以CIELAB色空间为研究方法,以△E*,a*,b*值为评价指标,测定添加不同种类、浓度的金属离子后紫甘蓝花青素水提液的颜色变化情况,探讨了不同金属离子对紫甘蓝花青素水提液稳定性的影响。结果表明:Na~+,Mg~(2+),K~+,Ca~(2+),Zn~(2+)对紫甘蓝花青素水提液的颜色稳定性不会产生显著影响;Al~(3+)对紫甘蓝花青素水提液增色作用明显;高浓度Cu~(2+)则对紫甘蓝花青素有显著褪色作用;Fe~(3+)对紫甘蓝花青素水提液颜色稳定性的影响最大,能直接使其变色;Fe~(2+)对紫甘蓝花青素水提液也会产生一定的褪色作用。该结果可为紫甘蓝花青素的工业应用提供理论基础以及技术支持。     

红阳猕猴桃色素理化性质及其稳定性研究

本实验对红阳猕猴桃色素的理化性质和稳定性进行研究.结果表明,红阳猕猴桃色素易溶于水、酸;酸度对色素颜色影响大;色素不耐高温,紫外光稳定性好,日光稳定差;金属离子Mg2+对该红素有一定的增色作用,pb2+使色素颜色变浅,其他几种金属离子无显著影响;在强酸性条件下,色素对还原剂H2SO3有较强的耐受性,防腐剂山梨酸钾对该色素无显著影响.     

乙醇浸提与树脂吸附法从茄子皮中提取花青素

花青素属于多酚类化合物,具有较强的清除自由基和抗氧化能力。其中,飞燕草型花青素具有更强的抗氧化能力。茄子皮中色素含量较高,主要含有飞燕草型花青素。该试验先采用浓度为50%～80%的乙醇溶液作为提取剂对茄子皮浸泡得到花青素粗溶液,然后采用6种树脂分别对不同的花青素粗溶液进行纯化处理。试验结果表明当提取剂为70%乙醇溶液,吸附树脂为D113型时,得到的花青素提取率最高为1.83 mg/g。与标准样品进行比对后,确认从茄子皮中所提取到的花青素类型为飞燕草型花青素。     

雪峰蜜橘果皮色素的稳定性研究

利用CO2超临界萃取技术提取雪峰蜜橘果皮色素,用紫外可见分光光度法测定色素在不同条件下最大吸收波长处的吸光度研究色素的稳定性。结果表明,光照、时间、温度、金属离子、氧化剂对雪峰蜜橘果皮色素的稳定性有不同程度的影响,其中长时间的光照对色素稳定性影响明显,氧化剂双氧水的存在对橘皮色素的稳定性有一定影响,但0.5%、1%、2%、3%四个浓度的H2O2对同一样品色素的稳定性影响不大,该类色素有一定的抗氧化作用。同时研究发现,不同萃取条件下得到的果皮色素对光照、时间、温度、金属离子、氧化剂的稳定性不同,说明不同萃取条件下得到的果皮色素组分、含量有差异。     

定西地产“黑美人”马铃薯中花青素稳定性及抗氧化性能研究

研究了定西地产"黑美人"马铃薯中花青素的稳定性及抗氧化性能。结果表明,花青素在pH值≤3时比较稳定,随着pH值的增大,花青素的保存率不断下降。在低温及室温下,花青素较稳定,放置时间较长;但随着温度升高,其稳定性逐渐下降。另外,在低温及室温条件下,花青素避光保存时,稳定性较好,可以存放较长时间,而日光直射时,其稳定性显著下降。部分金属离子对花青素的稳定性有一定的影响。Fe2+的加入使花青素溶液的稳定性下降,而Al 3+的加入可以提高花青素溶液的吸光度值,具有增色作用,Mg2+和Ca2+对色素的破坏作用较大。食品添加剂如蔗糖、苯甲酸钠、醋酸、淀粉对花青素稳定性的影响都不大。花青素含量越高,DPPH自由基清除率越高,其抗氧化活性越强。     

