3种2-丁烯醛类食用香料的稳定性研究

为研究2-丁烯醛类食用香料在不同储存条件下的稳定性,采用气相色谱-质谱联用仪考察了储存温度、相对湿度和顶空气体中氧气的体积分数对反-2-甲基-2-丁烯醛、3-甲基-2-丁烯醛和2-苯基-2-丁烯醛在储存过程中稳定性影响。结果表明,在考察的3种因素中对2-丁烯醛类食用香料的稳定性影响由大到小依次为顶空气体中氧气的体积分数、储存温度和相对湿度。装有2-丁烯醛类香料的容器顶空中含有空气时,在室温下储存20周,其含量降到90%左右。为了保证2-丁烯醛类香料的质量,包装打开后建议在12周内用完;这类香料不耐高温,在调配耐高温香精时应该少量使用。为确定3种2-丁烯醛在储存过程中生成的新物质,采用质谱和两种不同极性色谱柱上的保留指数对生成的新物质进行了初步定性。结果表明:反-2-甲基-2-丁烯醛和3-甲基-2-丁烯醛容易被氧化生成反-2-甲基-2-丁烯酸和3-甲基-2-丁烯酸,而2-苯基-2-丁烯醛在储存过程中产生的主要物质是2-甲基-3-苯基-2-丙烯酸和苯丙酮。这类香料应该保存在低温和惰性氛围中。     

花香型红茶加工过程中香气成分变化分析

为了解花香型红茶的香气成分在加工过程中的变化,本研究以黄山群体种一芽二、三叶的茶鲜叶为材料,通过传统加工工艺制得普通工夫红茶,通过萎凋、摇青、揉捻、发酵、干燥的制作工序,制得花香型红茶。利用顶空固相微萃取法和气相色谱-质谱联用仪分析其香气成分及组成比例,并探讨其变化规律。结果表明：花香型红茶与普通工夫红茶在香叶醇、水杨酸甲酯、α-毕橙茄醇、香叶基丙酮等成分上存在显著区别,其中水杨酸甲酯、反-2-己烯基己酸等在摇青叶中大量生成,苯甲醛、香叶醇等在发酵阶段相对含量大量增加,3,7-二甲基-1,5,7-辛三烯-3-醇、反,反-2,4-壬二烯醛、（Z）-己酸-3-己烯酯等在成品茶干燥阶段相对含量增加;在花香型红茶的加工过程中,反-2-辛烯醛、苯乙醛等物质的相对含量发生了较大变化,反,反-2,4-壬二烯醛、反-2,4-癸二烯醛、（Z）-己酸-3-己烯酯、反-2-己烯基己酸等物质相对含量逐渐升高,香叶醇、水杨酸甲酯、α-毕橙茄醇等物质相对含量逐渐降低。     

超声对花色苷稳定性的影响及其降解动力学

为研究超声对花色苷稳定性影响规律及其降解动力学,采用单因素试验在超声提取模拟体系中研究4 种因 素（功率密度、温度、溶剂、pH值）对5 种常见花色苷稳定性的影响规律,采用试错法分析花色苷超声降解动力 学,并结合液相色谱-质谱联用技术分析超声处理后的降解产物。结果表明：随着温度的升高,花色苷在超声处理 下的降解率下降;5 种花色苷在体积分数70%乙醇溶液中降解最少;pH 1～5范围内,花色苷降解率呈先增加后减 少趋势。飞燕草素-3-葡萄糖苷的超声降解符合一级动力学模型,矢车菊素-3-葡萄糖苷、天竺葵素-3-葡萄糖苷、锦 葵素-3-葡萄糖苷、芍药素-3-葡萄糖苷的超声降解符合零级动力学模型。在天竺葵素-3-葡萄糖苷、锦葵素-3-葡萄糖 苷、芍药素-3-葡萄糖苷、矢车菊素-3-葡萄糖苷的降解产物中都检测到8-β-D-吡喃葡萄糖基-2,4-二羟基-6-氧代环己 基-2,4-二烯基乙酸,同时也检测到山柰酚、槲皮素、丁香酸、阿魏酸、2,6-二甲氧基苯酚等。     

花椒羟基-α-山椒素在紫外照射下的降解动力学及其转化机理研究

为了研究花椒中典型酰胺类物质羟基-α-山椒素在紫外照射下的变化趋势及转化方向,从花椒油中提取、分离、纯化得到羟基-α-山椒素,对其进行紫外照射处理,利用HPLC法测定不同照射时间各物质的含量。结果表明,羟基-α-山椒素在紫外照射下迅速减少,8h后减少了95.9%,浓度与时间满足一级反应速率方程C=490.68e~(-0.346 9t),且转化为其同分异构体羟基-ε-山椒素,使羟基-ε-山椒素含量在3h后升高至初始含量的8.56倍,而羟基-β-山椒素在照射过程中持续减少,说明紫外照射对花椒及其制品的麻味有很大的影响。     

不同贮藏温度对冰淇淋品质及保质期的影响研究

通过测定产品在-12、-15、-18、-22℃及波动温度贮藏时的融化率、水分丢失和体积收缩的变化,对不同贮藏温度对冰淇淋品质的影响进行了研究。在此基础上结合Arrhenius关系式和Q10模型,选取-2、-5、-8℃进行加速试验,测定产品加速贮藏过程中水分丢失的变化,预测产品货架期。结果表明,贮藏期间冰淇淋的抗融性下降,表面水分丢失严重,且在恒温贮藏时出现严重的体积收缩。冰淇淋在-12、-15、-18、-22℃贮藏的货架期分别为45、79、233、601 d。     

4-甲基-4-烷硫基-2-戊酮类化合物的合成研究

对4-甲基-4-烷硫基-2-戊酮类化合物的合成与香气特征进行了研究。具体方法是:在四氢呋喃溶剂中,4-甲基-3-戊烯-2-酮与各种硫醇在哌啶的催化作用下回流反应20h,得到5种4-甲基-4-烷硫基-2-戊酮类新型食用香料化合物,产率40.3%～65.1%,其中烷硫基分别为乙硫基、丙硫基、丁硫基、己硫基、糠硫基。4-甲基-3-戊烯-2-酮是通过丙酮醇在碘催化剂作用下加热脱水制取的。采用IR、GC-MS、1HNMR分析并确证了上述合成化合物的结构,并对其香气特征进行了描述,它们可能是潜在的食用香料。     

不同类型的碱对三氯蔗糖合成过程中氯代液中和效果的影响

蔗糖的DMF溶液与原酸酯在对甲苯磺酸的催化下生成蔗糖-4-乙酸酯和蔗糖-6-乙酸酯的混合物,在特丁胺作用下,将4-乙酸酯转换为6-乙酸酯,蔗糖-6-乙酸酯在DMF溶液中,由DMF和氯化亚砜制备的vilsmeier试剂作为氯化试剂生成的氯代液,分别用氢氧化钠的水溶液、氢氧化钾的水溶液、氨水、三乙胺进行后处理.通过中和后溶...     

2-甲基-2-苯基-1,3-二硫环庚烷的合成及香气研究

以硫代硫酸钠、1,4-二氯丁烷和苯甲醛为原料,用BunteSalts法,经过一步操作合成了2-甲基-2-苯基-1,3-二硫环庚烷,其收率为60%。实验表明,当1,4-二氯丁烷与硫代硫酸钠以等摩尔投料时,可减少盐酸用量,并能避免单质硫的析出而影响分离提纯。用IR、1HNMR、MS证实了目标化合物结构,并对2-甲基-2-苯基-1,3-二硫环庚烷的香气进行了鉴定,结果表明2-甲基-2-苯基-1,3-二硫环庚烷具有浓郁的葱蒜气味,其阈值在水中为0.24×10-6,在植物油中为15.00×10-6。     

相溶解度法研究环糊精对二氢黄酮苷的增溶作用

采用相溶解度法,在不同温度下测定二氢黄酮苷在不同浓度的β-环糊精、α-环糊精、γ-环糊精、甲基-β-环糊精、羟乙基-β-环糊精、2-羟丙基-β-环糊精、麦芽糖基-β-环糊精溶液中的溶解度,绘制相溶解度曲线,研究环糊精对二氢黄酮苷的增溶作用及包合过程中的热力学参数变化。结果表明,随着环糊精浓度的增加,二氢黄酮苷的溶解度随之增大,相溶解度曲线为AL型,说明二氢黄酮苷与环糊精1∶1包合。7种环糊精均对二氢黄酮苷有增溶作用,增溶顺序为甲基-β-环糊精羟乙基-β-环糊精 2-羟丙基-β-环糊精β-环糊精麦芽糖基-β-环糊精γ-环糊精α-环糊精。     