葡萄籽中原花青素稳定性研究

考察了温度、pH值、金属离子、Vc、光照等因素对原花青素稳定性的影响.结果表明,温度低于50℃时,原花青素很稳定,当温度高于50℃时,稳定性随温度的升高而降低;在相同温度条件下,pH值越低,原花青素的稳定性就越高,随着pH值的升高,稳定性逐渐降低;在相同pH值条件下,温度越高,原花青素的含量下降越快.在不同pH值条件下原花青素呈现不同的颜色;金属离子中以Fe3+和Ca2+的影响最为显著,Zn2+、Ni2+、Na+离子影响较小;Vc可以提高原花青素的稳定性,且提高的效果同浓度有关;光照使原花青素发生光解变质并使其稳定性降低.     

Role of melanin and artificial hair color in preventing photo-oxidative damage to hair

This research is a multifaceted study which investigates not only the role of melanin in providing photostability to natural hair color and hair proteins, but also the claim that the presence of specific artificial colors in hair slows down the rate of photodegradation of hair proteins. In earlier studies, the extractability of protein from photodegraded hair was investigated and showed that many of the cleaved proteins could not be extracted because of photo‐oxidative cross‐linking. The current study investigates the effect of the amount of melanin in hair of different ethnicity and the presence of artificial hair colors on the extractability of the main classes of hair proteins. Furthermore, the data are used in the interpretation of the effect of these components in being able to prevent photo‐oxidative damage to hair proteins. When exposed to sunlight, hair undergoes changes in chemical, mechanical and morphological properties. The UVB and UVA regions of the solar spectrum are the most damaging to human hair. Of these two, the UVA region is predominant in the solar spectrum at low altitudes. Hair of different ethnicity responds differently to the damaging radiation of the solar spectrum, because of different amounts of melanin present in hair. Melanin absorbs the impinging radiation (especially at the lower wavelengths (254–350 nm), and converts it by some complex internal mechanism into heat. Because of this, melanin provides a photochemical protection to natural hair color and hair proteins and prevents their photodegradation. However, the melanin pigments act sacrificially and become themselves degraded in the process of protecting the proteins from light. As a result, this «protective» effect of the melanin pigments does not last during long‐term intense exposure, when, regardless of the amount of melanin in hair, most matrix, intermediate filament and high molecular weight hair proteins undergo photo‐oxidative cross‐linking into higher molecular weight species, and their extractability from hair decreases significantly. The goal of this study is to demonstrate how UV‐radiation affects natural and artificial hair color during long‐term exposures. Bright‐field and UV‐microspectrophotometry and an electrophoretic separation technique (SDS‐PAGE) were chosen as investigative techniques for these studies, because they are well‐suited to accurately and reproducibly investigate the initial properties of a specific hair sample and the changes in these properties as a result of long‐term light‐exposure. The goal of this paper is not to relate this to the content and type of melanin in hair. Electrophoresis, while not measuring the exact quantitative amount of protein extracted, is a semi‐quantitative method, where increases in brightness of the bands represent increased amounts of proteins that were extracted of that specific protein from hair. This electrophoretic study attempts to determine whether the presence of natural or artificial color in hair influences the protein extractability in unaltered hair and the photo‐oxidative cross‐linking during light‐exposure. The bright‐field microspectrophotometric study showed that high concentrations of melanin provide protection to the melanin itself and that they prevent loss of natural hair color during light‐exposure. However, neither large amounts of melanin in hair of different ethnicity, nor artificial hair colors (even a dye with an absorption in the UV region) provide protection to the hair proteins against photodegradation under the conditions used in this study. UV‐microspectrophotometry has suggested the formation of high levels of photo‐oxidized proteins as a result of light‐exposure. Electrophoresis revealed photo‐oxidative cross‐linking of most matrix, intermediate filament and high molecular weight hair proteins into their higher molecular weight analogues, rendering them less extractable due to their lowered diffusivity. Only very low levels of low molecular weight matrix proteins could be extracted.     

Anthocyanin stability studies in Tibouchina semidecandra L.