低温贮藏条件下青鱼肉中蛋白和组织结构的变化对鱼肉品质的影响

采用低场核磁共振技术、差示扫描量热法和组织切片等方法,研究了贮藏温度(4、-0.5、-3和-20℃)对青鱼肉中水分和蛋白变化及其青鱼肉品质的影响。差示扫描量热法测定结果显示:在4和-0.5℃下主要是肌浆蛋白发生变化,而在-3和-20℃下主要是肌球蛋白结构发生改变。组织切片结果显示:在4和-0.5℃条件下鱼肉肌纤维结构相对完整,而在-3和-20℃条件下受冰晶影响,鱼肉肌纤维结构破坏严重。低场核磁共振结果同差示扫描量热法测定结果和组织切片结果一致,在4和-0.5℃条件下青鱼肉中水分分部状态稳定,不易流动水变化缓慢,而在-3和-20℃条件下水分分布状态变化明显,其中不易流动水变化最明显。与此对应,汁液流失率在4和-0.5℃条件下较低,而在-3和-20℃条件下较高。鱼肉剪切力在-0.5和-3℃下逐步下降,而在4和-20℃下,前3天变化迅速,随后变化缓慢。不同贮藏温度下,青鱼肉中蛋白和组织结构的变化会影响鱼肉中水分的分布状态,进而导致鱼肉汁液流失率和质构的变化呈现出不同的趋势。     

The effect of nutrition on intestinal flora

In several groups of probands the influence of nutrition on the gut flora has been examined. In old people there is a striking decrease in the numbers of Bifidobacteria whereas those of Clostridium perfringens strongly increase and those of Enterobacteriaceae and Lactobacilli can be found somewhat higher than in the compared group. In a group of longevitial old aged men nourished with a fibre-rich diet these alterations are found less striking. Changing from a mixed Japanese diet to a "western diet" a tendentious decrease in the total number of bacteria and in the numbers of Bifidobacteria, Eubacteria, and in moderate, in the numbers of Streptococci, too, could be determined. Simultaneously, a considerable development of nitrosamines occurred. In C3H/Hemice a glucomannan containing (fibre-rich) diet caused a substantial increase in the evidence frequency of Bifidobacterium and in the numbers of Enterobacteriaceae. Parallel with these results incidence and average number of noduli of manifested hepatic carcinoma decreased remarkably.     

Effect of adrenocorticotrophic hormone on the development of oestrogen-induced changes and hyperplasia formation in the mouse uterus

The aim of this study was to examine the role of adrenocorticotrophic hormone (ACTH) in proliferative and morphogenetic reactions in the uterus under continuous oestrogen treatment. Ovariectomized mice received injections of oestradiol dipropionate or vehicle once a week (2 microg per 100 g), and injections of ACTH (10 microg per 100 g) once a day or once a week for 30 days. Additional control mice received oestradiol and saline, vehicle of oestradiol, and ACTH once a day or once a week, or vehicle of ACTH, for 30 days. This study shows for the first time that ACTH affects oestrogen-dependent reactions in the uterus. Treatment with ACTH once a day resulted in a decrease in uterine mass, in cell proliferation (assessed by the number of mitotic and bromodeoxyuridine (BrdU)-labelled cells) and in the incidence of endometrial hyperplasia, in particular complex and atypical hyperplasia. Treatment with ACTH once a week led to a marked reduction in the incidence of endometrial hyperplasia, a slight increase in uterine mass and had almost no effect on cell proliferation. Daily treatment with ACTH reduced the concentration of oestrogen receptor alpha in all uterine compartments, but weekly ACTH administration had the opposite effect. Expression of glucocorticoid receptors, beta-catenin and glycogen synthase kinase-3beta in uterine tissues was lower in animals treated with oestradiol and ACTH once a day or once a week. When olive oil was used instead of oestradiol, treatments with ACTH did not produce detectable changes in all parameters examined. Thus, glucocorticoid receptor, oestrogen receptor alpha, beta-catenin and glycogen synthase kinase-3beta are involved in the effects of ACTH on oestrogen-induced changes in uterine mass, cell proliferation and the incidence of hyperplasia.     

Chicory inulin does not increase stool weight or speed up intestinal transit time in healthy male subjects

Inulin is a non-digestible oligosaccharide classified as a prebiotic, a substrate that promotes the growth of certain beneficial microorganisms in the gut. We examined the effect of a 20 g day(-1) supplement of chicory inulin on stool weight, intestinal transit time, stool frequency and consistency, selected intestinal microorganisms and enzymes, fecal pH, short chain fatty acids and ammonia produced as by-products of bacterial fermentation. Twelve healthy male volunteers consumed a well-defined, controlled diet with and without a 20 g day(-1) supplement of chicory inulin (degree of polymerization (DP) ranging for 2-60), with each treatment lasting for 3 weeks in a randomized, double-blind crossover trial. Inulin was consumed in a low fat ice cream. No differences were found in flavor or appeal between the control and inulin-containing ice creams. Inulin consumption resulted in a significant increase in total anaerobes and Lactobacillus species and a significant decrease in ammonia levels and β-glucuronidase activity. Flatulence increased significantly with the inulin treatment. No other significant differences were found in bowel function with the addition of inulin to the diet. Thus, inulin is easily incorporated into a food product and has no negative effects on food acceptability. Twenty grams of inulin was well tolerated, but had minimal effects on measures of laxation in healthy, human subjects.     

Heterogeneity of subunit composition in lupin globulins. Comparison of proteins from a single seed and from a number of seeds

The subunit compositions of a legumin-like (globulin 8) and a vicilin-like protein (globulin 4) extracted from a plurality of seeds and from a single seed both in commercial and in a selected cultivar of Lupinus albus were studied. In the case of globulin 4, a very similar number of bands were observed in SDS-PAGE, in the protein extracted from a batch of seed and in the same globulin isolated from a single seed. For globulin 8 the SDS-PAGE pattern showed fewer subunits in the protein from the batch of seeds than in that from a single seed. This is more pronounced in the single seed and in the plurality of seeds of a selected cultivar. Reasons for this behaviour are discussed.     

Expression of Col1a1, Col1a2 and procollagen I in germ cells of immature and adult mouse testis

The objective of this study was to compare the expression of Col1a1, Col1a2, and procollagen I in the seminiferous tubules of immature and adult mice and to characterize the cellular expression pattern of procollagen I in germ cells during spermatogenesis in order to provide necessary groundwork for further functional studies in the process of spermatogenesis. Microarray analysis demonstrated that Col1a1 and Col1a2 were abundantly expressed in the seminiferous tubules of 6-day-old mice compared with 60-day-old mice, and the expression levels of Col1a1 and Col1a2 mRNA were validated using a semi-quantitative RT-PCR assay. Western blot analysis further confirmed that procollagen I was expressed at a higher level in the seminiferous tubules of 6-day-old mice compared with 60-day-old mice. Immunohistochemical analysis revealed that type A spermatogonia were positive for procollagen I in the testis of 6-day-old mice, whereas Sertoli cells were negative for this protein. The in vivo procollagen I staining in type A spermatogonia was corroborated in spermatogonia exhibiting a high potential for proliferation and the ability to form germ cell colonies in in vitro culture. Moreover, procollagen I was also detected in type A spermatogonia, intermediate spermatogonia, type B spermatogonia, and preleptotene spermatocytes in the adult mouse testes, but positive staining disappeared in more differentiated germ cell lineages detaching from the basement membrane, including leptotene spermatocytes, pachytene spermatocytes, round spermatids and elongated spermatids. These data suggest that Col1a1, Col1a2 and procollagen I are associated with type A spermatogonia and play a potential role in mediating the detachment and migration of germ cells during spermatogenesis.     

Increasing access to smoking cessation treatment in a low-income, HIV-positive population: the feasibility of using cellular telephones.