The effects of pH, storage period, temperature, light and dark conditions on the stability of anthocyanins extracted from Tibouchina semidecandra flowers of different developmental stages was evaluated. Fully formed but unopened flower bud had the highest amount of total anthocyanin extracted from fresh petals. The anthocyanin contents for all flower developmental stages were stable at pH 0.5–3.0 but the colour of the extracts faded at higher pH values. Degradation percentages of total anthocyanins in the extracts kept at 25 °C were 7–20% lower than that maintained at 31 °C. Extracts stored in darkness at 25 °C maintained their purple colour for 26 days while light exposure reduced it to an average of 10 days. The study shows that suitable storage condition for coloured anthocyanin pigments in extracted form is in acidic conditions in the dark. This implies the potential usage of coloured anthocyanins as natural food colourants and shelf life indicator for acidic foods.     

黑莓天然维生素E纯化技术研究

目的建立一种硅胶柱层析纯化黑莓种籽油中天然VE的方法。方法采用单因素实验的方法,以维生素E的含量为考察指标,对洗脱剂种类、洗脱剂配比、硅胶用量、洗脱剂用量进行优化。结果黑莓天然VE的最优纯化工艺参数为:硅胶与维生素E粗提物的质量比3?1;乙醇?正己烷(8?1,V/V)为洗脱剂,洗脱剂用量为粗提物的15倍。在此条件下,纯化物中维生素E的含量可以达到(51.5±0.530)%。结论采用硅胶柱层析方法可以有效纯化黑莓天然维生素E。     

酸浆花萼色素的提取及理化性质研究

采用不同的试剂提取酸浆花萼的天然色素，并且对色素的理化性质进行研究。结果表明：该色素在丙酮中提取效果最好，其最大吸收峰在406nm处；色素在不同温度下稳定性良好：在不同食品添加剂条件下稳定性良好：在太阳光照条件下对色素有减色作用；色素有较明显的抑菌作用。     

天然植物型抑菌剂的配制及抗菌性能评价

对豆蔻、肉桂、百里香、意大利蜡菊、贯叶连翘、甘草和迷迭香7种香辛料用无水乙醇进行提取,并测定各种提取液对大肠杆菌(Escherichia coli)、金黄色葡萄球菌(Staphyloccocus aureus)、副溶血性弧菌(Vibrio parahaemolyticus)和鼠伤寒沙门氏菌(Salmonella typhimurium)的最小抑菌浓度(minimum inhibitory concentration,MIC)。结果表明,豆蔻提取液的MIC大于0.5%(V/V),肉桂提取液对大肠杆菌和金黄色葡萄球菌的MIC为0.2%(V/V),其余香辛料提取液的MIC均为0.5%(V/V)。根据各种香辛料提取液的MIC,选择除豆蔻以外的6种香辛料作为原材料配制一种天然植物型抑菌剂,其抗菌性能评价试验表明,所配制的天然植物型抑菌剂对6种参试菌均具有显著的抑菌效果,其抑菌率达到99.99%。在对草莓的保鲜试验中,天然植物型抑菌剂显示了较好的保鲜效果,它能有效地将草莓的保鲜期从7 d之内延长至10 d。     

Stability of the Stevia‐Derived Sweetener Rebaudioside A in Solution as Affected by Ultraviolet Light Exposure

Rebaudioside A is a natural noncaloric high‐potency sweetener extracted from the leaves of Stevia rebaudiana. With rebaudioside A use increasing in foods, understanding the factors affecting its stability is necessary. This project evaluated the degradation rate constants of rebaudioside A in water, 0.1 M phosphate buffer, and 0.1 M citrate buffer at pH 3 and 7 as a function of ultraviolet (UV) light intensity (365 nm, 0 μW/cm² for dark conditions, 27 μW/cm² for low intensity, and 190 μW/cm² for high intensity) at 32.5 °C. Rebaudioside A stability was adversely affected by light exposure. The pseudo‐1st‐order degradation rate constants increased significantly (P < 0.05) with increasing light intensity in all solutions. Under dark conditions, rebaudioside A in phosphate buffers was more susceptible to breakdown than in water and citrate buffers at both pH levels. However, exposure to UV light resulted in rebaudioside A degradation occurring approximately 10 times faster in citrate than in phosphate buffers at both pH levels. The sensitivity of rebaudioside A to UV light was greater in citrate buffers than in water or phosphate buffers. The use of light‐protective packaging for beverages containing rebaudioside A will improve its stability.     