This study examined the feasibility of using cellular telephones to improve access to smoking cessation counseling in a low-income, HIV-positive population. Two pilot studies were conducted: (a). A survey of interest and barriers in participating in a smoking cessation intervention (n=49) and (b). a cellular telephone smoking cessation intervention in which participants were provided with free cellular telephones and received six telephone counseling sessions over a 2-week period (n=20). A primary care clinic serving a multiethnic, medically indigent, HIV-positive population served as the setting. Demographics and smoking status were assessed by self-report and expired-air carbon monoxide testing. In study 1, participants reported multiple barriers to participating in a smoking cessation intervention, including transportation, transience, and telephone availability. However, they also reported a high level of interest in participating in a smoking cessation intervention, with the greatest interest in a cellular telephone intervention. In study 2, 19 of the 20 participants successfully completed 2 weeks of smoking cessation counseling with a 93% (106 of 114 calls) contact rate. A total of 19 participants made a quit attempt, and the 2-week end of treatment point-prevalence abstinence rate was 75%. The provision of cellular telephones allowed for the implementation of a proactive telephone smoking cessation intervention providing an underserved population with access to care. Cellular telephones also may provide unique benefits because of the intensity of counseling and support provided as well as the ability to provide counseling in real-world, real-time situations (in vivo counseling).     

Myosin filament depolymerizes in a low ionic strength solution containing l-histidine

Myosin, one of the major myofibrillar proteins, forms a filamentous polymer and is insoluble in physiological and low ionic strength solutions. We have shown that myosin is soluble in a low ionic strength solution containing l-histidine. In this study, to clarify the role of l-histidine in the solubilization of myosin, we investigated effects of l-histidine on the filament formation and the morphology of myosin at a low ionic strength. In the presence of l-histidine, myosin formed a filamentous polymer in a physiological ionic strength solution and dispersed in a low ionic strength solution. Transmission electron microscopy showed that light meromyosin (LMM), the rod region of myosin, in a low ionic strength solution containing l-histidine was longer than that in a high ionic strength solution without l-histidine. l-histidine causes the elongation of LMM region of myosin contributing to the weakening of the myosin filament and the dissociation of myosin in a low ionic strength solution.     

Vitamins in brewing: effects of post‐fermentation treatments and exposure and maturation on the thiamine and riboflavin vitamer content of beer

Post‐fermentation processes and maturation are important steps in beer production as they help to shape the organoleptic properties and stabilize the final product. Brewers can use a variety of processing aids (e.g. isinglass, PVPP, etc.) and processes (e.g. pasteurization, bottle conditioning, etc.) to achieve a desired final product with a desirable shelf life; however, these processes can have detrimental effects on the vitamin content of the beer. This research found that heat treatments have a marked influence on the decrease in the thiamine diphosphate vitamer, while PVPP and silica treatments have a greater influence on the decrease in riboflavin vitamers. Refrigeration, filtration or centrifugation have no, or only very limited, influence on thiamine or riboflavin vitamers, while application of isinglass, bentonite, tannic acid and SO₂ causes a decrease in both thiamine and riboflavin vitamers. Storage of beer at refrigerated temperatures appears to provide protection against significant degradation of both thiamine and riboflavin vitamers; however, storage of filtered beer at elevated temperatures shows a decrease in thiamine diphosphate and riboflavin. Storage of bottle‐conditioned beer at elevated temperatures shows a marked decrease in yeast viability, accompanied by a decrease in thiamine diphosphate and free riboflavin, and a marked increase in free thiamine. These findings provide an insight into the reason why there is a significant variation in the vitamer content of beers, even within a single beer style. Copyright © 2016 The Institute of Brewing & Distilling     

A combined approach in characterization of an effective w/o hand cream: the influence of emollient on textural, sensorial and in vivo skin performance

To formulate a consumer-acceptable cosmetic product, numerous demands have to be fulfilled, and as the most important, efficacy (both real and perceived), adequate aesthetic (visual perception) and all sensorial characteristics have to be achieved. In this study, four model water-in-oil creams intended for hand care, varying in one emollient component, were submitted to rheological, sensory and textural characterization, and their efficacy was evaluated in in vivo study on human volunteers. Our results indicate that certain alteration restricted to the oil phase induced a change in all investigated characteristics, showing that each instrumental measurement can be used as a sensitive tool in the characterization of cream samples. Regarding the correlation between physical measurements and certain sensory attributes, it is possible to formulate a product with specific sensory characteristics by using pre-defined rheological or textural parameters. To obtain a complete sensory profile of a cosmetic product, a detailed sensory evaluation should be carried out according to the existing standard practices, which are both time- and money-consuming. However, a modified sensory study could be useful for fast in-line screening along with instrumental characterization of a novel cosmetic emulsion product and could be particularly helpful in the process of distinguishing a single formulation from several differing in one component.