托柄菝葜果色素提取及其性质研究

以民族药托柄菝葜的成熟果实为材料,对其红色素的提取条件及理化性质进行研究.结果表明,托柄菝葜果色素提取的最佳条件为:40％vol乙醇水溶液、浸提温度60℃、浸提时间lh.托柄菝葜果色素在自然光照下稳定,但添加金属离子的色素溶液对光不稳定;色素溶液在酸性环境中呈现鲜艳的橙红色,在中性及碱性环境中变为褐绿色.VC对托柄菝葜色素具有增色作用;柠檬酸、EDTA对色素无明显影响;亚硫酸钠、高锰酸钾及苯甲酸钠对色素具有减色作用.金属离子Ca2+、Mn2+、Zn2+、K+、Na+、Fe2+、Mg2+、Cu2+、Co2+、Al3+、Pb2+等离子能减弱托柄菝葜果色素对光的稳定性;Sn2+、Fe3+影响色素稳定性.     

橄榄油、葵花籽油和米糠油的氧化稳定性

对橄榄油、葵花籽油和米糠油3种植物油进行氧化稳定性研究。选取在空气、光照、煎炸条件下,测定3种植物油的酸值(AV)、碘值(IV)和过氧化值(POV)。同时,在煎炸条件下,选取阿魏酸、番茄红素、β-胡萝卜素3种天然抗氧化剂对米糠油进行抗氧化性研究。结果表明：过氧化值和酸值在实验条件中上升顺序为煎炸＞光照＞空气,碘值的下降也具有此顺序。3种植物油酸值、碘值和过氧化值变化幅度的顺序为：葵花籽油＞米糠油＞橄榄油。3种天然抗氧化剂氧化速率变化顺序为：阿魏酸＞番茄红素＞β-胡萝卜素。     

油茶种仁总蛋白提取及双向电泳分析

以油茶种仁为实验材料,用不同方法提取油茶种仁总蛋白,同时对双向电泳条件进行了探索与优化,建立了一套适合油茶种仁总蛋白双向电泳分析的优化体系。结果表明:改良后的TCA-丙酮法可以有效提取出油茶种仁总蛋白,得到了816个蛋白点,蛋白点主要集中在等电点p H 4.0~6.0之间;选用17 cm p H 4~7 IPG胶条,优化的等电聚焦程序为250 V 0.5 h、1 000 V 2 h、8 000 V5 h、8 000 V 60 000 Vh和500 V 24 h,可获得背景清晰、分辨率较高的双向电泳图谱。     

烤烟立体育苗中不同 LED 红蓝光补光组合效果分析

为筛选合理的 LED红蓝光补光组合用于烤烟立体育苗,研究了 6种组合对烟苗的影响并从中选择 2种研究其对烟株田间生长及烟叶产质量的影响。结果表明: 1)随蓝光比例增加光照强度增强;2)红蓝光比 1:1、1:2、1:3和 1:4处理的烟苗成苗率显著高于对照处理,所育烟苗干物质积累较多;补光处理烟苗叶绿素相对含量显著高于对照,而烟苗根系活力则显著低于对照。红蓝光比 1:1和 1:4处理烟苗根系活力明显强于其他红蓝光比组合;3)补光处理烟苗移栽入大田后在伸根期生长要比对照缓慢,但进入旺长期后则生长加速,进入成熟期已与对照处理无明显差异,烟叶经济性状和烟叶化学成分与对照处理无明显差异。综上,红蓝光比1:1和 1:4两种组合均能满足立体育苗补光需要,且能提高育苗成苗率,提高烟苗叶片叶绿素含量,促进烟苗干物质积累。